WorldWideScience

Sample records for biodegradable copolymer incorporating

  1. Bioactive, mechanically favorable, and biodegradable copolymer nanocomposites for orthopedic applications.

    Science.gov (United States)

    Victor, Sunita Prem; Muthu, Jayabalan

    2014-06-01

    We report the synthesis of mechanically favorable, bioactive, and biodegradable copolymer nanocomposites for potential bone applications. The nanocomposites consist of in situ polymerized biodegradable copolyester with hydroxyapatite (HA). Biodegradable copolyesters comprise carboxy terminated poly(propylene fumarate) (CT-PPF) and poly(trimethylol propane fumarate co mannitol sebacate) (TF-Co-MS). Raman spectral imaging clearly reveals a uniform homogenous distribution of HA in the copolymer matrix. The mechanical studies reveal that improved mechanical properties formed when crosslinked with methyl methacrylate (MMA) when compared to N-vinyl pyrrolidone (NVP). The SEM micrographs of the copolymer nanocomposites reveal a serrated structure reflecting higher mechanical strength, good dispersion, and good interfacial bonding of HA in the polymer matrix. In vitro degradation of the copolymer crosslinked with MMA is relatively more than that of NVP and the degradation decreases with an increase in the amount of the HA filler. The mechanically favorable and degradable MMA based nanocomposites also have favorable bioactivity, blood compatibility, cytocompatibility and cell adhesion. The present nanocomposite is a more promising material for orthopedic applications.

  2. Biodegradation of polystyrene-graft-starch copolymers in three different types of soil.

    Science.gov (United States)

    Nikolic, Vladimir; Velickovic, Sava; Popovic, Aleksandar

    2014-01-01

    Materials based on polystyrene and starch copolymers are used in food packaging, water pollution treatment, and textile industry, and their biodegradability is a desired characteristic. In order to examine the degradation patterns of modified, biodegradable derivates of polystyrene, which may keep its excellent technical features but be more environmentally friendly at the same time, polystyrene-graft-starch biomaterials obtained by emulsion polymerization in the presence of new type of initiator/activator pair (potassium persulfate/different amines) were subjected to 6-month biodegradation by burial method in three different types of commercially available soils: soil rich in humus and soil for cactus and orchid growing. Biodegradation was monitored by mass decrease, and the highest degradation rate was achieved in soil for cactus growing (81.30%). Statistical analysis proved that microorganisms in different soil samples have different ability of biodegradation, and there is a significant negative correlation between the share of polystyrene in copolymer and degree of biodegradation. Grafting of polystyrene on starch on one hand prevents complete degradation of starch that is present (with maximal percentage of degraded starch ranging from 55 to 93%), while on the other hand there is an upper limit of share of polystyrene in the copolymer (ranging from 37 to 77%) that is preventing biodegradation of degradable part of copolymers.

  3. Weathering and Biodegradation Study on Graft Copolymer Compatibilized Hybrid Bionanocomposites of Poly(Lactic Acid)

    Science.gov (United States)

    Sajna, VP; Nayak, Sanjay K.; Mohanty, Smita

    2016-07-01

    This work reports on the influence of moisture absorption and accelerated weathering on the properties of graft copolymer compatibilized bionanocomposites of poly(lactic acid) (PLA). Moisture absorption tests were conducted for 30 days by immersing the samples in a distilled water bath at room temperature, and the amount of moisture absorbed in each time interval was measured. The rate of moisture uptake decreased by incorporation of C30B nanoclay and graft copolymer into fiber-reinforced PLA composites. Changes in the mechanical properties of composites in each time interval of moisture absorption were investigated using tensile and impact tests. Exposure to moisture caused significant drops in the mechanical properties. The morphological characterization of biocomposites during the aforementioned tests has been made using SEM, while bionanocomposites were analyzed by TEM. Further, this paper also reported the effect of accelerated weathering on the mechanical properties and the results are confirmed through SEM analysis. Biodegradation behaviors of PLA biocomposites and bionanocomposites have also been studied.

  4. Synthesis and characterization of biodegradable materials: PDLLA-(MAh-Diol)n-PDLLA copolymer

    Institute of Scientific and Technical Information of China (English)

    Jia Chen; Yuan Liang Wang; Mei Na Huang

    2007-01-01

    The novel biodegradable copolymer PDLLA-(MAH-Diol)n-PDLLA with unsaturated bond was synthesized by copolymerizing lactide and prepolymer, which was prepared by the polycondensation of maleic anhydride and poly(ethylene glycol), using ptoluene sulphonic acid as catalyst. The new copolymer has improved hydrophilicity and flexibility. The structure and properties of the novel polymers were studied by FTIR, NMR, GPC-MALLS and DSC.

  5. Biodegradation of starch–graft–polystyrene and starch–graft–poly(methacrylic acid copolymers in model river water

    Directory of Open Access Journals (Sweden)

    Nikolić Vladimir

    2013-01-01

    Full Text Available In this paper the biodegradation study of grafted copolymers of polystyrene (PS and corn starch and poly(methacrylic acid and corn starch in model river water is described. These copolymers were obtained in the presence of different amine activators. The synthesized copolymers and products of degradation were characterized by Fourier Transform Infrared Spectroscopy (FTIR and Scanning Electron Microscopy (SEM. Biodegradation was monitored by mass decrease and number of microorganisms by Koch’s method. Biodegradation of both copolymers advanced with time, poly(methacrylic acid-graft-starch copolymers completely degraded after 21 day, and polystyrene-graft-starch partially degraded (45.78-93.09 % of total mass after 27 days. Differences in the degree of biodegradation are consequences of different structure of the samples, and there is a significant negative correlation between the share of polystyrene in copolymer and degree of biodegradation. The grafting degree of PS necessary to prevent biodegradation was 54 %. Based on experimental evidence, mechanisms of both biodegradation processes are proposed, and influence of degree of starch and synthetic component of copolymers on degradation were established. [Projekat Ministarstva nauke Republike Srbije, br. 172001 i br. 172062

  6. Facile synthesis and characterization of novel biodegradable amphiphilic block copolymers bearing pendant hydroxyl groups

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Gaicen; Fan, Xiaoshan; Xu, Bingcan; Zhang, Delong; Hu, Zhiguo, E-mail: zghu@htu.cn

    2014-10-01

    Novel amphiphilic block copolymers bearing pendant hydroxyl groups polylactide-b–poly(3,3-bis(Hydroxymethyl–triazolylmethyl) oxetane)-b–polylactide (PLA-b–PHMTYO-b–PLA) were synthesized via a facile and efficient method. First, the block copolymer intermediates polylactide-b–poly(3,3-Diazidomethyloxetane)-b–polylactide (PLA-b–PBAMO-b–PLA) were synthesized through ring-opening polymerization of lactide using PBAMO as a macroinitiator. Following “Click” reaction of PLA-b–PBAMO-b–PLA with propargyl alcohol provided the targeted amphiphilic block copolymers PLA-b–PHMTYO-b–PLA with pendant hydroxyl groups. The composition and structure of prepared copolymers were characterized by {sup 1}H nuclear magnetic resonance ({sup 1}H NMR) spectroscopy, Fourier transform infrared (FT-IR) and gel permeation chromatography (GPC). The self-assembly behavior of the copolymers in water was investigated by transmission electron microscope (TEM), dynamic light scattering (DLS) and static light scattering (SLS). The results showed that the novel copolymers PLA-b–PHMTYO-b–PLA self-assembled into spherical micelles with diameters ranging from 100 nm to 200 nm in aqueous solution. These copolymers also exhibited low critical micellar concentrations (CMC: 6.9 × 10{sup −4} mg/mL and 3.9 × 10{sup −5} mg/mL, respectively). In addition, the in vitro cytotoxicity of these copolymers was determined in the presence of L929 cells. The results showed that the block copolymers PLA-b–PHMTYO-b–PLA exhibited better biocompatibility. Therefore, these well-defined copolymers are expected to find some applications in drug delivery or tissue engineering. - Highlights: • The method to synthesize PLA-b–PHMTYO-b–PLA is relatively facile and efficient. • PLA-b–PHMTYO-b–PLA self-assembles into spherical micelles with low CMC in water. • PLA-b–PHMTYO-b–PLA exhibits better biocompatibility and biodegradability.

  7. Factors influencing the biodegradability of biocomposites based on ethylene-octene copolymer (EOC) and vegetable fillers

    Science.gov (United States)

    Zykova, A. K.; Pantyukhov, P. V.; Monakhova, T. V.; Kolesnikova, N. N.; Popov, A. A.; Ramos, C. C.

    2016-11-01

    In this study the role of the content of filler, its nature (particle geometry in particular) and the type of the copolymer matrix were examined. For the study three grades of ethylene-octene copolymer were chosen. Composites were mixed in proportion from 70 to 30 wt % of the polymer matrix content. Water absorption was determined; thermal oxidative degradation was studied; and a biodegradation test on recovered soil was carried out. It was concluded that water absorption and weight loss correlate with the filler content. It was found that biocomposites with oil flax straw are more prone to water absorption and weight loss than the same ones with wood flour. The most stable matrix to oxidation was Lucene 370, then Lucene 670 and Lucene 760. Therefore, biocomposites based on Lucene 760 should be more biodegradable than others.

  8. Fungal biodegradation of lignopolystyrene graft copolymers. [Pleurotus ostreatus; Phanerochaete chrysosporium; Trametes versicolor; Gloeophyllum trabeum

    Energy Technology Data Exchange (ETDEWEB)

    Milstein, O.; Gersonde, R.; Huttermann, A. (Forstbotanisches Inst. der Univ. Gottingen (Germany)); MengJiu Chen; Meister, J.J (Univ. of Detroit Mercy, MI (United States))

    1992-10-01

    White rot basidiomycetes were able to biodegrade styrene (1-phenylethene) graft copolymers of lignin containing different proportions of lignin and polystyrene (poly(1-phenylethylene)). The biodegradation tests were run on lignin-styrene copolymerization products which contained 10.3, 32.2, and 50.4{percent} (wt/wt) lignin. The polymer samples were incubated with the white rot fungi Pleurotus ostreatus, Phanerochaete chrysosporium, and Trametes versicolor and the brown rot fungus Gloeophyllum trabeum. White rot fungi degraded the plastic samples at a rate which increased with increasing lignin content in the copolymer sample. Both polystyrene and lignin components of the copolymer were readily degraded. Polystyrene pellets were not degradable in these tests. Degradation was verified for both incubated and control samples by weight loss, quantitative UV spectrophotometric analysis of both lignin and styrene residues, scanning electron microscopy of the plastic surface, and the presence of enzymes active in degradation during incubation. Brown rot fungus did not affect any of the plastics. White rot fungi produced and secreted oxidative enzymes associated with lignin degradation in liquid media during incubation with lignin-polystyrene copolymer.

  9. Rapid synthesis of biodegradable poly(epsilon-caprolactone-co-p-dioxanone) random copolymers under microwave irradiation

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Biodegradable poly(epsilon-caprolactone-co-p-dioxanone)(PCDO) random copolymers have been synthesized by ring-opening polymerization of epsilon-caprolactone(CL) and p-dioxanone(PDO) under microwave irradiation.The effects of irradiation time and different CL/PDO molar feed ratios on the microwave-assisted ring-opening polymerization(MROP) of PCDO have been discussed.The resultant products were characterized by ~1H NMR,GPC and DSC.It was found that the polymerization was completed within 20 min at 140℃.In...

  10. Tailored protein release from biodegradable poly(ε-caprolactone-PEG)- b-poly(ε-caprolactone) multiblock-copolymer implants

    NARCIS (Netherlands)

    Stankovic, Milica; Tomar, Jasmine; Hiemstra, Christine; Steendam, Rob; Frijlink, Henderik W.; Hinrichs, Wouter L. J.

    2014-01-01

    In this study, the in vitro release of proteins from novel, biodegradable phase-separated poly(ε-caprolactone-PEG)-block-poly(ε-caprolactone), [PCL-PEG]-b-[PCL]) multiblock copolymers with different block ratios and with a low melting temperature (49-55 °C) was studied. The effect of block ratio and

  11. Controlled synthesis of biodegradable lactide polymers and copolymers using novel in situ generated or single-site stereoselective polymerization initiators

    NARCIS (Netherlands)

    Zhong, Zhiyuan; Dijkstra, Pieter J.; Feijen, Jan

    2004-01-01

    Polylactides and their copolymers are key biodegradable polymers used widely in biomedical, pharmaceutical and ecological applications. The development of synthetic pathways and catalyst/initiator systems to produce pre-designed polylactides, as well as the fundamental understanding of the polymeriz

  12. Syntheses of amphiphilic biodegradable copolymers of poly(ethyl ethylene phosphate) and poly(3-hydroxybutyrate) for drug delivery

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Biodegradable and amphiphilic triblock copolymers poly(ethyl ethylene phosphate)-poly(3-hydroxybutyrate)-poly(ethyl ethylene phosphate) (PEEP-b-PHB-b-PEEP) have been successfully synthesized through ring-opening polymerization. The structures are confirmed by gel permeation chromatography and NMR analyses. Crystallization investigated by X-ray diffraction reveals that the block copolymer with higher content of poly(ethyl ethylene phosphate) (PEEP) is more amorphous, showing decreased crystallizability. The obtained copolymers self-assemble into biodegradable nanoparticles with a coreshell micellar structure in aqueous solution, verified by the probe-based fluorescence measurements and transmission electronic microscopy (TEM) observation. The hydrophobic poly(3-hydroxybutyrate) (PHB) block serves as the core of the micelles and the micelles are stabilized by the hydrophilic PEEP block. The size and size distribution are related to the compositions of the copolymers. Paclitaxel (PTX) has been encapsulated into the micelles as a model drug and a sustained drug release from the micelles is observed. MTT assay also demonstrates that the block copolymers are biocompatible, rendering these copolymers attractive for drug delivery.

  13. Syntheses of amphiphilic biodegradable copolymers of poly(ethyl ethylene phosphate) and poly(3-hydroxybutyrate) for drug delivery

    Institute of Scientific and Technical Information of China (English)

    CHENG Jing; WANG Jun

    2009-01-01

    Biodegradable and amphiphilic triblock copolymers poly(ethyl ethylene phosphate)-poly(3-hydroxybutyrate)-poly(ethyl ethylene phosphate) (PEEP-b-PHB-b-PEEP) have been successfully synthesized through ring-opening polymerization.The structures are confirmed by gel permeation chromatography and NMR analyses.Crystallization investigated by X-ray diffraction reveals that the block copolymer with higher content of poly(ethyl ethylene phosphate) (PEEP) is more amorphous,showing decreased crystallizability.The obtained copolymers self-assemble into biodegradable nanoparticles with a coreshell micellar structure in aqueous solution,verified by the probe-based fluorescence measurements and transmission electronic microscopy (TEM) observation.The hydrophobic poly(3-hydroxybutyrate) (PHB) block serves as the core of the micelles and the micelles are stabilized by the hydrophilic PEEP block.The size and size distribution are related to the compositions of the copolymers.Paclitaxel (PTX) has been encapsulated into the micelles as a model drug and a sustained drug release from the micelles is observed.MTT assay also demonstrates that the block copolymers are biocompatible,rendering these copolymers attractive for drug delivery.

  14. Controlled synthesis of biodegradable lactide polymers and copolymers using novel in situ generated or single-site stereoselective polymerization initiators.

    Science.gov (United States)

    Zhong, Zhiyuan; Dijkstra, Pieter J; Feijen, Jan

    2004-01-01

    Polylactides and their copolymers are key biodegradable polymers used widely in biomedical, pharmaceutical and ecological applications. The development of synthetic pathways and catalyst/initiator systems to produce pre-designed polylactides, as well as the fundamental understanding of the polymerization reactions, has continuously been an important topic. Here, we will address the recent advances in the ring-opening polymerization of lactides, with an emphasis on the highly versatile in situ generated initiator systems and single-site stereoselective initiators. The in situ generated initiators including in situ formed yttrium, calcium and zinc alkoxides all have been shown to bring about a rapid and living polymerization of lactides under mild conditions, which facilitated the preparation of a variety of advanced lactide-based biomaterials. For example, well-defined di- and tri-block copolymers consisting of hydrophilic poly(ethylene glycol) blocks and hydrophobic polyester blocks, which form novel biodegradable polymersomes or biodegradable thermosensitive hydrogels, have been prepared. In the past few years, significant progress has also been made in the area of stereoselective polymerization of lactides. This new generation of initiators has enabled the production of polylactide materials with novel microstructures and/or properties, such as heterotactic (--RRSSRRSSRRSS--) polylactide, crystalline syndiotactic (--RSRSRSRSRSRS--) polylactide and isotactic stereoblock (--Rn Sn Rn Sn--) polylactide, exhibiting a high melting temperature. The recently developed polymerizations using in situ generated initiators and stereoselective polymerizations have no doubt opened a brand-new avenue for the design and exploration of polylactides and their copolymers.

  15. Synthesis of biodegradable amphiphilic Y-shaped block co-polymers via ring-opening polymerization for drug delivery.

    Science.gov (United States)

    Jia, Lin; Yan, Lifeng; Li, Yang

    2011-01-01

    A series of novel Y-shaped biodegradable block co-polymers of poly(ε-caprolactone) (PCL) and poly(ethyl ethylene phosphate) (PEEP) (PCL-(PEEP)2) were synthesized via ring-opening polymerization (ROP) of EEP with bis-hydroxy-functional ROP initiator (init-PCL-(OH)2). The init-PCL-(OH)2 was synthesized by ROP of CL using 4-hydroxybutyl acrylate (HBA) as initiator and L-tartaric acid as catalyst in bulk, and subsequently the resulting vinyl-terminated PCL was end-capped by acetyl chloride, followed by Michael addition using excess diethanolamine. The Y-shaped co-polymers and their intermediates were characterized by (1)H-, (13)C-, (31)P-NMR, FT-IR and gel-permeation chromatography. The results indicated that the molecular weight of the Y-shaped co-polymers increased with the increasing of the molar ratios of EEP to init-PCL-(OH)2 in the feed, while the PCL chain length was kept constant. The amphiphilic block co-polymers could self-assemble into micelles in aqueous solution, which was demonstrated by dynamic light scattering, (1)H-NMR and atomic force microscopy. A study of controlled release of indomethacin indicated that the amphiphilic block co-polymers could potentially provide novel vehicles for drug delivery.

  16. In situ gelling pH- and temperature-sensitive biodegradable block copolymer hydrogels for drug delivery.

    Science.gov (United States)

    Singh, Narendra K; Lee, Doo Sung

    2014-11-10

    Stimuli-sensitive injectable polymeric hydrogels have been extensively investigated during the past decade as bioactive agent delivery vehicles and for tissue engineering applications. An aqueous solution of these polymers undergoes a sol-to-gel phase transition in response to external stimuli such as pH, temperature, salt, light, biomolecules, electromagnetic field, etc. Bioactive molecules or cells can be mixed into the low-viscosity state of the polymer solution and injected into the body at a target site, forming an in situ hydrogel depot, which can then serve as bioactive-molecule-releasing carriers or a cell-growing microenvironment. This review systematically summarizes the recent progress in biodegradable and injectable block copolymer hydrogels, giving special attention to the novel and promising pH- and temperature-sensitive injectable block copolymer hydrogels for biomedical applications. The gelation mechanism, formation of ionic complexes, and biodegradation are highlighted as key factors responsible for controlled protein/drug delivery. The advantages and perspectives of pH- and temperature-sensitive injectable block copolymer hydrogels are also highlighted.

  17. Cisplatin-incorporated nanoparticles of poly(acrylic acid-co-methyl methacrylate copolymer

    Directory of Open Access Journals (Sweden)

    Lee KD

    2013-08-01

    Full Text Available Kyung Dong Lee,1,* Young-Il Jeong,2,* Da Hye Kim,3,4 Gyun-Taek Lim,2 Ki-Choon Choi5 1Department of Oriental Medicine Materials, Dongshin University, Naju, South Korea; 2Department of Polymer Engineering, Chonnam National University, Gwangju, South Korea; 3Faculty of Life and Environmental Science, Shimane University, Matsue, Japan; 4United Graduate School of Agricultural Sciences, Tottori University, Tottori, Japan; 5Grassland and Forages Division, National Institute of Animal Science, Rural Development Administration, Cheonan, South Korea *These authors contributed equally to this work Background: Although cisplatin is extensively used in the clinical field, its intrinsic toxicity limits its clinical use. We investigated nanoparticle formations of poly(acrylic acid-co-methyl methacrylate (PAA-MMA incorporating cisplatin and their antitumor activity in vitro and in vivo. Methods: Cisplatin-incorporated nanoparticles were prepared through the ion-complex formation between acrylic acid and cisplatin. The anticancer activity of cisplatin-incorporated nanoparticles was assessed with CT26 colorectal carcinoma cells. Results: Cisplatin-incorporated nanoparticles have small particle sizes of less than 200 nm with spherical shapes. Drug content was increased according to the increase of the feeding amount of cisplatin and acrylic acid content in the copolymer. The higher acrylic acid content in the copolymer induced increase of particle size and decrease of zeta potential. Cisplatin-incorporated nanoparticles showed a similar growth-inhibitory effect against CT26 tumor cells in vitro. However, cisplatin-incorporated nanoparticles showed improved antitumor activity against an animal tumor xenograft model. Conclusion: We suggest that PAA-MMA nanoparticles incorporating cisplatin are promising carriers for an antitumor drug-delivery system. Keywords: cisplatin, nanoparticle, poly(acrylic acid-co-methyl methacrylate, ion complexes

  18. Incorporation of biodegradable electrospun fibers into calcium phosphate cement for bone regeneration.

    NARCIS (Netherlands)

    Zuo, Y.; Yang, F.; Wolke, J.G.C.; Li, Yubao; Jansen, J.A.

    2010-01-01

    Inherent brittleness and slow degradation are the major drawbacks for the use of calcium phosphate cements (CPCs). To address these issues, biodegradable ultrafine fibers were incorporated into the CPC in this study. Four types of fibers made of poly(epsilon-caprolactone) (PCL) (PCL12: 1.1 microm, P

  19. Biodegradable shape-memory block co-polymers for fast self-expandable stents.

    Science.gov (United States)

    Xue, Liang; Dai, Shiyao; Li, Zhi

    2010-11-01

    Block co-polymers PCTBVs (M(n) of 36,300-65,300 g/mol, T(m) of 39-40 and 142 degrees C) containing hyperbranched three-arm poly(epsilon-caprolactone) (PCL) as switching segment and microbial polyester PHBV as crystallizable hard segment were designed as biodegradable shape-memory polymer (SMP) for fast self-expandable stent and synthesized in 96% yield by the reaction of three-arm PCL-triol (M(n) of 4200 g/mol, T(m) of 47 degrees C) with methylene diphenyl 4,4'-diisocyanate isocynate (MDI) to form the hyperbrached MDI-linked PCL (PTCM; M(n) of 25,400 g/mol and a T(m) of 38 degrees C), followed by further polymerization with PHBV-diol (M(n) of 2200 g/mol, T(m) of 137 and 148 degrees C). The polymers were characterized by (1)H NMR, GPC, DSC, tensile test, and cyclic thermomechanical tensile test. PCTBVs showed desired thermal properties, mechanical properties, and ductile nature. PCTBV containing 25 wt% PHBV (PCTBV-25) demonstrated excellent shape-memory property at 40 degrees C, with R(f) of 94%, R(r) of 98%, and shape recovery within 25s. PCTBV-25 was also shown as a safe material with good biocompatibility by cytotoxicity tests and cell growth experiments. The stent made from PCTBV-25 film showed nearly complete self-expansion at 37 degrees C within only 25 s, which is much better and faster than the best known self-expandable stents.

  20. Synthesis and self-assembly behavior of a biodegradable and sustainable soybean oil-based copolymer nanomicelle

    Science.gov (United States)

    Bao, Lixia; Bian, Longchun; Zhao, Mimi; Lei, Jingxin; Wang, Jiliang

    2014-08-01

    Herein, we report a novel amphiphilic biodegradable and sustainable soybean oil-based copolymer (SBC) prepared by grafting hydrophilic and biocompatible hydroxyethyl acrylate (HEA) polymeric segments onto the natural hydrophobic soybean oil chains. FTIR, H1-NMR, and GPC measurements have been used to investigate the molecular structure of the obtained SBC macromolecules. Self-assembly behaviors of the prepared SBC in aqueous solution have also been extensively evaluated by fluorescence spectroscopy and transmission electron microscopy. The prepared SBC nanocarrier with the size range of 40 to 80 nm has a potential application in the biomedical field.

  1. Photoinduced graft-copolymer synthesis and characterization of methacrylic acid onto natural biodegradable lignocellulose fiber.

    Science.gov (United States)

    Khan, Ferdous

    2004-01-01

    UV radiation induced graft copolymerization of methacrylic acid onto natural lignocellulose (jute) fiber was carried out both by "simultaneous irradiation and grafting" and by preirradiation methods using 1-hydroxycyclohexyl-phenyl ketone as a photoinitiator. In the "simultaneous irradiation and grafting" method, the variation of graft weight with UV-radiation time, monomer concentration, and the concentration of photoinitiator was investigated. In the case of the preirradiation method, the incorporation of 2-methyl-2-propene 1-sulfonic acid, sodium salt, into the grafting reaction solution played a most important role in suppressing the homopolymer/gel formation and facilitating graft copolymerization. The optimum value of the reaction parameters on the percentage of grafting was evaluated. In comparison, results showed that the method of graft-copolymer synthesis has significant influence on graft weight. The study on the mechanical and thermal properties of grafted samples was conducted. The results showed that the percentage of grafting has a significant effect on the mechanical and thermal properties in the case of grafted samples. Considering the water absorption property, the jute-poly(methacrylic acid)-grafted sample showed a maximum up to 42% increase in hydrophilicity with respect to that of the "as received" sample. Attenuated total reflection infrared studies indicate that the estimation of the degree of grafting could be achieved by correlating band intensities with the percent graft weight.

  2. Biodegradable amphiphilic block copolymers containing functionalized PEO blocks:Controlled synthesis and biomedical potentials

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    A series of controllable amphiphilic block copolymers composed of poly(ethylene oxide)(PEO) as the hydrophilic block and poly(ε-caprolactone)(PCL) as the hydrophobic block with the amino terminal group at the end of the PEO chain(PCL-b-PEO-NH2) were synthesized.Based on the further reaction of reactive amino groups,diblock copolymers with functional carboxyl groups(PCL-b-PEO-COOH) and functional compounds RGD(PCL-b-PEO-RGD) as well as the triblock copolymers with thermosensitive PNIPAAm blocks(PCL-b-PEO-b-PNIPAAM) were synthesized.The well-controlled structures of these copolymers with functional groups and blocks were characterized by gel permeation chromatography(GPC) and 1H NMR spectroscopy.These copolymers with functionalized hydrophilic blocks were fabricated into microspheres for the examination of biofunctions via cell culture experiments and in vitro drug release.The results indicated the significance of introducing functional groups(e.g.,NH2,COOH and RGD) into the end of the hydrophilic block of amphiphilic block copolymers for biomedical potentials in tissue engineering and controlled drug release.

  3. STUDIES ON GRAFT COPOLYMERIZATION OF DL—LACTIDE ON CORN STARCH AND BIODEGRADABILITY OF THE COPOLYMERS

    Institute of Scientific and Technical Information of China (English)

    YOUYingcai; ZHUChangying; 等

    2000-01-01

    The starch/D,L-lactide graft copolymers were synthesized by reacting D,L-lactide with corn starch in N,N-dimethylacetamide(DMAM)in the presence of triethylamine(NEt3)and anhydrous lithium chloride.The effect of reaction time and the molar ratio of D,L-lactide to glucose structural unit of starch on monomer conversion(C%),graft(G%)and graft efficiency(GE%)were studied,The C%,G%and GE% could approach 37.3% 179.7%and 68.0%,respectively when the molar ratio of D,L-lactide to glucose structuralunit of starch is 10:1 and the graft copolymerization was carried out at 80-85℃ for 4hr under nitrogen atmosphere.The Fourier transforms infra-red (FTIR) spectroscopy.differential scanning calorimetry(DSC)and X_ray diffraction (XRD) spectroscopy were used in order to characterize the graft copolymers.FTIR spectra show that absorption band at 1740cm-1 confirmed the formation of ester bond,indicating the starch /D,L-lactide graft copolymers were produced,the DSC characteristic results show the melting temperature of the graft copolymer were elevated slightly as the molar ratio of D,L-lactide to glucose structural units of starch increased and the X-ray diffraction spectra show the synthesized graft copolymers were amorphous.The degradability of graft copolymer was tested with the aid of acid,alkali and microbe such as bacillus subtilis and staphylococcus aureus.The results of water rsistance show the graft copolymer produced can be used as a component of impermeable coating for cardboard.

  4. Thymine-functionalized amphiphilic biodegradable copolymers for high-efficiency loading and controlled release of methotrexate.

    Science.gov (United States)

    Cheng, Dong-Bing; Li, You-Mei; Cheng, Yin-Jia; Wu, Yan; Chang, Xiu-Peng; He, Feng; Zhuo, Ren-Xi

    2015-12-01

    In this study, a novel thymine-functionalized six-membered cyclic carbonate monomer (TAC) was synthesized by the Michael-addition reaction between thymine and acryloyl carbonate (AC). The corresponding functional amphiphilic block copolymer mPEG-b-PTAC was further successfully synthesized by ring-opening polymerization using immobilized porcine pancreas lipase (IPPL) as the catalyst and mPEG as the macroinitiator. Meanwhile, mPEG-b-P(TAC-co-DTC) and mPEG-b-PDTC were also synthesized by the same enzymatic methods for comparison on different TAC contents. The structures of monomer and copolymers were characterized by (1)H-NMR, (13)C-NMR and FTIR. All the amphiphilic block copolymers could self-assemble to form nano-sized micelles in aqueous solution. Transmission electron microscopy (TEM) observation showed that the micelles dispersed in spherical shape with nano-size before and after MTX loading. (1)H-NMR and FTIR results confirmed the successful formation of multiple hydrogen-bonding interactions between exposed thymine groups of hydrophobic PTAC segments and 2,6-diaminopyridine (DAP) groups of MTX molecules, which resulting in the higher drug loading capacity and the pH-sensitive drug release behavior. MTT assays also indicated lower toxicity of copolymer but higher potent cytotoxic activity of MTX-loaded copolymer against HeLa cells.

  5. Enzymatic synthesis and characterization of novel biodegradable copolymers of 5-benzyloxy-trimethylene carbonate with 1,4-dioxan-2-one.

    Science.gov (United States)

    He, Feng; Jia, Hua-Li; Liu, Gang; Wang, Yan-Ping; Feng, Jun; Zhuo, Ren-Xi

    2006-08-01

    Enzymatic ring-opening copolymerization of 5-benzyloxy-trimethylene carbonate (BTMC) and 1,4-dioxan-2-one (DON) was investigated for the first time. Immobilized porcine pancreas lipase (IPPL) on silica particles was selected to perform the copolymerization. A series of novel biodegradable copolymers with different compositions were characterized by (1)H NMR, (13)C NMR, and GPC. The influences of reaction conditions such as polymerization time and catalyst concentration on the yield and molecular weight of the copolymers were also studied. The copolymerizations of different monomer feed ratios were carried out in bulk at 150 degrees C with 4.5 wt per thousand IPPL as a catalyst for 24 h. With the increase of the BTMC molar feed ratio from 20% to 79%, the M(n) of the resulting copolymers increased from 5600 to 63400. Water uptake and static contact angle experiments showed that the hydrophilicity of copolymers could be improved with increasing DON content in the copolymers. Moreover, the in vitro drug release rate (ibuprofen as the model drug) of the resulting copolymers also increased along with the DON content in the copolymers.

  6. Advanced drug and gene delivery systems based on functional biodegradable polycarbonates and copolymers

    NARCIS (Netherlands)

    Chen, Wei; Meng, F.; Cheng, R.; Deng, C.; Feijen, J.; Zhong, Z.

    2014-01-01

    Biodegradable polymeric nanocarriers are one of the most promising systems for targeted and controlled drug and gene delivery. They have shown several unique advantages such as excellent biocompatibility, prolonged circulation time, passive tumor targeting via the enhanced permeability and retention

  7. Polyethyleneimine-poly(ethylene glycol)-star-copolymers as efficient and biodegradable vectors for mammalian cell transfection.

    Science.gov (United States)

    Ladewig, Katharina; Xu, Zhi Ping; Gray, Peter; Max Lu, G Q

    2014-07-01

    High molecular weight (MW) polyethyleneimine (PEI) has been successfully used for the transfection of a broad variety of cell lines. In contrast to low MW PEI, which exhibits low transfection efficiencies but also low cytotoxicity, high MW PEI-mediated transfection achieves much higher efficiencies but at the cost of cell viability; therefore its use in commercial scale transfection and clinical application is limited. In this work we address this problem by constructing biodegradable high MW PEI mimics built from low MW PEI building blocks. The end-groups of small 5-arm star polyethylene glycol (PEG) prepolymers were decorated with linear oligo-ethyleneimine (OEI)/PEI arms of various MW via azomethine linkages. The resultant PEI-PEG-star-copolymers were investigated for their ability to complex plasmid DNA. Polymer/DNA complexes were characterized using techniques such as dynamic light scattering and transmission electron microscopy. Having established their cytotoxicity limits, they were tested as gene delivery vehicles for the transfection of suspension adapted Chinese hamster ovary (CHO-S) cells under serum-free conditions and adherent human embryonic kidney cells (HEK293T) in serum containing medium. Our PEI-PEG-star-copolymers showed a reduced cytotoxicity compared to high MW PEI while maintaining the ability to complex plasmid DNA and transfect mammalian cells, with significant transfection efficiencies. The effects of the optimum parameters on the transfection of mammalian cells using such novel polymers are discussed.

  8. Thermoplastic biodegradable elastomers based on ε-caprolactone and L-lactide block co-polymers: a new synthetic approach.

    Science.gov (United States)

    Lipik, Vitali T; Kong, Jen Fong; Chattopadhyay, Sujay; Widjaja, Leonardus K; Liow, Sing S; Venkatraman, Subbu S; Abadie, Marc J M

    2010-11-01

    Although biodegradable polymers have found extensive application in medical devices, there are very few commercially available elastomeric biodegradable polymers. In this work, starting with the well-known monomers L-lactide and ε-caprolactone, we developed elastomers using a multiblock co-polymer approach. This ensures that the degradation products of such elastomers are also acceptable from a cytotoxicity standpoint. A series of polymers with various structures was synthesized utilizing a design of experiment approach. The basic structure is that of a diblock, with each block being modified by the addition of co-monomer. The synthesized polymers exhibited a range of mechanical properties from a typical thermoplastic polymer to that approaching a good thermoplastic elastomer. 13C nuclear magnetic resonance analysis, size exclusion chromatography and differential scanning calorimetry measurements have been utilized to relate the observed range of mechanical properties to the structure. In addition, the elastomeric nature has been established with the use of creep and recovery measurements. Such elastomers may find a variety of biomedical applications, ranging from stent coatings to atrial septal defect occluders.

  9. Synthesis and Properties of Biodegradable Copolymers of 9-Phenyl-2,4,8,10-tetraoxaspiro-[5,5]undcane-3-one and Ethylene Ethyl Phosphate

    Institute of Scientific and Technical Information of China (English)

    Jian XU; Zhi Lan LIU; Ren Xi ZHUO

    2006-01-01

    Novel biodegradable copolymer poly(CC-co-EEP) was synthesized by ring-opening copolymerization of cyclic carbonate 9-phenyl-2, 4, 8, 10-tetraoxaspiro-[5, 5]undcane-3-one (CC)and ethylene ethyl phosphate (EEP). The obtained poly (CC-co-EEP)s were characterized by FTIR, 1H NMR, 13C NMR and gel permeation chromatography (GPC). In vitro hydrolytic degradation of the copolymers were investigated in phosphate buffer solution (pH=7.4).Hydrophilic phosphate units apparently improved the degradability of poly(carbonate-phosphate).

  10. Platinum-Incorporating Poly(N-vinylpyrrolidone)-poly(aspartic acid) Pseudoblock Copolymer Nanoparticles for Drug Delivery.

    Science.gov (United States)

    Yao, Xikuang; Xie, Chen; Chen, Weizhi; Yang, Chenchen; Wu, Wei; Jiang, Xiqun

    2015-07-13

    Cisplatin-incorporating pseudoblock copolymer nanoparticles with high drug loading efficiency (ca. 50%) were prepared built on host-guest inclusion complexation between β-cyclodextrin end-capped poly(N-vinylpyrrolidone) block and admantyl end-capped poly(aspartic acid) block, followed by the coordination between cisplatin and carboxyl groups in poly(aspartic acid). The host-guest interaction between the two polymer blocks was examined by two-dimensional nuclear overhauser effect spectroscopy. The size and morphology of nanoparticles formed were characterized by dynamic light scattering, zeta potential, transmission electron microscopy, and atomic force microscopy. The size control of nanoparticles was carried out by varying the ratio of poly(N-vinylpyrrolidone) to poly(aspartic acid). The nanoparticles were stable in the aqueous medium with different pH values but disintegrated in the medium containing Cl(-) ions. The in vitro and in vivo antitumor effects of cisplatin-loaded nanoparticles were evaluated. The biodistribution of the nanoparticles in vivo was studied by noninvasive near-infrared fluorescence imaging and ion-coupled plasma mass spectrometry. It was found that cisplatin-loaded nanoparticles could effectively accumulate in the tumor site and exhibited significant superior in vivo antitumor activity to the commercially available free cisplatin by combining the tumor volume, body weight, and survival rate measurements.

  11. MANUFACTURING BIODEGRADABLE COMPOSITE MATERIALS BASED ON POLYETHYLENE AND FUNCTIONALIZED BY ALCOHOLYSIS OF ETHYLENE-VINYL ACETATE COPOLYMER

    Directory of Open Access Journals (Sweden)

    Aleksandr A. Shabarin

    2016-06-01

    Full Text Available Introduction. The continuous growth of production and consumption of plastic packaging creates a serious problem of disposal of package. This problem has ecological character, because the contents of the landfills decompose for decades, emit toxic com¬pounds and pollute the environment. The work is devoted to obtaining and investigation mechanical and rheological properties of biodegradable composite materials based on polyethylene and starch. Materials and Methods. In this work the author used polyethylene grade HDPE 273- 83 (GOST 16338-85, Sevilen brand 12206-007 (TU 6-05-1636-97 and potato starch (GOST 53876-2010 as a filler. Functionalization of sevilen was carried in the 30 % ethanol solution KOH at a temperature 80 °C during 3 hours. Compounding components was carried out at the laboratory of the two rotary mixer HAAKE PolyLab Rheomix 600 OS with rotors Banbury. Formation of plates for elastic strength and rheological studies were carried out on a hydraulic press Gibitre. Elastic and strength tests were carried out on the tensile machine the UAI-7000 M. Rheology tests were carried out on the rheometer Haake MARS III. The humidity filler (starch authors determined by the thermogravimetric method on the analyzer of moisture “Evlas-2M”. Results. It is shown, that the filler should not contain more than 7% moisture. Functionalization of ethylene with vinyl acetate copolymer (sevilen has performed by the method of alkaline alcoholysis. By the method of IC – spectroscopy the authors confirmed the presence of hydroxyl groups in the polymer. Using as a compatibilizer functionalized by the method of alcoholises has greatly ( significantly improved physical, mechanical and rheological properties of composite materials. Optimal content of sevilen (F in the compound according to the results of experiments amount 10 %. Discussion and Conclusions. Using of functionalized by the method of alcoholysis ethy-lene-vinyl acetate copolymer as a

  12. Selective adsorption of Pb (II) ions by amylopectin-g-poly (acrylamide-co-acrylic acid): A bio-degradable graft copolymer.

    Science.gov (United States)

    Sasmal, Dinabandhu; Maity, Jayanta; Kolya, Haradhan; Tripathy, Tridib

    2017-04-01

    Amylopectin-g-poly (acrylamide-co-acrylic acid) [AP-g-poly (AM-co-AA)] was synthesised in water medium by using potassium perdisulphate as an initiator. The graft copolymer was characterized by molecular weight determination by size exclusion chromatography (SEC), fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR) spectroscopy, scanning electron microscope (SEM) studies, thermal analysis, measurement of neutralisation equivalent and biodegradation studies. The graft copolymer was used for Pb (II) ion removal from aqueous solution. The Pb (II) ion removal capacity of the graft copolymer was also compared with another laboratory developed graft copolymer Amylopectin-g-poly (acrylamide) (AP-g-PAM). Both the graft copolymers were also used for the competitive metal ions removal with Pb (II)/Cd (II), Pb (II)/Zn (II), Pb (II)/Ni (II), Pb (II)/Cu (II) pairs separately under similar conditions. AP-g-poly (AM-co-AA) showed better Pb (II) ion adsorbing power over AP-g-PAM and also much selective towards Pb (II) ions. The adsorption follows a second order rate equation and Langmuir isotherm model.

  13. Enhanced visualization of biodegradable polymeric vascular scaffolds by incorporation of gold, silver and magnetite nanoparticles.

    Science.gov (United States)

    Luderer, Frank; Begerow, Ivonne; Schmidt, Wolfram; Martin, Heiner; Grabow, Niels; Bünger, Carsten M; Schareck, Wolfgang; Schmitz, Klaus-Peter; Sternberg, Katrin

    2013-08-01

    Due to improved tissue regeneration and the enabling of post-operative minimally invasive interventions in the same vessel segment, biodegradable polymeric scaffolds represent a competitive approach to permanent metallic stents in vascular applications. Despite these advantages some challenges, such as the improvement of the scaffold mechanics and enhancement of scaffold visibility during the implantation procedure, are persisting. Therefore, the scope of our studies was to investigate the potential of gold, silver and magnetite nanoparticles incorporated in a polymeric blend of poly(L-lactide)/poly(4-hydroxybutyrate) for image enhancement in X-ray, magnetic resonance or near-infrared imaging. Their impact on mechanical properties of such modified scaffold materials was also evaluated.

  14. Incorporation of biodegradable electrospun fibers into calcium phosphate cement for bone regeneration.

    Science.gov (United States)

    Zuo, Yi; Yang, Fang; Wolke, Joop G C; Li, Yubao; Jansen, John A

    2010-04-01

    Inherent brittleness and slow degradation are the major drawbacks for the use of calcium phosphate cements (CPCs). To address these issues, biodegradable ultrafine fibers were incorporated into the CPC in this study. Four types of fibers made of poly(epsilon-caprolactone) (PCL) (PCL12: 1.1 microm, PCL15: 1.4 microm, PCL18: 1.9 microm) and poly(l-lactic acid) (PLLA4: 1.4 microm) were prepared by electrospinning using a special water pool technique, then mixed with the CPC at fiber weight fractions of 1%, 3%, 5% and 7%. After incubation of the composites in simulated body fluid for 7 days, they were characterized by a gravimetric measurement for porosity evaluation, a three-point bending test for mechanical properties, microcomputer topography and scanning electron microscopy for morphological observation. The results indicated that the incorporation of ultrafine fibers increases the fracture resistance and porosity of CPCs. The toughness of the composites increased with the fiber fraction but was not affected by the fiber diameter. It was found that the incorporated fibers formed a channel-like porous structure in the CPCs. After degradation of the fibers, the created space and high porosity of the composite cement provides inter-connective channels for bone tissue in growth and facilitates cement resorption. Therefore, we concluded that this electrospun fiber-CPC composite may be beneficial to be used as bone fillers.

  15. Injectable biocompatible and biodegradable pH-responsive hollow particle gels containing poly(acrylic acid): the effect of copolymer composition on gel properties.

    Science.gov (United States)

    Halacheva, Silvia S; Adlam, Daman J; Hendow, Eseelle K; Freemont, Tony J; Hoyland, Judith; Saunders, Brian R

    2014-05-12

    The potential of various pH-responsive alkyl (meth)acrylate ester- and (meth)acrylic acid-based copolymers, including poly(methyl methacrylate-co-acrylic acid) (PMMA-AA) and poly(n-butyl acrylate-co-methacrylic acid) (PBA-MAA), to form pH-sensitive biocompatible and biodegradable hollow particle gel scaffolds for use in non-load-bearing soft tissue regeneration have been explored. The optimal copolymer design criteria for preparation of these materials have been established. Physical gels which are both pH- and redox-sensitive were formed only from PMMA-AA copolymers. MMA is the optimal hydrophobic monomer, whereas the use of various COOH-containing monomers, e.g., MAA and AA, will always induce a pH-triggered physical gelation. The PMMA-AA gels were prepared at physiological pH range from concentrated dispersions of swollen, hollow, polymer-based particles cross-linked with either cystamine (CYS) or 3,3'-dithiodipropionic acid dihydrazide (DTP). A linear relationship between particle swelling ratios, gel elasticity, and ductility was observed. The PMMA-AA gels with lower AA contents feature lower swelling ratios, mechanical strengths, and ductilities. Increasing the swelling ratio (e.g., through increasing AA content) decreased the intraparticle elasticity; however, intershell contact and gel elasticity were found to increase. The mechanical properties and performance of the gels were tuneable upon varying the copolymers' compositions and the structure of the cross-linker. Compared to PMMA-AA/CYS, the PMMA-AA/DTP gels were more elastic and ductile. The biodegradability and cytotoxicity of the new hollow particle gels were tested for the first time and related to their composition, mechanical properties, and morphology. The new PMMA-AA/CYS and PMMA-AA/DTP gels have shown good biocompatibility, biodegradability, strength, and interconnected porosity and therefore have good potential as a tissue repair agent.

  16. Nanocomposite scaffold fabrication by incorporating gold nanoparticles into biodegradable polymer matrix: Synthesis, characterization, and photothermal effect

    Energy Technology Data Exchange (ETDEWEB)

    Abdelrasoul, Gaser N.; Farkas, Balazs; Romano, Ilaria; Diaspro, Alberto; Beke, Szabolcs, E-mail: szabolcs.beke@iit.it

    2015-11-01

    Nanoparticle incorporation into scaffold materials is a valuable route to deliver various therapeutic agents, such as drug molecules or large biomolecules, proteins (e.g. DNA or RNA) into their targets. In particular, gold nanoparticles (Au NPs) with their low inherent toxicity, tunable stability and high surface area provide unique attributes facilitating new delivery strategies. A biodegradable, photocurable polymer resin, polypropylene fumarate (PPF) along with Au NPs were utilized to synthesize a hybrid nanocomposite resin, directly exploitable in stereolithography (SL) processes. To increase the particles' colloidal stability, the Au NP nanofillers were coated with polyvinyl pyrrolidone (PVP). The resulting resin was used to fabricate a new type of composite scaffold via mask projection excimer laser stereolithography. The thermal properties of the nanocomposite scaffolds were found to be sensitive to the concentration of NPs. The mechanical properties were augmented by the NPs up to 0.16 μM, though further increase in the concentration led to a gradual decrease. Au NP incorporation rendered the biopolymer scaffolds photosensitive, i.e. the presence of Au NPs enhanced the optical absorption of the scaffolds as well, leading to possible localized temperature rise when irradiated with 532 nm laser, known as the photothermal effect. - Highlights: • Gold nanoparticle incorporation into biopolymer resin was realized. • Gold incorporation into biopolymer resin is a big step in tissue engineering. • Composite scaffolds were synthesized and thoroughly characterized. • Gold nanoparticles are remarkable candidates to be utilized as “transport vehicles”. • The photothermal effect was demonstrated using a 532-nm laser.

  17. Nanocomposite scaffold fabrication by incorporating gold nanoparticles into biodegradable polymer matrix: Synthesis, characterization, and photothermal effect.

    Science.gov (United States)

    Abdelrasoul, Gaser N; Farkas, Balazs; Romano, Ilaria; Diaspro, Alberto; Beke, Szabolcs

    2015-11-01

    Nanoparticle incorporation into scaffold materials is a valuable route to deliver various therapeutic agents, such as drug molecules or large biomolecules, proteins (e.g. DNA or RNA) into their targets. In particular, gold nanoparticles (Au NPs) with their low inherent toxicity, tunable stability and high surface area provide unique attributes facilitating new delivery strategies. A biodegradable, photocurable polymer resin, polypropylene fumarate (PPF) along with Au NPs were utilized to synthesize a hybrid nanocomposite resin, directly exploitable in stereolithography (SL) processes. To increase the particles' colloidal stability, the Au NP nanofillers were coated with polyvinyl pyrrolidone (PVP). The resulting resin was used to fabricate a new type of composite scaffold via mask projection excimer laser stereolithography. The thermal properties of the nanocomposite scaffolds were found to be sensitive to the concentration of NPs. The mechanical properties were augmented by the NPs up to 0.16μM, though further increase in the concentration led to a gradual decrease. Au NP incorporation rendered the biopolymer scaffolds photosensitive, i.e. the presence of Au NPs enhanced the optical absorption of the scaffolds as well, leading to possible localized temperature rise when irradiated with 532nm laser, known as the photothermal effect.

  18. Synthesis and Characterization of a Biodegradable Copolymer: RGD Peptide Modification of Poly (lactic acid-co-lysine)

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The poly ( lactic acid- co-lysine ) was synthesized using IR and 1 H NMR to characterize the copolymer. And then the RGD modification copolymer RGD-PLAL was prepared. The contact angles were used to see the RGD modification occurrence. Also high molecular weight polymer was controlled to the reaction of polymerization of copolymer.

  19. Incorporation of Amphipathic Diblock Copolymer in Lipid Bilayer for Improving pH Responsiveness

    Directory of Open Access Journals (Sweden)

    Tian Xia

    2016-01-01

    Full Text Available Diblock copolymers (mPEG-b-PDPA, which were designed to possess pH-sensitivity as well as amphipathy, were used as an intelligent lock in the liposomal membrane. The so-called pH-sensitive liposomes were prepared by simple mixing of the synthesized mPEG-b-PDPA with phospholipids and cholesterol. Fluorescence polarization at pH 7.4 showed that the membrane stability of the hybrid liposome was significantly increased compared with the pure liposome. Therefore, in the neutral environment, the leakage of doxorubicin (DOX was inhibited. However, when pH decreased to 6.0, DOX release rate increased by 60% due to the escape of copolymer. The effects of the membrane composition and the PDPA segment length on bilayer membrane functions were investigated. These results revealed that the synthesized copolymers increased the difference in DOX cumulative release between pH 7.4 and 6.0, that is, improved the pH-controllability of the drug release from hybrid liposomes.

  20. Biodegradable Nanoparticles of mPEG-PLGA-PLL Triblock Copolymers as Novel Non-Viral Vectors for Improving siRNA Delivery and Gene Silencing

    Directory of Open Access Journals (Sweden)

    Qiu-Sheng Shi

    2012-01-01

    Full Text Available Degradation of mRNA by RNA interference is one of the most powerful and specific mechanisms for gene silencing. However, insufficient cellular uptake and poor stability have limited its usefulness. Here, we report efficient delivery of siRNA via the use of biodegradable nanoparticles (NPs made from monomethoxypoly(ethylene glycol-poly(lactic-co-glycolic acid-poly-l-lysine (mPEG-PLGA-PLL triblock copolymers. Various physicochemical properties of mPEG-PLGA-PLL NPs, including morphology, size, surface charge, siRNA encapsulation efficiency, and in vitro release profile of siRNA from NPs, were characterized by scanning electron microscope, particle size and zeta potential analyzer, and high performance liquid chromatography. The levels of siRNA uptake and targeted gene inhibition were detected in human lung cancer SPC-A1-GFP cells stably expressing green fluorescent protein. Examination of the cultured SPC-A1-GFP cells with fluorescent microscope and flow cytometry showed NPs loading Cy3-labeled siRNA had much higher intracellular siRNA delivery efficiencies than siRNA alone and Lipofectamine-siRNA complexes. The gene silencing efficiency of mPEG-PLGA-PLL NPs was higher than that of commercially available transfecting agent Lipofectamine while showing no cytotoxicity. Thus, the current study demonstrates that biodegradable NPs of mPEG-PLGA-PLL triblock copolymers can be potentially applied as novel non-viral vectors for improving siRNA delivery and gene silencing.

  1. HIGH-MOLECULAR-WEIGHT COPOLYMERS OF L-LACTIDE AND EPSILON-CAPROLACTONE AS BIODEGRADABLE ELASTOMERIC IMPLANT MATERIALS

    NARCIS (Netherlands)

    GRIJPMA, DW; ZONDERVAN, GJ; PENNINGS, AJ

    1991-01-01

    High molecular weight copolymers of L-lactide and epsilon-caprolactone have been synthesized by ring opening copolymerization with stannous octoate as catalyst. The good mechanical properties of the 50/50 copolymers make it a suitable material for biomedical applications such as nerve guides etc., w

  2. Temperature-sensitivity and cell biocompatibility of freeze-dried nanocomposite hydrogels incorporated with biodegradable PHBV

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Qingsong, E-mail: zqs8011@163.com; Chen, Li, E-mail: chenlis@tjpu.edu.cn; Dong, Youyu; Lu, Si

    2013-04-01

    The structure, morphology, thermal behaviors and cytotoxicity of novel hydrogels, composed of poly(N-isopropylacrylamide)(PNIPAM) and biodegradable polyester poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) under nanoclay hectorite “Laponite XLG” severed as physical cross-linker, were characterized by X-ray diffraction, scanning electron microscopy, gravimetric method, differential scanning calorimetry, and cell culture experiments. It was found that, due to the introduction of hydrophobic PHBV, the homogeneity of interior pore in the pure PNIPAM nanocomposite hydrogel was disrupted, the transparency and swelling degree gradually decreased. Although the weight ratio between PHBV and NIPAM increased from 5 to 40 wt.%, the volume phase transition temperature (VPTTs) of hydrogel were not altered compared with the pure PNIPAM nanocomposite hydrogel. No matter what PHBV content, the PHBV/PNIPAM/Hectorite hydrogels always exhibit good stimuli-responsibility. In addition, human hepatoma cells(HepG2) adhesion and spreading on the surface of PHBV-based hydrogels was greatly improved than that of pure PNIPAM nanocomposite hydrogel at 37 °C due to the introduction of PHBV. Highlights: ► Thermo-responsive and cell biocompatible hydrogels incorporated PHBV was synthesized. ► The introduction of PHBV decreases the transparency of nanocomposite hydrogel. ► The introduction of PHBV has a little shift on VPTTs of nanocomposite hydrogel. ► The HepG2 cells could adhere and spread on the surface of PHBV-based hydrogels. ► Cell sheet could be detached simultaneously from the surface of hydrogels.

  3. Projection Stereolithographic Fabrication of Human Adipose Stem Cell-incorporated Biodegradable Scaffolds for Cartilage Tissue Engineering

    Directory of Open Access Journals (Sweden)

    Aaron X Sun

    2015-08-01

    Full Text Available Poor self-healing ability of cartilage necessitates the development of methods for cartilage regeneration. Scaffold construction with live stem cell incorporation and subsequent differentiation presents a promising route. Projection stereolithography (PSL offers high resolution and processing speed as well as the ability to fabricate scaffolds that precisely fit the anatomy of cartilage defects using medical imaging as the design template. We report here the use of a visible-light based PSL (VL-PSL system to encapsulate human adipose-derived stem cells (hASCs into a biodegradable polymer (poly-D,L-lactic acid/polyethylene glycol/ poly-D,L-lactic acid (PDLLA-PEG/hyaluronic acid (HA matrix to produce live cell constructs with customized architectures. After fabrication, hASCs showed high viability (84% and were uniformly distributed throughout the constructs, which possessed high mechanical property with a compressive modulus of 780 kPa. The hASC-seeded constructs were then cultured in Control or TGF-β3-containing chondrogenic medium for up to 28 days. In chondrogenic medium treated group (TGF-β3 group hASCs maintained 77% viability and expressed chondrogenic genes Sox9, collagen type II, and aggrecan at 11, 232, and 2.29 x 10(5 fold increases, respectively, compared to levels at day 0 in non-chondrogenic medium. The TGF-β3 group also produced a collagen type II and glycosaminoglycan (GAG-rich extracellular matrix, detected by immunohistochemistry, and Alcian blue and Safranin O staining suggesting robust chondrogenesis within the scaffold. Without chondroinductive addition (Control group, cell viability decreased with time (65% at 28 days and showed poor cartilage matrix deposition. After 28 days, mechanical strength of the TGF-β3 group remained high at 240 kPa. Thus, the PSL- and PLLA-PEG/HA based fabrication method using adult stem cells is a promising approach in producing mechanically competent engineered cartilage for joint cartilage

  4. Biodegradable gadolinium-chelated cationic poly(urethane amide) copolymers for gene transfection and magnetic resonance imaging

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Xiaolong [Department of Radiology, Tongji Hospital, Tongji University School of Medicine, Shanghai 200065 (China); Wang, Gangmin [Department of Urology, Huashan Hospital, Fudan University, Shanghai 200040 (China); Shi, Ting [The Institute for Translational Nanomedicine, Shanghai East Hospital, Institute for Biomedical Engineering and Nanoscience, Tongji University School of Medicine, Shanghai 200092 (China); Shao, Zhihong [Department of Radiology, Tongji Hospital, Tongji University School of Medicine, Shanghai 200065 (China); Zhao, Peng; Shi, Donglu [The Institute for Translational Nanomedicine, Shanghai East Hospital, Institute for Biomedical Engineering and Nanoscience, Tongji University School of Medicine, Shanghai 200092 (China); Ren, Jie [Institute of Nano and Biopolymeric Materials, School of Materials Science and Engineering, Tongji University, 4800 Caoan Road, Shanghai 201804 (China); Lin, Chao, E-mail: chaolin@tongji.edu.cn [The Institute for Translational Nanomedicine, Shanghai East Hospital, Institute for Biomedical Engineering and Nanoscience, Tongji University School of Medicine, Shanghai 200092 (China); Wang, Peijun, E-mail: tjpjwang@sina.com [Department of Radiology, Tongji Hospital, Tongji University School of Medicine, Shanghai 200065 (China)

    2016-08-01

    Theranostic nano-polyplexes containing gene and imaging agents hold a great promise for tumor diagnosis and therapy. In this work, we develop a group of new gadolinium (Gd)-chelated cationic poly(urethane amide)s for gene delivery and T{sub 1}-weighted magnetic resonance (MR) imaging. Cationic poly(urethane amide)s (denoted as CPUAs) having multiple disulfide bonds, urethane and amide linkages were synthesized by stepwise polycondensation reaction between 1,4-bis(3-aminopropyl)piperazine and a mixture of di(4-nitrophenyl)-2, 2′-dithiodiethanocarbonate (DTDE-PNC) and diethylenetriaminepentaacetic acid (DTPA) dianhydride at varied molar ratios. Then, Gd-chelated CPUAs (denoted as GdCPUAs) were produced by chelating Gd(III) ions with DTPA residues of CPUAs. These GdCPUAs could condense gene into nanosized and positively-charged polyplexes in a physiological condition and, however, liberated gene in an intracellular reductive environment. In vitro transfection experiments revealed that the GdCPUA at a DTDE-PNC/DTPA residue molar ratio of 85/15 induced the highest transfection efficiency in different cancer cells. This efficiency was higher than that yielded with 25 kDa branched polyethylenimine as a positive control. GdCPUAs and their polyplexes exhibited low cytotoxicity when an optimal transfection activity was detected. Moreover, GdCPUAs may serve as contrast agents for T{sub 1}-weighted magnetic resonance imaging. The results of this work indicate that biodegradable Gd-chelated cationic poly(urethane amide) copolymers have high potential for tumor theranostics. - Highlights: • Novel cationic gadolinium-chelated poly(urethane amide)s (GdCPUAs) are prepared. • GdCPUAs can induce a high transfection efficacy in different cancer cells. • GdCPUAs reveal good cyto-compatibility against cancer cells. • GdCPUAs may be applied as T{sub 1}-contrast agents for magnetic resonance imaging. • GdCPUAs hold high potential for cancer theranostics.

  5. Synthesis and Characterization of a Novel Functional Biodegradable Copolymer-Poly(lactic acid-4-hydroxyproline-polyethylene glycol)

    Institute of Scientific and Technical Information of China (English)

    Jiu Fang DUAN; Yu Bin ZHENG

    2006-01-01

    A series of poly(lactic acid-4-hydroxyproline-polyethylene glycol) (PLA-Hpr-PEG) copolymers were synthesized by direct melt copolymerization of D,L-lactic acid and 4-hydroxyproline with different feed amount of polyethylene glycol (PEG) 0.1%, 0.5%, 1% and 5%, respectively. The properties of these copolymers were characterized by using IR spectroscopy, proton nuclear magnetic resonance (1H-NMR) spectroscopy, gel permeation chromatography (GPC), X-ray diffraction and differential scaning calorimetry (DSC). PLA-Hpr-PEG are amorphous copolymers. Copolymers showed increasing water uptake capacity with increasing PEG percentage in the feed, which result in an increasing degradable rate in phosphate buffer solution (pH 7.4) at 37℃.

  6. New Biodegradable Thermoplastic Multiblock Copolymers from Lactic Acid, ε-Caprolactone, Poly(Ethylene Oxide) and Toluene Diisocyanate

    Institute of Scientific and Technical Information of China (English)

    Jen(o) Borda; Sándor Kéki; Ildikó Bodnár; Nóra Németh; Miklós Zsuga

    2005-01-01

    @@ 1Introduction The interest in finding new biodegradable materials for applications in important areas has been motivated by environmental protection aspects. Foremost among the potentially biodegradable and biocompatible polymers, poly(lactic acid) and poly(ε-caprolactone) received considerable attention as their potential application in a wide range of biomedical and pharmaceutical areas was recognized.

  7. Anthocyanin Incorporated Dental Copolymer: Bacterial Growth Inhibition, Mechanical Properties, and Compound Release Rates and Stability by 1H NMR

    Directory of Open Access Journals (Sweden)

    Halyna Hrynash

    2014-01-01

    Full Text Available Objective. To evaluate bacterial growth inhibition, mechanical properties, and compound release rate and stability of copolymers incorporated with anthocyanin (ACY; Vaccinium macrocarpon. Methods. Resin samples were prepared (Bis-GMA/TEGDMA at 70/30 mol% and incorporated with 2 w/w% of either ACY or chlorhexidine (CHX, except for the control group. Samples were individually immersed in a bacterial culture (Streptococcus mutans for 24 h. Cell viability (n=3 was assessed by counting the number of colony forming units on replica agar plates. Flexural strength (FS and elastic modulus (E were tested on a universal testing machine (n=8. Compound release and chemical stability were evaluated by UV spectrophotometry and 1H NMR (n=3. Data were analyzed by one-way ANOVA and Tukey’s test (α = 0.05. Results. Both compounds inhibited S. mutans growth, with CHX being most effective (P<0.05. Control resin had the lowest FS and E values, followed by ACY and CHX, with statistical difference between control and CHX groups for both mechanical properties (P<0.05. The 24 h compound release rates were ACY: 1.33 μg/mL and CHX: 1.92 μg/mL. 1H NMR spectra suggests that both compounds remained stable after being released in water. Conclusion. The present findings indicate that anthocyanins might be used as a natural antibacterial agent in resin based materials.

  8. Corrosion behavior and cytocompatibility of fluoride-incorporated plasma electrolytic oxidation coating on biodegradable AZ31 alloy

    Science.gov (United States)

    Tian, Peng; Peng, Feng; Wang, Donghui; Liu, Xuanyong

    2017-01-01

    Fluoride-incorporated plasma electrolytic oxidation (PEO) coating was fabricated on biodegradable AZ31 alloy. The surface morphologies and phases were investigated by scanning electron microscopy and X-ray diffraction. The effect of fluoride incorporation in coatings on corrosion behaviour was investigated in simulated body fluid and in vitro cytocompatibility of the coatings was also studied by evaluating cytotoxicity, adhesion, proliferation and live–dead stain of osteoblast cells (MC3T3-E1). Furthermore, the corrosion morphologies in vivo were examined. The results showed that the fluoride could be incorporated into the coating to form MgF2 phase. In vitro and in vivo degradation tests revealed that the corrosion resistance of the coating could be improved by the incorporation of fluoride, which may attribute to the chemical stability of MgF2 phase. Moreover, good cytocompatibility of fluoride-incorporated coating was confirmed with no obvious cytotoxicity, enhanced cell adhesion and proliferation. However, when the fluoride content was high, a slight inhibition of cell growth was observed. The results indicate that although fluoride incorporation can enhance the corrosion resistance of the coatings, thus resulting a more suitable environment for cells, the high content of fluoride in the coating also kill cells ascribed to the high released of fluorine. If the content of fluoride is well controlled, the PEO coating with MgF2 phase is a promising surface modification of Mg alloys. PMID:28149524

  9. Corrosion behavior and cytocompatibility of fluoride-incorporated plasma electrolytic oxidation coating on biodegradable AZ31 alloy.

    Science.gov (United States)

    Tian, Peng; Peng, Feng; Wang, Donghui; Liu, Xuanyong

    2017-02-01

    Fluoride-incorporated plasma electrolytic oxidation (PEO) coating was fabricated on biodegradable AZ31 alloy. The surface morphologies and phases were investigated by scanning electron microscopy and X-ray diffraction. The effect of fluoride incorporation in coatings on corrosion behaviour was investigated in simulated body fluid and in vitro cytocompatibility of the coatings was also studied by evaluating cytotoxicity, adhesion, proliferation and live-dead stain of osteoblast cells (MC3T3-E1). Furthermore, the corrosion morphologies in vivo were examined. The results showed that the fluoride could be incorporated into the coating to form MgF2 phase. In vitro and in vivo degradation tests revealed that the corrosion resistance of the coating could be improved by the incorporation of fluoride, which may attribute to the chemical stability of MgF2 phase. Moreover, good cytocompatibility of fluoride-incorporated coating was confirmed with no obvious cytotoxicity, enhanced cell adhesion and proliferation. However, when the fluoride content was high, a slight inhibition of cell growth was observed. The results indicate that although fluoride incorporation can enhance the corrosion resistance of the coatings, thus resulting a more suitable environment for cells, the high content of fluoride in the coating also kill cells ascribed to the high released of fluorine. If the content of fluoride is well controlled, the PEO coating with MgF2 phase is a promising surface modification of Mg alloys.

  10. P(MMA-EMA Random Copolymer Electrolytes Incorporating Sodium Iodide for Potential Application in a Dye-Sensitized Solar Cell

    Directory of Open Access Journals (Sweden)

    Nurul Akmaliah Dzulkurnain

    2015-02-01

    Full Text Available Polymer electrolytes based on 90 wt% of methyl methacrylate and 10 wt% of ethyl methacrylate (90MMA-co-10EMA incorporating different weight ratios of sodium iodide were prepared using the solution casting method. The complexation between salt and copolymer host has been investigated using Fourier transform infrared spectroscopy. The ionic conductivity and thermal stability of the electrolytes were measured using impedance spectroscopy and differential scanning calorimetry, respectively. Scanning electron microscopy was used to study the morphology of the polymer electrolytes. The ionic conductivity and glass transition temperature increased up to 20 wt% of sodium iodide (5.19 × 10−6 S·cm−1 and decreased with the further addition of salt concentration, because of the crosslinked effect. The morphology behavior of the highest conducting sample also showed smaller pores compared to the other concentration. The total ionic transference number proved that this system was mainly due to ions, and the electrochemical stability window was up to 2.5 V, which is suitable for a dye-sensitized solar cell application. This sample was then tested in a dye-sensitized solar cell and exhibited an efficiency of 0.62%.

  11. Synthesis and Characterization of Biodegradable Amphiphilic Star and Y-Shaped Block Copolymers as Potential Carriers for Vinorelbine

    Directory of Open Access Journals (Sweden)

    Fatemeh Bahadori

    2014-01-01

    Full Text Available Two amphiphilic block copolymers using hydrophobic poly(ε-caprolactone (PCL and hydrophilic poly(ethylene glycol (PEG were successfully synthesized. One of them is an (A-b-B4 type star polymer [(PCL-b-PEG4] and the other one is a Y-shaped PEG–(PCL2. A star-shaped polymer (PCL-b-PEG4 was prepared by ring-opening polymerization (ROP of ε-caprolactone continued by click reaction of (PCL-azide4 and PEG-alkyne. The synthesis of Y-shaped PEG–(PCL2 block copolymer was carried out via Diels-Alder click reaction of a furan protected maleimide end-functionalized PEG (PEG-MI with an anthracene end-functionalized PCL following the ROP of ε-caprolactone. The characterization of micelles is carried out using both materials in aqueous media as drug delivery vehicles, which showed satisfying results and enhanced the cytotoxic effect of the anti-cancer drug vinorelbine (VLB. However, micelles consisted of Y-shaped unimers were found to be more convenient for delivery of hydrophobic drugs such as VLB because they formed in lower concentration, carrying a higher amount of drugs and owing a monomodal distribution. We concluded that the free tails of hydrophobic chains in Y-shaped block copolymer facilitate the assembly of amphiphilic material in water to form micelles.

  12. PGA-incorporated collagen: Toward a biodegradable composite scaffold for bone-tissue engineering.

    Science.gov (United States)

    Toosi, Shirin; Naderi-Meshkin, Hojjat; Kalalinia, Fatemeh; Peivandi, Mohammad Taghi; HosseinKhani, Hossein; Bahrami, Ahmad Reza; Heirani-Tabasi, Asieh; Mirahmadi, Mahdi; Behravan, Javad

    2016-08-01

    Nowadays composite scaffolds based on synthetic and natural biomaterials have got attention to increase healing of non-union bone fractures. To this end, different aspects of collagen sponge incorporated with poly(glycolic acid) (PGA) fiber were investigated in this study. Collagen solution (6.33 mg/mL) with PGA fibers (collagen/fiber ratio [w/w]: 4.22, 2.11, 1.06, 0.52) was freeze-dried, followed by dehydrothermal cross-linking to obtain collagen sponge incorporating PGA fibers. Properties of scaffold for cell viability, proliferation, and differentiation of mesenchymal stem cells (MSCs) were evaluated. Scanning electron microscopy showed that collagen sponge exhibited an interconnected pore structure with an average pore size of 190 μm, irrespective of PGA fiber incorporation. The collagen-PGA sponge was superior to the original collagen sponge in terms of the initial attachment, proliferation rate, and osteogenic differentiation of the bone marrow-MSCs (BM-MSC). The shrinkage of sponges during cell culture was significantly suppressed by fiber incorporation. Incorporation of PGA fiber is a simple and promising way to reinforce collagen sponge without impairing biocompatibility. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 2020-2028, 2016.

  13. Nanofibers extraction from palm mesocarp fiber for biodegradable polymers incorporation; Extracao de nanofibras a partir do mesocarpo do dende para incorporacao em polimeros biodegradsveis

    Energy Technology Data Exchange (ETDEWEB)

    Kuana, Vanessa A.; Rodrigues, Vanessa B.; Takahashi, Marcio C., E-mail: ayu.kuana@gmail.com [Universidade Federal de Sao Carlos (UFSCar), Sao Carlos, SP (Brazil); Campos, Adriana de; Sena Neto, Alfredo R.; Mattoso, Luiz H.C.; Marconcini, Jose M. [Embrapa Instrumentacao (EMBRAPA/CNPDIA), Sao Carlos, SP (Brazil)

    2013-07-01

    The palm mesocarp fibers are residues produced by the palm oil industries. The objective of this paper is to determine an efficient treatment to extract crystal cellulose nanofibers from the palm mesocarp fibers to be incorporated in biodegradable polymeric composites. The fibers were saponified, bleached and analyzed with thermal gravimetric analysis, X-ray diffraction, Fourier transform infrared spectroscopy and scanning electron microscopy. (author)

  14. Characterisation of copolymer, poly (hydroxybutyrate-co-hydroxyvalerate) (PHB-co-PHV) produced by Halomonas campisalis (MCM B-1027), its biodegradability and potential application.

    Science.gov (United States)

    Kulkarni, Snehal O; Kanekar, Pradnya P; Jog, Jyoti P; Patil, Prashant A; Nilegaonkar, Smita S; Sarnaik, Seema S; Kshirsagar, Pranav R

    2011-06-01

    Characterisation of polyhydroxyalkanoate (PHA) film produced by haloalkalitolerant Halomonas campisalis (MCM B-1027) in 14L SS fermenter revealed it to have composition of monomer units, HB:HV as 96:4 as analysed by (1)H NMR indicating the PHA as a co-polymer of PHB-co-PHV, molecular weight by gel permeation chromatography as 2.08 × 10(6), melting temperature 166.51°C, tensile strength 18.8 MPa; two relaxations namely beta transition corresponding to the glass rubber transition and alpha transition corresponding to crystalline relaxation by Dynamic Mechanical Thermal analysis and only one relaxation corresponding to MWS interfacial polarisation with activation energy of 129 kJ/mol by broadband dielectric spectroscopy. Optical microscopic studies showed typical Maltese-cross pattern of spherulites. The PHA film was found to be biodegradable by standard ASTM method as well as by soil burial method. The leak proof polymer bags prepared from the film could be used as a packaging material.

  15. INCLUSION COMPLEX FORMATION BETWEEN α-CYCLODEXTRIN AND BIODEGRADABLE COMBLIKE COPOLYMERS WITH POLY(α,β-MALIC ACID) BACKBONES AND mPEG SIDE CHAINS

    Institute of Scientific and Technical Information of China (English)

    Jing Zeng; Yuan Li; Jia-jing Li; Rui Wang; Bin He; Yu Nie; Xiang-lin Luo; Zhi-rong Zhang; Zhong-wei Gua

    2009-01-01

    Inclusion complexes(ICs)composed of ocyclodextrins(α-CD)and biodegradable comblike copolymers with poly(α,β-malic acid)(PMA)backbones and methylated poly(ethylene glycol)(mPEG)side chains were prepared by the host-guest reaction.Two series of ICs with mPEG750 and mPEG2000 were prepared.The stoichiometry(EG/CD)of all the ICs in mPEG2000 series was 3.1,no matter what the graft degree was.While in mPEG750 series,the stoichiometry(EG/CD)was very different;it increased with the amount of mPEG decreasing.The decomposition temperatures of the fragments in ICs were closely related to graft degrees.The stack of α-CDs in ICs was a channel-type structure.The crystal of ICs was lamellar,and it could be reorganized to well-defined supermolecular structure.

  16. Anthracycline antibiotics non-covalently incorporated into the block copolymer micelles: in vivo evaluation of anti-cancer activity.

    Science.gov (United States)

    Batrakova, E V; Dorodnych, T Y; Klinskii, E Y; Kliushnenkova, E N; Shemchukova, O B; Goncharova, O N; Arjakov, S A; Alakhov, V Y; Kabanov, A V

    1996-11-01

    The chemosensitising effects of poly(ethylene oxide)-poly(propylene oxide)-poly-(ethylene oxide) (PEO-PPO-PEO) block copolymers (Pluronic) in multidrug-resistant cancer cells has been described recently (Alakhov VY, Moskaleva EY, Batrakova EV, Kabanov AV 1996, Biocon. Chem., 7, 209). This paper presents initial studies on in vivo evaluation of Pluronic copolymers in the treatment of cancer. The anti-tumour activity of epirubicin (EPI) and doxorubicin (DOX), solubilised in micelles of Pluronic L61, P85 and F108, was investigated using murine leukaemia P388 and daunorubicin-sensitive Sp2/0 and -resistant Sp2/0(DNR) myeloma cells grown subcutaneously (s.c.). The study revealed that the lifespan of the animals and inhibition of tumour growth were considerably increased in mice treated with drug/copolymer compositions compared with animals treated with the free drugs. The anti-tumour activity of the drug/copolymer compositions depends on the concentration of the copolymer and its hydrophobicity, as determined by the ratio of the lengths of hydrophilic PEO and hydrophobic PPO segments. The data suggest that higher activity is associated with more hydrophobic copolymers. In particular, a significant increase in lifespan (T/C> 150%) and tumour growth inhibition (> 90%) was observed in animals with Sp2/0 tumours with EPI/P85 and DOX/L61 compositions. The effective doses of these compositions caused inhibition of Sp2/0 tumour growth and complete disappearance of tumour in 33-50% of animals. Future studies will focus on the evaluation of the activity of Pluronic-based compositions against human drug-resistant tumours.

  17. Biodegradable gelatin-chitosan films incorporated with essential oils as antimicrobial agents for fish preservation.

    Science.gov (United States)

    Gómez-Estaca, J; López de Lacey, A; López-Caballero, M E; Gómez-Guillén, M C; Montero, P

    2010-10-01

    Essential oils of clove (Syzygium aromaticum L.), fennel (Foeniculum vulgare Miller), cypress (Cupressus sempervirens L.), lavender (Lavandula angustifolia), thyme (Thymus vulgaris L.), herb-of-the-cross (Verbena officinalis L.), pine (Pinus sylvestris) and rosemary (Rosmarinus officinalis) were tested for their antimicrobial activity on 18 genera of bacteria, which included some important food pathogen and spoilage bacteria. Clove essential oil showed the highest inhibitory effect, followed by rosemary and lavender. In an attempt to evaluate the usefulness of these essential oils as food preservatives, they were also tested on an extract made of fish, where clove and thyme essential oils were the most effective. Then, gelatin-chitosan-based edible films incorporated with clove essential oil were elaborated and their antimicrobial activity tested against six selected microorganisms: Pseudomonas fluorescens, Shewanella putrefaciens, Photobacterium phosphoreum, Listeria innocua, Escherichia coli and Lactobacillus acidophilus. The clove-containing films inhibited all these microorganisms irrespectively of the film matrix or type of microorganism. In a further experiment, when the complex gelatin-chitosan film incorporating clove essential oil was applied to fish during chilled storage, the growth of microorganisms was drastically reduced in gram-negative bacteria, especially enterobacteria, while lactic acid bacteria remained practically constant for much of the storage period. The effect on the microorganisms during this period was in accordance with biochemical indexes of quality, indicating the viability of these films for fish preservation.

  18. Unusual Emission of Polystyrene-Based Alternating Copolymers Incorporating Aminobutyl Maleimide Fluorophore-Containing Polyhedral Oligomeric Silsesquioxane Nanoparticles

    Directory of Open Access Journals (Sweden)

    Mohamed Gamal Mohamed

    2017-03-01

    Full Text Available In this study, we synthesized an unusual 2-aminobutyl maleimide isobutyl polyhedral oligomeric silsesquioxane (MIPOSS-NHBu monomer lacking conventional fluorescent groups. We then prepared poly(styrene-alt-2-aminobutyl maleimide isobutyl POSS [poly(S-alt-MIPOSS-NHBu] and poly(4-acetoxystyrene-alt-2-aminobutyl maleimide isobutyl POSS [poly(AS-alt-MIPOSS-NHBu] copolymers through facile free radical copolymerizations using azobisisobutyronitrile as the initiator and tetrahydrofuran as the solvent. A poly(4-hydroxystyrene-alt-2-aminobutyl maleimide isobutyl POSS [poly(HS-alt-MIPOSS-NHBu] copolymer was prepared through acetoxyl hydrazinolysis of poly(AS-alt-MIPOSS-NHBu. We employed 1H, 13C, and 29Si nuclear magnetic resonance spectroscopy; Fourier transform infrared spectroscopy; differential scanning calorimetry; and photoluminescence spectroscopy to investigate the structures and the thermal and optical properties of the monomers and novel POSS-containing alternating copolymers. Intramolecular hydrogen bonding between the amino and dihydrofuran-2,5-dione group and clustering of the locked C=O groups from the POSS nanoparticles in the MIPOSS-NHBu units restricted the intramolecular motion of the polymer chain, causing it to exhibit strong light emission. As a result, the MIPOSS-NHBu monomer and the poly(AS-alt-MIPOSS-NHBu copolymer both have potential applicability in the detection of metal ions with good selectivity.

  19. Synthesis, Characteristics and Potential Application of Poly(β-Amino Ester Urethane)-Based Multiblock Co-Polymers as an Injectable, Biodegradable and pH/Temperature-Sensitive Hydrogel System.

    Science.gov (United States)

    Huynh, Cong Truc; Nguyen, Minh Khanh; Jeong, In Ki; Kim, Sung Wan; Lee, Doo Sung

    2012-01-01

    Physical polymeric hydrogels have significant potential for use as injectable depot drug/protein-delivery systems. In this study, a series of novel injectable, biodegradable and pH/temperature-sensitive multiblock co-polymer physical hydrogels composed of poly(ethylene glycol) (PEG) and poly(β-amino ester urethane) (PEU) was synthesized by the polyaddition between the isocyanate groups of 1,6-diisocyanato hexamethylene and the hydroxyl groups of PEG and a synthesized monomer BTB (or ETE) in chloroform in the presence of dibutyltin dilaurate as a catalyst. The synthesized co-polymers were characterized by nuclear magnetic resonance spectroscopy, Fourier transform infrared spectroscopy and gel-permeation chromatography. Aqueous solutions of the co-polymers showed a sol-to-gel phase transition with increasing pH and a gel-to-sol phase transition with increasing temperature. The gel regions covered the physiological conditions (37°C, pH 7.4) and could be controlled by changing the molecular weight of PEG, PEG/PEU ratio and co-polymer solution concentration. A gel formed rapidly in situ after injecting the co-polymer solution subcutaneously into SD rats and remained for more than 2 weeks in the body. The cytotoxicity tests confirmed the non-cytotoxicity of this co-polymer hydrogel. The controlled in vitro release of the model anticancer drug, doxorubicin, from this hydrogel occurred over a 7-day period. This hydrogel is a potential candidate for biomedical applications and drug/protein-delivery systems.

  20. Biodegradable block poly(ester-urethane)s based on poly(3-hydroxybutyrate-co-4-hydroxybutyrate) copolymers.

    Science.gov (United States)

    Ou, Wenfeng; Qiu, Handi; Chen, Zhifei; Xu, Kaitian

    2011-04-01

    A series of block poly(ester-urethane)s (abbreviated as PU3/4HB) based on biodegradable poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P3/4HB) segments were synthesized by a facile way of melting polymerization using 1,6-hexamethylene diisocyanate (HDI) as the coupling agent and stannous octanoate (Sn(Oct)(2)) as catalyst, with different 4HB contents and segment lengths. The chemical structure, molecular weight and distribution were systematically characterized by (1)H nuclear magnetic resonance spectrum (NMR), Fourier transform infrared spectroscopy (FTIR) and gel permeation chromatography (GPC). The thermal property was studied by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The hydrophilicity was investigated by static contact angle of deionized water and CH(2)I(2). DSC curves revealed that the PU3/4HB polyurethanes have their T(g) from -25.6 °C to -4.3 °C, and crystallinity from 2.5% to 25.3%, being almost amorphous to semi-crystalline. The obtained PU3/4HBs are hydrophobic (water contact angle 77.4°-95.9°), and their surface free energy (SFE) were studied. The morphology of platelets adhered on the polyurethane film observed by scanning electron microscope (SEM) showed that platelets were activated on the PU3/4HB films which would lead to blood coagulation. The lactate dehydrogenase (LDH) assay revealed that the PU3/4HBs displayed higher platelet adhesion property than raw materials and biodegradable polymer polylactic acid (PLA) and would be potential hemostatic materials. Crystallinity degree, hydrophobicity, surface free energy and urethane linkage content play important roles in affecting the LDH activity and hence the platelet adhesion. CCK-8 assay showed that the PU3/4HB is non-toxic and well for cell growth and proliferation of mouse fibroblast L929. It showed that the hydrophobicity is an important factor for cell growth while 3HB content of the PU3/4HB is important for the cell proliferation. Through changing the

  1. Photocurable biodegradable liquid copolymers: synthesis of acrylate-end-capped trimethylene carbonate-based prepolymers, photocuring, and hydrolysis.

    Science.gov (United States)

    Matsuda, Takehisa; Kwon, Il Keun; Kidoaki, Satoru

    2004-01-01

    Various photocurable liquid biodegradable trimethylene carbonate (TMC)-based (co)oligomers were prepared by ring-opening (co)polymerization of TMC with or without L-lactide (LL) using low molecular weight poly(ethylene glycol) (PEG) (mol wt 200, 600, or 1000) or trimethylolpropane (TMP) as an initiator. Resultant (co)oligomers were pastes, viscous liquids, or liquids at room temperature, depending on the monomer composition and monomer/initiator ratio. Liquid (co)oligomers were subsequently end-capped with acrylate groups. Upon visible-light irradiation in the presence of camphorquinone as a radical generator, rapid liquid-to-solid transformation occurred to produce photocured solid. The photocuring yield increased with photoirradiation time, photointensity, and camphorquinone concentration. The photocured polymers derived from low molecular weight PEG (PEG200) and TMP exhibited much reduced hydrolysis potential compared with PEG1000-derived polymers in terms of weight loss, water uptake, and swelling depth. Force-distance curve measurements by nanoindentation using atomic force microscopy clearly showed that Young's moduli of the photocured polymer films decreased with increasing hydrolysis time. Their potential biomedical applications are discussed.

  2. Injectable biodegradable hybrid hydrogels based on thiolated collagen and oligo(acryloyl carbonate)-poly(ethylene glycol)-oligo(acryloyl carbonate) copolymer for functional cardiac regeneration.

    Science.gov (United States)

    Xu, Guohui; Wang, Xiaolin; Deng, Chao; Teng, Xiaomei; Suuronen, Erik J; Shen, Zhenya; Zhong, Zhiyuan

    2015-03-01

    Injectable biodegradable hybrid hydrogels were designed and developed based on thiolated collagen (Col-SH) and multiple acrylate containing oligo(acryloyl carbonate)-b-poly(ethylene glycol)-b-oligo(acryloyl carbonate) (OAC-PEG-OAC) copolymers for functional cardiac regeneration. Hydrogels were readily formed under physiological conditions (37°C and pH 7.4) from Col-SH and OAC-PEG-OAC via a Michael-type addition reaction, with gelation times ranging from 0.4 to 8.1 min and storage moduli from 11.4 to 55.6 kPa, depending on the polymer concentrations, solution pH and degrees of substitution of Col-SH. The collagen component in the hybrid hydrogels retained its enzymatic degradability against collagenase, and the degradation time of the hydrogels increased with increasing polymer concentration. In vitro studies showed that bone marrow mesenchymal stem cells (BMSCs) exhibited rapid cell spreading and extensive cellular network formation on these hybrid hydrogels. In a rat infarction model, the infarcted left ventricle was injected with PBS, hybrid hydrogels, BMSCs or BMSC-encapsulating hybrid hydrogels. Echocardiography demonstrated that the hybrid hydrogels and BMSC-encapsulating hydrogels could increase the ejection fraction at 28 days compared to the PBS control group, resulting in improved cardiac function. Histology revealed that the injected hybrid hydrogels significantly reduced the infarct size and increased the wall thickness, and these were further improved with the BMSC-encapsulating hybrid hydrogel treatment, probably related to the enhanced engraftment and persistence of the BMSCs when delivered within the hybrid hydrogel. Thus, these injectable hybrid hydrogels combining intrinsic bioactivity of collagen, controlled mechanical properties and enhanced stability provide a versatile platform for functional cardiac regeneration.

  3. Preliminary evaluation of radionuclides incorporation in biocompatible and biodegradable seeds; Avaliacao preliminar da incorporacao de radionuclideos em sementes biocompativeis e biodegradaveis

    Energy Technology Data Exchange (ETDEWEB)

    Roberto, Wanderley dos Santos [Centro Federal de Educacao Tecnologica de Ouro Preto (CEFET-OP), MG (Brazil); Pereira, Marivalda M.; Campos, Tarcisio P.R. de [Minas Gerais Univ., Belo Horizonte, MG (Brazil). Dept. de Engenharia Nuclear

    2001-07-01

    The present work aims the development of radioactive seeds, biocompatible and biodegradable, with the objective of adding options in the cancer treatment. The work focus on the production of seeds biodegradable that incorporate radioisotopes with half life inferior than the degradation time of the material. The idea of producing devices with biodegradable materials impregnated with radioisotopes of short half life will offer new possibilities in the cancer treatment, since they can be used following the same procedures of the permanent interstitial brachytherapy, but using degradable materials compatible with the physiological environment. It will be discussed in particular the possible application of these seeds in the treatment of prostate cancer. A review of the subject and a preliminary evaluation of the viability of production of the seeds will be presented. The method of production of the seeds is based on the incorporation of Iodine and Samarium in glass matrixes obtained by sol-gel processing, XRF, and was done in the samples produced and the incorporation of Iodine and Samarium atoms was confirmed. (author)

  4. Viability of biocompatible and biodegradable seeds production with incorporated radionuclides; Viabilidade da producao de sementes biocompativeis e biodegradaveis com radionuclideos incorporados

    Energy Technology Data Exchange (ETDEWEB)

    Roberto, W.S. [Centro Federal de Educacao Tecnologica de Ouro Preto (CEFET/OP), MG (Brazil); Pereira, M.M.; Vasconcelos, W.L.; Campos, T.P.R. [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil)], e-mail: wanderley@nuclear.ufmg.br

    2000-07-01

    The present work aims the development of radioactive seeds, biocompatible and biodegradable, with the objective of adding options in the cancer treatment. The work focus on the production of seeds biodegradable that incorporate radioisotopes with half life inferior than the degradation time of the material. The idea of producing devices with biodegradable materials impregnated with radioisotopes of short half life will offer new possibilities in the cancer treatment, since they can be used following the same procedures of the permanent interstitial brachytherapy, but using degradable materials compatible with the physiological environment. It will be discussed in particular the possible application of these seeds in the treatment of prostate cancer. A review of the subject and a preliminary evaluation of the viability of production of the seeds will be presented. The method of production of the seeds is based on the incorporation of Iodine and Samarium in glass matrixes obtained by sol-gel processing. X-ray fluorescence was done in the samples produced and the incorporation of Iodine and Samarium atoms was confirmed. (author)

  5. Biodegradable elastomeric scaffolds for soft tissue engineering

    NARCIS (Netherlands)

    Pego, Ana Paula; Poot, André A.; Grijpma, Dirk W.; Feijen, Jan

    2003-01-01

    Elastomeric copolymers of 1,3-trimethylene carbonate (TMC) and ε-caprolactone (CL) and copolymers of TMC and D,L-lactide (DLLA) have been evaluated as candidate materials for the preparation of biodegradable scaffolds for soft tissue engineering. TMC-DLLA copolymers are amorphous and degrade more r

  6. Mathematical modelling of oil spill fate and transport in the marine environment incorporating biodegradation kinetics of oil droplets

    Science.gov (United States)

    Spanoudaki, Katerina

    2016-04-01

    Oil biodegradation by native bacteria is one of the most important natural processes that can attenuate the environmental impacts of marine oil spills. However, very few numerical models of oil spill fate and transport include biodegradation kinetics of spilled oil. Furthermore, in models where biodegradation is included amongst the oil transformation processes simulated, it is mostly represented as a first order decay process neglecting the effect of several important parameters that can limit biodegradation rate, such as oil composition and oil droplets-water interface. To this end, the open source numerical model MEDSKIL-II, which simulates oil spill fate and transport in the marine environment, has been modified to include biodegradation kinetics of oil droplets dispersed in the water column. MEDSLIK-II predicts the transport and weathering of oil spills following a Lagrangian approach for the solution of the advection-diffusion equation. Transport is governed by the 3D sea currents and wave field provided by ocean circulation models. In addition to advective and diffusive displacements, the model simulates several physical and chemical processes that transform the oil (evaporation, emulsification, dispersion in the water column, adhesion to coast). The fate algorithms employed in MEDSLIK-II consider the oil as a uniform substance whose properties change as the slick weathers, an approach that can lead to reduced accuracy, especially in the estimation of oil evaporation and biodegradation. Therefore MEDSLIK-II has been modified by adopting the "pseudo-component" approach for simulating weathering processes. Spilled oil is modelled as a relatively small number of discrete, non-interacting components (pseudo-components). Chemicals in the oil mixture are grouped by physical-chemical properties and the resulting pseudo-component behaves as if it were a single substance with characteristics typical of the chemical group. The fate (evaporation, dispersion

  7. Influence of organophilic ammonium-free nano clay incorporation on the mechanical properties and biodegradability of the Ecoflex; Influencia da adicao de nanoargila organofilica livre de sal de amonio nas propriedades mecanicas e na biodegradacao do Ecoflex

    Energy Technology Data Exchange (ETDEWEB)

    Morita, Reinaldo Y.; Barbosa, Ronilson V. [Empresa IOTO International - Divisao Masterbatches, Campo Magro, PR (Brazil)], e-mail: juliana.kloss@gmail.com; Richart, Fabio S.; Kloss, Juliana R. [Universidade Federal do Parana, Departamento de Quimica - UFPR, Curitiba, PR (Brazil)

    2011-07-01

    The disposable of polymeric materials, petroleum derived, represents a growing global environmental problem, causing environmental pollution to assume alarming proportions. In this context, the interest in the use and production of biodegradable materials that have character and policy has raged in various sectors of society. Besides biodegradation, is also significant investment in research and development in the nanotechnology area. Given these factors, the objective of this work was the incorporation of organophilic nanoclay ammonium-free salt (Novaclay) in the Ecoflex, mechanical properties evaluation and influences this material of the biodegradation, according to ASTM G 160. The products were characterized before and after biodegradation by analysis: visual, weight loss, differential scanning calorimetry, mechanical testing and scanning electron microscopy. The results showed that the pure Ecoflex and Ecoflex/Novaclay nanocomposite were partially biodegraded in the method used and showed morphological and mechanical properties changes. (author)

  8. Fabrication of hybrid nanocomposite scaffolds by incorporating ligand-free hydroxyapatite nanoparticles into biodegradable polymer scaffolds and release studies

    Directory of Open Access Journals (Sweden)

    Balazs Farkas

    2015-11-01

    Full Text Available We report on the optical fabrication approach of preparing free-standing composite thin films of hydroxyapatite (HA and biodegradable polymers by combining pulsed laser ablation in liquid and mask-projection excimer laser stereolithography (MPExSL. Ligand-free HA nanoparticles were prepared by ultrafast laser ablation of a HA target in a solvent, and then the nanoparticles were dispersed into the liquid polymer resin prior to the photocuring process using MPExSL. The resin is poly(propylene fumarate (PPF, a photo-polymerizable, biodegradable material. The polymer is blended with diethyl fumarate in 7:3 w/w to adjust the resin viscosity. The evaluation of the structural and mechanical properties of the fabricated hybrid thin film was performed by means of SEM and nanoindentation, respectively, while the chemical and degradation studies were conducted through thermogravimetric analysis, and FTIR. The photocuring efficiency was found to be dependent on the nanoparticle concentration. The MPExSL process yielded PPF thin films with a stable and homogenous dispersion of the embedded HA nanoparticles. Here, it was not possible to tune the stiffness and hardness of the scaffolds by varying the laser parameters, although this was observed for regular PPF scaffolds. Finally, the gradual release of the hydroxyapatite nanoparticles over thin film biodegradation is reported.

  9. Biodegradable Tri-Block Copolymer Poly(lactic acid-poly(ethylene glycol-poly(L-lysine(PLA-PEG-PLL as a Non-Viral Vector to Enhance Gene Transfection

    Directory of Open Access Journals (Sweden)

    Na Zhang

    2011-02-01

    Full Text Available Low cytotoxicity and high gene transfection efficiency are critical issues in designing current non-viral gene delivery vectors. The purpose of the present work was to synthesize the novel biodegradable poly (lactic acid-poly(ethylene glycol-poly(L-lysine (PLA-PEG-PLL copolymer, and explore its applicability and feasibility as a non-viral vector for gene transport. PLA-PEG-PLL was obtained by the ring-opening polymerization of Lys(Z-NCA onto amine-terminated NH2-PEG-PLA, then acidolysis to remove benzyloxycarbonyl. The tri-block copolymer PLA-PEG-PLL combined the characters of cationic polymer PLL, PLA and PEG: the self-assembled nanoparticles (NPs possessed a PEG loop structure to increase the stability, hydrophobic PLA segments as the core, and the primary ε-amine groups of lysine in PLL to electrostatically interact with negatively charged phosphate groups of DNA to deposit with the PLA core. The physicochemical properties (morphology, particle size and surface charge and the biological properties (protection from nuclease degradation, plasma stability, in vitro cytotoxicity, and in vitro transfection ability in HeLa and HepG2 cells of the gene-loaded PLA-PEG-PLL nanoparticles (PLA-PEG-PLL NPs were evaluated, respectively. Agarose gel electrophoresis assay confirmed that the PLA-PEG-PLL NPs could condense DNA thoroughly and protect DNA from nuclease degradation. Initial experiments showed that PLA-PEG-PLL NPs/DNA complexes exhibited almost no toxicity and higher gene expression (up to 21.64% in HepG2 cells and 31.63% in HeLa cells than PEI/DNA complexes (14.01% and 24.22%. These results revealed that the biodegradable tri-block copolymer PLA-PEG-PLL might be a very attractive candidate as a non-viral vector and might alleviate the drawbacks of the conventional cationic vectors/DNA complexes for gene delivery in vivo.

  10. Synthesis, characterizations and biocompatibility of novel biodegradable star block copolymers based on poly[(R)-3-hydroxybutyrate] and poly(epsilon-caprolactone)

    DEFF Research Database (Denmark)

    Wang, Liang; Wang, Xiaojuan; Xu, Kaitian;

    2010-01-01

    Star block copolymers based on poly[(R)-3-hydroxybutyrate] (PHB) and poly(epsilon-caprolactone) (PCL), termed SPHBCL, were successfully synthesized with structural variation on arm numbers and lengths via coupling reactions and ring opening polymerizations. Arm numbers 3, 4 and 6 of SPHBCL were...

  11. Antibacterial modification of an injectable, biodegradable, non-cytotoxic block copolymer-based physical gel with body temperature-stimulated sol-gel transition and controlled drug release.

    Science.gov (United States)

    Wang, Xiaowen; Hu, Huawen; Wang, Wenyi; Lee, Ka I; Gao, Chang; He, Liang; Wang, Yuanfeng; Lai, Chuilin; Fei, Bin; Xin, John H

    2016-07-01

    Biomaterials are being extensively used in various biomedical fields; however, they are readily infected with microorganisms, thus posing a serious threat to the public health care. We herein presented a facile route to the antibacterial modification of an important A-B-A type biomaterial using poly (ethylene glycol) methyl ether (mPEG)- poly(ε-caprolactone) (PCL)-mPEG as a typical model. Inexpensive, commercial bis(2-hydroxyethyl) methylammonium chloride (DMA) was adopted as an antibacterial unit. The effective synthesis of the antibacterial copolymer mPEG-PCL-∼∼∼-PCL-mPEG (where ∼∼∼ denotes the segment with DMA units) was well confirmed by FTIR and (1)H NMR spectra. At an appropriate modification extent, the DMA unit could render the copolymer mPEG-PCL-∼∼∼-PCL-mPEG highly antibacterial, but did not largely alter its fascinating intrinsic properties including the thermosensitivity (e.g., the body temperature-induced sol-gel transition), non-cytotoxicity, and controlled drug release. A detailed study on the sol-gel-sol transition behavior of different copolymers showed that an appropriate extent of modification with DMA retained a sol-gel-sol transition, despite the fact that a too high extent caused a loss of sol-gel-sol transition. The hydrophilic and hydrophobic balance between mPEG and PCL was most likely broken upon a high extent of quaternization due to a large disturbance effect of DMA units at a large quantity (as evidenced by the heavily depressed PCL segment crystallinity), and thus the micelle aggregation mechanism for the gel formation could not work anymore, along with the loss of the thermosensitivity. The work presented here is highly expected to be generalized for synthesis of various block copolymers with immunity to microorganisms. Light may also be shed on understanding the phase transition behavior of various multiblock copolymers.

  12. Increased axonal regeneration through a biodegradable amnionic tube nerve conduit: effect of local delivery and incorporation of nerve growth factor/hyaluronic acid media.

    Science.gov (United States)

    Mohammad, J A; Warnke, P H; Pan, Y C; Shenaq, S

    2000-01-01

    The authors emphasize the possible pharmacological enhancement of axonal regeneration using a specific growth factor/ extracellular media incorporated in a biodegradable nonneural nerve conduit material. They investigated the early effects on nerve regeneration of continuous local delivery of nerve growth factor (NGF) and the local incorporation of hyaluronic acid (HA) inside a newly manufactured nerve conduit material from fresh human amnionic membrane. Human amnionic membrane contains important biochemical factors that play a major neurotrophic role in the nerve regeneration process. The process of manufacturing a nerve conduit from fresh human amnionic membrane is described. This nerve conduit system was used in rabbits to bridge a 25-mm nerve gap over 3 months. NGF was released locally, over 28 days, at the distal end of the tube via a system of slow release, and HA was incorporated inside the lumen of the tube at the time of surgery. NGF/HA treatment promoted axonal regeneration across the amnionic tube nerve conduit (8,962 +/- 383 myelinated axons) 45% better than the nontreated amnionic tube group (6,180 +/- 353 myelinated axons). The authors demonstrate that NGF/HA media enhances additional axonal regeneration in the amnionic tube nerve conduit. This result is secondary to the effect of the amnion promoting biochemical factors, in combination with the NGF/HA effect on facilitating early events in the nerve regeneration process.

  13. Efficacy of Cinnamaldehyde Against Enteric Viruses and Its Activity After Incorporation Into Biodegradable Multilayer Systems of Interest in Food Packaging.

    Science.gov (United States)

    Fabra, M J; Castro-Mayorga, J L; Randazzo, W; Lagarón, J M; López-Rubio, A; Aznar, R; Sánchez, G

    2016-06-01

    Cinnamaldehyde (CNMA), an organic compound that gives cinnamon its flavor and odor, was investigated for its virucidal activity on norovirus surrogates, murine norovirus (MNV) and feline calicivirus (FCV), and hepatitis A virus (HAV). Initially, different concentrations of CNMA (0.1, 0.5 and 1 %) were individually mixed with each virus at titers of ca. 6-7 log10 TCID50/ml and incubated 2 h at 4 and 37 °C. CNMA was effective in reducing the titers of norovirus surrogates in a dose-dependent manner after 2 h at 37 °C, while HAV titers were reduced by 1 log10 after treatment with 1 % of CNMA. When incubation time was extended, HAV titers were reduced by 3.4 and 2.7 log10 after overnight incubation at 37 °C with 1 and 0.5 % of CNMA, respectively. Moreover, this paper analyzed, for the first time, the antiviral activity of adding an active electrospun interlayer based on zein and CNMA to a polyhydroxybutyrate packaging material (PHB) in a multilayer form. Biodegradable multilayer systems prepared with 2.60 mg/cm(2) (~9.7 %) of CNMA completely inactivated FCV according to ISO 22196:2011, while MNV titers were reduced by 2.75 log10. When the developed multilayer films were evaluated after one month of preparation or at 25 °C, the antiviral activity was reduced as compared to freshly prepared multilayer films evaluated at 37 °C. The results show the excellent potential of this system for food contact applications as well as for active packaging technologies in order to maintain or extend food quality and safety.

  14. Biodegradable thermogels.

    Science.gov (United States)

    Park, Min Hee; Joo, Min Kyung; Choi, Bo Gyu; Jeong, Byeongmoon

    2012-03-20

    All living creatures respond to external stimuli. Similarly, some polymers undergo conformational changes in response to changes in temperature, pH, magnetic field, electrical field, or the wavelength of light. In one type of stimuli-responsive polymer, thermogel polymers, the polymer aqueous solution undergoes sol-to-gel transition as the temperature increases. Drugs or cells can be mixed into the polymer aqueous solution when it is in its lower viscosity solution state. After injection of the solution into a target site, heating prompts the formation of a hydrogel depot in situ, which can then act as a drug releasing system or a cell growing matrix. In this Account, we describe key materials developed in our laboratory for the construction of biodegradable thermogels. We particularly emphasize recently developed polypeptide-based materials where the secondary structure and nanoassembly play an important role in the determining the material properties. This Account will provide insights for controlling parameters, such as the sol-gel transition temperature, gel modulus, critical gel concentration, and degradability of the polymer, when designing a new thermogel system for a specific biomedical application. By varying the stereochemistry of amino acids in polypeptides, the molecular weight of hydrophobic/hydrophilic blocks, the composition of the polypeptides, the hydrophobic end-capping of the polypeptides, and the microsequences of a block copolymer, we have controlled the thermosensitivity and nanoassembly patterns of the polymers. We have investigated a series of thermogel biodegradable polymers. Polymers such as poly(lactic acid-co-glycolic acid), polycaprolactone, poly(trimethylene carbonate), polycyanoacrylate, sebacic ester, polypeptide were used as hydrophobic blocks, and poly(ethylene glycol) and poly(vinyl pyrrolidone) were used as hydrophilic blocks. To prepare a polymer sensitive to pH and temperature, carboxylic acid or amine groups were introduced

  15. Evaluation of electron beam radiation effects in the incorporation of Piassava fibers (Attalea funifera Mart.) on ethylene vinyl alcohol copolymer (EVOH); Avaliacao dos efeitos da radiacao ionizante por feixe de eletrons na incorporacao de fibra de Piacava (Attalea funifera Mart.) no copolimero de etileno e alcool vinilico (EVOH)

    Energy Technology Data Exchange (ETDEWEB)

    Nogueira, Beatriz Ribeiro

    2012-07-01

    The aim of this work is to explore the contribution of ionizing radiation in the incorporation of piassava fibers (derived from wastes from broom factories) in the ethylene vinyl alcohol copolymer (EVOH), to obtain a composite material, {sup E}VOH-Piassava{sup ,} for packaging applications. The interest in this fiber is due to its inherent properties and morphology as well as being biodegradable. The EVOH composite reinforced with 5% or 10%, by weight of piassava fiber powder with a particle size equal to or less than 125 {mu}m, untreated or treated with 1% silane, were obtained by extrusion, using a twin screw extruder. For carrying out the tensile tests and oxygen barrier of the materials obtained, films were produced from composite materials and EVOH resin was obtained using the process of flat extrusion. Samples of EVOH and the composites were irradiated using an electron accelerator, at doses from 0 to 500 kGy. The results of SEM analysis and X-ray diffraction of composites suggest a good fiber-matrix adhesion, which can be also confirmed by its higher tensile strength at break, compared to that of neat EVOH. The results showed that the incorporation of piassava fibers can promote better oxygen barrier compared to the neat EVOH, in conditions of high humidity. It was observed that, after irradiation, the EVOH film showed better oxygen barrier in high humidity condition, when compared to the non-irradiated EVOH under the same condition, indicating radiation as an effective treatment to improve oxygen barrier in the studied conditions. (author)

  16. Biodegradable polymeric prodrugs of naltrexone

    NARCIS (Netherlands)

    Bennet, D.B.; Li, X.; Adams, N.W.; Kim, S.W.; Hoes, C.J.T.; Feijen, J.

    1991-01-01

    The development of a biodegradable polymeric drug delivery system for the narcotic antagonist naltrexone may improve patient compliance in the treatment of opiate addiction. Random copolymers consisting of the ¿-amino acids N5-(3-hydroxypropyl--glutamine and -leucine were synthesized with equimolar

  17. Rapid self-assembly of block copolymers to photonic crystals

    Energy Technology Data Exchange (ETDEWEB)

    Xia, Yan; Sveinbjornsson, Benjamin R; Grubbs, Robert H; Weitekamp, Raymond; Miyake, Garret M; Atwater, Harry A; Piunova, Victoria; Daeffler, Christopher Scot; Hong, Sung Woo; Gu, Weiyin; Russell, Thomas P.

    2016-07-05

    The invention provides a class of copolymers having useful properties, including brush block copolymers, wedge-type block copolymers and hybrid wedge and polymer block copolymers. In an embodiment, for example, block copolymers of the invention incorporate chemically different blocks comprising polymer size chain groups and/or wedge groups that significantly inhibit chain entanglement, thereby enhancing molecular self-assembly processes for generating a range of supramolecular structures, such as periodic nanostructures and microstructures. The present invention also provides useful methods of making and using copolymers, including block copolymers.

  18. PCL-PDMS-PCL copolymer-based microspheres mediate cardiovascular differentiation from embryonic stem cells

    Science.gov (United States)

    Song, Liqing

    Poly-epsilon-caprolactone (PCL) based copolymers have received much attention as drug or growth factor delivery carriers and tissue engineering scaffolds due to their biocompatibility, biodegradability, and tunable biophysical properties. Copolymers of PCL and polydimethylsiloxane (PDMS) also have shape memory behaviors and can be made into thermoresponsive shape memory polymers for various biomedical applications such as smart sutures and vascular stents. However, the influence of biophysical properties of PCL-PDMS-PCL copolymers on stem cell lineage commitment is not well understood. In this study, PDMS was used as soft segments of varying length to tailor the biophysical properties of PCL-based co-polymers. While low elastic modulus (embryonic stem cells, the range of 60-100 MPa PCL-PDMS-PCL showed little influence on the differentiation. Then different size (30-140 mum) of microspheres were fabricated from PCL-PDMS-PCL copolymers and incorporated within embryoid bodies (EBs). Mesoderm differentiation was induced using bone morphogenetic protein (BMP)-4 for cardiovascular differentiation. Differential expressions of mesoderm progenitor marker KDR and vascular markers CD31 and VE-cadherin were observed for the cells differentiated from EBs incorporated with microspheres of different size, while little difference was observed for cardiac marker alpha-actinin expression. Small size of microspheres (30 mum) resulted in higher expression of KDR while medium size of microspheres (94 mum) resulted in higher CD31 and VE-cadherin expression. This study indicated that the biophysical properties of PCL-based copolymers impacted stem cell lineage commitment, which should be considered for drug delivery and tissue engineering applications.

  19. Skin delivery by block copolymer nanoparticles (block copolymer micelles).

    Science.gov (United States)

    Laredj-Bourezg, Faiza; Bolzinger, Marie-Alexandrine; Pelletier, Jocelyne; Valour, Jean-Pierre; Rovère, Marie-Rose; Smatti, Batoule; Chevalier, Yves

    2015-12-30

    Block copolymer nanoparticles often referred to as "block copolymer micelles" have been assessed as carriers for skin delivery of hydrophobic drugs. Such carriers are based on organic biocompatible and biodegradable materials loaded with hydrophobic drugs: poly(lactide)-block-poly(ethylene glycol) copolymer (PLA-b-PEG) nanoparticles that have a solid hydrophobic core made of glassy poly(d,l-lactide), and poly(caprolactone)-block-poly(ethylene glycol) copolymer (PCL-b-PEG) nanoparticles having a liquid core of polycaprolactone. In vitro skin absorption of all-trans retinol showed a large accumulation of retinol in stratum corneum from both block copolymer nanoparticles, higher by a factor 20 than Polysorbate 80 surfactant micelles and by a factor 80 than oil solution. Additionally, skin absorption from PLA-b-PEG nanoparticles was higher by one order of magnitude than PCL-b-PEG, although their sizes (65nm) and external surface (water-swollen PEG layer) were identical as revealed by detailed structural characterizations. Fluorescence microscopy of histological skin sections provided a non-destructive picture of the storage of Nile Red inside stratum corneum, epidermis and dermis. Though particle cores had a different physical states (solid or liquid as measured by (1)H NMR), the ability of nanoparticles for solubilization of the drug assessed from their Hildebrand solubility parameters appeared the parameter of best relevance regarding skin absorption.

  20. Glycine/Glycolic acid based copolymers

    NARCIS (Netherlands)

    Veld, in 't Peter J.A.; Shen, Zheng-Rong; Takens, Gijsbert A.J.; Dijkstra, Pieter J.; Feijen, Jan

    1994-01-01

    Glycine/glycolic acid based biodegradable copolymers have been prepared by ring-opening homopolymerization of morpholine-2,5-dione, and ring-opening copolymerization of morpholine-2,5-dione and glycolide. The homopolymerization of morpholine-2,5-dione was carried out in the melt at 200°C for 3 min u

  1. Remarkably enhanced thermal stability of an irradiation-crosslinked ethylene-octene copolymer by incorporation of a novel organic/inorganic hybrid nano-sensitizer

    Science.gov (United States)

    Zhang, Sideng; Sun, Bin; Jiang, Xiaoze; Li, Lili; Meng, Zhouqi; Zhu, Meifang

    2015-01-01

    We report a novel method to improve the anti-thermal-deformation performance of an ethylene-octene copolymer (POE) using vinyl functionalized silica nanoparticles (M-SiO2) as a sensitizer to enhance radiation-induced crosslinking. The M-SiO2 nanoparticles were prepared by coupling commercially available silica nanoparticles with KH570 (γ-methacryloxypropyl-trimethoxysilane, γ-MPS) and were blended with POE by melt blending. Then, the mixture was irradiated with γ-rays under a nitrogen atmosphere to form the crosslinked POE/M-SiO2 nanocomposite. The novel nanocomposites were characterized, and the results showed that the gel fraction was proportional to the content of M-SiO2 in the loading range studied in this work. When the content of M-SiO2 was 10 wt%, the gel fraction of POE was increased by approximately 50%, and the softening temperature (T0.5D) increased from 104.4 °C to 224.6 °C after a 120 kGy dose of radiation. The tensile strength of the POE/M-SiO2-10 nanocomposite was better than that of the neat POE copolymer irradiated with an absorption dose up to 100 kGy. In contrast, the elongation of the POE/M-SiO2-10 nanocomposite was lower than that of the neat POE irradiated under the same conditions, due to the increased degree of crosslinking by radiation. These results clearly demonstrated that the use of M-SiO2 as an irradiation sensitizer effectively enhanced the radiation-induced crosslinking of POE.

  2. Stereocomplexation in Copolymer Networks Incorporating Enantiomeric Glycerol-Based 3-Armed Lactide Oligomers and a 2-Armed ɛ-Caprolactone Oligomer

    Directory of Open Access Journals (Sweden)

    Ayaka Shibita

    2016-07-01

    Full Text Available The reactions of enantiomeric glycerol-based 3-armed lactide oligomers (H3DLAO and H3LLAO and a diethylene glycol-based 2-armed ɛ-caprolactone oligomer (H2CLO with hexamethylene diisocyanate (HDI produced polyesterurethane copolymer networks (PEU-3scLAO/2CLOs 100/0, 75/25, 50/50, 25/75 and 0/100 with different feed ratios of stereocomplex (sc lactide oligomer (H3scLAO = H3DLAO + H3LLAO, H3DLAO/H3LLAO = 1/1 and H2CLO. Thermal and mechanical properties of the copolymer networks were compared with those of a simple homochiral (hc network (PEU-3DLAO produced by the reaction of H3DLAO and HDI. X-ray diffraction and differential scanning calorimetric analyses revealed that sc crystallites are formed without any hc crystallization for PEU-3scLAO/2CLOs, and that PEU-3DLAO is amorphous. The melting temperatures of sc crystallites for PEU-3scLAO/2CLOs were much higher than that of hc crystallites of H3DLAO. The polarized optical microscopic analysis revealed that the nucleation efficiency is enhanced with increasing feed of H3scLAO fraction, whereas the spherulite growth rate is accelerated with increasing feed H2CLO fraction over 100/0-50/50 networks. PEU-3scLAO/2CLO 100/0 (i.e., PEU-3scLAO exhibited a higher tensile strength and modulus than PEU-3DLAO. The elongation at break and tensile toughness for PEU-3scLAO/2CLOs increased with an increasing feed amount of H2CLO.

  3. Drug governs the morphology of polyalkylated block copolymer aggregates.

    Science.gov (United States)

    Le Dévédec, F; Her, S; Vogtt, K; Won, A; Li, X; Beaucage, G; Yip, C; Allen, C

    2017-02-16

    Polyalkylated copolymers based on mPEG-b-(AGE-C6,12 or 18)25 have been used to formulate clinically relevant concentrations of doxorubicin (DOX) and the impact of drug incorporation on copolymer aggregation behaviour was examined. The copolymer aggregates were analyzed by various microscopy techniques (TEM, cryo-TEM and AFM) and scattering methods (SANS, DLS). In the absence of the drug, the copolymers formed largely non-spherical aggregates (i.e. cylinders, vesicles). Drug incorporation during copolymer aggregate formation directed the formation of only spherical aggregates. As well, the nature of the core-forming block was found to influence drug release and cytotoxicity of the formulations.

  4. Volatile organic compound detection using nanostructured copolymers.

    Science.gov (United States)

    Li, Bo; Sauvé, Genevieve; Iovu, Mihaela C; Jeffries-El, Malika; Zhang, Rui; Cooper, Jessica; Santhanam, Suresh; Schultz, Lawrence; Revelli, Joseph C; Kusne, Aaron G; Kowalewski, Tomasz; Snyder, Jay L; Weiss, Lee E; Fedder, Gary K; McCullough, Richard D; Lambeth, David N

    2006-08-01

    Regioregular polythiophene-based conductive copolymers with highly crystalline nanostructures are shown to hold considerable promise as the active layer in volatile organic compound (VOC) chemresistor sensors. While the regioregular polythiophene polymer chain provides a charge conduction path, its chemical sensing selectivity and sensitivity can be altered either by incorporating a second polymer to form a block copolymer or by making a random copolymer of polythiophene with different alkyl side chains. The copolymers were exposed to a variety of VOC vapors, and the electrical conductivity of these copolymers increased or decreased depending upon the polymer composition and the specific analytes. Measurements were made at room temperature, and the responses were found to be fast and appeared to be completely reversible. Using various copolymers of polythiophene in a sensor array can provide much better discrimination to various analytes than existing solid state sensors. Our data strongly indicate that several sensing mechanisms are at play simultaneously, and we briefly discuss some of them.

  5. BIODEGRADABLE MICROSPHERES: A REVIEW

    Directory of Open Access Journals (Sweden)

    Kaur Dupinder

    2012-12-01

    Full Text Available Microspheres are characteristically free flowing powders consisting of proteins or synthetic polymers having a particle size ranging from 1-1000 μm. The range of techniques for the preparation of microspheres offers a variety of opportunities to control aspects of drug administration and enhance the therapeutic efficacy of a given drug. Of the many polymeric drug delivery systems, biodegradable polymers have been used widely as drug delivery systems because of their biocompatibility and biodegradability. The majority of biodegradable polymers have been used in the form of microparticles, from which the incorporated drug is released to the environment in a controlled manner. They can be employed to deliver medication in a rate-controlled and sometimes targeted manner. Medication is released from a microsphere by drug leaching from the polymer or by degradation of the polymer matrix. This review discusses characteristics and degradation behaviors of biodegradable polymers which are currently used in drug delivery.

  6. FRET Imaging Trackable Long-Circulating Biodegradable Nanomedicines for Ovarian Cancer Therapy

    Science.gov (United States)

    2014-09-01

    Award Number: W81XWH-13-1-0160 TITLE: FRET Imaging Trackable Long-Circulating Biodegradable ...TITLE AND SUBTITLE FRET Imaging Trackable Long-Circulating Biodegradable Nanomedicines for Ovarian Cancer Therapy 5a. CONTRACT NUMBER...strategy, which permits visualizing the biodegradation of copolymer-drug conjugates at the body, tissue and cell levels in real time. The information

  7. A free-standing, sheet-shaped, "hydrophobic" biomaterial containing polymeric micelles formed from poly(ethylene glycol)-poly(lactic acid) block copolymer for possible incorporation/release of "hydrophilic" compounds.

    Science.gov (United States)

    Moroishi, Hitomi; Yoshida, Chikara; Murakami, Yoshihiko

    2013-02-01

    Sheet-shaped materials with a large contact area relative to the drug targeting site lead to advantages over conventional particle-shaped drug carriers and have several advantages for their biomedical applications. The present study proposes a methodology for preparing a novel sheet-shaped "hydrophobic" and biocompatible biomaterial in which polymeric micelles are uniformly dispersed for the incorporation of "hydrophilic" compounds into the sheet. The methoxy-terminated poly(ethylene glycol)-block-poly(lactic acid) block copolymer (CH(3)O-PEG-b-PLA) was successfully synthesized by means of the anionic ring-opening polymerization of both ethylene oxide and dl-lactide. CH(3)O-PEG-b-PLA was self-assembled and formed stable micelle-like w/o emulsion with a hydrophilic inner core in organic solvents. A sheet-shaped material containing a hydrophilic inner space for incorporating hydrophilic compounds was obtained by spin-coating both the micelle solution and a sheet-forming polymer. Fluorescent images of the sheet proved that polymeric micelles providing hydrophilic spaces were uniformly dispersed in the hydrophobic sheet. The facile technique presented in this paper can be a tool for fabricating sheet-shaped biomaterials that have a hydrophilic inner core and, consequently, that are suitable for the sustained release of hydrophilic compounds.

  8. Polyhydroxyalkanoate copolymers from forest biomass.

    Science.gov (United States)

    Keenan, Thomas M; Nakas, James P; Tanenbaum, Stuart W

    2006-07-01

    The potential for the use of woody biomass in poly-beta-hydroxyalkanoate (PHA) biosynthesis is reviewed. Based on previously cited work indicating incorporation of xylose or levulinic acid (LA) into PHAs by several bacterial strains, we have initiated a study for exploring bioconversion of forest resources to technically relevant copolymers. Initially, PHA was synthesized in shake-flask cultures of Burkholderia cepacia grown on 2.2% (w/v) xylose, periodically amended with varying concentrations of levulinic acid [0.07-0.67% (w/v)]. Yields of poly(beta-hydroxybutyrate-co-beta-hydroxyvalerate) [P(3HB-co-3HV)] from 1.3 to 4.2 g/l were obtained and could be modulated to contain from 1.0 to 61 mol% 3-hydroxyvalerate (3HV), as determined by 1H and 13C NMR analyses. No evidence for either the 3HB or 4HV monomers was found. Characterization of these P(3HB-co-3HV) samples, which ranged in molecular mass (viscometric, Mv) from 511-919 kDa, by differential scanning calorimetry and thermogravimetric analyses (TGA) provided data which were in agreement for previously reported P(3HB-co-3HV) copolymers. For these samples, it was noted that melting temperature (Tm) and glass transition temperature (Tg) decreased as a function of 3HVcontent, with Tm demonstrating a pseudoeutectic profile as a function of mol% 3HV content. In order to extend these findings to the use of hemicellulosic process streams as an inexpensive carbon source, a detoxification procedure involving sequential overliming and activated charcoal treatments was developed. Two such detoxified process hydrolysates (NREL CF: aspen and CESF: maple) were each fermented with appropriate LA supplementation. For the NREL CF hydrolysate-based cultures amended with 0.25-0.5% LA, P(3HB-co-3HV) yields, PHA contents (PHA as percent of dry biomass), and mol% 3HV compositions of 2.0 g/l, 40% (w/w), and 16-52 mol% were obtained, respectively. Similarly, the CESF hydrolysate-based shake-flask cultures yielded 1.6 g/l PHA, 39% (w

  9. Biodegradable polymersomes for targeted ultrasound imaging

    NARCIS (Netherlands)

    Zhou, W.; Meng, F.; Engbers, G.H.M.; Feijen, J.

    2006-01-01

    Biodegradable polymersomes with a sub-micron size were prepared by using poly(ethylene glycol)–polylactide (PEG–PDLLA) block-copolymers in aqueous media. Air-encapsulated polymersomes could be obtained by a lyophilization/rehydration procedure. Preliminary results showed that these polymersomes were

  10. Tuning the processability, morphology and biodegradability of clay incorporated PLA/LLDPE blends via selective localization of nanoclay induced by melt mixing sequence

    Directory of Open Access Journals (Sweden)

    S. H. Jafari

    2013-01-01

    Full Text Available Polylactic acid (PLA/linear low density polyethylene (LLDPE blend nanocomposites based on two different commercial-grade nanoclays, Cloisite® 30B and Cloisite® 15A, were produced via different melt mixing procedures in a counter-rotating twin screw extruder. The effects of mixing sequence and clay type on morphological and rheological behaviors as well as degradation properties of the blends were investigated. The X-ray diffraction (XRD results showed that generally the level of exfoliation in 30B based nanocomposites was better than 15A based nanocomposites. In addition, due to difference in hydrophilicity and kind of modifiers in these two clays, the effect of 30B on refinement of dispersed phase and enhancement of biodegradability of PLA/LLDPE blend was much more remarkable than that of 15A nanoclay. Unlike the one step mixing process, preparation of nanocomposites via a two steps mixing process improved the morphology. Based on the XRD and TEM (transmission electron microscopic results, it is found that the mixing sequence has a remarkable influence on dispersion and localization of the major part of 30B nanoclay in the PLA matrix. Owing to the induced selective localization of nanoclays in PLA phase, the nanocomposites prepared through a two steps mixing sequence exhibited extraordinary biodegradability, refiner morphology and better melt elasticity.

  11. In vitro biocompatibility and antibacterial efficacy of a degradable poly(L-lactide-co-epsilon-caprolactone) copolymer incorporated with silver nanoparticles.

    Science.gov (United States)

    Samberg, Meghan E; Mente, Peter; He, Ting; King, Martin W; Monteiro-Riviere, Nancy A

    2014-07-01

    Silver nanoparticles (Ag-nps) are currently used as a natural biocide to prevent undesired bacterial growth in clothing, cosmetics and medical products. The objective of the study was to impart antibacterial properties through the incorporation of Ag-nps at increasing concentrations to electrospun degradable 50:50 poly(L-lactide-co-epsilon-caprolactone) scaffolds for skin tissue engineering applications. The biocompatibility of the scaffolds containing Ag-nps was evaluated with human epidermal keratinocytes (HEK); cell viability and proliferation were evaluated using Live/Dead and alamarBlue viability assays following 7 and 14 days of cell culture on the scaffolds. Significant decreases in cell viability and proliferation were noted for the 1.0 mg(Ag) g(scaffold)(-1) after 7 and 14 days on Ag-nps scaffolds. After 14 days, scanning electron microscopy revealed a confluent layer of HEK on the surface of the 0.0 and 0.1 mg(Ag) g(scaffold)(-1). Both 0.5 and 1.0 mg(Ag) g(scaffold)(-1) were capable of inhibiting both Gram positive and negative bacterial strains. Uniaxial tensile tests revealed a significant (p < 0.001) decrease in the modulus of elasticity following Ag-nps incorporation compared to control. These findings suggest that a scaffold containing between 0.5 and 1.0 mg(Ag) g(scaffold)(-1) is both biocompatible and antibacterial, and is suitable for skin tissue engineering graft scaffolds.

  12. Incorporation of Hexa-peri-hexabenzocoronene (HBC) into Carbazole-Benzo-2,1,3-thiadiazole Copolymers to Improve Hole Mobility and Photovoltaic Performance.

    Science.gov (United States)

    Gao, Chen; Jiang, Pei; Shi, Keli; Ma, Di; Li, Yongfang; Yu, Gui; Li, Xiaoyu; Wang, Haiqiao

    2016-03-04

    Hexa-peri-hexabenzocoronene (HBC) is a discotic-shaped conjugated molecule with strong π-π stacking property, high intrinsic charge mobility, and good self-assembly properties. For a long time, however, organic photovoltaic (OPV) solar cells based on HBC demonstrated low power conversion efficiencies (PCEs). In this study, two conjugated terpolymers, poly[N-9'-heptadecanyl-2,7-carbazole-alt-5,5'-(4',7'-di-2-thienyl-2',1',3'-benzothiadiazole)] (PCDTBT)-5 HBC and PCDTBT-10 HBC, were synthesized by incorporating different amounts of HBC as the third component into poly[N-9'-heptadecanyl-2,7-carbazole-alt-5,5'-(4',7'-di-2-thienyl-2',1',3'-benzothiadiazole)] (PCDTBT) through Suzuki coupling polymerization. For comparison, the donor-acceptor (D-A) conjugated dipolymer PCDTBT was also synthesized to investigate the effect of HBC units on conjugated polymers. The HBC-containing polymers exhibited higher thermal stabilities, broader absorption spectra, and lower highest-occupied molecular orbital (HOMO) energy levels. In particular, the field-effect mobilities were enhanced by more than one order of magnitude after the incorporation of HBC into the conjugated polymer backbone on account of increased interchain π-π stacking interactions. The bulk heterojunction (BHJ) polymer solar cells (PSCs) fabricated with the polymers as donor and PC71 BM as acceptor demonstrated gradual improvement of open-circuit voltage (VOC ) and short-circuit current (JSC ) with the increase in HBC content. As a result, the PCEs were improved from 3.21 % for PCDTBT to 3.78 % for PCDTBT-5 HBC and then to 4.20 % for PCDTBT-10 HBC.

  13. Incorporação de urucum como aditivo antioxidante em embalagens biodegradáveis a base de quitosana The incorporation of annatto as antioxidant additive based biodegradable packaging chitosan

    Directory of Open Access Journals (Sweden)

    Maria Cecília Castelo Branco de Santana

    2013-03-01

    Full Text Available O objetivo do trabalho foi desenvolver e caracterizar uma embalagem biodegradável, utilizando como matriz polimérica a quitosana, plastificada com glicerol, bem como avaliar o efeito da adição de um aditivo antioxidante natural (urucum nas embalagens na proteção antioxidante. As embalagens foram preparadas por casting contendo 1,5% de quitosana, 0,15% de glicerol e 0,25 a 1,0% de urucum. O azeite de dendê embalado com os filmes contendo o aditivo foi monitorado aos 0, 7, 15, 30 e 45 dias de armazenamento sob condições de oxidação acelerada (63%UR/30°C. O azeite de dendê embalado no filme que continha o maior percentual de urucum (1,0% foi o que menos oxidou ao longo do período estudado. Constatou-se que, à medida que aumentam as perdas de Fenóis Totais nas formulações dos filmes, ocorre uma redução nos aumentos do Índice de Peróxidos do produto embalado, demonstrando assim que, ao invés do produto, os compostos da embalagem é quem estão sofrendo oxidação.The objective was to develop and characterize a biodegradable packaging using chitosan as polymeric matrix, plasticized with glycerol, as well as evaluate the effect of adding a natural antioxidant additives (annatto in antioxidant protection in packaging. The cans were prepared by casting containing 1.5% of chitosan, 0.15% glycerol and 0.25 to 1.0% of coloring. Palm oil packed with the films containing the additive was monitored at 0, 7, 15, 30 and 45 days of storage under accelerated oxidation conditions (63% UR/30°C. Palm oil packed in the film that contained the highest percentage of annatto (1.0% was the least oxidized during the study period. It was found that, as they increase the losses of phenolic compounds in the formulations of the films, there is a reduction in the peroxide increases the packaged product, thus demonstrating that instead of the product, the compounds of the package's who are suffering oxidation.

  14. Poly(butylene cyclohexanedicarboxylate/diglycolate random copolymers reinforced with SWCNTs for multifunctional conductive biopolymer composites

    Directory of Open Access Journals (Sweden)

    E. Fortunati

    2016-02-01

    Full Text Available The objective of this work was to develop a versatile strategy for preparing multifunctional composite films with tunable properties. Novel conductive composites based on the combination of single walled carbon nanotubes (SWCNTs and biodegradable poly(butylene cyclohexanedicarboxylate/diglycolate random copolymers (P(BCEmBDGn are here presented. In particular, synthesized PBCE homopolymer and two copolymers containing different amounts of ether–oxygen containing co-units, P(BCE90BDG10 and P(BCE70BDG30, have been considered as matrices of SWCNTs based composites. The effect of incorporation of different amounts of SWCNTs (0.1–0.5–0.75–1 wt% on morphological, thermal, mechanical and electrical properties was deeply investigated. The morphology of the fracture surfaces is affected by the SWCNT presence, while the increase in the SWCNT content does not provide significant microstructure modifications. The thermal properties underlined that nanotubes can act as nucleating agents, favouring the polymer crystallization process. The mechanical behavior demonstrated that the introduction of carbon nanotubes both in the case of PBCE homopolymer and in random copolymers based formulations exerted a reinforcing effect. All composites exhibit high electrical conductivity in comparison to the neat polymers. This work demonstrates that this combinatorial approach can be used to develop materials with tunable and advanced functional properties.

  15. Biodegradable Polymers

    Directory of Open Access Journals (Sweden)

    Isabelle Vroman

    2009-04-01

    Full Text Available Biodegradable materials are used in packaging, agriculture, medicine and other areas. In recent years there has been an increase in interest in biodegradable polymers. Two classes of biodegradable polymers can be distinguished: synthetic or natural polymers. There are polymers produced from feedstocks derived either from petroleum resources (non renewable resources or from biological resources (renewable resources. In general natural polymers offer fewer advantages than synthetic polymers. The following review presents an overview of the different biodegradable polymers that are currently being used and their properties, as well as new developments in their synthesis and applications.

  16. Environmental biodegradation of haloarchaea-produced poly(3-hydroxybutyrate-co-3-hydroxyvalerate) in activated sludge

    DEFF Research Database (Denmark)

    Liu, Xiao-Bin; Wu, Linping; Hou, Jing

    2016-01-01

    Novel poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBHV) copolymers produced by haloarchaea are excellent candidate biomaterials. However, there is no report hitherto focusing on the biodegradation of PHBHV synthesized by haloarchaea. In this study, an environmental biodegradation of haloarchaea......-order copolymer PHBHV-1 (O-PHBHV-1) possessing the highest surface roughness. The order of biodegradation rate was in the opposite trend to the degree of crystallizability of the films. Meanwhile, thermal degradation temperature of most films decreased after biodegradation. Additionally, the surface erosion...

  17. RESEARCH ON DEGRADATION PERFORMANCE OF BIODEGRADABLE MATERIALS-POLYLACTIC ACID AND ITS COPOLYMERS%生物降解材料聚乳酸及其共聚物的降解研究

    Institute of Scientific and Technical Information of China (English)

    李金良; 周才根

    2011-01-01

    The fundamental nature, biodegradable process and machanism of PLA were introduced. The research progress of biodegrade method of PLA at home and abroad was reviewed. The effecting factors of PLA degradation were discussed. The development and application prospect of PLA were outlooked.%论述了聚乳酸(PLA)的基本性质、降解过程、降解机理,综述了国内外PLA降解方法的研究进展,探讨了降解的影响因素,并展望了PLA的开发和应用前景.

  18. A biodegradable ocular implant for long-term suppression of intraocular pressure.

    Science.gov (United States)

    Ng, Xu Wen; Liu, Kerh Lin; Veluchamy, Amutha Barathi; Lwin, Nyein Chan; Wong, Tina T; Venkatraman, Subbu S

    2015-10-01

    Timolol maleate (TM) has been used for many years for the reduction of intraocular pressure (IOP) in glaucoma patients. However, the topical mode of administration (eyedrops) is far from optimal because of the issues of low bioavailability, high drug wastage, and lack of patient compliance. Suboptimal control of the IOP leads to disease progression and eventually to blindness. Ideally, TM is delivered to the patient so that its action is both localized and sustained for 3 months or more. In this work, we developed a subconjunctival TM microfilm for sustained, long-term delivery of TM to the eyes, using the biodegradable elastomer poly(lactide-co-caprolactone) (PLC). The copolymer is biocompatible and has flexibility and mechanical characteristics suitable for a patient-acceptable implant. Controlling the release of TM for 3 months is challenging, and this work describes how, by using a combination of multilayering and blending with poly(ethylene glycol) (PEG) copolymers, we were able to develop a TM-incorporated biodegradable film that can deliver TM at a therapeutic dose for 90 days in vitro. The data was further confirmed in a diseased primate model, with sustained IOP-lowering effects for 5 months with a single implant, with acceptable biocompatibility and partial degradation.

  19. Poly(butylene succinate) and its copolymers: research, development and industrialization.

    Science.gov (United States)

    Xu, Jun; Guo, Bao-Hua

    2010-11-01

    Poly(butylene succinate) (PBS) and its copolymers are a family of biodegradable polymers with excellent biodegradability, thermoplastic processability and balanced mechanical properties. In this article, production of the monomers succinic acid and butanediol, synthesis, processing and properties of PBS and its copolymers are reviewed. The physical properties and biodegradation rate of PBS materials can be varied in a wide range through copolymerization with different types and various contents of monomers. PBS has a wide temperature window for thermoplastic processing, which makes the resin suitable for extrusion, injection molding, thermoforming and film blowing. Finally, we summarized industrialization and applications of PBS.

  20. A NEW PLLA PCL COPOLYMER FOR NERVE REGENERATION

    NARCIS (Netherlands)

    DENDUNNEN, WFA; SCHAKENRAAD, JM; ZONDERVAN, GJ; PENNINGS, AJ; VANDERLEI, B; ROBINSON, PH

    1993-01-01

    The aim of this study is to evaluate the functional and cell biological applicability of a two-ply nerve guide constructed of a PLLA/PCL (i.e. poly-L-lactide and poly-epsilon-caprolactone) copolymer. To do so, we performed a cytotoxicity test, a subcutaneous biodegradation test and an in situ implan

  1. POLY (β-HYDROXYALKANOATES): NATURAL BIOCOMPATIBLE AND BIODEGRADABLE POLYESTERS PRODUCED BY BACTERIA

    Institute of Scientific and Technical Information of China (English)

    ROBERT W.LENZ; RICHARD A.GROSS; HELMUT BRANDL; R.CLINTON FULLER

    1989-01-01

    A wide variety of different types of microorganisms are known to produce intracellular energy and carbon storage products, which have been generally described as being poly (β-hydroxybutyrate ), PHB, but which are, more often than not, copolymers containing different alkyl groups at the β-position. Hence, PHB belongs to the family ofpoly (β-hydroxyalkanoastes), PHA, all of which are usually formed as intracellular inclusions in bacteria under unbalanced growth conditions. Recently, it became of industrial interest to evaluate these PHA polyesters as natural biodegradable and biocompatible plastics for a wide range of possible applications, such as surgical sutures or packaging containers. For industrial applications, the controlled incorporation of repeating units with different chain lengths into a series ofcopolymers is desirable in order to produce polyesters with a range of material properties because physical and chemical characteristics depend strongly on the polymer composition. Such "tailor- made" copolymers can be produced under controlled growth conditions in that, if a defined mixture of substrates for a certain type of microorganisms is supplied, a well defined and reproducible copolymer is formed.

  2. Radiation crosslinking of Bionolle and its biodegradation

    Energy Technology Data Exchange (ETDEWEB)

    Suhartini, Meri; Mitomo, H. [Gunma Univ., Faculty of Engineering, Dept. of Biological and Chemical Engineering, Kiryu, Gunma (Japan); Nagasawa, Naotsugu; Yoshii, Fumio; Kume, Tamikazu [Japan Atomic Energy Research Inst., Takasaki, Gunma (Japan). Takasaki Radiation Chemistry Research Establishment

    2002-03-01

    Biodegradable aliphatic polymer such as poly(butylene succinate) (Bionolle no.1001), poly(butylene succinate adipate copolymer) (Bionolle no.3001 and no.3020) were irradiated to give crosslinking structure in the presence of inorganic materials. Pure Bionolle no.1001, Bionolle no.3001 and no. 3020 have low gel fraction in radiation. These samples have high gel fraction by irradiation in the presence of silicon dioxide and carbon black, especially for Bionolle no.3001. Biodegradability of crosslinked Bionolle no.3001 evaluated by enzymatic and soil burial tests were accelerated by addition of inorganic materials. (author)

  3. Incorporation of aqueous reaction kinetics and biodegradation intoTOUGHREACT: Application of a multi-region model to hydrobiogeoChemicaltransport of denitrification and sulfate reduction

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Tianfu

    2006-07-13

    The need to consider aqueous and sorption kinetics andmicrobiological processes arises in many subsurface problems. Ageneral-rate expression has been implemented into the TOUGHREACTsimulator, which considers multiple mechanisms (pathways) and includesmultiple product, Monod, and inhibition terms. This paper presents aformulation for incorporating kinetic rates among primary species intomass-balance equations. The space discretization used is based on aflexible integral finite difference approach that uses irregular griddingto model bio-geologic structures. A general multi-region model forhydrological transport interacted with microbiological and geochemicalprocesses is proposed. A 1-D reactive transport problem with kineticbiodegradation and sorption was used to test the enhanced simulator,which involves the processes that occur when a pulse of water containingNTA (nitrylotriacetate) and cobalt is injected into a column. The currentsimulation results agree very well with those obtained with othersimulators. The applicability of this general multi-region model wasvalidated by results from a published column experiment ofdenitrification and sulfate reduction. The matches with measured nitrateand sulfate concentrations were adjusted with the interficial areabetween mobile hydrological and immobile biological regions. Resultssuggest that TOUGHREACT can not only be a useful interpretative tool forbiogeochemical experiments, but also can produce insight into processesand parameters of microscopic diffusion and their interplay withbiogeochemical reactions. The geometric- and process-based multi-regionmodel may provide a framework for understanding field-scalehydrobiogeochemical heterogeneities and upscaling parameters.

  4. Study on biodegradable aromatic/aliphatic copolyesters

    Energy Technology Data Exchange (ETDEWEB)

    Yiwang Chen; Licheng Tan; Lie Chen; Yan, Yang; Xiaofeng Wang [Nanchang University, Nanchang (China). School of Materials Science and Engineering. Inst. of Polymer Materials]. E-mail: ywchen@ncu.edu.cn

    2008-04-15

    Progress on biodegradable aromatic/aliphatic copolyesters based on aliphatic and aromatic diacids, diols and ester monomers was reviewed. The aromatic/aliphatic copolyesters combined excellent mechanical properties with biodegradability. Physical properties and biodegradability of copolyesters varied with chain length of the aliphatic polyester segment and atacticity of copolyesters. The process ability of copolyesters could be improved significantly after incorporating a stiff chain segment through copolymerization of aliphatic polyesters with an aromatic liquid crystal element. The aromatic/aliphatic copolyesters as a new type of biodegradable materials could replace some general plastics in certain applications, namely biomedical and environmental friendly fields. (author)

  5. Additive-driven assembly of block copolymers

    Science.gov (United States)

    Lin, Ying; Daga, Vikram; Anderson, Eric; Watkins, James

    2011-03-01

    One challenge to the formation of well ordered hybrid materials is the incorporation of nanoscale additives including metal, semiconductor and dielectric nanoparticles at high loadings while maintaining strong segregation. Here we describe the molecular and functional design of small molecule and nanoparticle additives that enhance phase segregation in their block copolymer host and enable high additive loadings. Our approach includes the use of hydrogen bond interactions between the functional groups on the additive or particle that serve as hydrogen bond donors and one segment of the block copolymer containing hydrogen bond acceptors. Further, the additives show strong selectively towards the targeted domains, leading to enhancements in contrast between properties of the phases. In addition to structural changes, we explore how large changes in the thermal and mechanical properties occur upon incorporation of the additives. Generalization of this additive-induced ordering strategy to various block copolymers will be discussed.

  6. High Temperature, Low Relative Humidity, Polymer-type Membranes Based on Disulfonated Poly(arylene ether) Block and Random Copolymers Optionally Incorporating Protonic Conducting Layered Water insoluble Zirconium Fillers

    Energy Technology Data Exchange (ETDEWEB)

    McGrath, James E.; Baird, Donald G.

    2010-06-03

    Our research group has been engaged in the past few years in the synthesis of biphenol based partially disulfonated poly(arylene ether sulfone) random copolymers as potential PEMs. This series of polymers are named as BPSH-xx, where BP stands for biphenol, S stands for sulfonated, H stands for acidified and xx represents the degree of disulfonation. All of these sulfonated copolymers phase separate to form nano scale hydrophilic and hydrophobic morphological domains. The hydrophilic phase containing the sulfonic acid moieties causes the copolymer to absorb water. Water confined in hydrophilic pores in concert with the sulfonic acid groups serve the critical function of proton (ion) conduction and water transport in these systems. Both Nafion and BPSH show high proton conductivity at fully hydrated conditions. However proton transport is especially limited at low hydration level for the BPSH random copolymer. It has been observed that the diffusion coefficients of both water and protons change with the water content of the pore. This change in proton and water transport mechanisms with hydration level has been attributed to the solvation of the acid groups and the amount of bound and bulk-like water within a pore. At low hydration levels most of the water is tightly associated with sulfonic groups and has a low diffusion coefficient. This tends to encourage isolated domain morphology. Thus, although there may be significant concentrations of protons, the transport is limited by the discontinuous morphological structure. Hence the challenge lies in how to modify the chemistry of the polymers to obtain significant protonic conductivity at low hydration levels. This may be possible if one can alter the chemical structure to synthesize nanophase separated ion containing block copolymers. Unlike the BPSH copolymers, where the sulfonic acid groups are randomly distributed along the chain, the multiblock copolymers will feature an ordered sequence of hydrophilic and

  7. An amphiphilic graft copolymer-based nanoparticle platform for reduction-responsive anticancer and antimalarial drug delivery

    Science.gov (United States)

    Najer, Adrian; Wu, Dalin; Nussbaumer, Martin G.; Schwertz, Geoffrey; Schwab, Anatol; Witschel, Matthias C.; Schäfer, Anja; Diederich, François; Rottmann, Matthias; Palivan, Cornelia G.; Beck, Hans-Peter; Meier, Wolfgang

    2016-08-01

    Medical applications of anticancer and antimalarial drugs often suffer from low aqueous solubility, high systemic toxicity, and metabolic instability. Smart nanocarrier-based drug delivery systems provide means of solving these problems at once. Herein, we present such a smart nanoparticle platform based on self-assembled, reduction-responsive amphiphilic graft copolymers, which were successfully synthesized through thiol-disulfide exchange reaction between thiolated hydrophilic block and pyridyl disulfide functionalized hydrophobic block. These amphiphilic graft copolymers self-assembled into nanoparticles with mean diameters of about 30-50 nm and readily incorporated hydrophobic guest molecules. Fluorescence correlation spectroscopy (FCS) was used to study nanoparticle stability and triggered release of a model compound in detail. Long-term colloidal stability and model compound retention within the nanoparticles was found when analyzed in cell media at body temperature. In contrast, rapid, complete reduction-triggered disassembly and model compound release was achieved within a physiological reducing environment. The synthesized copolymers revealed no intrinsic cellular toxicity up to 1 mg mL-1. Drug-loaded reduction-sensitive nanoparticles delivered a hydrophobic model anticancer drug (doxorubicin, DOX) to cancer cells (HeLa cells) and an experimental, metabolically unstable antimalarial drug (the serine hydroxymethyltransferase (SHMT) inhibitor (+/-)-1) to Plasmodium falciparum-infected red blood cells (iRBCs), with higher efficacy compared to similar, non-sensitive drug-loaded nanoparticles. These responsive copolymer-based nanoparticles represent a promising candidate as smart nanocarrier platform for various drugs to be applied to different diseases, due to the biocompatibility and biodegradability of the hydrophobic block, and the protein-repellent hydrophilic block.Medical applications of anticancer and antimalarial drugs often suffer from low aqueous

  8. Lubricant Biodegradation Enhancers:Designed Chemistry and Engineered Technology

    Institute of Scientific and Technical Information of China (English)

    Chen Boshui; Gao Lingyue; Fang Jianhua; Zhang Nan; Wu Jiang; Wang Jiu

    2015-01-01

    In recent decades, a growing worldwide trend of developing the biodegradable lubricants has been prevailing to form a speciifc ifeld of green chemistry and green engineering. Enhancement of biodegradability of unreadily biodegradable petroleum-based lubricants has as such become an urgent must. For over a decade the authors have been focusing on the im-provement of biodegradability of unreadily biodegradable lubricants such as petroleum-based lubricating oils and greases. A new idea of lubricant biodegradation enhancer was put forward by the authors with the aim to stimulate the biodegradation of unreadily biodegradable lubricants by incorporating the enhancer into the lubricants in order to turn the lubricants into greener biodegradable ones and to help in situ bioremediation of lubricant-contaminated environment. This manuscript sum-marizes our recent efforts relating to the chemistry and technology of biodegradation enhancers for lubricants. Firstly, the chemistry of lubricant biodegradation enhancers was designed based on the principles of bioremediation for the treatment of hydrocarbon contaminated environment. Secondly, the ability of the designed biodegradation enhancers for increasing the biodegradability of unreadily biodegradable industrial lubricants was investigated through biodegradability evaluation tests, microbial population analysis, and biodegradation kinetics modeling. Finally, the impact of biodegradation enhancers on some crucial performance characteristics of lubricants such as lubricity and oxidation stability was tested via tribological evaluation and oxidation determinations. Our results have shown that the designed chemistry of nitrogenous and/or phos-phorous compounds such as lauroyl glutamine, oleoyl glycine, oleic diethanolamide phosphate and lauric diethanolamide borate was outstanding in boosting biodegradation of petroleum-based lubricants which was ascribed to increase the micro-bial population and decrease the oil-water interfacial

  9. Multifunctional Electrospun Nanofibers Incorporated with an Anti-infection Drug and Immobilized with Proteins

    Science.gov (United States)

    Zhou, Shufei

    Electrospinning has been used to fabricate ultrafine fibers with sizes ranging from nano to micrometers. Nanofibers electrospun from biocompatible and biodegradable polymers have been extensively investigated for their potential applications in wound healing and tissue regeneration. These nanofiber materials can be modified to incorporate bioactive molecules, such as antibacterial agents that provide infection control, or functional proteins which promote cell proliferation and tissue reconstruction. Despite the numerous studies on the development and design of nanofibers for biomedical applications, there has been little research on multifunctional nanofibers that are incorporated with both antibacterial drug(s) and bioactive proteins. The objective of the current study is, therefore, to develop nanofibers that are functionalized by several bioactive molecules. In this study, electrospinning was utilized to fabricate nanofibers from biodegradable polymers PLLA (Poly-L-lactide) and the copolymer PLLA-PEG (Polyethylene glycol)-NH2.A water soluble antibiotic drug, Tetracycline Hydrochloride (TCH), was incorporated into the electrospun nanofibers via emulsion electrospinning. The TCH-loaded nanofibers were surface modified to produce functional groups that can be further conjugated with a model protein, Bovine Serum Albumin (BSA).Drug releasing profiles of the medicated nanofibers were monitored and their antimicrobial properties were evaluated. Proteins (BSAs) immobilized on the fiber surface were verified by ATR-FTIR. The number of immobilized BSAs was determined using a UV-Vis spectrophotometer. The results of the study suggested that this multifunctional nanofibrous material could be a promising material for wound dressing or scaffolds for tissue engineering.

  10. CAVITATION PROPERTIES OF BLOCK COPOLYMER STABILIZED PHASE-SHIFT NANOEMULSIONS USED AS DRUG CARRIERS

    OpenAIRE

    Rapoport, Natalya; Christensen, Douglas A.; KENNEDY, ANNE M.; NAM, KWEONHO

    2010-01-01

    Cavitation properties of block copolymer stabilized perfluoropentane nanoemulsions have been investigated. The nanoemulsions were stabilized by two biodegradable amphiphilic block copolymers differing in the structure of the hydrophobic block, poly(ethylene oxide)-co-poly(L-lactide) (PEG-PLLA) and poly(ethylene oxide)-co-polycaprolactone (PEG-PCL). Cavitation parameters were measured in liquid emulsions and gels as a function of ultrasound pressure for unfocused or focused 1-MHz ultrasound. A...

  11. Synthesis and Characterization of Chitosan-g-poly(D, L-lactic acid) Copolymer

    Institute of Scientific and Technical Information of China (English)

    Hua YANG; Shao Bing ZHOU; Xian Mo DENG

    2005-01-01

    Biodegradable chitosan-g-poly (D, L-lactic acid) copolymers were prepared via two methods. (1) The lactide was grafted onto hydroxyl groups of chitosan by using macromolecular initiator sodium of trimethylsilyl-chitosan, (2) poly (D,L-lactic acid)(PLA) with low molecular weight can be linked to the amino group by coupling activated PLA to trimethylsilyl-chitosan. Two graft copolymers had hydrophilic-hydrophobic character and can be applied as carriers for drug delivery.

  12. Anaerobic biodegradability of macropollutants

    DEFF Research Database (Denmark)

    Angelidaki, Irini

    2002-01-01

    A variety of test procedures for determination of anaerobic biodegradability has been reported. This paper reviews the methods developed for determination of anaerobic biodegradability of macro-pollutants. Anaerobic biodegradability of micro-pollutants is not included. Furthermore, factors import...

  13. Biodegradation and bioremediation

    DEFF Research Database (Denmark)

    Albrechtsen, H.-J.

    1996-01-01

    Anmeldelse af Alexander,M.: Biodegradation and bioremediation. Academic Press, Sandiego, USA, 1994......Anmeldelse af Alexander,M.: Biodegradation and bioremediation. Academic Press, Sandiego, USA, 1994...

  14. Block and Graft Copolymers of Polyhydroxyalkanoates

    Science.gov (United States)

    Marchessault, Robert H.; Ravenelle, François; Kawada, Jumpei

    2004-03-01

    Polyhydroxyalkanoates (PHAs) were modified for diblock copolymer and graft polymer by catalyzed transesterification in the melt and by chemical synthesis to extend the side chains of the PHAs, and the polymers were studied by transmission electron microscopy (TEM) X-ray diffraction, thermal analysis and nuclear magnetic resonance (NMR). Catalyzed transesterification in the melt is used to produce diblock copolymers of poly[3-hydroxybutyrate] (PHB) and monomethoxy poly[ethylene glycol] (mPEG) in a one-step process. The resulting diblock copolymers are amphiphilic and self-assemble into sterically stabilized colloidal suspensions of PHB crystalline lamellae. Graft polymer was synthesized in a two-step chemical synthesis from biosynthesized poly[3-hydroxyoctanoate-co-3-hydroxyundecenoate] (PHOU) containing ca. 25 mol chains. 11-mercaptoundecanoic acid reacts with the side chain alkenes of PHOU by the radical addition creating thioether linkage with terminal carboxyl functionalities. The latter groups were subsequently transformed into the amide or ester linkage by tridecylamine or octadecanol, respectively, producing new graft polymers. The polymers have different physical properties than poly[3-hydroxyoctanoate] (PHO) which is the main component of the PHOU, such as non-stickiness and higher thermal stability. The combination of biosynthesis and chemical synthesis produces a hybrid thermoplastic elastomer with partial biodegradability.

  15. Resisting protein adsorption on biodegradable polyester brushes.

    Science.gov (United States)

    Hu, Xinfang; Gorman, Christopher B

    2014-08-01

    The protein adsorption and degradation behaviors of poly(lactic acid), poly(glycolic acid) (PGA) and poly(ε-caprolactone) (PCL) brushes and their co-polymer brushes with oligo(ethylene glycol) (OEG) were studied. Both brush structure and relative amount of OEG and polyester were found to be important to the protein resistance of the brushes. A protein-resisting surface can be fabricated either by using OEG as the top layer of a copolymer brush or by increasing the amount of OEG relative to polyester when using a hydroxyl terminated OEG (OEG-OH) and a methoxy terminated OEG (OEG-OMe) mixture as the substrate layer. The degradation of single polyester brushes and their co-polymer brushes using OEG-OH as a substrate layer or using OEG as a top layer was hindered. This phenomenon was rationalized by the inhibition of the proposed back-biting process as the hydroxy end groups of polyester were blocked by OEG molecules. Among these brushes tested, PGA co-polymer brushes using the methoxy/hydroxyl OEG mixture as the substrate layer proved to be both protein-resistant and degradable due to the relatively large amount of OEG moieties and the good biodegradability of PGA.

  16. Biodegradable long-circulating polymeric nanospheres.

    Science.gov (United States)

    Gref, R; Minamitake, Y; Peracchia, M T; Trubetskoy, V; Torchilin, V; Langer, R

    1994-03-18

    Injectable nanoparticulate carriers have important potential applications such as site-specific drug delivery or medical imaging. Conventional carriers, however, cannot generally be used because they are eliminated by the reticulo-endothelial system within seconds or minutes after intravenous injection. To address these limitations, monodisperse biodegradable nanospheres were developed from amphiphilic copolymers composed of two biocompatible blocks. The nanospheres exhibited dramatically increased blood circulation times and reduced liver accumulation in mice. Furthermore, they entrapped up to 45 percent by weight of the drug in the dense core in a one-step procedure and could be freeze-dried and easily redispersed without additives in aqueous solutions.

  17. Polyester-based (bio)degradable polymers as environmentally friendly materials for sustainable development.

    Science.gov (United States)

    Rydz, Joanna; Sikorska, Wanda; Kyulavska, Mariya; Christova, Darinka

    2014-12-29

    This review focuses on the polyesters such as polylactide and polyhydroxyalkonoates, as well as polyamides produced from renewable resources, which are currently among the most promising (bio)degradable polymers. Synthetic pathways, favourable properties and utilisation (most important applications) of these attractive polymer families are outlined. Environmental impact and in particular (bio)degradation of aliphatic polyesters, polyamides and related copolymer structures are described in view of the potential applications in various fields.

  18. Biodegradable polyesters based on succinic acid

    Directory of Open Access Journals (Sweden)

    Nikolić Marija S.

    2003-01-01

    Full Text Available Two series of aliphatic polyesters based on succinic acid were synthesized by copolymerization with adipic acid for the first series of saturated polyesters, and with fumaric acid for the second series. Polyesters were prepared starting from the corresponding dimethyl esters and 1,4-butanediol by melt transesterification in the presence of a highly effective catalyst tetra-n-butyl-titanate, Ti(0Bu4. The molecular structure and composition of the copolyesters was determined by 1H NMR spectroscopy. The effect of copolymer composition on the physical and thermal properties of these random polyesters were investigated using differential scanning calorimetry. The degree of crystallinity was determined by DSC and wide angle X-ray. The degrees of crystallinity of the saturated and unsaturated copolyesters were generally reduced with respect to poly(butylene succinate, PBS. The melting temperatures of the saturated polyesters were lower, while the melting temperatures of the unsaturated copolyesters were higher than the melting temperature of PBS. The biodegradability of the polyesters was investigated by enzymatic degradation tests. The enzymatic degradation tests were performed in a buffer solution with Candida cylindracea lipase and for the unsaturated polyesters with Rhizopus arrhizus lipase. The extent of biodegradation was quantified as the weight loss of polyester films. Also the surface of the polyester films after degradation was observed using optical microscopy. It could be concluded that the biodegradability depended strongly on the degree of crystallinity, but also on the flexibility of the chain backbone. The highest biodegradation was observed for copolyesters containing 50 mol.% of adipic acid units, and in the series of unsaturated polyesters for copolyesters containing 5 and 10 mol.% of fumarate units. Although the degree of crystallinity of the unsaturated polyesters decreased slightly with increasing unsaturation, the biodegradation

  19. STUDY ON SOME PROPERTIES OF Si-CONTAINING POLYESTER-POLYETHER MULTIBLOCK COPOLYMERS

    Institute of Scientific and Technical Information of China (English)

    LI Zhenyi; ZHU Jin

    1997-01-01

    Some physical properties of the polyester-polyether multiblock copolymers with Si-containing hard segment were further examined by a series of physical methods. The hydrophobicity of the copolymers was improved with the incorporation of increasing amount of orgauosilicone, XPS test proved that silicon element was enriched at the surface of the Si-containing polyester-polyether copolymers. It was also found that their heat resistance and gas permeability for O2 and N2 were greatly improved. The study on semipermeability of films made of the Si-containing copolymers was also followed with interest.

  20. Electrochemical behavior and conductivity measurements of electropolymerized selenophene-based copolymers

    Directory of Open Access Journals (Sweden)

    Alakhras Fadi

    2015-03-01

    Full Text Available Electrochemical copolymerization of selenophene and thiophene was performed at a constant electrode potential. The obtained homopolymer films and copolymers were studied and characterized with cyclic voltammetry and conductivity measurements, from which conductivity values around 13.35 S · cm-1 were determined. The influence of the applied electropolymerization potential and the monomer feed ratio of selenophene and thiophene on the copolymers properties was investigated. The obtained copolymers showed good stability of the redox activity in an acetonitrile-based electrolyte solution. At higher polymerization potentials and at higher concentrations of thiophene in the feed, more thiophene units were incorporated into the copolymer chain. The conductivities of the copolymers were between those of homopolymers, implying that oxidation of both monomers was possible and the copolymer chains might accordingly be composed of both selenophene and thiophene units.

  1. [Biodegradable catheters and urinary stents. When?

    Science.gov (United States)

    Soria, F; Morcillo, E; López de Alda, A; Pastor, T; Sánchez-Margallo, F M

    2016-10-01

    One of the main wishes in the field of urinary catheters and stents is to arm them with biodegradable characteristics because we consider a failure of these devices the need for retrieval, the forgotten catheter syndrome as well as the adverse effects permanent devices cause after fulfilling their aim. The efforts focused in new designs, coatings and biomaterials aim to increase the biocompatibility of theses internal devices. Lately, there have been correct advances to answer the main challenges regarding biodegradable ureteral devices. Thus, modulation of the rate of degradation has been achieved thanks to new biomaterials and the use of copolymers that enable to choose the time of permanence as it is programmed with conventional double J catheters. Biocompatibility has improved with the use of new polymers that adapt better to the urine. Finally, one of the main problems is elimination of degraded fragments and experimentally it has be demonstrated that new designs elicit controlled degradation, from distal to proximal; using stranding and combination of copolymers degradation may be caused by dilution, reducing fragmentation to the last stages of life of the prosthesis. Moreover, it has been demonstrated that biodegradable catheters potentially may cause less urinary tract infection, less encrustation and predictably they will diminish catheter morbidity, since their degradation process reduces adverse effects. Regarding the development of biodegradable urethral stents, it is necessary to find biomaterials that enable maintaining their biomechanical properties in the long term, keeping open the urethral lumen both in patients with BPH and urethral stenosis. Modulation of the time of degradation of the prosthesis has been achieved, but the appearance of urothelial hyperplasia is still a constant in the initial phases after implantation. The development of drug eluting stents, anti-proliferative or anti-inflammatory, as well as biodegradable stents biocoated is a

  2. Biodegradable synthetic bone composites

    Science.gov (United States)

    Liu, Gao; Zhao, Dacheng; Saiz, Eduardo; Tomsia, Antoni P.

    2013-01-01

    The invention provides for a biodegradable synthetic bone composition comprising a biodegradable hydrogel polymer scaffold comprising a plurality of hydrolytically unstable linkages, and an inorganic component; such as a biodegradable poly(hydroxyethylmethacrylate)/hydroxyapatite (pHEMA/HA) hydrogel composite possessing mineral content approximately that of human bone.

  3. Synthesis and Characterization of ABBA Block Copolymer of Glycolide and ε-Caprolactone

    Institute of Scientific and Technical Information of China (English)

    CHEN Li; CHEN Xue-si; DENG Ming-xiao; JING Xia-bin

    2005-01-01

    A biodegradable ABBA block copolymer was synthesized via the ring-opening co-polymerization of ε-caprolactone(CL, B) and glycolide(A) by means of step polymerization in the presence of ethylene glycol as an initiator and stannous octanoate as a catalyst at 110 ℃ for 48 h. The molecular length of the PCL pre-polymer(BB) could be adjusted by controlling the molar ratio of the ethylene glycol initiator to ε-caprolactone monomer. The structure and the composition of the block copolymer were determined by the weight ratio of the monomer glycolide(A) to PCL pre-polymer(BB). The block copolymers were characterized by 1H NMR, GPC, DSC and X-ray. The results confirm the successful synthesis of an ABBA block copolymer.

  4. Functional Nanoporous Polymers from Block Copolymer Precursors

    DEFF Research Database (Denmark)

    Guo, Fengxiao

    functionalities remains a great challenge due to the limitation of available polymer synthesis and the nanoscale confinement of the porous cavities. The main topic of this thesis is to develop methods for fabrication of functional nanoporous polymers from block copolymer precursors. A method has been developed...... functional nanoporous polymers based on nanoporous 1,2- polybuatdiene 1,2-PB, which is derived from a 1,2-PB-b-PDMS diblock copolymer precursor. As a result, nanoporous 1,2-PB with pores decorated of polyacrylates, sulfonated polymers and poly(ethylene glycol) are created. A method of vapor phase deposition...... has also been generated to obtain nanoporous polymers with functional coatings on pore walls. Vapor phase polymerization of pyrrole is performed to incorporate an ultra thin film of polypyrrole into nanoporous 1,2-PB. The preliminary test shows that nanoporous 1,2-PB gains conductivity. Generally...

  5. Photothermal degradation of ethylene/vinylacetate copolymer

    Science.gov (United States)

    Liang, R. H.; Chung, S.; Clayton, A.; Di Stefano, S.; Oda, K.; Hong, S. D.; Gupta, A.

    1983-01-01

    Photothermal degradation studies were conducted on a 'stabilized' formulation of ethylene/vinyl acetate copolymer (EVA) in the temperature range 25-105 C under three different oxygen environments (in open air, with limited access to O2, and in a dark closed stagnant oven). These studies were performed in order to evaluate the utility of EVA as an encapsulation material for photovoltaic modules. Results showed that at low temperature (25 C), slow photooxidation of the polymer occurred via electronic energy transfer involving the UV absorber incorporated in the polymer. However, no changes in the physical properties of the bulk polymer were detected up to 1500 hours of irradiation. At elevated temperatures, leaching and evaporation of the additives occurred, which ultimately resulted in the chemical crosslinking of the copolymer and the formation of volatile photoproducts such as acetic acid.

  6. Hybrid, Nanoscale Phospholipid/Block Copolymer Vesicles

    Directory of Open Access Journals (Sweden)

    Bo Liedberg

    2013-09-01

    Full Text Available Hybrid phospholipid/block copolymer vesicles, in which the polymeric membrane is blended with phospholipids, display interesting self-assembly behavior, incorporating the robustness and chemical versatility of polymersomes with the softness and biocompatibility of liposomes. Such structures can be conveniently characterized by preparing giant unilamellar vesicles (GUVs via electroformation. Here, we are interested in exploring the self-assembly and properties of the analogous nanoscale hybrid vesicles (ca. 100 nm in diameter of the same composition prepared by film-hydration and extrusion. We show that the self-assembly and content-release behavior of nanoscale polybutadiene-b-poly(ethylene oxide (PB-PEO/1-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidylcholine (POPC hybrid phospholipid/block copolymer vesicles can be tuned by the mixing ratio of the amphiphiles. In brief, these hybrids may provide alternative tools for drug delivery purposes and molecular imaging/sensing applications and clearly open up new avenues for further investigation.

  7. Biodegradation of Polypropylene Nonwovens

    Science.gov (United States)

    Keene, Brandi Nechelle

    The primary aim of the current research is to document the biodegradation of polypropylene nonwovens and filament under composting environments. To accelerate the biodegradat ion, pre-treatments and additives were incorporated into polypropylene filaments and nonwovens. The initial phase (Chapter 2) of the project studied the biodegradation of untreated polypropylene with/without pro-oxidants in two types of composting systems. Normal composting, which involved incubation of samples in food waste, had little effect on the mechanical properties of additive-free spunbond nonwovens in to comparison prooxidant containing spunbond nonwovens which were affected significantly. Modified composting which includes the burial of samples with food and compressed air, the polypropylene spunbond nonwovens with/without pro-oxidants displayed an extreme loss in mechanical properties and cracking on the surface cracking. Because the untreated spunbond nonwovens did not completely decompose, the next phase of the project examined the pre-treatment of gamma-irradiation or thermal aging prior to composting. After exposure to gamma-irradiation and thermal aging, polypropylene is subjected to oxidative degradation in the presence of air and during storage after irradiat ion. Similar to photo-oxidation, the mechanism of gamma radiation and thermal oxidative degradation is fundamentally free radical in nature. In Chapter 3, the compostability of thermal aged spunbond polypropylene nonwovens with/without pro-oxidant additives. The FTIR spectrum confirmed oxidat ion of the polypropylene nonwovens with/without additives. Cracking on both the pro-oxidant and control spunbond nonwovens was showed by SEM imaging. Spunbond polypropylene nonwovens with/without pro-oxidants were also preirradiated by gamma rays followed by composting. Nonwovens with/without pro-oxidants were severely degraded by gamma-irradiation after up to 20 kGy exposure as explained in Chapter 4. Furthermore (Chapter 5), gamma

  8. [Biodegradation of polyethylene].

    Science.gov (United States)

    Yang, Jun; Song, Yi-ling; Qin, Xiao-yan

    2007-05-01

    Plastic material is one of the most serious solid wastes pollution. More than 40 million tons of plastics produced each year are discarded into environment. Plastics accumulated in the environment is highly resistant to biodegradation and not be able to take part in substance recycle. To increase the biodegradation efficiency of plastics by different means is the main research direction. This article reviewed the recent research works of polyethylene biodegradation that included the modification and pretreatment of polyethylene, biodegradation pathway, the relevant microbes and enzymes and the changes of physical, chemical and biological properties after biodegradation. The study directions of exploiting the kinds of life-forms of biodegradation polyethylene except the microorganisms, isolating and cloning the key enzymes and gene that could produce active groups, and enhancing the study on polyethylene biodegradation without additive were proposed.

  9. Biodegradable p(DLLA-epsilon-CL) nerve guides versus autologous nerve grafts : Electromyographic and video analysis

    NARCIS (Netherlands)

    Meek, MF; Nicolai, JPA; Gramsbergen, A; van der Werf, J.F.A.

    2001-01-01

    The aim of this study was to evaluate the functional effects of bridging a gap in the sciatic nerve of the rat with either a biodegradable copolymer of (DL)-lactide and epsilon -caprolactone [p(DLLA-epsilon -CL)] nerve guide or an autologous nerve graft. Electromyograms (EMGs) of the gastrocnemius (

  10. New Polytetrahydrofuran Graft Copolymers.

    Science.gov (United States)

    1979-03-15

    chioroprene) , chiorobutyl - ~~~~~ rubber , bromobutyl rubber , chlorinated EPDM , chlorinated poly(buta— diene) and chlorinated butadiene styrene copolymer...for initial detailed studies (3 ,4 , 6 , 7 — 9 ) . Many soluble metal salts with cations capable of stabilizing an on].um ion polymerization (SO3CF 3

  11. Block coordination copolymers

    Energy Technology Data Exchange (ETDEWEB)

    Koh, Kyoung Moo; Wong-Foy, Antek G; Matzger, Adam J; Benin, Annabelle I; Willis, Richard R

    2014-11-11

    The present invention provides compositions of crystalline coordination copolymers wherein multiple organic molecules are assembled to produce porous framework materials with layered or core-shell structures. These materials are synthesized by sequential growth techniques such as the seed growth technique. In addition, the invention provides a simple procedure for controlling functionality.

  12. Block coordination copolymers

    Science.gov (United States)

    Koh, Kyoung Moo; Wong-Foy, Antek G; Matzger, Adam J; Benin, Annabelle I; Willis, Richard R

    2012-11-13

    The present invention provides compositions of crystalline coordination copolymers wherein multiple organic molecules are assembled to produce porous framework materials with layered or core-shell structures. These materials are synthesized by sequential growth techniques such as the seed growth technique. In addition, the invention provides a simple procedure for controlling functionality.

  13. Molecular Design of Synthetic Biodegradable Polymers as Cell Scaffold Materials

    Institute of Scientific and Technical Information of China (English)

    WANG Shen-guo; WAN Yu-qing; CAI Qing; HE Bin; CHEN Wen-na

    2004-01-01

    Poly(lactic acid) and its copolymers are regarded as the most useful biomaterials. The good biocompatibility, biodegradability and mechanical properties of them make the synthetic biodegradable polymers have primary application to tissue engineering. The advantages and disadvantages of the synthetic biodegradable polymers as cell scaffold materials are evaluated. This article reviews the modification of polylactide-family aliphatic polymers to improve the cell affinity when the polymers are used as cell scaffolds. We have developed four main approaches: to modify polyester cell scaffolds in combination of plasma treating and collagen coating; to introduce hydrophilic segments into aliphatic polyester backbones; to introduce pendant functional groups into polyester chains; to modify polyester with dextran. The results of the cell cultures prove that the approaches mentioned above have improved the cell affinity of the polyesters and have modulated cell function such as adhesion, proliferation and migration.

  14. Meter-long multiblock copolymer microfibers via interfacial bioorthogonal polymerization.

    Science.gov (United States)

    Liu, Shuang; Zhang, Han; Remy, Roddel A; Deng, Fei; Mackay, Michael E; Fox, Joseph M; Jia, Xinqiao

    2015-05-01

    High-molecular-weight multiblock copolymers are synthesized as robust polymer fibers via interfacial bioorthogonal polymerization employing the rapid cycloaddition of s-tetrazines with strained trans-cyclooctenes. When cell-adhesive peptide is incorporated in the tetrazine monomer, the resulting protein-mimetic polymer fibers provide guidance cues for cell attachment and elongation.

  15. Synthesis and characterization of biodegradable amphiphilic PEG-grafted poly(DTC-co-CL)

    Institute of Scientific and Technical Information of China (English)

    Qiu Jin Zhang; Wei Pu Zhu; Zhi Quan Shen

    2010-01-01

    A novel biodegradable copolymer,poly(5,5-dibromomethyltrimethylene carbonate-co-ε-caprolactone)(poly(DBTC-co-CL))with pendant bromine groups,was synthesized via ring-opening polymerization(ROP)of ε-caprolactone(CL)and 5,5-dibromomethyltrimethylene carbonate(DBTC)using stannous octoate(Sn(Oct)2)as catalyst.Then the pendant bromine groups were completely converted into azide form,which permitted"click"reaction with alkyne-terminated polyethylene(A-PEG)by Huisgen 1,3-dipolar cycloadditions preparing biodegradable amphiphilic poly(DTC-co-CL)-g-PEG graft copolymer.The graft copolymer was characterized by nuclear magnetic resonance(NMR)and size-exclusion chromatography(SEC).

  16. New adhesive systems based on functionalized block copolymers

    Energy Technology Data Exchange (ETDEWEB)

    Kent, M.; Saunders, R.; Hurst, M.; Small, J.; Emerson, J.; Zamora, D.

    1997-05-01

    The goal of this work was to evaluate chemically-functionalized block copolymers as adhesion promoters for metal/thermoset resin interfaces. Novel block copolymers were synthesized which contain pendant functional groups reactive toward copper and epoxy resins. In particular, imidazole and triazole functionalities that chelate with copper were incorporated onto one block, while secondary amines were incorporated onto the second block. These copolymers were found to self-assemble from solution onto copper surfaces to form monolayers. The structure of the adsorbed monolayers were studied in detail by neutron reflection and time-of-flight secondary ion mass spectrometry. The monolayer structure was found to vary markedly with the solution conditions and adsorption protocol. Appropriate conditions were found for which the two blocks form separate layers on the surface with the amine functionalized block exposed at the air surface. Adhesion testing of block copolymer-coated copper with epoxy resins was performed in both lap shear and peel modes. Modest enhancements in bond strengths were observed with the block copolymer applied to the native oxide. However, it was discovered that the native oxide is the weak link, and that by simply removing the native oxide, and then applying an epoxy resin before the native oxide can reform, excellent bond strength in the as-prepared state as well as excellent retention of bond strength after exposure to solder in ambient conditions are obtained. It is recommended that long term aging studies be performed with and without the block copolymer. In addition, the functionalized block copolymer method should be evaluated for another system that has inherently poor bonding, such as the nickel/silicone interface, and for systems involving metals and alloys which form oxides very rapidly, such as aluminum and stainless steel, where bonding strategies involve stabilizing the native oxide.

  17. Synthesis and Characterization of Graft Copolymer of Dextran and 2-Acrylamido-2-methylpropane Sulphonic Acid

    Directory of Open Access Journals (Sweden)

    Venkanna Azmeera

    2012-01-01

    Full Text Available A novel biodegradable graft copolymer of dextran (Dx and 2-acrylamido-2-methyl-1-propane sulphonic acid (AMPS was synthesized by grafting poly-AMPS chains onto dextran backbone by free radical polymerization using ceric ammonium nitrate (CAN as an initiator. Different amounts of AMPS were used to synthesize four different grades of graft copolymers with different side chain lengths. These grafted polymers were characterized by elemental analysis, FTIR, 1HNMR, rheological technique, scanning electron microscopy (SEM, thermogravimetric analysis (TGA, and X-ray diffractometry (XRD. They exhibited efficient flocculation performance in kaolin suspension.

  18. SYNTHESIS OF POLY(ETHYLENE TEREPHTHALATE)-POLYCAPROLACTONE BLOCK COPOLYMER BY DIRECT COPOLYMERIZATION

    Institute of Scientific and Technical Information of China (English)

    Shen-guo Wang; Kai Tang

    1999-01-01

    Poly(ethylene terephthalate)-polycaprolactone block copolymer (PCL-b-PET) is a polyester with improved biodegradability. In the present paper, a new direct copolymerization method of ε-caprolactone (ε-CL) and bishydroxyethylene terephthalate (BHET) in the presence of Ti(OBu)4 was proposed for the synthesis of PCL-b-PET. The PCL-b-PET copolymer was characterized by IR, GPC and 1H-NMR techniques, and the effects of synthesis conditions, such as temperature, reaction time and concentration of catalyst on the copolymerization were discussed.

  19. STUDY ON PET-PA66 COPOLYMER

    Institute of Scientific and Technical Information of China (English)

    WU Rongrui; SHI Weitong

    1992-01-01

    In this work the PET-PA66 copolymers are obtained. The characterization of chemical structure of copolymer chain by NMR method is also given . It is shown that when the 66 Nylon salt is added in the copolycondensation, the adipic acid and hexamethylenediamine reacted mainly by itself and the obtained copolymer is a random copolymer, and when the Nylon 66 oligomer is added, the obtained copolymer is a block copolymer. The result of NMR analysis is demonstrated by properties investigation.

  20. Block copolymer adhesion promoters via ring-opening metathesis polymerization

    Science.gov (United States)

    Kent, M.S.; Saunders, R.

    1997-02-18

    Coupling agents are disclosed based on functionalized block copolymers for bonding thermoset polymers to solid materials. These are polymers which possess at least two types of functional groups, one which is able to attach to and react with solid surfaces, and another which can react with a thermoset resin, which are incorporated as pendant groups in monomers distributed in blocks (typically two) along the backbone of the chain. The block copolymers in this invention are synthesized by living ring-opening metathesis polymerization. 18 figs.

  1. Block copolymer battery separator

    Science.gov (United States)

    Wong, David; Balsara, Nitash Pervez

    2016-04-26

    The invention herein described is the use of a block copolymer/homopolymer blend for creating nanoporous materials for transport applications. Specifically, this is demonstrated by using the block copolymer poly(styrene-block-ethylene-block-styrene) (SES) and blending it with homopolymer polystyrene (PS). After blending the polymers, a film is cast, and the film is submerged in tetrahydrofuran, which removes the PS. This creates a nanoporous polymer film, whereby the holes are lined with PS. Control of morphology of the system is achieved by manipulating the amount of PS added and the relative size of the PS added. The porous nature of these films was demonstrated by measuring the ionic conductivity in a traditional battery electrolyte, 1M LiPF.sub.6 in EC/DEC (1:1 v/v) using AC impedance spectroscopy and comparing these results to commercially available battery separators.

  2. Biodegradability of plastics.

    Science.gov (United States)

    Tokiwa, Yutaka; Calabia, Buenaventurada P; Ugwu, Charles U; Aiba, Seiichi

    2009-08-26

    Plastic is a broad name given to different polymers with high molecular weight, which can be degraded by various processes. However, considering their abundance in the environment and their specificity in attacking plastics, biodegradation of plastics by microorganisms and enzymes seems to be the most effective process. When plastics are used as substrates for microorganisms, evaluation of their biodegradability should not only be based on their chemical structure, but also on their physical properties (melting point, glass transition temperature, crystallinity, storage modulus etc.). In this review, microbial and enzymatic biodegradation of plastics and some factors that affect their biodegradability are discussed.

  3. Biodegradation of polyethoxylated nonylphenols.

    Science.gov (United States)

    Ruiz, Yassellis; Medina, Luis; Borusiak, Margarita; Ramos, Nairalith; Pinto, Gilberto; Valbuena, Oscar

    2013-01-01

    Polyethoxylated nonylphenols, with different ethoxylation degrees (NPEO x ), are incorporated into many commercial and industrial products such as detergents, domestic disinfectants, emulsifiers, cosmetics, and pesticides. However, the toxic effects exerted by their degradation products, which are persistent in natural environments, have been demonstrated in several animal and invertebrate aquatic species. Therefore, it seems appropriate to look for indigenous bacteria capable of degrading native NPEO x and its derivatives. In this paper, the isolation of five bacterial strains, capable of using NPEO 15 , as unique carbon source, is described. The most efficient NPEO 15 degrader bacterial strains were identified as Pseudomonas fluorescens (strain Yas2) and Klebsiella pneumoniae (strain Yas1). Maximal growth rates were reached at pH 8, 27°C in a 5% NPEO 15 medium. The NPEO 15 degradation extension, followed by viscometry assays, reached 65% after 54.5 h and 134 h incubation times, while the COD values decreased by 95% and 85% after 24 h for the Yas1 and Yas2 systems, respectively. The BOD was reduced by 99% and 99.9% levels in 24 h and 48 h incubations. The viscosity data indicated that the NPEO 15 biodegradation by Yas2 follows first-order kinetics. Kinetic rate constant (k) and half life time (τ) for this biotransformation were estimated to be 0.0072 h(-1) and 96.3 h, respectively.

  4. Low-Temperature Processable Block Copolymers That Preserve the Function of Blended Proteins.

    Science.gov (United States)

    Iwasaki, Yasuhiko; Takemoto, Kyohei; Tanaka, Shinya; Taniguchi, Ikuo

    2016-07-11

    Low-temperature processable polymers have attracted increasing interest as ecological materials because of their reduced energy consumption during processing and suitability for making composites with heat-sensitive biomolecules at ambient temperature. In the current study, low-temperature processable biodegradable block copolymers were synthesized by ring-opening polymerization of l-lactide (LLA) using polyphosphoester as a macroinitiator. The polymer films could be processed under a hydraulic pressure of 35 MPa. The block copolymer films swelled in water because the polyphosphoester block was partially hydrated. Interestingly, the swelling ratio of the films changed with temperature. The pressure-induced order-to-disorder transition of the block copolymers was characterized by small-angle X-ray scattering; a crystallinity reduction in the block copolymers was observed after application of pressure. The crystallinity of the block copolymers was recovered after removing the applied pressure. The Young's modulus of the block copolymer films increased as the LLA unit content increased. Moreover, the modulus did not change after multiple processing cycles and the recyclability of the block copolymers was also confirmed. Finally, polymer films with embedded proteinase K as a model protein were prepared. The activity of catalase loaded into the polymer films was evaluated after processing at different temperatures. The activity of catalase was preserved when the polymer films were processed at room temperature but was significantly reduced after high-temperature processing. The suitability of low-temperature processable biodegradable polymers for making biofunctional composites without reducing protein activity was clarified. These materials will be useful for biomedical and therapeutic applications.

  5. Biodegradable Hybrid Stomatocyte Nanomotors for Drug Delivery.

    Science.gov (United States)

    Tu, Yingfeng; Peng, Fei; André, Alain A M; Men, Yongjun; Srinivas, Mangala; Wilson, Daniela A

    2017-02-28

    We report the self-assembly of a biodegradable platinum nanoparticle-loaded stomatocyte nanomotor containing both PEG-b-PCL and PEG-b-PS as a potential candidate for anticancer drug delivery. Well-defined stomatocyte structures could be formed even after incorporation of 50% PEG-b-PCL polymer. Demixing of the two polymers was expected at high percentage of semicrystalline poly(ε-caprolactone) (PCL), resulting in PCL domain formation onto the membrane due to different properties of two polymers. The biodegradable motor system was further shown to move directionally with speeds up to 39 μm/s by converting chemical fuel, hydrogen peroxide, into mechanical motion as well as rapidly delivering the drug to the targeted cancer cell. Uptake by cancer cells and fast doxorubicin drug release was demonstrated during the degradation of the motor system. Such biodegradable nanomotors provide a convenient and efficient platform for the delivery and controlled release of therapeutic drugs.

  6. 新型药物载体聚乙醇-聚丙交酯载药颗粒的制备及表征%Preparation and characterization of biodegradable nanoparticles from methoxy poly(ethylene glycol)-poly(D,L-lactide)block copolymers as novel drug carriers

    Institute of Scientific and Technical Information of China (English)

    姜维; 王运东; 张建铮; 甘泉; 张汉威; 贝建中; 赵秀文; 费维扬

    2006-01-01

    Methoxy poly(ethylene glycol)-poly(D,L-lactide) block copolymers (PEG-PLA) were prepared through ring-opening polymerization.The oil in water suspension method was used to prepare block copolymer micelles. The critical micelle concentration (CMC) by fluorescence spectroscopy was 0.0056 mg·ml-1. The physical state of the inner core region of micelles was characterized with 1HNMR. The size of indomethacin (IMC) loaded micelles measured by dynamic light scattering (DLS) showed narrow monodisperse size distribution and the average diameters were less than 50 nm. In addition, the nanoparticles with relatively high drug loading content (DLC) were obtained.

  7. Biodegradable fiksasyon malzemeleri

    OpenAIRE

    Seber, Sinan

    2004-01-01

    Problems related to metallic implant had increased the interest to biodegradables. In this paper, the physical and chemical properties, degradation modalities, implant design, clinical studies with techniques, and complications of biodegradable implants, especially polylactic and polyglycolic acid, were reviewed. Also our studies, on the antibiotic delivery capacities of these implants; and the prediction of immunological reactions with our clinical experiences were presented.

  8. Synthesis of morpholine-2,5-dione derivative copolymer and its degradation in vitro

    Institute of Scientific and Technical Information of China (English)

    ZHAO Yanchao; CHENG Shujun; CHEN Jianding

    2007-01-01

    In this experiment we prepared the copolymer of L-lactide (L-LA) and (3s)-[(benzyloxycarbonyl) methyl] morpholine-2,5-dione (BMD) using tin(Ⅱ)-octanoate initiat-ed ring-opening copolymerization. The maximum relative number-average molecular weight (Mn) of copolymer was over 8.0×104. The degradation study proceeded in vitro and poly(L-lactide-co-glycollide) used as the control sample.Changes in mass and molecular weight were studied during the immersion in buffer solutions [phosphate-buffered saline solution (PBS), pH = 7.4] at 37℃. The hydrolytic degrada-tion of both the morpholine-2,5-dione derivative copolymer and the control sample were completed in 3 months. A palladium on charcoal catalyst [Pd/C (5%)] was used as the catalyzer for hydrogenolysis.1H-NMR (nuclear magnetic resonance) analysis and gel permeation chromatography (GPC) were used to investigate the degree of the hydroge-nolysis of the copolymer with different Mn. The contact angle showed that the biodegradable copolymer had good hydro- philicity. These findings suggested that this copolymer would have a high potential application for pharmaceutical products.

  9. Preferential Incorporation of Azelaic Acid Units into the Crystalline Phase of the Copoly(Alkylene Dicarboxylate Derived from 1,9-Nonanediol and an Equimolar Mixture of Pimelic and Azelaic Acids

    Directory of Open Access Journals (Sweden)

    Angélica Díaz

    2015-09-01

    Full Text Available The crystalline structure of two biodegradable odd-odd polyesters (i.e., poly(nonamethylene pimelate (PES 9,7 and poly(nonamethylene azelate (PES 9,9 was investigated by means of electron and X-ray diffraction of single crystals and oriented fibers, respectively. Truncated rhombic crystals were obtained with an aspect ratio that was strongly depended on the supercooling degree. The crystalline structure of both homopolyesters was defined by an orthorhombic P21ab space group and a large unit cell containing four molecular segments with an all-trans conformation. Nevertheless, the structure in the chain axis projection was equivalent to a simpler cell containing only two segments. Crystalline lamellae were effectively degraded by lipases, starting the enzymatic attack on the lamellar surfaces. The random copolymer constituted by an equimolar amount of pimelate and azelate units (COPES 9,7/9 crystallized according to regular lamellae with a similar molecular arrangement in the chain axis projection. The structure of this copolymer was preferably conditioned by the azelate component as could be deduced from both, diffraction and spectroscopic data. Analysis of small angle X-ray scattering patterns pointed out that less crystalline lamellae with higher amorphous thickness had developed in the copolymer. This feature was interpreted as a consequence of the preferential incorporation of pimelate comonomer units in the folding surface.

  10. Cytocompatibility of biodegradable poly(ethylene glycol)-b-poly(L-lactide)-b-poly(L-glutamic acid) tri-block copolymer with human umbilical vein endothelial cells%生物可降解材料聚乙二醇-聚乳酸-聚谷氨酸三嵌段共聚物与人脐静脉内皮细胞的相容性

    Institute of Scientific and Technical Information of China (English)

    刘斌; 宋显晶; 刘婕妤; 姜锋; 史永峰; 双东思; 李智博

    2008-01-01

    BACKGROUND: Poly(ethylene glycol)-b-poly(L-lactide)-b-poly(L-glutamic acid) (PEG-PLA-PGL) tri-block copolymers have good applied foreground in constructing tissue engineering scaffold materials. Whether endothelial cells survive and grow on the materials has a direct influence on the application as a biodegradable material for the scaffold of endothelial cell vector.OBJECTIVE: To explore the cytocompatibility of PEG-PLA-PGL tri-block copolymers with human umbilical vein endothelial cells (HUVECs).DESIGN: Randomized control observation.SETTING: the Second Hospital of Jilin University.MATERIALS: The experiment was carried out in the Department of Pathobiology, School of Basic Medical Sciences, Jilin University from February to October in 2006. Human umbilical cord about 20 cm length came from one neonatal infant who was delivered normally after enough months in the Department of Gynecology and Obstetrics, the Second Hospital of Jilin University. Human umbilical cord was sampled in the informed consents of the infant's family member. The experimentation was authorized by the medical ethic committee of the hospital. PEG-PLA-PGL membranes were provided by Changchun Institute of Applied Chemistry, Chinese Academy of Sciences. Inverted microscope and phase-contrast microscope were bought from Olympus Company (Japan).METHODS: HUVECs cultivated and grew steadily, were inoculated onto PEG-PLA-PGL membranes, serving as the experiment group. While the culture medium without PEG-PLA-PGL membranes were taken as the control group.①Cytocompatibility of PEG-PLA-PGL membranes with HUVECs was evaluated by observing cellular growth through phase-contrast microscope.②The proliferation index of cells was detected by MTT method in 1, 3, 5 and 7 days after inoculation.MAIN OUTCOME MEASURES: ①Cytocompatibility of PEG-PLA-PGL membranes with HUVECs;②The proliferation index of cells in l, 3, 5 and 7 days after inoculationRESULTS: ①Cytocompatibility of PEG-PLA-PGL membranes with

  11. Polyether/Polyester Graft Copolymers

    Science.gov (United States)

    Bell, Vernon L., Jr.; Wakelyn, N.; Stoakley, D. M.; Proctor, K. M.

    1986-01-01

    Higher solvent resistance achieved along with lower melting temperature. New technique provides method of preparing copolymers with polypivalolactone segments grafted onto poly (2,6-dimethyl-phenylene oxide) backbone. Process makes strong materials with improved solvent resistance and crystalline, thermally-reversible crosslinks. Resulting graft copolymers easier to fabricate into useful articles, including thin films, sheets, fibers, foams, laminates, and moldings.

  12. Formation of nanophases in epoxy thermosets containing amphiphilic block copolymers with linear and star-like topologies.

    Science.gov (United States)

    Wang, Lei; Zhang, Chongyin; Cong, Houluo; Li, Lei; Zheng, Sixun; Li, Xiuhong; Wang, Jie

    2013-07-11

    In this work, we investigated the effect of topological structures of block copolymers on the formation of the nanophase in epoxy thermosets containing amphiphilic block copolymers. Two block copolymers composed of poly(ε-caprolactone) (PCL) and poly(2,2,2-trifluoroethyl acrylate) (PTFEA) blocks were synthesized to possess linear and star-shaped topologies. The star-shaped block copolymer composed a polyhedral oligomeric silsesquioxane (POSS) core and eight poly(ε-caprolactone)-block-poly(2,2,2-trifluoroethyl acrylate) (PCL-b-PTFEA) diblock copolymer arms. Both block copolymers were synthesized via the combination of ring-opening polymerization and reversible addition-fragmentation chain transfer/macromolecular design via the interchange of xanthate (RAFT/MADIX) process; they were controlled to have identical compositions of copolymerization and lengths of blocks. Upon incorporating both block copolymers into epoxy thermosets, the spherical PTFEA nanophases were formed in all the cases. However, the sizes of PTFEA nanophases from the star-like block copolymer were significantly lower than those from the linear diblock copolymer. The difference in the nanostructures gave rise to the different glass transition behavior of the nanostructured thermosets. The dependence of PTFEA nanophases on the topologies of block copolymers is interpreted in terms of the conformation of the miscible subchain (viz. PCL) at the surface of PTFEA microdomains and the restriction of POSS cages on the demixing of the thermoset-philic block (viz. PCL).

  13. Structure-Property Relationships of Poly(lactide)-based Triblock and Multiblock Copolymers

    Science.gov (United States)

    Panthani, Tessie Rose

    Replacing petroleum-based plastics with alternatives that are degradable and synthesized from annually renewable feedstocks is a critical goal for the polymer industry. Achieving this goal requires the development of sustainable analogs to commodity plastics which have equivalent or superior properties (e.g. mechanical, thermal, optical etc.) compared to their petroleum-based counterparts. This work focuses on improving and modulating the properties of a specific sustainable polymer, poly(lactide) (PLA), by incorporating it into triblock and multiblock copolymer architectures. The multiblock copolymers in this work are synthesized directly from dihydroxy-terminated triblock copolymers by a simple step-growth approach: the triblock copolymer serves as a macromonomer and addition of stoichiometric quantities of either an acid chloride or diisocyanate results in a multiblock copolymer. This work shows that over wide range of compositions, PLA-based multiblock copolymers have superior mechanical properties compared to triblock copolymers with equivalent chemical compositions and morphologies. The connectivity of the blocks within the multiblock copolymers has other interesting consequences on properties. For example, when crystallizable poly(L-lactide)-based triblock and multiblock copolymers are investigated, it is found that the multiblock copolymers have much slower crystallization kinetics. Additionally, the total number of blocks connected together is found to effect the linear viscoelastic properties as well as the alignment of lamellar domains under uniaxial extension. Finally, the synthesis and characterization of pressure-sensitive adhesives based upon renewable PLA-containing triblock copolymers and a renewable tackifier is detailed. Together, the results give insight into the effect of chain architecture, composition, and morphology on the mechanical behavior, thermal properties, and rheological properties of PLA-based materials.

  14. The influence of pendant hydroxyl groups on enzymatic degradation and drug delivery of amphiphilic poly[glycidol-block-(epsilon-caprolactone)] copolymers.

    Science.gov (United States)

    Mao, Jing; Gan, Zhihua

    2009-11-10

    An amphiphilic diblock copolymer PG-b-PCL with well-controlled structure and pendant hydroxyl groups along hydrophilic block was synthesized by sequential anionic ring-opening polymerization. The micellization and drug release of PG-b-PCL copolymers using pyrene as a fluorescence probe were investigated for determining the influences of copolymer composition and lipase concentration on drug loading capacity and controlled release behavior. The biodegradation of PG-b-PCL copolymers was studied with microspheres as research samples. It has been concluded that the polar hydroxyl groups along each repeat unit of hydrophilic PG block in PG-b-PCL copolymer have great influences on drug encapsulation, drug release, and enzymatic degradation of micelles and microspheres.

  15. Biodegradable polyesters reinforced with triclosan loaded polylactide micro/nanofibers: Properties, release and biocompatibility

    Directory of Open Access Journals (Sweden)

    L. J. del Valle

    2012-04-01

    Full Text Available Mechanical properties and drug release behavior were studied for three biodegradable polyester matrices (polycaprolactone, poly(nonamethylene azelate and the copolymer derived from 1,9-nonanediol and an equimolar mixture of azelaic and pimelic acids reinforced with polylactide (PLA fibers. Electrospinning was used to produce suitable mats constituted by fibers of different diameters (i.e. from micro- to nanoscale and a homogeneous dispersion of a representative hydrophobic drug (i.e. triclosan. Fabrics were prepared by a molding process, which allowed cold crystallization of PLA micro/nanofibers and hot crystallization of the polyester matrices. The orientation of PLA molecules during electrospinning favored the crystallization process, which was slightly enhanced when the diameter decreased. Incorporation of PLA micro/nanofibers led to a significant increase in the elastic modulus and tensile strength, and in general to a decrease in the strain at break. The brittle fracture was clearer when high molecular weight samples with high plastic deformation were employed. Large differences in the release behavior were detected depending on the loading process, fiber diameter size and hydrophobicity of the polyester matrix. The release of samples with the drug only loaded into the reinforcing fibers was initially fast and then became slow and sustained, resulting in longer lasting antimicrobial activity. Biocompatibility of all samples studied was demonstrated by adhesion and proliferation assays using HEp-2 cell cultures.

  16. Ion Transport in Nanostructured Block Copolymer/Ionic Liquid Membranes

    Science.gov (United States)

    Hoarfrost, Megan Lane

    Incorporating an ionic liquid into one block copolymer microphase provides a platform for combining the outstanding electrochemical properties of ionic liquids with a number of favorable attributes provided by block copolymers. In particular, block copolymers thermodynamically self-assemble into well-ordered nanostructures, which can be engineered to provide a durable mechanical scaffold and template the ionic liquid into continuous ion-conducting nanochannels. Understanding how the addition of an ionic liquid affects the thermodynamic self-assembly of block copolymers, and how the confinement of ionic liquids to block copolymer nanodomains affects their ion-conducting properties is essential for predictable structure-property control. The lyotropic phase behavior of block copolymer/ionic liquid mixtures is shown to be reminiscent of mixtures of block copolymers with selective molecular solvents. A variety of ordered microstructures corresponding to lamellae, hexagonally close-packed cylinders, body-centered cubic, and face-centered cubic oriented micelles are observed in a model system composed of mixtures of imidazolium bis(trifluoromethylsulfonyl)imide ([Im][TFSI]) and poly(styrene- b-2-vinyl pyridine) (PS-b-P2VP). In contrast to block copolymer/molecular solvent mixtures, the interfacial area occupied by each PS-b-P2VP chain decreases upon the addition of [Im][TFSI], indicating a considerable increase in the effective segregation strength of the PS-b-P2VP copolymer with ionic liquid addition. The relationship between membrane structure and ionic conductivity is illuminated through the development of scaling relationships that describe the ionic conductivity of block copolymer/ionic liquid mixtures as a function of membrane composition and temperature. It is shown that the dominant variable influencing conductivity is the overall volume fraction of ionic liquid in the mixture, which means there is incredible freedom in designing the block copolymer architecture

  17. Block copolymer mixtures as antimicrobial hydrogels for biofilm eradication.

    Science.gov (United States)

    Lee, Ashlynn L Z; Ng, Victor W L; Wang, Weixin; Hedrick, James L; Yang, Yi Yan

    2013-12-01

    Current antimicrobial strategies have mostly been developed to manage infections due to planktonic cells. However, microbes in their nature state will tend to exist by attaching to and growing on living and inanimate surfaces that result in the formation of biofilms. Conventional therapies for treating biofilm-related infections are likely to be insufficient due to the lower susceptibility of microbes that are embedded in the biofilm matrix. In this study, we report the development of biodegradable hydrogels from vitamin E-functionalized polycarbonates for antimicrobial applications. These hydrogels were formed by incorporating positively-charged polycarbonates containing propyl and benzyl side chains with vitamin E moiety into physically cross-linked networks of "ABA"-type polycarbonate and poly(ethylene glycol) triblock copolymers. Investigations of the mechanical properties of the hydrogels showed that the G' values ranged from 1400 to 1600 Pa and the presence of cationic polycarbonate did not affect the stiffness of the hydrogels. Shear-thinning behavior was observed as the hydrogels displayed high viscosity at low shear rates that dramatically decreased as the shear rate increased. In vitro antimicrobial studies revealed that the more hydrophobic VE/BnCl(1:30)-loaded hydrogels generally exhibited better antimicrobial/antifungal effects compared to the VE/PrBr(1:30) counterpart as lower minimum biocidal concentrations (MBC) were observed in Staphylococcus aureus (Gram-positive), Escherichia coli (Gram-negative) and Candida albicans (fungus) (156.2, 312.5, 312.5 mg/L for VE/BnCl(1:30) and 312.5, 2500 and 625 mg/L for VE/PrBr(1:30) respectively). Similar trends were observed for the treatment of biofilms where VE/BnCl(1:30)-loaded hydrogels displayed better efficiency with regards to eradication of biomass and reduction of microbe viability of the biofilms. Furthermore, a high degree of synergistic antimicrobial effects was also observed through the co

  18. 3D structuring of biocompatible and biodegradable polymers via stereolithography.

    Science.gov (United States)

    Gill, Andrew A; Claeyssens, Frederik

    2011-01-01

    The production of user-defined 3D microstructures from biocompatible and biodegradable materials via free-form fabrication is an important step to create off-the-shelf technologies to be used as tissue engineering scaffolds. One method of achieving this is the microstereolithography of block copolymers, allowing high resolution microstructuring of materials with tuneable physical properties. A versatile protocol for the production and photofunctionalisation of pre-polymers for microstereolithography is presented along with a discussion of the possible microstereolithography set-ups and previous work in the field.

  19. On the Use of Self-Assembling Block Copolymers to Toughen A Model Epoxy

    Science.gov (United States)

    Chen, Yilin

    Block copolymers have been receiving considerable attention in toughening epoxy due to their ability to form a wide variety of nanostructures. This study focuses on using both triblock and diblock copolymers to improve the fracture toughness of an aromatic-amine cured epoxy system. The curing system consisted of 1,3- phenylenediamine (mPDA) as curing agent and aniline as a chain extender. Three triblock copolymers and three diblock copolymers were incorporated in the same lightly crosslinked model epoxy system, which was chosen to mimic an underfill material in flip-chip packaging for the microelectronics industry. In this research, rubber particles were formed in situ using self-assembling block copolymers. Mechanical, thermal and microscopic studies were conducted with the main goal to study the relationship between the block parameters and the final morphologies and their effects on static and dynamic mechanical properties of the toughened resin, especially fracture toughness. In these block-copolymer-modified epoxies, spherical micelles and wormlike micelles were obtained by varying block lengths, molecular weight, polarities and compositions. It was found that miscibility of the epoxy-miscible block played a crucial role in the formation of different types of morphologies. At a low loading level, diblock copolymers were able to toughen the model epoxy as effectively as triblock copolymers. The fracture toughness was improved to almost three times with respect to that of the neat resin with addition of 10 phr AM*-27. At the same time, other mechanical properties, such as yield strength and modulus, were well retained. Incorporation of block copolymers did not have a significant effect on glass transition temperature but caused an increase in coefficient of thermal expansion (CTE) of the modified epoxy. Particle cavitation and matrix void growth were proved to be the toughening mechanisms for SBM-Modified epoxies. However, these typical toughening mechanisms for

  20. BIODEGRADATION BEHAVIOR OF POLY(METHYL METHACRYLATE GRAFTED SAGO STARCH BIOPOLYMER

    Directory of Open Access Journals (Sweden)

    Isam Yassin Qudsieh

    2010-09-01

    Full Text Available The graft copolymerization of poly(methyl methacrylate (PMMA onto sago starch (sago starch-g-PMMA was carried out using ceric ammonium nitrate (CAN as an initiator. PMMA was grafted onto sago starch using CAN as an initiator under nitrogen gas atmosphere. The maximum percentage of grafting (%G was determined to be 246% at the optimum conditions. The copolymers produced were characterized by Fourier Transform Infrared Spectrophotometry (FTIR, The FTIR spectra of the copolymers clearly indicated the presence of characteristic peaks of PMMA and sago starch, which suggested that PMMA had been successfully grafted on the sago starch. Biodegradability studies of sago starch-g-PMMA and sago starch were carried out by ?-amylase enzyme. Maximum biodegradation of the biopolymer was achieved after 3 days of incubation, while for the product was 7 days. The maximum production of glucose was achieved when the concentration of -amylase was 50 ppm.

  1. Imparting superhydrophobicity to biodegradable poly(lactide-co-glycolide) electrospun meshes.

    Science.gov (United States)

    Kaplan, Jonah A; Lei, Hongyi; Liu, Rong; Padera, Robert; Colson, Yolonda L; Grinstaff, Mark W

    2014-07-14

    The synthesis of a family of new poly(lactic acid-co-glycerol monostearate) (PLA-PGC18) copolymers and their use as biodegradable polymer dopants is reported to enhance the hydrophobicity of poly(lactic acid-co-glycolic acid) (PLGA) nonwoven meshes. Solutions of PLGA are doped with PLA-PGC18 and electrospun to form meshes with micrometer-sized fibers. Fiber diameter, percent doping, and copolymer composition influence the nonwetting nature of the meshes and alter their mechanical (tensile) properties. Contact angles as high as 160° are obtained with 30% polymer dopant. Lastly, these meshes are nontoxic, as determined by an NIH/3T3 cell biocompatibility assay, and displayed a minimal foreign body response when implanted in mice. In summary, a general method for constructing biodegradable fibrous meshes with tunable hydrophobicity is described for use in tissue engineering and drug delivery applications.

  2. Synthesis and characterization of a novel PNIPAAm-based copolymer with hydrolysis-dependent thermosensitivity.

    Science.gov (United States)

    Rosellini, Elisabetta; Cristallini, Caterina; Guerra, Giulio D; Barbani, Niccoletta; Giusti, Paolo

    2010-06-01

    The aim of this work was the synthesis and characterization of a novel poly(N-isopropylacrylamide)-based copolymer, with hydrolysis-dependent thermosensitivity, for bioengineering applications. For this purpose, N-isopropylacrylamide (NIPAAm) and 2-hydroxyethylmethacrylate-6-hydroxyhexanoate (HEMAHex) monomers were chosen. The poly(NIPAAm-co-HEMAHex) copolymer was synthesized by radical polymerization. The physicochemical, mechanical, functional and biological properties of the copolymer were investigated. The physicochemical characterization confirmed that the copolymerization was successfully carried out. In addition, the newly synthesized poly(NIPAAm-co-HEMAHex) copolymer showed temperature sensitivity, with a phase separation temperature under body temperature (at 23 °C). Fourier transform infrared spectroscopy and differential scanning calorimetry results after hydrolysis tests indicated that the incorporation of the HEMAHex ester groups provides the cleavage of the lateral chain, which leads to an increase in the hydrophilicity of the copolymer and, consequently, to an increase in the lower critical solution temperature (LCST) with time. Since the LCST increases above body temperature (up to 40.4 °C), the copolymer becomes soluble again and diffuses away. It was also demonstrated that the hydrolysis occurred on the peripheral ester bond of the lateral chain, with the release of 6-hydroxyhexanoic acid, whose bioresorbibility has been reported in the literature. Therefore, the properties of this copolymer are very interesting and make it particularly attractive for biomedical applications.

  3. Molecularly Imprinted Biodegradable Nanoparticles

    Science.gov (United States)

    Gagliardi, Mariacristina; Bertero, Alice; Bifone, Angelo

    2017-01-01

    Biodegradable polymer nanoparticles are promising carriers for targeted drug delivery in nanomedicine applications. Molecu- lar imprinting is a potential strategy to target polymer nanoparticles through binding of endogenous ligands that may promote recognition and active transport into specific cells and tissues. However, the lock-and-key mechanism of molecular imprinting requires relatively rigid cross-linked structures, unlike those of many biodegradable polymers. To date, no fully biodegradable molecularly imprinted particles have been reported in the literature. This paper reports the synthesis of a novel molecularly- imprinted nanocarrier, based on poly(lactide-co-glycolide) (PLGA) and acrylic acid, that combines biodegradability and molec- ular recognition properties. A novel three-arm biodegradable cross-linker was synthesized by ring-opening polymerization of glycolide and lactide initiated by glycerol. The resulting macromer was functionalized by introduction of end-functions through reaction with acryloyl chloride. Macromer and acrylic acid were used for the synthesis of narrowly-dispersed nanoparticles by radical polymerization in diluted conditions in the presence of biotin as template molecule. The binding capacity of the imprinted nanoparticles towards biotin and biotinylated bovine serum albumin was twentyfold that of non-imprinted nanoparti- cles. Degradation rates and functional performances were assessed in in vitro tests and cell cultures, demonstrating effective biotin-mediated cell internalization. PMID:28071745

  4. Molecularly Imprinted Biodegradable Nanoparticles

    Science.gov (United States)

    Gagliardi, Mariacristina; Bertero, Alice; Bifone, Angelo

    2017-01-01

    Biodegradable polymer nanoparticles are promising carriers for targeted drug delivery in nanomedicine applications. Molecu- lar imprinting is a potential strategy to target polymer nanoparticles through binding of endogenous ligands that may promote recognition and active transport into specific cells and tissues. However, the lock-and-key mechanism of molecular imprinting requires relatively rigid cross-linked structures, unlike those of many biodegradable polymers. To date, no fully biodegradable molecularly imprinted particles have been reported in the literature. This paper reports the synthesis of a novel molecularly- imprinted nanocarrier, based on poly(lactide-co-glycolide) (PLGA) and acrylic acid, that combines biodegradability and molec- ular recognition properties. A novel three-arm biodegradable cross-linker was synthesized by ring-opening polymerization of glycolide and lactide initiated by glycerol. The resulting macromer was functionalized by introduction of end-functions through reaction with acryloyl chloride. Macromer and acrylic acid were used for the synthesis of narrowly-dispersed nanoparticles by radical polymerization in diluted conditions in the presence of biotin as template molecule. The binding capacity of the imprinted nanoparticles towards biotin and biotinylated bovine serum albumin was twentyfold that of non-imprinted nanoparti- cles. Degradation rates and functional performances were assessed in in vitro tests and cell cultures, demonstrating effective biotin-mediated cell internalization.

  5. Hydrophilization of poly(caprolactone copolymers through introduction of oligo(ethylene glycol moieties.

    Directory of Open Access Journals (Sweden)

    Jonathan J Wurth

    Full Text Available In this study, a new family of poly(ε-caprolactone (PCL copolymers that bear oligo(ethylene glycol (OEG moieties is described. The synthesis of three different oligo(ethylene glycol functionalized epoxide monomers derived from 2-methyl-4-pentenoic acid, and their copolymerization with ε-caprolactone (CL to poly(CL-co-OEG-MPO copolymers is presented. The statistical copolymerization initiated with SnOct2/BnOH yielded the copolymers with varying OEG content and composition. The linear relationship between feed ratio and incorporation of the OEG co-monomer enables control over backbone functional group density. The introduction of OEG moieties influenced both the thermal and the hydrophilic characteristics of the copolymers. Both increasing OEG length and backbone content resulted in a decrease in static water contact angle. The introduction of OEG side chains in the PCL copolymers had no adverse influence on MC-3TE3-E1 cell interaction. However, changes to cell form factor (Φ were observed. While unmodified PCL promoted elongated (anisotropic morphologies (Φ = 0.094, PCL copolymer with tri-ethylene glycol side chains at or above seven percent backbone incorporation induced more isotropic cell morphologies (Φ = 0.184 similar to those observed on glass controls (Φ = 0.151.

  6. Synthesis and properties of acrylic copolymers for ocular implants

    Science.gov (United States)

    Reboul, Adam C.

    There is a need for flexible polymers with higher refractive index and extended UV absorbing properties for improved intraocular lenses (IOLs). This research was devoted to the synthesis of new acrylic copolymers for foldable IOLs and to studies concerning IOL polymer properties. New polymers were synthesized from phenylated acrylates copolymerized with N-vinyl carbazole derivatives using bulk free radical addition methods. The copolymers had low Tg values, high refractive index, and were flexible. The N-vinyl carbazole derivatives were characterized by NMR and copolymers were characterized by DSC, UV-Vis, and refractometry. New phenothiazine based UV absorbers with high extinction coefficients were also synthesized for incorporation into ocular materials. Patent disclosures on UV absorbers and high refractive index polymers were prepared. A so called "glistening" phenomenon that occurs in all foldable intraocular lenses currently in clinical use is poorly understood and was studied. Research on this microvoid forming behavior included studies and development of methods to inhibit glistening in low Tg acrylic based copolymers. Glistenings were characterized using SEM and optical microscopy. A novel technique for inhibiting glistening was found and a patent disclosure was prepared.

  7. Inducing Order from Disordered Copolymers: On Demand Generation of Triblock Morphologies Including Networks

    Energy Technology Data Exchange (ETDEWEB)

    Tureau, Maëva S.; Kuan, Wei-Fan; Rong, Lixia; Hsiao, Benjamin S.; Epps, III, Thomas H. (Delaware); (Buffalo)

    2015-10-15

    Disordered block copolymers are generally impractical in nanopatterning applications due to their inability to self-assemble into well-defined nanostructures. However, inducing order in low molecular weight disordered systems permits the design of periodic structures with smaller characteristic sizes. Here, we have induced nanoscale phase separation from disordered triblock copolymer melts to form well-ordered lamellae, hexagonally packed cylinders, and a triply periodic gyroid network structure, using a copolymer/homopolymer blending approach, which incorporates constituent homopolymers into selective block domains. This versatile blending approach allows one to precisely target multiple nanostructures from a single disordered material and can be applied to a wide variety of triblock copolymer systems for nanotemplating and nanoscale separation applications requiring nanoscale feature sizes and/or high areal feature densities.

  8. Green and biodegradable electronics

    Directory of Open Access Journals (Sweden)

    Mihai Irimia-Vladu

    2012-07-01

    Full Text Available We live in a world where the lifetime of electronics is becoming shorter, now approaching an average of several months. This poses a growing ecological problem. This brief review will present some of the initial steps taken to address the issue of electronic waste with biodegradable organic electronic materials. Many organic materials have been shown to be biodegradable, safe, and nontoxic, including compounds of natural origin. Additionally, the unique features of such organic materials suggest they will be useful in biofunctional electronics; demonstrating functions that would be inaccessible for traditional inorganic compounds. Such materials may lead to fully biodegradable and even biocompatible/biometabolizable electronics for many low-cost applications. This review highlights recent progress in these classes of material, covering substrates and insulators, semiconductors, and finally conductors.

  9. BARRIER PROPERTIES OF VINYLIDENE CHLORIDE COPOLYMERS

    Institute of Scientific and Technical Information of China (English)

    LI Yuesheng; WENG Zhixue; HUANG Zhiming; PAN Zuren

    1996-01-01

    The permeability coefficients of a series of copolymers of vinylidene chloride (VDC)with methyl acrylate (MA), butyl acrylate (BA) or vinyl chloride (VC) (as comonomer)to oxygen and carbon dioxide have been measured at 1.0 MPa and 30℃, while those to water vapor have been measured at 30℃ and 100% relative humidity. All the copolymers are semicrystalline. VDC/MA copolymers have lower melting temperature compared with VDC/BA copolymers, while that melting temperature of VDC/VC copolymer is higher than that of VDC/acrylate copolymers with the same VDC content. The barrier property of the copolymers is predominantly controlled by crystallite, free volume fraction, and cohesive energy. The permeability coefficients of VDC/MA copolymers to oxygen, carbon dioxide, and water vapor were successfully correlated with the ratio of free volume to cohesive energy.

  10. Lignin poly(lactic acid) copolymers

    Energy Technology Data Exchange (ETDEWEB)

    Olsson, Johan Vilhelm; Chung, Yi-Lin; Li, Russell Jingxian; Waymouth, Robert; Sattely, Elizabeth; Billington, Sarah; Frank, Curtis W.

    2017-02-14

    Provided herein are graft co-polymers of lignin and poly(lactic acid) (lignin-g-PLA copolymer), thermoset and thermoplastic polymers including them, methods of preparing these polymers, and articles of manufacture including such polymers.

  11. Nanomechanical properties of multi-block copolymer microspheres for drug delivery applications.

    Science.gov (United States)

    Moshtagh, P R; Rauker, J; Sandker, M J; Zuiddam, M R; Dirne, F W A; Klijnstra, E; Duque, L; Steendam, R; Weinans, H; Zadpoor, A A

    2014-06-01

    Biodegradable polymeric microspheres are interesting drug delivery vehicles for site-specific sustained release of drugs used in treatment of osteoarthritis. We study the nano-mechanical properties of microspheres composed of hydrophilic multi-block copolymers, because the release profile of the microspheres may be dependent on the mechanical interactions between the host tissues and the microspheres that aim to incorporate between the cartilage surfaces. Three different sizes of monodisperse microspheres, namely 5, 15, and 30μm, were tested in both dry and hydrated (swollen) states. Atomic force microscopy was used for measuring nanoindentation-based force-displacement curves that were later used for calculating the Young׳s moduli using the Hertz׳s contact theory. For every microsphere size and condition, the measurements were repeated 400-500 times at different surface locations and the histograms of the Young׳s modulus were plotted. The mean Young׳s modulus of 5, 15, and 30μm microspheres were respectively 56.1±71.1 (mean±SD), 94.6±103.4, and 57.6±58.6MPa under dry conditions and 226.4±54.2, 334.5±128.7, and 342.5±136.8kPa in the swollen state. The histograms were not represented well by the average Young׳s modulus and showed three distinct peaks in the dry state and one distinct peak in the swollen state. The peaks under dry conditions are associated with the different parts of the co-polymeric material at the nano-scale. The measured mechanical properties of swollen microspheres are within the range of the nano-scale properties of cartilage, which could favor integration of the microspheres with the host tissue.

  12. Editorial: Biodegradable Materials

    Directory of Open Access Journals (Sweden)

    Carl Schaschke

    2014-11-01

    Full Text Available This Special Issue “Biodegradable Materials” features research and review papers concerning recent advances on the development, synthesis, testing and characterisation of biomaterials. These biomaterials, derived from natural and renewable sources, offer a potential alternative to existing non-biodegradable materials with application to the food and biomedical industries amongst many others. In this Special Issue, the work is expanded to include the combined use of fillers that can enhance the properties of biomaterials prepared as films. The future application of these biomaterials could have an impact not only at the economic level, but also for the improvement of the environment.

  13. Orthopaedic applications for PLA-PGA biodegradable polymers.

    Science.gov (United States)

    Athanasiou, K A; Agrawal, C M; Barber, F A; Burkhart, S S

    1998-10-01

    Biodegradable polymers, especially those belonging to the family of polylactic acid (PLA) and polyglycolic acid (PGA), play an increasingly important role in orthopaedics. These polymers degrade by hydrolysis and enzymatic activity and have a range of mechanical and physical properties that can be engineered appropriately to suit a particular application. Their degradation characteristics depend on several parameters including their molecular structure, crystallinity, and copolymer ratio. These biomaterials are also rapidly gaining recognition in the fledging field of tissue engineering because they can be fashioned into porous scaffolds or carriers of cells, extracellular matrix components, and bioactive agents. Although their future appears to be bright, several questions regarding the biocompatibility of these materials linger and should be addressed before their wide-scale use. In the context of musculoskeletal tissue, this report provides a comprehensive review of properties and applications of biodegradable PLA/PGA polymers and their copolymers. Of special interest are orthopaedic applications, biocompatibility studies, and issues of sterilization and storage of these versatile biomaterials. Also discussed is the fact that terms such as PLA, PGA, or PLA-PGA do not denote one material, but rather a large family of materials that have a wide range of differing bioengineering properties and concomitant biological responses. An analysis of some misconceptions, problems, and potential solutions is also provided.

  14. Micellization and Dynamics of a Block Copolymer

    DEFF Research Database (Denmark)

    Hvidt, Søren

    2006-01-01

    Triblock copolymers of the type EPE, where E and P denote ethylene oxide and propylene oxide blocks, respectively, are industrially important copolymers often called Pluronics or Poloxamers. EPE copolymers form micelles with a core of P blocks and different micellar shapes depending on block leng...

  15. Copolymers For Capillary Gel Electrophoresis

    Science.gov (United States)

    Liu, Changsheng; Li, Qingbo

    2005-08-09

    This invention relates to an electrophoresis separation medium having a gel matrix of at least one random, linear copolymer comprising a primary comonomer and at least one secondary comonomer, wherein the comonomers are randomly distributed along the copolymer chain. The primary comonomer is an acrylamide or an acrylamide derivative that provides the primary physical, chemical, and sieving properties of the gel matrix. The at least one secondary comonomer imparts an inherent physical, chemical, or sieving property to the copolymer chain. The primary and secondary comonomers are present in a ratio sufficient to induce desired properties that optimize electrophoresis performance. The invention also relates to a method of separating a mixture of biological molecules using this gel matrix, a method of preparing the novel electrophoresis separation medium, and a capillary tube filled with the electrophoresis separation medium.

  16. Biodegradable Materials for Nonwovens

    Science.gov (United States)

    Demand for nonwovens is increasing globally, particularly in the disposable products area. As the consumption of nonwoven products with short life increases, the burden on waste disposal also rises. In this context, biodegradable nonwovens become more important today and for the future. Several new ...

  17. Grey water biodegradability

    NARCIS (Netherlands)

    Abu Ghunmi, L.; Zeeman, G.; Fayyad, M.; Van Lier, J.B.

    2010-01-01

    Knowing the biodegradability characteristics of grey water constituents is imperative for a proper design and operation of a biological treatment system of grey water. This study characterizes the different COD fractions of dormitory grey water and investigates the effect of applying different condi

  18. Grey water biodegradability

    NARCIS (Netherlands)

    Abu Ghunmi, L.; Zeeman, G.; Fayyad, M.; Lier, van J.B.

    2011-01-01

    Knowing the biodegradability characteristics of grey water constituents is imperative for a proper design and operation of a biological treatment system of grey water. This study characterizes the different COD fractions of dormitory grey water and investigates the effect of applying different condi

  19. Preparation of biodegradable PLA/PLGA membranes with PGA mesh and their application for periodontal guided tissue regeneration

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Eun Jin; Kang, Inn-Kyu [Department of Polymer Science, Kyungpook National University, 1370 Sankyuk-dong, Buk-gu, Daegu 702-701 (Korea, Republic of); Yoon, Suk Joon [Department of Biology, Sookmyung Women' s University, Hyochangwongil 52, Yongsan-gu, Seoul 140-742 (Korea, Republic of); Yeo, Guw-Dong; Pai, Chaul-Min, E-mail: ikkang@knu.ac.k [Samyang Central R and D Center, 63-2 Hwaam-dong, Yusung-gu, Daejeon 305-717 (Korea, Republic of)

    2009-10-15

    A biodegradable polylactic acid (PLA)/poly(glycolide-co-lactide) copolymer (PLGA) membrane with polyglycolic acid (PGA) mesh was prepared to aid the effective regeneration of defective periodontal tissues. The microporous membrane used in this study consists of biodegradable polymers, and seems to have a structure to provide appropriate properties for periodontal tissue regeneration. Based on the albumin permeation test, it is known that the biodegradable membrane exhibits the suitable permeability of nutrients. The membrane maintained its physical integrity for 6-8 weeks, which could be sufficient to retain space in the periodontal pocket. Cell attachment and cytotoxicity tests were performed with respect to the evaluation of biocompatibility of the membrane. As a result, the membrane did not show any cytotoxicity. The safety and therapeutic efficacies of the biodegradable membranes were confirmed in animal tests.

  20. Preparation of biodegradable PLA/PLGA membranes with PGA mesh and their application for periodontal guided tissue regeneration.

    Science.gov (United States)

    Kim, Eun Jin; Yoon, Suk Joon; Yeo, Guw-Dong; Pai, Chaul-Min; Kang, Inn-Kyu

    2009-10-01

    A biodegradable polylactic acid (PLA)/poly(glycolide-co-lactide) copolymer (PLGA) membrane with polyglycolic acid (PGA) mesh was prepared to aid the effective regeneration of defective periodontal tissues. The microporous membrane used in this study consists of biodegradable polymers, and seems to have a structure to provide appropriate properties for periodontal tissue regeneration. Based on the albumin permeation test, it is known that the biodegradable membrane exhibits the suitable permeability of nutrients. The membrane maintained its physical integrity for 6-8 weeks, which could be sufficient to retain space in the periodontal pocket. Cell attachment and cytotoxicity tests were performed with respect to the evaluation of biocompatibility of the membrane. As a result, the membrane did not show any cytotoxicity. The safety and therapeutic efficacies of the biodegradable membranes were confirmed in animal tests.

  1. Synthesis and physicochemical characterization of copolymers of 3-octylthiophene and thiophene functionalized with azo chromophore

    Energy Technology Data Exchange (ETDEWEB)

    Nicho, M.E., E-mail: menicho@uaem.mx [Centro de Investigacion en Ingenieria y Ciencias Aplicadas, Universidad Autonoma del Estado de Morelos (UAEM), Av. Universidad 1001, Col. Chamilpa, C.P. 62209, Cuernavaca, Morelos (Mexico); Garcia-Carvajal, S.; Marquez-Aguilar, P.A.; Gueizado-Rodriguez, M. [Centro de Investigacion en Ingenieria y Ciencias Aplicadas, Universidad Autonoma del Estado de Morelos (UAEM), Av. Universidad 1001, Col. Chamilpa, C.P. 62209, Cuernavaca, Morelos (Mexico); Escalante-Garcia, J. [Centro de Investigaciones Quimicas, UAEM, C.P. 62210, Cuernavaca, Morelos (Mexico); Medrano-Baca, G. [Centro de Investigacion en Ingenieria y Ciencias Aplicadas, Universidad Autonoma del Estado de Morelos (UAEM), Av. Universidad 1001, Col. Chamilpa, C.P. 62209, Cuernavaca, Morelos (Mexico)

    2011-10-03

    Highlights: {yields} Azo chromophore in the copolymer showed an additional color to the P3OT. {yields} Non-linear optical properties by Z-scan technique in states: neutral and oxidized. {yields} The copolymers showed a change of non-linearity sign when the films were doped. {yields} We determined that the nonlinearity of the polymer films was a Kerr type. {yields} This study is the first report of NLO characterization of this material. - Abstract: Polythiophene derivatives with azo chromophore were synthesized via copolymerization of 3-octylthiophene (3OT) and 2-[N-ethyl-N-[4-[(4-nitrophenyl)azo]phenyl]amino]ethyl 3-thienylacetate (3-DRT). This copolymer has interesting optoelectronic properties and a variety of applications such as electrochromic and electronic devices. The polymerization process of 3OT and the functionalized thiophene was carried out via FeCl{sub 3} oxidative polymerization. Thin films of poly(3OT-co-3-DRT) copolymer were prepared by spin-coating technique from toluene. FTIR and {sup 1}H NMR spectroscopy revealed the presence of chromophore groups in the copolymer chain. Molecular weight and polydispersity of the polymers were measured by size exclusion chromatography. Changes in the surface topography of copolymers were analyzed by atomic force microscopy; the results showed that the copolymers presented some protuberances of variable size unlike the homogeneous granular morphology of P3OT. It is believed that these changes appeared by the incorporation of 3-DRT in the polymer. P3ATs are electrochromic materials that show color change upon oxidation-reduction process. We report that electrochemical characterization of poly(3OT-co-3-DRT) copolymer films synthesized chemically on indium-tin oxide (ITO) glass substrates showed an additional color to the P3OT homopolymer. Optical absorption properties of the polymer films were analyzed in the undoped and doped states and as a function of 3-DRT concentration in the copolymer. The nonlinear optical

  2. Development and characterization of biodegradable polymer blends - PHBV/PCL irradiated with gamma rays

    Energy Technology Data Exchange (ETDEWEB)

    Rosario, F. [Faculdade de Tecnologia da Zona Leste (FATEC-ZL), Sao Paulo, SP (Brazil). Centro Paulo Souza; Casarin, S.A.; Agnelli, J.A.M. [Universidade Federal de Sao Carlos (DEMa/UFSCar), SP (Brazil). Dept. de Engenharia de Materiais; Souza Junior, O.F. de [Universidade de Sao Paulo (IFSC/USP), Sao Carlos, SP (Brazil). Inst. de Fisica

    2010-07-01

    This paper presents the results of a study that aimed to develop PHBV biodegradable polymer blends, in a major concentration with PCL, irradiate the pure polymers and blends in two doses of gamma radiation and to analyze the changes in chemical and mechanical properties. The blends used in this study were from natural biodegradable copolymer poly (hydroxybutyrate-valerate) (PHBV) and synthetic biodegradable polymer poly (caprolactone) (PCL 2201) with low molar mass (2,000 g/mol). Several samples were prepared in a co-rotating twin-screw extruder and afterwards, the tensile specimens were injected for the irradiation treatment with 50 kGy to 100 kGy doses and for the mechanical tests. The characterization of the samples before and after the irradiation treatments was performed through scanning electron microscopy (SEM), dynamic mechanical thermal analysis (DMTA), differential scanning calorimetry (DSC) and mechanical tensile tests. (author)

  3. Development in Synthesis and Modification of Biodegradable Poly(butylene succinate) and its Copolymers%可生物降解聚丁二酸丁二醇酯及其共聚物的合成及改性研究进展

    Institute of Scientific and Technical Information of China (English)

    王国利; 徐军; 郭宝华

    2011-01-01

    Poly(butylene succinate) (PBS) as one of most important biodegradable polymers are paid lot of concerns in its synthesis and modification. The use of biodegradable polymers can decrease “White Pollution" caused by using of common polymers, such as PP, PE and etc. In this paper the polycondensation methods and process of PBS are reviewed. In order to enhance their properties and extend their application fields, the physical and chemical modifications of PBS are also given an introduction.%聚丁二酸丁二醇酯(PBS)是一种重要的可生物降解聚合物材料,在一定程度上可以缓解由于使用传统聚合物材料造成的"白色污染"问题.其合成和改性研究受到广泛的关注.本论文对PBS的聚合工艺及方法等方面进行了综述,并对PBS材料物理或化学改性进行了阐述.

  4. Effect of solvents on the enzyme mediated degradation of copolymers

    Science.gov (United States)

    Banerjee, Aditi; Chatterjee, Kaushik; Madras, Giridhar

    2015-09-01

    The biodegradation of polycaprolactone (PCL), polylactic acid (PLA), polyglycolide (PGA) and their copolymers, poly (lactide-co-glycolide) and poly (D, L-lactide-co-caprolactone) (PLCL) was investigated. The influence of different solvents on the degradation of these polymers at 37 °C in the presence of two different lipases namely Novozym 435 and the free lipase of porcine pancreas was investigated. The rate coefficients for the polymer degradation and enzyme deactivation were determined using continuous distribution kinetics. Among the homopolymers, the degradation of PGA was nearly an order of magnitude lower than that for PCL and PLA. The overall rate coefficients of the copolymers were higher than their respective homopolymers. Thus, PLCL degraded faster than either PCL or PLA. The degradation was highly dependent on the viscosity of the solvent used with the highest degradation observed in acetone. The degradation of the polymers in acetone was nearly twice that observed in dimethyl sulfoxide indicating that the degradation decreases with increase in the solvent viscosity. The degradation of the polymers in water-solvent mixtures indicated an optimal water content of 2.5 wt% of water.

  5. Poly(amino carbonate urethane)-based biodegradable, temperature and pH-sensitive injectable hydrogels for sustained human growth hormone delivery

    Science.gov (United States)

    Phan, V. H. Giang; Thambi, Thavasyappan; Duong, Huu Thuy Trang; Lee, Doo Sung

    2016-07-01

    In this study, a new pH-/temperature-sensitive, biocompatible, biodegradable, and injectable hydrogel based on poly(ethylene glycol)-poly(amino carbonate urethane) (PEG-PACU) copolymers has been developed for the sustained delivery of human growth hormone (hGH). In aqueous solutions, PEG-PACU-based copolymers existed as sols at low pH and temperature (pH 6.0, 23 °C), whereas they formed gels in the physiological condition (pH 7.4, 37 °C). The physicochemical characteristics, including gelation rate, mechanical strength and viscosity, of the PEG-PACU hydrogels could be finely tuned by varying the polymer weight, pH and temperature of the copolymer. An in vivo injectable study in the back of Sprague-Dawley (SD) rats indicated that the copolymer could form an in situ gel, which exhibited a homogenous porous structure. In addition, an in vivo biodegradation study of the PEG-PACU hydrogels showed controlled degradation of the gel matrix without inflammation at the injection site and the surrounding tissue. The hGH-loaded PEG-PACU copolymer solution readily formed a hydrogel in SD rats, which subsequently inhibited the initial hGH burst and led to the sustained release of hGH. Overall, the PEG-PACU-based copolymers prepared in this study are expected to be useful biomaterials for the sustained delivery of hGH.

  6. Polyether-polyester graft copolymer

    Science.gov (United States)

    Bell, Vernon L. (Inventor)

    1987-01-01

    Described is a polyether graft polymer having improved solvent resistance and crystalline thermally reversible crosslinks. The copolymer is prepared by a novel process of anionic copolymerization. These polymers exhibit good solvent resistance and are well suited for aircraft parts. Previous aromatic polyethers, also known as polyphenylene oxides, have certain deficiencies which detract from their usefulness. These commercial polymers are often soluble in common solvents including the halocarbon and aromatic hydrocarbon types of paint thinners and removers. This limitation prevents the use of these polyethers in structural articles requiring frequent painting. In addition, the most popular commercially available polyether is a very high melting plastic. This makes it considerably more difficult to fabricate finished parts from this material. These problems are solved by providing an aromatic polyether graft copolymer with improved solvent resistance and crystalline thermally reversible crosslinks. The graft copolymer is formed by converting the carboxyl groups of a carboxylated polyphenylene oxide polymer to ionic carbonyl groups in a suitable solvent, reacting pivalolactone with the dissolved polymer, and adding acid to the solution to produce the graft copolymer.

  7. Liquid ethylene-propylene copolymers

    Science.gov (United States)

    Rhein, R. A.; Ingham, J. D.; Humphrey, M. F.

    1975-01-01

    Oligomers are prepared by heating solid ethylene-propylene rubber in container that retains solid and permits liquid product to flow out as it is formed. Molecular weight and viscosity of liquids can be predetermined by process temperature. Copolymers have low viscosity for given molecular weight.

  8. Syntheses and Surface Properties of Polyacrylonitrile-based Copolymer Membranes Containing Sugar Moieties

    Institute of Scientific and Technical Information of China (English)

    HUANG Xiao-jun; WAN Ling-shu; DAI Zheng-wei; KOU Rui-qiang; XU Zhi-kang

    2005-01-01

    To improve the hydrophilicity of polyacrylonitrile-based membranes, sugar moieties were incorporated into acrylonitrile-based copolymers via the radical copolymerization of α-allyl glucoside(AG) with acrylonitrile(AN) with 2,2'-azobis-iso-butyronitrile(AIBN) as the initiator in dimethyl sulphoxide(DMSO). It was found that the yield increased with the increase of the initiator concentration and reaction time, while it decreased with the increase of the monomer molar ratio of AG to AN. Raising the AG proportion in the monomer mixture resulted in the increase of the AG content in the copolymer. Mv of the copolymers decreased with increasing the AG monomer fraction in feed. The copolymers were fabricated into dense membranes and their surface properties were studied by means of the water contact angle measurement and platelet adhesion tests. It was found that the static water contact angle on the membrane decreased significantly from 70° to 33° with the increase of the AG content. The adhesive number of platelets on the membrane surface also decreased significantly with increasing AG content in the copolymers. These results demonstrate that the hydrophilicity and biocompatibility of the acrylonitrile-based copolymer membranes could be improved efficiently by the copolymerization of acrylonitrile with vinyl carbohydrates.

  9. Neutral, anionic, cationic, and zwitterionic diblock copolymers featuring poly(2-methoxyethyl acrylate) hydrophobic segments

    DEFF Research Database (Denmark)

    Javakhishvili, Irakli; Jankova Atanasova, Katja; Hvilsted, Søren

    2013-01-01

    Amphiphilic diblock copolymers incorporating hydrophobic poly(2-methoxyethyl acrylate) (PMEA) and hydrophilic neutral poly(ethylene glycol) monomethyl ether (mPEG), anionic poly(acrylic acid) (PAA) and poly(methacrylic acid) (PMAA), cationic poly(2-dimethylaminoethyl methacrylate) (PDMAEMA), and ...

  10. Soil Quality and Colloid Transport under Biodegradable Mulches

    Science.gov (United States)

    Sintim, Henry; Bandopadhyay, Sreejata; Ghimire, Shuresh; Flury, Markus; Bary, Andy; Schaeffer, Sean; DeBruyn, Jennifer; Miles, Carol; Inglis, Debra

    2016-04-01

    Polyethylene (PE) mulch is commonly used in agriculture to increase water use efficiency, to control weeds, manage plant diseases, and maintain a favorable micro-climate for plant growth. However, producers need to retrieve and safely dispose PE mulch after usage, which creates enormous amounts of plastic waste. Substituting PE mulch with biodegradable plastic mulches could alleviate disposal needs. However, repeated applications of biodegradable mulches, which are incorporated into the soil after the growing season, may cause deterioration of soil quality through breakdown of mulches into colloidal fragments, which can be transported through soil. Findings from year 1 of a 5-year field experiment will be presented.

  11. Chitosan-graft poly(p-dioxanone) copolymers: preparation, characterization, and properties.

    Science.gov (United States)

    Wang, Xiu-Li; Huang, Yan; Zhu, Jiang; Pan, Yan-Bo; He, Rui; Wang, Yu-Zhong

    2009-04-21

    A new biodegradable copolymer of chitosan and poly(p-dioxanone) (PPDO) was prepared through a protection-graft-deprotection procedure using N-phthaloyl-chitosan as an intermediate. PPDO terminated with the isocyanate group was allowed to react with hydroxyl groups of the N-phthaloyl-protected chitosan, and then the phthaloyl group was cleaved to give the free amino groups. The length of PPDO graft chains can be controlled easily by using the prepolymers of PPDO with different molecular weights. The resulting products were thoroughly characterized with FT-IR, (1)H NMR, TG, DSC, SEM, and WAXD. The copolymers were used as drug carriers for sinomenine (7,8-didehydro-4-hydroxy-3,7-dimethoxy-17-methyl-9alpha,13alpha,14alpha-morphinan-6-one) and these exhibited a significant controlled drug-releasing behavior whether in artificial gastric juice or in neutral phosphate buffer solution.

  12. Absorbable and biodegradable polymers

    CERN Document Server

    Shalaby, Shalaby W

    2003-01-01

    INTRODUCTION NOTES: Absorbable/Biodegradable Polymers: Technology Evolution. DEVELOPMENT AND APPLICATIONOF NEW SYSTEMS: Segmented Copolyesters with Prolonged Strength Retention Profiles. Polyaxial Crystalline Fiber-Forming Copolyester. Polyethylene Glycol-Based Copolyesters. Cyanoacrylate-Based Systems as Tissue Adhesives. Chitosan-Based Systems. Hyaluronic Acid-Based Systems. DEVELOPMENTS IN PREPARATIVE, PROCESSING, AND EVALUATION METHODS: New Approaches to the Synthesis of Crystalline. Fiber-Forming Aliphatic Copolyesters. Advances in Morphological Development to Tailor the Performance of Me

  13. Safe biodegradable fluorescent particles

    Science.gov (United States)

    Martin, Sue I.; Fergenson, David P.; Srivastava, Abneesh; Bogan, Michael J.; Riot, Vincent J.; Frank, Matthias

    2010-08-24

    A human-safe fluorescence particle that can be used for fluorescence detection instruments or act as a safe simulant for mimicking the fluorescence properties of microorganisms. The particle comprises a non-biological carrier and natural fluorophores encapsulated in the non-biological carrier. By doping biodegradable-polymer drug delivery microspheres with natural or synthetic fluorophores, the desired fluorescence can be attained or biological organisms can be simulated without the associated risks and logistical difficulties of live microorganisms.

  14. Biodegradation of Silk Biomaterials

    OpenAIRE

    Bochu Wang; Yang Cao

    2009-01-01

    Silk fibroin from the silkworm, Bombyx mori, has excellent properties such as biocompatibility, biodegradation, non-toxicity, adsorption properties, etc. As a kind of ideal biomaterial, silk fibroin has been widely used since it was first utilized for sutures a long time ago. The degradation behavior of silk biomaterials is obviously important for medical applications. This article will focus on silk-based biomaterials and review the degradation behaviors of silk materials.

  15. Impacts of Repeat Unit Structure and Copolymer Architecture on Thermal and Solution Properties in Homopolymers, Copolymers, and Copolymer Blends

    Science.gov (United States)

    Marrou, Stephen Raye

    Gradient copolymers are a relatively new type of copolymer architecture in which the distribution of comonomers gradually varies over the length of the copolymer chain, resulting in a number of unusual properties derived from the arrangement of repeat units. For example, nanophase-segregated gradient copolymers exhibit extremely broad glass transition temperatures (Tgs) resulting from the wide range of compositions present in the nanostructure. This dissertation presents a number of studies on how repeat unit structure and copolymer architecture dictate bulk and solution properties, specifically taking inspiration from the gradient copolymer architecture and comparing the response from this compositionally heterogeneous material to other more conventional materials. The glass transition behavior of a range of common homopolymers was studied to determine the effects of subunit structure on Tg breadth, observing a significant increase in T g breadth with increasing side chain length in methacrylate-based homopolymers and random copolymers. Additionally, increasing the composition distribution of copolymers, either by blending individual random copolymers of different overall composition or synthesizing random copolymers to high conversion, resulted in significant increases to Tg breadth. Plasticization of homopolymers and random copolymers with low molecular weight additives also served to increase the Tg breadth; the most dramatic effect was observed in the selective plasticization of a styrene/4-vinylpyridine gradient copolymer with increases in T g breadth to values above 100 °C. In addition, the effects of repeat unit structure and copolymer architecture on other polymer properties besides Tg were also investigated. The intrinsic fluorescence of styrene units in styrene-containing copolymers was studied, noting the impact of repeat unit structure and copolymer architecture on the resulting fluorescence spectra in solution. The impact of repeat unit structure on

  16. Anaerobic Biodegradation of Detergent Surfactants

    Directory of Open Access Journals (Sweden)

    Erich Jelen

    2009-03-01

    Full Text Available Detergent surfactantscan be found in wastewater in relevant concentrations. Most of them are known as ready degradable under aerobic conditions, as required by European legislation. Far fewer surfactants have been tested so far for biodegradability under anaerobic conditions. The natural environment is predominantly aerobic, but there are some environmental compartments such as river sediments, sub-surface soil layer and anaerobic sludge digesters of wastewater treatment plants which have strictly anaerobic conditions. This review gives an overview on anaerobic biodegradation processes, the methods for testing anaerobic biodegradability, and the anaerobic biodegradability of different detergent surfactant types (anionic, nonionic, cationic, amphoteric surfactants.

  17. Potential for polyhydroxyalkanoates and policaprolactone copolymer use as tissue-engineered scaffolds in cardiovascular surgery

    Directory of Open Access Journals (Sweden)

    L. V. Antonova

    2012-01-01

    Full Text Available The absence of reliably functioning small-diameter vascular grafts for coronary artery bypass graft surgery remains one of the most important issues of cardiovascular surgery. Tissue-engineered grafts have to be characterized by highly hemocompatible, biomechanical and biocompatible properties, be quickly biodegradable and have non-toxic degradation products. This article presents polyhydroxyalkanoate and policaprolactone main characteristics and evaluates their potential use as polymers for producing vascular grafts. Biocompatibility, good physical and mechanical properties of these polymers and their better performance in copolymer scaffolds were demonstrated.

  18. Gas Permeation through Polystyrene-Poly(ethylene oxide) Block Copolymers

    Science.gov (United States)

    Hallinan, Daniel, Jr.; Minelli, Matteo; Giacinti-Baschetti, Marco; Balsara, Nitash

    2013-03-01

    Lithium air batteries are a potential technology for affordable energy storage. They consist of a lithium metal anode and a porous air cathode separated by a solid polymer electrolyte membrane, such as PEO/LiTFSI (PEO = poly(ethylene oxide), LiTFSI = lithium bis-trifluoromethane sulfonimide). For extended operation of such a battery, the polymer electrolyte must conduct lithium ions while blocking electrons and gases present in air. In order to maintain a pressure difference the membrane must be mechanically robust, which can be achieved by incorporating the PEO into a block copolymer with a glassy block such as PS (PS = polystyrene). To protect the lithium electrode, the membrane must have low permeability to gases in air such as CO2, N2, and O2. We have therefore studied the permeation of pure gases through a PS-PEO block copolymer. A high molecular weight, symmetric block copolymer with a lamellar morphology was used to cast free-standing membranes. Gas permeability was measured through these membranes with a standard, pressure-based technique. A model was developed to account for transport through the polymer membrane consisting of semi-crystalline PEO lamellae and amorphous PS lamellae. PEO crystallinity was extracted from the permeation model and compares well with values from differential scanning calorimetry measurements.

  19. Graphene oxide-enhanced sol-gel transition sensitivity and drug release performance of an amphiphilic copolymer-based nanocomposite

    Science.gov (United States)

    Hu, Huawen; Wang, Xiaowen; Lee, Ka I.; Ma, Kaikai; Hu, Hong; Xin, John H.

    2016-08-01

    We report the fabrication of a highly sensitive amphiphilic copolymer-based nanocomposite incorporating with graphene oxide (GO), which exhibited a low-intensity UV light-triggered sol-gel transition. Non-cytotoxicity was observed for the composite gels after the GO incorporation. Of particular interest were the microchannels that were formed spontaneously within the GO-incorporated UV-gel, which expedited sustained drug release. Therefore, the present highly UV-sensitive, non-cytotoxic amphiphilic copolymer-based composites is expected to provide enhanced photothermal therapy and chemotherapy by means of GO’s unique photothermal properties, as well as through efficient passive targeting resulting from the sol-gel transition characteristic of the copolymer-based system with improved sensitivity, which thus promises the enhanced treatment of patients with cancer and other diseases.

  20. Graphene oxide-enhanced sol-gel transition sensitivity and drug release performance of an amphiphilic copolymer-based nanocomposite.

    Science.gov (United States)

    Hu, Huawen; Wang, Xiaowen; Lee, Ka I; Ma, Kaikai; Hu, Hong; Xin, John H

    2016-08-19

    We report the fabrication of a highly sensitive amphiphilic copolymer-based nanocomposite incorporating with graphene oxide (GO), which exhibited a low-intensity UV light-triggered sol-gel transition. Non-cytotoxicity was observed for the composite gels after the GO incorporation. Of particular interest were the microchannels that were formed spontaneously within the GO-incorporated UV-gel, which expedited sustained drug release. Therefore, the present highly UV-sensitive, non-cytotoxic amphiphilic copolymer-based composites is expected to provide enhanced photothermal therapy and chemotherapy by means of GO's unique photothermal properties, as well as through efficient passive targeting resulting from the sol-gel transition characteristic of the copolymer-based system with improved sensitivity, which thus promises the enhanced treatment of patients with cancer and other diseases.

  1. Multifunctional nanoassemblies of block copolymers for future cancer therapy

    Directory of Open Access Journals (Sweden)

    Horacio Cabral and Kazunori Kataoka

    2010-01-01

    Full Text Available Nanoassemblies from amphiphilic block copolymers are promising nanomedicine platforms for cancer diagnosis and therapy due to their relatively small size, high loading capacity of drugs, controlled drug release, in vivo stability and prolonged blood circulation. Recent clinical trials with self-assembled polymeric micelles incorporating anticancer drugs have shown improved antitumor activity and decreased side effects encouraging the further development of nanoassemblies for drug delivery. This review summarizes recent approaches considering stimuli-responsive, multifunctionality and more advanced architectures, such as vesicles or worm-like micelles, for tumor-specific drug and gene delivery.

  2. The influence of chain stretching on the phase behavior of multiblock copolymer and comb copolymer melts

    NARCIS (Netherlands)

    Angerman, HJ; ten Brinke, G

    2003-01-01

    The subject of this paper is inspired by microphase-separated copolymer melts in which a small-scale structure is present inside one of the phases of a large-scale structure. Such a situation can arise in a diblock copolymer melt, if one of the blocks of the diblock is in itself a multiblock copolym

  3. Third-order nonlinear optical characterization of side-chain copolymers

    Science.gov (United States)

    Norwood, Robert A.; Sounik, James R.; Popolo, J.; Holcomb, Douglas P.

    1991-12-01

    Third order nonlinear optical properties of side-chain methacrylate copolymers incorporating 4-amino-4'-nitrostilbene, 4-oxy-4'nitrostilbene, and functionalized silicon phthalocyanine chromophores are measured by picosecond degenerate four wave mixing at 598 nm. The nonresonant stilbene system exhibits a pulse limited ultrafast response, while the resonant phthalocyanine system has a large excited state nonlinearity. Comparison of silicon phthalocyanine copolymers with solubilized guest/host systems dispersed in polymethylmethacrylate illustrate the importance of aggregation and phthalocyanine ring interaction in determining the linear optical properties and the magnitude and speed of the nonlinear optical response.

  4. Silk fibroin/copolymer composite hydrogels for the controlled and sustained release of hydrophobic/hydrophilic drugs.

    Science.gov (United States)

    Zhong, Tianyi; Jiang, Zhijuan; Wang, Peng; Bie, Shiyu; Zhang, Feng; Zuo, Baoqi

    2015-10-15

    In the present study, a composite system for the controlled and sustained release of hydrophobic/hydrophilic drugs is described. Composite hydrogels were prepared by blending silk fibroin (SF) with PLA-PEG-PLA copolymer under mild aqueous condition. Aspirin and indomethacin were incorporated into SF/Copolymer hydrogels as two model drugs with different water-solubility. The degradation of composite hydrogels during the drug release was mainly caused by the hydrolysis of copolymers. SF with stable β-sheet-rich structure was not easily degraded which maintained the mechanical integrity of composite hydrogel. The hydrophobic/hydrophilic interactions of copolymers with model drugs would significantly alter the morphological features of composite hydrogels. Various parameters such as drug load, concentration ratio, and composition of copolymer were considered in vitro drug release. Aspirin as a hydrophilic drug could be controlled release from composite hydrogel at a constant rate for 5 days. Its release was mainly driven by diffusion-based mechanism. Hydrophobic indomethacin could be encapsulated in copolymer nanoparticles distributing in the composite hydrogel. Its sustained release was mainly degradation controlled which could last up to two weeks. SF/Copolymer hydrogel has potential as a useful composite system widely applying for controlled and sustained release of various drugs.

  5. Copolymers of fluorinated polydienes and sulfonated polystyrene

    Science.gov (United States)

    Mays, Jimmy W.; Gido, Samuel P.; Huang, Tianzi; Hong, Kunlun

    2009-11-17

    Copolymers of fluorinated polydienes and sulfonated polystyrene and their use in fuel cell membranes, batteries, breathable chemical-biological protective materials, and templates for sol-gel polymerization.

  6. JTEC monograph on biodegradable polymers and plastics in Japan: Research, development, and applications

    Science.gov (United States)

    Lenz, Robert W.

    1995-01-01

    A fact-finding team of American scientists and engineers visited Japan to assess the status of research and development and applications in biodegradable polymers. The visit was sponsored by the National Science Foundation and industry. In Japan, the team met with representatives of 31 universities, government ministries and institutes, companies, and associations. Japan's national program on biodegradable polymers and plastics evaluates new technologies, testing methods, and potential markets for biodegradables. The program is coordinated by the Biodegradable Plastics Society of Japan, which seeks to achieve world leadership in biodegradable polymer technology and identify commercial opportunities for exploiting this technology. The team saw no major new technology breakthroughs. Japanese scientists and engineers are focusing on natural polymers from renewable resources, synthetic polymers, and bacterially-produced polymers such as polyhydroxyalkanoates, poly(amino acids), and polysaccharides. The major polymers receiving attention are the Zeneca PHBV copolymers, Biopol(registered trademark), poly(lactic acid) from several sources, polycaprolactone, and the new synthetic polyester, Bionolle(registered trademark), from Showa High Polymer. In their present state of development, these polymers all have major deficiencies that inhibit their acceptance for large-scale applications.

  7. A new biodegradable and biocompatible gadolinium (III) -polymer for liver magnetic resonance imaging contrast agent.

    Science.gov (United States)

    Xiao, Yan; Xue, Rong; You, Tianyan; Li, Xiaojing; Pei, Fengkui

    2015-07-01

    A new biodegradable and biocompatible gadolinium (III) -copolymer (ACL-A2-DOTA-Gd) has been developed as a potential liver magnetic resonance imaging (MRI) contrast agent. ACL-A2-DOTA-Gd consisted of a poly (aspartic acid-co-leucine) unit bound with 1,4,7,10-tetraazacyclododecan-1,4,7,10-tetraacetic acid-gadolinium (Gd-DOTA) via the linkage of ethylenediamine. In vitro, the biodegradable experiment and cytotoxicity assay showed the biodegradability and biocompatibility of this gadolinium-polymer. ACL-A2-DOTA-Gd presented an increase in relaxivity of 2.4 times than the clinical Gd-DOTA. In vivo, gadolinium (III)-copolymer was mainly accumulated in the liver, and it could be excreted via the renal and hepatobiliary mechanism. The average enhancement of ACL-A2-DOTA-Gd (60.71±5.93%, 50-80 min) in liver was 2.62-fold greater than that of Gd-DOTA (23.16±3.55%, 10-30 min). ACL-A2-DOTA-Gd could be as a potential liver MRI contrast agent with a long time-window.

  8. PHASE STRUCTURE AND THERMAL BEHAVIOR OF LIQUID CRYSTALLINE MULTI-BLOCK COPOLYMERS,POLY[1,6-BIS(4-OXYBENZOYL-OXY)HEXANE TEREPHTHALATE]-b-BISPHENOL A POLYCARBONATE

    Institute of Scientific and Technical Information of China (English)

    Hui-qing Zhang; Xiong-yan Zhao; De-shan Liu; Qi-xiang Zhou

    1999-01-01

    Liquid crystalline multi-block copolymers poly[1,6-bis(4-oxybenzoyl-oxy)hexane terephthalate]-b-bisphenol A polycarbonate (PHTH-6-b-PC) with different segments of polycarbonate (PC) and thermotropic polyester PHTH-6 were synthesized in tetrachloroethane at 144~146℃. The influence of segment length on the resulting phase structure and thermal behavior of block copolymers was also discussed. It is demonstrated by TEM and DMA that the resulting block copolymers show a considerable microphase separation. The degree of phase separation and the thermal behavior of the block copolymers are strongly dependent on the molecular weight of the segments incorporated.

  9. Structural Color for Additive Manufacturing: 3D-Printed Photonic Crystals from Block Copolymers.

    Science.gov (United States)

    Boyle, Bret M; French, Tracy A; Pearson, Ryan M; McCarthy, Blaine G; Miyake, Garret M

    2017-03-28

    The incorporation of structural color into 3D printed parts is reported, presenting an alternative to the need for pigments or dyes for colored parts produced through additive manufacturing. Thermoplastic build materials composed of dendritic block copolymers were designed, synthesized, and used to additively manufacture plastic parts exhibiting structural color. The reflection properties of the photonic crystals arise from the periodic nanostructure formed through block copolymer self-assembly during polymer processing. The wavelength of reflected light could be tuned across the visible spectrum by synthetically controlling the block copolymer molecular weight and manufacture parts that reflected violet, green, or orange light with the capacity to serve as selective optical filters and light guides.

  10. Microbial biosurfactants and biodegradation.

    Science.gov (United States)

    Ward, Owen P

    2010-01-01

    Microbial biosurfactants are amphipathic molecules having typical molecular weights of 500-1500 Da, made up of peptides, saccharides or lipids or their combinations. In biodegradation processes they mediate solubilisation, mobilization and/or accession of hydrophobic substrates to microbes. They may be located on the cell surface or be secreted into the extracellular medium and they facilitate uptake of hydrophobic molecules through direct cellular contact with hydrophobic solids or droplets or through micellarisation. They are also involved in cell physiological processes such as biofilm formation and detachment, and in diverse biofilm associated processes such as wastewater treatment and microbial pathogenesis. The protection of contaminants in biosurfactants micelles may also inhibit uptake of contaminants by microbes. In bioremediation processes biosurfactants may facilitate release of contaminants from soil, but soils also tend to bind surfactants strongly which makes their role in contaminant desorption more complex. A greater understanding of the underlying roles played by biosurfactants in microbial physiology and in biodegradative processes is developing through advances in cell and molecular biology.

  11. Drug targeting to tumors using HPMA copolymers

    NARCIS (Netherlands)

    Lammers, T.G.G.M.

    2009-01-01

    Copolymers based on N-(2-hydroxypropyl)methacrylamide (HPMA) are prototypic and well-characterized polymeric drug carriers that have been broadly implemented in the delivery of anticancer agents. HPMA copolymers circulate for prolonged periods of time, and by means of the Enhance Permeability and Re

  12. PEO-related block copolymer surfactants

    DEFF Research Database (Denmark)

    Mortensen, K.

    2001-01-01

    Non-ionic block copolymer systems based on hydrophilic poly(ethylene oxide) and more hydrophobic co-polymer blocks are used intensively in a variety of industrial and personal applications. A brief description on the applications is presented. The physical properties of more simple model systems ...

  13. Micellization and Characterization of Block Copolymer Detergents

    DEFF Research Database (Denmark)

    Hvidt, Søren

    Triblock copolymers of the type EPE, where E and P denote ethylene oxide and propylene oxide blocks, respectively, are used widely in industry as emulsifiers, anti-foaming agents, and in delayed drug release. EPE copolymers form micelles with a core of P blocks and different micellar shapes depen...

  14. New inorganic/organic copolymers (ORMOCER{reg_sign}s) for dental applications

    Energy Technology Data Exchange (ETDEWEB)

    Wolter, H.; Storch, W. [Fraunhofer-Inst. fuer Silicatforschung, Wuerzburg (Germany); Ott, H. [Blendax GmbH, Mainz (Germany)

    1994-12-31

    Urethane and thioether (meth)acrylate alkoxysilanes have been used, as sol-gel precursors, for the preparation of a special family of inorganic/organic copolymers (ORMOCER{reg_sign}s). The basic silane type offers the following structural and synthetic possibilities for modifying the properties of the resulting copolymers: variation of the number of alkoxy groups, combination with other, different, sol-gel precursors, variation of the number of attached (meth)acrylate groups (1--5), and variation within the molecular segment (kind, structure and length) connecting the inorganic with the organic polymer structure. To achieve the additional organic polymer structure in the cured copolymer the use of different radically induced polymerization approaches (UV-, visible light-, thermal- and redox induced) is possible. Taking the incorporation of fillers into account, the Young`s modulus of these copolymers is adjustable in a range of 1--17,000 MPa, and the thermal expansion coefficient in a range of 17--250{center_dot}10{sup {minus}6}{center_dot}K{sup {minus}1} (5--50 C). Other advantages are the low shrinkage (1--2,8 vol.-%), the high flexural strength (up to 160 MPa), and the high abrasion resistance. This new copolymer type seems to have significant potential for medical applications, especially as dental filling material to replace the currently used controversial amalgam fillings.

  15. Long-term evaluation of functional nerve recovery after reconstruction with a thin-walled biodegradable poly (DL-lactide-epsilon-caprolactone) nerve guide, using walking track analysis and electrostimulation tests

    NARCIS (Netherlands)

    Meek, MF; Den Dunnen, WFA; Schakenraad, JM; Robinson, PH

    1999-01-01

    This study was performed to evaluate the long-term functional nerve recovery after reconstruction of a IO-mm gap in the sciatic nerve of the rat, with a thin-walled nerve guide, composed of a biodegradable copolymer of DL-lactide and epsilon-caprolactone [p(DLLA-epsilon-CL)]. To evaluate both motor

  16. Biodegradable nanocomposite hydrogel structures with enhanced mechanical properties prepared by photo-crosslinking solutions of poly(trimethylene carbonate)-poly(ethylene glycol)-poly(trimethylene carbonate) macromonomers and nanoclay particles

    NARCIS (Netherlands)

    Sharifi, S.; Blanquer, S.B.G.; Kooten, van T.G.; Grijpma, D.W.

    2012-01-01

    Soft hydrogels with elasticity modulus values lower than 100 kPa that are tough and biodegradable are of great interest in medicine and in tissue engineering applications. We have developed a series of soft hydrogel structures from different methacrylate-functionalized triblock copolymers of poly(et

  17. Controlled release of protein from biodegradable multi-sensitive injectable poly(ether-urethane) hydrogel.

    Science.gov (United States)

    Li, Xiaomeng; Wang, Yangyun; Chen, Jiaming; Wang, Yinong; Ma, Jianbiao; Wu, Guolin

    2014-03-12

    The synthesis and characterization of multi-sensitive polymers for use as injectable hydrogels for controlled protein/drug delivery is reported. A series of biodegradable multi-sensitive poly(ether-urethane)s were prepared through a simple one-pot condensation of poly(ethylene glycol), 2,2'-dithiodiethanol, N-methyldiethanolamine, and hexamethylene diisocyanate. The sol-gel phase transition behaviors of the obtained copolymers were investigated. Experimental results showed that the aqueous medium comprising the multi-segment copolymers underwent a sol-to-gel phase transition with increasing temperature and pH. At a certain concentration, the copolymer solution could immediately change to a gel under physiological conditions (37 °C and pH 7.4), indicating their suitability as in situ injectable hydrogels in vivo. Insulin was used as a model protein drug for evaluation of the injectable hydrogels as a site-specific drug delivery system. The controlled release of insulin from the hydrogel devices was demonstrated by degradation of the copolymer, which is modulated via the 2,2'-dithiodiethanol content in the poly(ether-urethane)s. These hydrogels having multi-responsive properties may prove to be promising candidates for injectable and controllable protein drug delivery devices.

  18. STUDY ON POLYSULFONE-POLYESTER BLOCK COPOLYMERS

    Institute of Scientific and Technical Information of China (English)

    DING Youjun; QI Daquan

    1988-01-01

    Synthesis and characterization of a series of Polysulfone (PSF)-Polyester (PEs) block copolymers were studied.The degree of randomness (B) of these block copolymers was calculated from the intensities of their proton signals in 1H NMR spectra and lies in the region of 0 < B < 1. It was shown that the degree of randomness (B) and the average sequence length (L) in block copolymers were relatively dependent on the reaction conditions, various feed ratios and structure of diols.The phenomenon was observed, when the PSF-PEs block copolymers dissolved in different solvents they had different viscosities and molecular conformations.The PSF-PEs block copolymers had better solvent resistance than homo-polysulfone.

  19. Biodegradable plastics from renewable sources.

    Science.gov (United States)

    Flieger, M; Kantorová, M; Prell, A; Rezanka, T; Votruba, J

    2003-01-01

    Plastic waste disposal is a huge ecotechnological problem and one of the approaches to solving this problem is the development of biodegradable plastics. This review summarizes data on their use, biodegradability, commercial reliability and production from renewable resources. Some commercially successful biodegradable plastics are based on chemical synthesis (i.e. polyglycolic acid, polylactic acid, polycaprolactone, and polyvinyl alcohol). Others are products of microbial fermentations (i.e. polyesters and neutral polysaccharides) or are prepared from chemically modified natural products (e.g., starch, cellulose, chitin or soy protein).

  20. Lung toxicity of biodegradable nanoparticles.

    Science.gov (United States)

    Fattal, Elias; Grabowski, Nadége; Mura, Simona; Vergnaud, Juliette; Tsapis, Nicolas; Hillaireau, Hervé

    2014-10-01

    Biodegradable nanoparticles exhibit high potentialities for local or systemic drug delivery through lung administration making them attractive as nanomedicine carriers. However, since particulate matter or some inorganic manufactured nanoparticles exposed to lung cells have provoked cytotoxic effects, inflammatory and oxidative stress responses, it becomes important to investigate nanomedicine toxicity towards the lungs. This is the reason why, in the present review, the behavior of biodegradable nanoparticles towards the different parts of the respiratory tract as well as the toxicological consequences, measured on several models in vitro, ex vivo or in vivo, are described. Taken all together, the different studies carried out so far conclude on no or slight toxicity of biodegradable nanoparticles.

  1. Poly(amino carbonate urethane)-based biodegradable, temperature and pH-sensitive injectable hydrogels for sustained human growth hormone delivery

    OpenAIRE

    V. H. Giang Phan; Thavasyappan Thambi; Huu Thuy Trang Duong; Doo Sung Lee

    2016-01-01

    In this study, a new pH-/temperature-sensitive, biocompatible, biodegradable, and injectable hydrogel based on poly(ethylene glycol)-poly(amino carbonate urethane) (PEG-PACU) copolymers has been developed for the sustained delivery of human growth hormone (hGH). In aqueous solutions, PEG-PACU-based copolymers existed as sols at low pH and temperature (pH 6.0, 23 °C), whereas they formed gels in the physiological condition (pH 7.4, 37 °C). The physicochemical characteristics, including gelatio...

  2. Biodegradable micromechanical sensors

    DEFF Research Database (Denmark)

    Keller, Stephan Sylvest; Greve, Anders; Schmid, Silvan

    The development of biopolymers for food packaging, medical engineering or drug delivery is a growing field of research [1]. At the same time, the interest in methods for detailed analysis of biopolymers is increasing. Micromechanical sensors are versatile tools for the characterization of mechani......The development of biopolymers for food packaging, medical engineering or drug delivery is a growing field of research [1]. At the same time, the interest in methods for detailed analysis of biopolymers is increasing. Micromechanical sensors are versatile tools for the characterization...... of biopolymers to microfabrication is challenging, as these polymers are affected by common processes such as photolithography or wet etching. Here, we present two methods for fabrication of biodegradable micromechanical sensors. First, we fabricated bulk biopolymer microcantilevers using nanoimprint lithography...

  3. Biodegradation of propellant ingredients

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Y.Z.; Sundaram, S.T.; Sharma, A. [Geo-centers, Inc., Lake Hopatcong, NJ (United States)] [and others

    1995-12-31

    This paper summarizes efforts to degrade nitrocellulose (NC) and nitroglycerin (NG) with fungi. Screening experiments were performed to determine the ability of mycelial fungi to biodegrade NC. The greatest amount of NC degradation was obtained with Sclerotium rolfsii ATCC 24459 and Fusarium solani IFO 31093. These fungi were then tested for NG degradation. It was found that the combined culture aerobically degraded 100% of the NG to form a mixture of 55% dinitroglycerin (DNG) and 5% of mononitroglycerin (MNG) in two days, with no further change observed afterward. In the presence of 1.2% glucose and 0.05% ammonium nitrate, NG was completely degraded in two days and a mixture of 20% DNG and 16% MNG was formed after 11 days. Based on these results, it appears that the combination of the fungi in a one to one ratio can be used to degrade both of these energetic compounds.

  4. Coating of poly(p-xylylene) by PLA-PEO-PLA triblock copolymers with excellent polymer-polymer adhesion for stent applications.

    Science.gov (United States)

    Hanefeld, Phillip; Westedt, Ullrich; Wombacher, Ralf; Kissel, Thomas; Schaper, Andreas; Wendorff, Joachim H; Greiner, Andreas

    2006-07-01

    Poly(p-xylylene) (PPX) was deposited by chemical vapor deposition (CVD) on stainless steel substrates. These PPX films were coated by solution casting of poly(lactide)-poly(ethylene oxide)-poly(lactide) triblock copolymers (PLA-PEO-PLA) loaded with 14C-labeled paclitaxel. Adhesion of PLA-PEO-PLA on PPX substrate coatings was measured using the blister test method. Excellent adhesion of the block copolymers on PPX substrates was found. Stress behavior and film integrity of PLA-PEO-PLA was compared to pure PLA on unexpanded and expanded stent bodies and was found to be superior for the block copolymers. The release of paclitaxel from the biodegradable coatings was studied under physiological conditions using the scintillation counter method. Burst release of paclitaxel was observed from PLA-PEO-PLA layers regardless of composition, but an increase in paclitaxel loading was observed with increasing content of PEO.

  5. Amphiphilic Spider Silk-Like Block Copolymers with Tunable Physical Properties and Morphology for Biomedical Applications

    Science.gov (United States)

    Huang, Wenwen; Krishnaji, Sreevidhya; Kaplan, David; Cebe, Peggy

    2013-03-01

    Silk-based materials are important candidates for biomedical applications because of their excellent biocompatibility and biodegradability. To generate silk amphiphilic biopolymers with potential use in guided tissue repair and drug delivery, a novel family of spider silk-like block copolymers was synthesized by recombinant DNA technology. Block copolymer thermal properties, structural conformations, protein-water interactions, and self-assembly morphologies were studied with respect to well controlled protein amino acid sequences. A theoretical model was used to predict the heat capacity of the protein and protein-water complex. Using thermal analysis, two glass transitions were observed: Tg1 is related to conformational changes caused by bound water removal, while Tg2 (>Tg1) is the glass transition of dry protein. Real-time infrared spectroscopy and X-ray diffraction confirmed that different secondary structural changes occur during the two Tg relaxations. Using scanning electron microscopy, fibrillar networks and hollow vesicles are observed, depending on protein block copolymer sequence. This study provides a deeper understanding of the relationship between protein physical properties and amino acid sequence, with implications for design of other protein-based materials. Support was provided from the NSF CBET-0828028 and the MRI Program under DMR-0520655 for thermal analysis instrumentation.

  6. Fabrication of pliable biodegradable polymer foams to engineer soft tissues.

    Science.gov (United States)

    Wake, M C; Gupta, P K; Mikos, A G

    1996-01-01

    We have fabricated pliable, porous, biodegradable scaffolds with poly(lactic-co-glycolic acid) (PLGA) and poly(ethylene glycol) (PEG) blends using a solvent-casting and particulate-leaching technique. Our study investigated the effects of four different processing parameters on pliability and pore morphology of the biodegradable scaffolds. The parameters investigated were the PLGA copolymer ratio, the PLGA/PEG blend ratio, the initial salt weight fraction, and the salt particle size. A wide range of shear moduli (0.59 to 9.55 MPa), porosities (0.798 to 0.942), and median pore diameters (71 to 154 microns) was able to be achieved by varying the combination of these parameters. Our study indicates that initial salt weight fraction and PLGA/PEG blend ratio have the most significant effects on the physico-mechanical properties of the scaffolds. Enhanced pliability of the three dimensional foams made with blends of PLGA and PEG is evidenced by the ability to roll them into a tube without macroscopic damage to the scaffold. Pliable polymer substrates hold great promise for regeneration of soft tissues such as skin, or those requiring a tubular conformation such as intestine or vascular grafts.

  7. NANOSTRUCTURES OF FUNCTIONAL BLOCK COPOLYMERS

    Institute of Scientific and Technical Information of China (English)

    Guojun Liu

    2000-01-01

    Nanostructure fabrication from block copolymers in my group normally involves polymer design, synthesis, selfassembly, selective domain crosslinking, and sometimes selective domain removal. Preparation of thin films with nanochannels was used to illustrate the strategy we took. In this particular case, a linear triblock copolymer polyisopreneblock-poly(2-cinnamoylethyl methacrylate)-block-poly(t-butyl acrylate), PI-b-PCEMA-b-PtBA, was used. Films, 25 to50μm thick, were prepared from casting on glass slides a toluene solution of PI-b-PCEMA-b-PtBA and PtBA homopolymer,hPtBA, where hPtBA is shorter than the PtBA block. At the hPtBA mass fraction of 20% relative to the triblock or the total PtBA (hPtBA and PtBA block) volume fraction of 0.44, hPtBA and PtBA formed a seemingly continuous phase in the matrix of PCEMA and PI. Such a block segregation pattern was locked in by photocrosslinking the PCEMA domain. Nanochannels were formed by extracting out hPtBA with solvent. Alternatively, larger channels were obtained from extracting out hPtBA and hydrolyzing the t-butyl groups of the PtBA block. Such membranes were not liquid permeable but had gas permeability constants ~6 orders of magnitude higher than that of low-density polyethylene films.

  8. Poly(trimethylene carbonate)-based polymers engineered for biodegradable functional biomaterials.

    Science.gov (United States)

    Fukushima, K

    2016-01-01

    Aliphatic polycarbonates have drawn attention as biodegradable polymers that can be applied to a broad range of resorbable medical devices. In particular, poly(trimethylene carbonate) (PTMC), its copolymers, and its derivatives are currently studied due to their unique degradation characteristics that are different from those of aliphatic polyesters. Furthermore, their flexible and hydrophobic nature has driven the application of PTMC-based polymers to soft tissue regeneration and drug delivery. This review presents the diverse applications and functionalization strategies of PTMC-based materials in relation to recent advances in medical technologies and their subsequent needs in clinical settings.

  9. Production of Polyhydroxybutyrate (Bioplastic and its Biodegradation by Pseudomonas Lemoignei and Aspergillus Niger

    Directory of Open Access Journals (Sweden)

    S. Kumaravel

    2010-01-01

    Full Text Available The biodegradation of polyhydroxybutyrate (PHB and its copolymer polyhydroxy butyrate-co-hydroxyvalerate (PHB-co-HV was studied. Bacterial as well as fungal isolates were isolated from the local industrial ecosystem. All these isolates were tested for the degradation of the above polymers in assay agar medium as well in liquid cultures. The culture biomass and the clear zone around the colonies were measured to evaluate the activity of these isolates. In all, the fungal isolates were found to degrade these polymers more rapidly when compared to bacteria, due to their versatile depolymerase activities.

  10. Biomedical Applications of Biodegradable Polyesters

    OpenAIRE

    Iman Manavitehrani; Ali Fathi; Hesham Badr; Sean Daly; Ali Negahi Shirazi; Fariba Dehghani

    2016-01-01

    The focus in the field of biomedical engineering has shifted in recent years to biodegradable polymers and, in particular, polyesters. Dozens of polyester-based medical devices are commercially available, and every year more are introduced to the market. The mechanical performance and wide range of biodegradation properties of this class of polymers allow for high degrees of selectivity for targeted clinical applications. Recent research endeavors to expand the application of polymers have be...

  11. Coarse Grained Simulation of Lipid Membrane and Triblock Copolymers

    Science.gov (United States)

    Hatakeyama, Masaomi; Faller, Roland

    2008-02-01

    We investigated the interaction between DPPC (Dipalmitoyl phosphatidylcholine) bilayer and polyethylene oxide-polypropylene oxide-polyethylene oxide (PEO-PPO-PEO) triblock copolymers using coarse grained simulation. We simulated two systems of DPPC bilayer and PEO-PPO-PEO triblock copolymer containing different mole fractions, and simulated DPPC vesicle with the copolymers. We found different adsorption mechanisms of triblock copolymers depending on concentration. And we also observed docking process between a lipid vesicle and a micelle of the copolymers.

  12. Block copolymer membranes for aqueous solution applications

    KAUST Repository

    Nunes, Suzana Pereira

    2016-03-22

    Block copolymers are known for their intricate morphology. We review the state of the art of block copolymer membranes and discuss perspectives in this field. The main focus is on pore morphology tuning with a short introduction on non-porous membranes. The two main strategies for pore formation in block copolymer membranes are (i) film casting and selective block sacrifice and (ii) self-assembly and non-solvent induced phase separation (SNIPS). Different fundamental aspects involved in the manufacture of block copolymer membranes are considered, including factors affecting the equilibrium morphology in solid films, self-assembly of copolymer in solutions and macrophase separation by solvent-non-solvent exchange. Different mechanisms are proposed for different depths of the SNIPS membrane. Block copolymer membranes can be prepared with much narrower pore size distribution than homopolymer membranes. Open questions and indications of what we consider the next development steps are finally discussed. They include the synthesis and application of new copolymers and specific functionalization, adding characteristics to respond to stimuli and chemical environment, polymerization-induced phase separation, and the manufacture of organic-inorganic hybrids.

  13. Biodegradable intestinal stents:A review

    Institute of Scientific and Technical Information of China (English)

    Zhanhui Wang; Nan Li; Rui Li; Yawei Li; Liqun Ruan

    2014-01-01

    Biodegradable stents are an attractive alternative to self-expanding metal stents in the treatment of intestinal strictures. Biodegradable stent can be made of biodegradable polymers and biodegradable metals (magnesium alloys). An overview on current biodegradable intestinal stents is presented. The future trends and perspectives in the development of biodegradable intestinal stents are proposed. For the biodegradable polymer intestinal stents, the clinical trials have shown promising results, although improved design of stents and reduced migration rate are expected. For the biodegradable magnesium intestinal stents, results of preliminary studies indicate magnesium alloys to have good biocompatibility. With many of the key fundamental and practical issues resolved and better methods for adjusting corrosion resistance and progressing biocompatibilities of magnesium alloys, it is possible to use biodegradable intestinal stents made of magnesium alloys in hospital in the not too distant future.

  14. Injectible bodily prosthetics employing methacrylic copolymer gels

    Science.gov (United States)

    Mallapragada, Surya K.; Anderson, Brian C.

    2007-02-27

    The present invention provides novel block copolymers as structural supplements for injectible bodily prosthetics employed in medical or cosmetic procedures. The invention also includes the use of such block copolymers as nucleus pulposus replacement materials for the treatment of degenerative disc disorders and spinal injuries. The copolymers are constructed by polymerization of a tertiary amine methacrylate with either a (poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide) polymer, such as the commercially available Pluronic.RTM. polymers, or a poly(ethylene glycol) methyl ether polymer.

  15. Enzyme cleavable nanoparticles from peptide based triblock copolymers

    Science.gov (United States)

    Fuchs, Adrian V.; Kotman, Niklas; Andrieu, Julien; Mailänder, Volker; Weiss, Clemens K.; Landfester, Katharina

    2013-05-01

    A solid-phase synthesis based approach towards protease cleavable polystyrene-peptide-polystyrene triblock copolymers and their formulation to nanoparticulate systems is presented. These nanoparticles are suitable for the optical detection of an enzyme and have the potential for application as a drug delivery system. Two different peptide sequences, one cleaved by trypsin (GFF), the other by hepsin (RQLRVVGG), a protease overexpressed in early stages of prostate cancer, are used as the central part of the triblock. For optical detection a fluorophore-quencher pair is introduced around the cleavage sequence. The solid phase synthesis is conduced such that two identical sequences are synthesized from one branching point. Eventually, carboxy-terminated polystyrene is introduced into the peptide synthesizer and coupled to the amino-termini of the branched sequence. Upon cleavage, a fragment is released from the triblock copolymer, which has the potential for use in drug delivery applications. Conducting the whole synthesis on a solid phase in the peptide synthesizer avoids solubility issues and post-synthetic purification steps. Due to the hydrophobic PS-chains, the copolymer can easily be formulated to form nanoparticles using a nanoprecipitation process. Incubation of the nanoparticles with the respective enzymes leads to a significant increase of the fluorescence from the incorporated fluorophore, thereby indicating cleavage of the peptide sequence and decomposition of the particles.A solid-phase synthesis based approach towards protease cleavable polystyrene-peptide-polystyrene triblock copolymers and their formulation to nanoparticulate systems is presented. These nanoparticles are suitable for the optical detection of an enzyme and have the potential for application as a drug delivery system. Two different peptide sequences, one cleaved by trypsin (GFF), the other by hepsin (RQLRVVGG), a protease overexpressed in early stages of prostate cancer, are used as the

  16. Preparation of hybrid scaffold from fibrin and biodegradable polymer fiber.

    Science.gov (United States)

    Hokugo, Akishige; Takamoto, Tomoaki; Tabata, Yasuhiko

    2006-01-01

    A biodegradable hybrid scaffold was prepared from fibrin and poly(glycolic acid) (PGA) fiber. Mixed fibrinogen and thrombin solution homogeneously dispersed in the presence of various amounts (0, 1.5, 3.0, and 6.0mg) of PGA fiber was freeze-dried to obtain fibrin sponges with or without PGA fiber incorporation. By scanning electron microscopy observation, the fibrin sponges had an interconnected pore structure, irrespective of the amount of PGA fiber incorporated. PGA fiber incorporation enabled the fibrin sponges to significantly enhance their compression strength. In vitro cell culture studies revealed that the number of L929 fibroblasts initially attached was significantly larger for any fibrin sponge with PGA fiber incorporation than for the fibrin sponge without PGA fiber. The shrinkage of sponges after cell seeding was suppressed by fiber incorporation. It is possible that the shrinkage suppression of sponges maintains their intraspace, resulting in the superior cell attachment of a sponge with PGA fiber incorporation. After subcutaneous implantation into the backs of mice, the residual volume of a fibrin sponge with PGA fiber incorporation was significant compared with that of a fibrin sponge without PGA fiber. Larger number of cells infiltrated deep inside the fibrin sponges with PGA fiber incorporation implanted subcutaneously. It is concluded that the fibrin sponge reinforced by fiber incorporation is a promising three-dimensional scaffold of cells for tissue engineering.

  17. Fully biodegradable coronary stents : progress to date.

    Science.gov (United States)

    Ramcharitar, Steve; Serruys, Patrick W

    2008-01-01

    The limitations of currently available metallic drug-eluting stents have renewed interest in biodegradable stents (BDS). Apart from removing the (offending) foreign material that may potentiate a thrombotic event, BDS have the advantage of avoiding 'full metal jackets,' and thus can preclude subsequent coronary surgery. In addition, they do not interfere with the diagnostic evaluation of non-invasive imaging such as cardiac magnetic resonance and CT. There are now several BDS in development or in clinical trials that incorporate a variety of biodegradable polymer technologies. Two broad categories of materials are generally used: those made from organic biopolymers and those made from corrodible metals. However, to date, none of the materials/stents tested have been able to establish a perfect balance between biocompatibility, the kinetics of degradation needed to maintain mechanical strength to limit recoil, and inflammation. However, studies, such as the ABSORB trial with the everolimus eluting poly-L-lactide stent, which demonstrated comparable restenotic rates with bare metallic stents and a low incidence of major adverse cardiac events (MACE) at 12 months of 3.3%, with only one patient having a non-Q-wave myocardial infarction and no target lesion revascularization, suggest that there has been significant progress with respect to the earlier prototypes. The acute recoil observed could potentially be addressed with the polytyrosine REVA stent currently being evaluated in the RESORB trial, which incorporates a novel locking mechanism within its design. Alternative BDS designs include the combination of an antiproliferative drug with endothelial progenitor cell capturing antibodies to facilitate epithelialization and/or dual eluting having, in addition to the antiproliferative drug, polymeric salicyclic acid to limit inflammation. Compared with biodegradable polymers, there are fewer metals used in the manufacture of BDS. The only metal BDS in trials is the

  18. Progress of biodegradable metals

    Institute of Scientific and Technical Information of China (English)

    Huafang Li; Yufeng Zheng; Ling Qin

    2014-01-01

    Biodegradable metals (BMs) are metals and alloys expected to corrode gradually in vivo, with an appropriate host response elicited by released corrosion products, then dissolve completely upon fulfilling the mission to assist with tissue healing with no implant residues. In the present review article, three classes of BMs have been systematically reviewed, including Mg-based, Fe-based and Zn-based BMs. Among the three BM systems, Mg-based BMs, which now have several systems reported the successful of clinical trial results, are considered the vanguards and main force. Fe-based BMs, with pure iron and Fe–Mn based alloys as the most promising, are still on the animal test stage. Zn-based BMs, supposed to have the degradation rate between the fast Mg-based BMs and the slow Fe-based BMs, are a rising star with only several reports and need much further research. The future research and development direction for the BMs are proposed, based on the clinical requirements on controllable degradation rate, prolonged mechanical stability and excellent biocompat-ibility, by optimization of alloy composition design, regulation on microstructure and mechanical properties, and following surface modification.

  19. Progress of biodegradable metals

    Directory of Open Access Journals (Sweden)

    Huafang Li

    2014-10-01

    Full Text Available Biodegradable metals (BMs are metals and alloys expected to corrode gradually in vivo, with an appropriate host response elicited by released corrosion products, then dissolve completely upon fulfilling the mission to assist with tissue healing with no implant residues. In the present review article, three classes of BMs have been systematically reviewed, including Mg-based, Fe-based and Zn-based BMs. Among the three BM systems, Mg-based BMs, which now have several systems reported the successful of clinical trial results, are considered the vanguards and main force. Fe-based BMs, with pure iron and Fe–Mn based alloys as the most promising, are still on the animal test stage. Zn-based BMs, supposed to have the degradation rate between the fast Mg-based BMs and the slow Fe-based BMs, are a rising star with only several reports and need much further research. The future research and development direction for the BMs are proposed, based on the clinical requirements on controllable degradation rate, prolonged mechanical stability and excellent biocompatibility, by optimization of alloy composition design, regulation on microstructure and mechanical properties, and following surface modification.

  20. Hydrogen-bonding layer-by-layer-assembled biodegradable polymeric micelles as drug delivery vehicles from surfaces.

    Science.gov (United States)

    Kim, Byeong-Su; Park, Sang Wook; Hammond, Paula T

    2008-02-01

    We present the integration of amphiphilic block copolymer micelles as nanometer-sized vehicles for hydrophobic drugs within layer-by-layer (LbL) films using alternating hydrogen bond interactions as the driving force for assembly for the first time, thus enabling the incorporation of drugs and pH-sensitive release. The film was constructed based on the hydrogen bonding between poly(acrylic acid) (PAA) as an H-bond donor and biodegradable poly(ethylene oxide)-block-poly(epsilon-caprolactone) (PEO-b-PCL) micelles as the H-bond acceptor when assembled under acidic conditions. By taking advantage of the weak interactions of the hydrogen-bonded film on hydrophobic surfaces, it is possible to generate flexible free-standing films of these materials. A free-standing micelle LbL film of (PEO-b-PCL/PAA)60 with a thickness of 3.1 microm was isolated, allowing further characterization of the bulk film properties, including morphology and phase transitions, using transmission electron microscopy and differential scanning calorimetry. Because of the sensitive nature of the hydrogen bonding employed to build the multilayers, the film can be rapidly deconstructed to release micelles upon exposure to physiological conditions. However, we could also successfully control the rate of film deconstruction by cross-linking carboxylic acid groups in PAA through thermally induced anhydride linkages, which retard the drug release to the surrounding medium to enable sustained release over multiple days. To demonstrate efficacy in delivering active therapeutics, in vitro Kirby-Bauer assays against Staphylococcus aureus were used to illustrate that the drug-loaded micelle LbL film can release significant amounts of an active antibacterial drug, triclosan, to inhibit the growth of bacteria. Because the micellar encapsulation of hydrophobic therapeutics does not require specific chemical interactions, we believe this noncovalent approach provides a new route to integrating active small

  1. Silica reinforced triblock copolymer gels

    DEFF Research Database (Denmark)

    Theunissen, E.; Overbergh, N.; Reynaers, H.

    2004-01-01

    The effect of silica and polymer coated silica particles as reinforcing agents on the structural and mechanical properties of polystyrene-poly(ethylene/butylene)-polystyrene (PS-PEB-PS) triblock gel has been investigated. Different types of chemically modified silica have been compared in order...... to evaluate the influence of the compatibility between gel and filler. Time-resolved SANS and small-angle X-ray scattering (SAXS) shows that the presence of silica particles affects the ordering of the polystyrene domains during gelsetting. The scattering pattern of silica-reinforced gels reveals strong...... a viscoclastic rubber to a plastic fluid and from a plastic fluid to a viscoelastic liquid are shifted to more elevated temperatures when silica is added to the triblock copolymer gel. (C) 2004 Elsevier Ltd. All rights reserved....

  2. Platform Approach to Produce Polymer Nanoparticles with Modular Functionality from Amphiphilic Block Copolymer Stabilizers

    Science.gov (United States)

    2014-04-01

    functionality, an amphiphilic BCP scaffold was devised to serve as an emulsion polymerization stabilizer. The PS-b-P(EO-co-AGE) BCP contained a PS...synthesized via emulsion polymerization using an amphiphilic block copolymer (BCP) surfactant. The polystyrene-block-poly(ethylene oxide-co-allyl...glycidyl ether) BCPs with various lengths and functional monomer incorporation were synthesized using anionic polymerization . Modification of the allyl

  3. MISCIBILITY IN COPOLYMER/HOMOPOLYMER BLENDS

    Institute of Scientific and Technical Information of China (English)

    JIANG Ming

    1988-01-01

    In order to study the miscibility of a copolymer with its corresponding homopolymers, varieties of multicomponent polymers including simple graft, multibranch, diblock, triblock and four-arm block copolymers and so-called ABCPs were synthesized and characterized. The morphologies of the blends comprising the covolymers and the corresponding homopolymers were examined by electron microscopy. It is concluded that beeides molecular weight, architecture of a copolymers has apparent effect on the miscibility, i.e. the more complex is molecular architecture, the greater is conformation restriction in microdomain formation and the less is solubility of homopolymer in corresponding domains. In addition, a density gradient model is suggested for describing the segment distribution of the bound and free chains in block-homopolymer systems. Using this model, Helfand's theory is extended to the blends of copolymer and homopolymer predicting the miscibility which is in good agreement with the experimental results.

  4. Synthesis and characterization of polyester copolymers based on poly(butylene succinate) and poly(ethylene glycol)

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Xiao-Ming, E-mail: xiaomingzhou@tust.edu.cn

    2012-12-01

    A series of polyester copolymers was synthesized from 1,4-succinic acid with 1,4-butanediol and poly(ethylene glycol) through a two-step process of esterification and polycondensation in this article. The composition and physical properties of copolyesters were investigated via GPC, {sup 1}HNMR, DSC and PLM. The copolymer composition was in good agreement with that expected from the feed composition of the reactants. The melting temperature (T{sub m}), crystallization temperature (T{sub c}), and crystallinity (X{sub c}) of these copolyesters decreased gradually as the content of PEG unit increased. Otherwise, experimental results also showed that the contents of PEG in copolymers had an effect on the molecular weight, distribution, thermal properties, hydrolysis degradation properties, and crystalline morphology of polyester copolymers. - Graphical abstract: The composition of polyester copolymer was determined from the {sup 1}H NMR spectra using the relative intensities of the proton peaks. As a sample, the {sup 1}H NMR spectrum of polyester copolymer with 10 mol% of PEG is shown in Fig. 2: CO-(CH{sub 2}){sub 2}-CO; O-CH{sub 2}- and C-(CH{sub 2}){sub 2}-C from the SA and BD unit at {delta}2.59; {delta} 4.08 and {delta}1.67; O-(CH{sub 2}CH{sub 2}){sub n}-O from the PEG unit at {delta} 3.61. The molar composition of polyester copolymer was measured as the area ratio of {delta}3.61/({delta}4.08 + {delta}1.67) peak. The PEG unit is incorporated into the copolymers in an amount of about 9.12mol% less than that of the feed proportion. These results showed that the composition of the copolymers is in good agreement with that expected from the feed proportion. Highlights: Black-Right-Pointing-Pointer The introduction of PEG unit changed the flexibility of PBS main chain. Black-Right-Pointing-Pointer PEG unit did not alter the crystal form of PBS in copolymers. Black-Right-Pointing-Pointer PEG unit hindered the formation of ring-banded spherulite morphology in copolymers

  5. Drug targeting to tumors using HPMA copolymers

    OpenAIRE

    Lammers, T.G.G.M.

    2009-01-01

    Copolymers based on N-(2-hydroxypropyl)methacrylamide (HPMA) are prototypic and well-characterized polymeric drug carriers that have been broadly implemented in the delivery of anticancer agents. HPMA copolymers circulate for prolonged periods of time, and by means of the Enhance Permeability and Retention (EPR) effect, they localize to tumors both effectively and selectively. As a consequence, the concentrations of attached active agents in tumors can be increased, and their accumulation in ...

  6. Amphiphilic diblock copolymers for molecular recognition

    OpenAIRE

    Nehring, Rainer

    2009-01-01

    In this thesis, the synthesis and the characterization of poly(butadiene)-blockpoly( ethylene oxide) copolymers with terminal Me2+-NTA groups (copper or nickel) is described for the first time. A convenient “one-pot” procedure that allows control over the individual block lengths of the copolymer and the end-group functionalization was successfully established. The formation of the metal-polymer complex has been confirmed by EPR and UV/VIS spectroscopy. Mixing of the Ni2+-NT...

  7. Silicone containing copolymers: Synthesis, properties and applications

    OpenAIRE

    Yılgör, Emel; Yılgör, İskender

    2013-01-01

    Accepted Manuscript Title: Silicone containing copolymers: Synthesis, properties and applications Author: Emel Yilgor Iskender Yilgor PII: S0079-6700(13)00141-X DOI: http://dx.doi.org/doi:10.1016/j.progpolymsci.2013.11.003 Reference: JPPS 848 To appear in: Progress in Polymer Science Received date: 1-8-2013 Revised date: 4-11-2013 Accepted date: 8-11-2013 Please cite this article as: Yilgor E, Yilgor I, Silicone containing copolymers: Synthesis, properties ...

  8. Responsive Copolymers for Enhanced Petroleum Recovery

    Energy Technology Data Exchange (ETDEWEB)

    McCormick, C.; Hester, R.

    2001-02-27

    The objectives of this work was to: synthesize responsive copolymer systems; characterize molecular structure and solution behavior; measure rheological properties of aqueous fluids in fixed geometry flow profiles; and to tailor final polymer compositions for in situ rheology control under simulated conditions. This report focuses on the synthesis and characterization of novel stimuli responsive copolymers, the investigation of dilute polymer solutions in extensional flow and the design of a rheometer capable of measuring very dilute aqueous polymer solutions at low torque.

  9. Adhesion of biocompatible and biodegradable micropatterned surfaces

    NARCIS (Netherlands)

    Kaiser, J.S.; Kamperman, M.M.G.; Souza, E.J.; Schick, B.; Arzt, E.

    2011-01-01

    We studied the effects of pillar dimensions and stiffness of biocompatible and biodegradable micropatterned surfaces on adhesion on different compliant substrates. The micropatterned adhesives were based on biocompatible polydimethylsiloxane (PDMS) and biodegradable poly(lactic-co-glycolic) acid (PL

  10. Facile Synthesis of Magnetic Copolymer Microspheres Based on Poly(glycidyl methacrylate-co-N-isopropylacrylamide/Fe3O4 by Suspension Photopolymerization

    Directory of Open Access Journals (Sweden)

    Siti Zulaikha Mazlan

    2014-01-01

    Full Text Available Magnetic copolymer based on poly(glycidyl methacrylate-co-N-isopropylacrylamide microspheres was prepared by 2,2-dimethoxy-2-phenylacetophenone- (DMPP- photo initiated and poly(vinyl alcohol- (PVA- stabilized single step suspension photopolymerization. The effect of chemical interaction, morphology, and thermal properties by adding 0.1% w/v Fe3O4 in the copolymer was investigated. Infrared analysis (FTIR showed that (C=C band disappeared after copolymerization, indicating that the magnetic copolymer microspheres were successfully synthesized and two important bands at 908 cm−1 and 1550 cm−1 appear. These are associated with the epoxy group stretching of GMA and secondary amide (N–H/C–H deformation vibration of NIPAAm in magnetic microspheres. The X-ray diffraction (XRD result proved the incorporation of Fe3O4 nanoparticles with copolymer microspheres as peak of Fe3O4 was observed. Morphology study revealed that magnetic copolymer exhibited uniform spheres and smoother appearance when entrapped with Fe3O4 nanoparticles. The lowest percentage of Fe3O4 nanoparticles leached from the copolymer microspheres was obtained at pH 7. Finally, thermal property of the copolymer microspheres was improved by adding a small amount of Fe3O4 nanoparticles that has been shown from the thermogram.

  11. Preparation and Characterization of Copolymer Micelles Formed by Poly(ethylene glycol)-Polylactide Block Copolymers as Novel Drug Carriers

    Institute of Scientific and Technical Information of China (English)

    姜维; 王运东; 甘泉; 张建铮; 赵秀文; 费维扬; 贝建中; 王身国

    2006-01-01

    Diblock copolymer poly(ethylene glycol) methyl ether-polylactide (MePEG-PLA) micelles were prepared by dialysis against water. Indomethacin (IMC) as a model drug was entrapped into the micelles by dialysis method. The critical micelle concentration (CMC) of the prepared micelles in distilled water investigated by fluorescence spectroscopy was 0.0051mg/mL which is lower than that of common low molecular weight surfactants. The diameters of MePEG-PLA micelles and IMC loaded MePEG-PLA micelles in a number-averaged scale measured by dynamic light scattering were 52.4 and 53.7 nm respectively. The observation with transmission electron microscope and scanning electron microscope showed that the appearance of MePEG-PLA micelles was in a spherical shape. The content of IMC incorporated in the core portion of the micelles was 18% (ω). The effects of the synthesis method of the copolymer on the polydispersity of the micelles and the yield of the micelles formation were discussed.

  12. Kinetics of biodegradation of phenolic wastewater in a biofilm reactor.

    Science.gov (United States)

    Lin, Yen-Hui; Hsien, Tzu-Yang

    2009-01-01

    This work presents a mathematical model to describe the biodegradation of phenolic wastewater in a fixed-biofilm process. The model incorporates diffusive mass transport and Haldane kinetics mechanisms. The model was solved using a combination of the orthogonal collocation method and Gear's method. A laboratory-scale column reactor was employed to verify the model. Batch kinetic tests were conducted independently to determine biokinetic parameters for the model simulation with the initial biofilm thickness assumed. The model simulated the phenol effluent concentration results well. Removal efficiency for phenol was approximately 94-96.5% for different hydraulic retention times at a steady-state condition. Model simulations results are in agreement with experimental results. The approaches of model and experiments presented in this paper could be used to design a pilot-scale or full-scale fixed-biofilm reactor system for the biodegradation of phenolic wastewater from petrochemical and oil refining plants.

  13. BODIPY-Based Donor-Acceptor Pi-Conjugated Alternating Copolymers

    Energy Technology Data Exchange (ETDEWEB)

    Popere, Bhooshan C.; Della Pelle, Andrea M.; Thayumanavan, S.

    2011-06-28

    Four novel π-conjugated copolymers incorporating 4,4-difluoro-4-borata-3a-azonia-4a-aza-s-indacene (BODIPY) core as the “donor” and quinoxaline (Qx), 2,1,3-benzothiadiazole (BzT), N,N'-di(2'-ethyl)hexyl-3,4,7,8-naphthalenetetracarboxylic diimide (NDI), and N,N'-di(2'-ethyl)hexyl-3,4,9,10-perylene tetracarboxylic diimide (PDI) as acceptors were designed and synthesized via Sonogashira polymerization. The polymers were characterized by ¹H NMR spectroscopy, gel permeation chromatography (GPC), UV–vis absorption spectroscopy, and cyclic voltammetry. Density functional theory (DFT) calculations were performed on polymer repeat units, and the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) energy levels were estimated from the optimized geometry using B3LYP functional and 6-311g(d,p) basis set. Copolymers with Qx and BzT possessed HOMO and LUMO energy levels comparable to those of BODIPY homopolymer, while PDI stabilized both HOMO and LUMO levels. Semiconductor behavior of these polymers was estimated in organic thin-film transistors (OTFT). While the homopolymer, Qx, and BzT-based copolymers showed only p-type semiconductor behavior, copolymers with PDI and NDI showed only n-type behavior.

  14. Acid-Labile Amphiphilic PEO-b-PPO-b-PEO Copolymers: Degradable Poloxamer Analogs.

    Science.gov (United States)

    Worm, Matthias; Kang, Biao; Dingels, Carsten; Wurm, Frederik R; Frey, Holger

    2016-05-01

    Poly ((ethylene oxide)-b-(propylene oxide)-b-(ethylene oxide)) triblock copolymers commonly known as poloxamers or Pluronics constitute an important class of nonionic, biocompatible surfactants. Here, a method is reported to incorporate two acid-labile acetal moieties in the backbone of poloxamers to generate acid-cleavable nonionic surfactants. Poly(propylene oxide) is functionalized by means of an acetate-protected vinyl ether to introduce acetal units. Three cleavable PEO-PPO-PEO triblock copolymers (Mn,total = 6600, 8000, 9150 g·mol(-1) ; Mn,PEO = 2200, 3600, 4750 g·mol(-1) ) have been synthesized using anionic ring-opening polymerization. The amphiphilic copolymers exhibit narrow molecular weight distributions (Ð = 1.06-1.08). Surface tension measurements reveal surface-active behavior in aqueous solution comparable to established noncleavable poloxamers. Complete hydrolysis of the labile junctions after acidic treatment is verified by size exclusion chromatography. The block copolymers have been employed as surfactants in a miniemulsion polymerization to generate polystyrene (PS) nanoparticles with mean diameters of ≈200 nm and narrow size distribution, as determined by dynamic light scattering and scanning electron microscopy. Acid-triggered precipitation facilitates removal of surfactant fragments from the nanoparticles, which simplifies purification and enables nanoparticle precipitation "on demand."

  15. Synthesis and properties of random copolymers of functionalised polybenzimidazoles for high temperature fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Mader, J.A.; Benicewicz, B.C. [Department of Chemistry and Biochemistry and USC Nanocenter, University of South Carolina, 631 Sumter St., Columbia, SC 29208 (United States)

    2011-04-15

    A series of polybenzimidazoles (PBIs) incorporating main chain sulphonic acid groups were synthesised as random copolymers with p-PBI in varying ratios using polyphosphoric acid (PPA) as both the polymerisation solvent and polycondensation reagent. The PPA process was used to produce high molecular weight phosphoric acid (PA) doped PBI gel membranes in a one-step procedure. These membranes exhibit excellent mechanical properties (0.528-2.51 MPa tensile stress and 130-300% tensile strain) even at high acid doping levels [20-40 mol PA/PRU (polymer repeat unit)] and high conductivities (0.148-0.291 S cm{sup -1}) at elevated temperatures (>100 C) with no external humidification, depending on copolymer composition. Fuel cell testing was conducted with hydrogen fuel and air or oxygen oxidants for all membrane compositions at temperatures greater than 100 C without external feed gas humidification. Initial studies showed a maximum fuel performance of 0.675 V for the 25 mol% s-PBI/75 mol% p-PBI random copolymer at 180 C and 0.2 A cm{sup -2} with hydrogen and air, and 0.747 V for the same copolymer at 180 C and 0.2 A cm{sup -2} with hydrogen and oxygen. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  16. PREPARATION OF BIODEGRADABLE FLAX SHIVE CELLULOSE-BASED SUPERABSORBENT POLYMER UNDER MICROWAVE IRRADIATION

    Directory of Open Access Journals (Sweden)

    Hao Feng

    2010-05-01

    Full Text Available Superabsorbent polymer was prepared by graft polymerization of acrylic acid onto the chain of cellulose from flax shive by using potassium persulfate (KPS as an initiator and N,N’-methylenebisacrylamide (MBA as a crosslinker under microwave irradiation. SEM photographs were also studied for more information about the shive, cellulose from shive, and the superabsorbent polymer. The structure of the graft copolymer was confirmed by FT-IR spectroscopy and thermogravimetric analysis (TGA. The biodegradability in soil was measured at 32 and 40 oC. The polymer was porous, and thermal stability of the polymer was observed up to approximately 200 oC. FT-IR analysis indicated that acrylic acid in polymer was successfully grafted onto the cellulose. The graft copolymer was found to be an effective superabsorbent resin, rapidly absorbing water to almost 1000 times its own dry weight at pH around 7.3. The water absorbency in 0.9% NaCl, KCl, FeCl3 solutions and urine were 56.47 g/g, 54.71g/g, 9.89g/g and 797.21g/g, respectively. The product biologically degraded up to 40% at 40 oC in 54 days, which shows good biodegradability.

  17. Use of alginate, chitosan and cellulose nanocrystals as emulsion stabilizers in the synthesis of biodegradable polymeric nanoparticles.

    Science.gov (United States)

    Rescignano, Nicoletta; Fortunati, Elena; Armentano, Ilaria; Hernandez, Rebeca; Mijangos, Carmen; Pasquino, Rossana; Kenny, José Maria

    2015-05-01

    Biopolymeric nanoparticles (NPs) based on a biodegradable poly(DL-Lactide-co-Glycolide) PLGA copolymer matrix combined with alginate, chitosan and nanostructured cellulose crystals as three different natural emulsion stabilizers, were synthesized by a double emulsion (water/oil/water) method with subsequent solvent evaporation. The morphological, thermal, chemical and rheological properties of the novel designed NPs and the effect of the different emulsion stabilizers used during the synthesis were deeply investigated in order to optimize the synthesis procedure and the development of biodegradable nanoparticles coated with natural polymers. The morphological analysis of the produced nanoparticles showed that all the different formulations presented a spherical shape with smooth surface. Infrared spectroscopy investigations showed that the PLGA copolymer maintained its backbone structure and confirmed the presence of chitosan, alginate and cellulose nanocrystals (CNC) on the nanoparticle surface. The obtained results suggest that PLGA nanoparticles with CNC as emulsion stabilizer might represent promising formulations opening new perspective in the field of self-assembly of biodegradable nanomaterials for medical and pharmaceutical applications.

  18. Biodegradable congress 2012; Bioschmierstoff-Kongress 2012

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2012-11-01

    Within the Guelzower expert discussions at 5th and 6th June, 2012 in Oberhausen (Federal Republic of Germany) the following lectures were held: (1) Promotion of biodegradable lubricants by means of research and development as well as public relations (Steffen Daebeler); (2) Biodegradable lubricants - An overview of the advantages and disadvantages of the engaged product groups (Hubertus Murrenhoff); (3) Standardization of biodegradable lubricants - CEN/DIN standard committees - state of the art (Rolf Luther); (4) Market research for the utilization of biodegradable lubricants and means of proof of sustainability (Norbert Schmitz); (5) Fields of application for high performance lubricants and requirements upon the products (Gunther Kraft); (6) Investigations of biodegradable lubricants in rolling bearings and gears (Christoph Hentschke); (7) Biodegradable lubricants in central lubrication systems Development of gears and bearings of offshore wind power installations (Reiner Wagner); (8) Investigations towards environmental compatibility of biodegradable lubricants used in offshore wind power installations (Tolf Schneider); (9) Development of glycerine based lubricants for the industrial metalworking (Harald Draeger); (10) Investigations and utilization of biodegradable oils as electroinsulation oils in transformers (Stefan Tenbohlen); (11) Operational behaviour of lubricant oils in vegetable oil operation and Biodiesel operation (Horst Hamdorf); (12) Lubrication effect of lubricating oil of the third generation (Stefan Heitzig); (13) Actual market development from the view of a producer of biodegradable lubricants (Frank Lewen); (14) Utilization of biodegradable lubricants in forestry harvesters (Guenther Weise); (15) New biodegradable lubricants based on high oleic sunflower oil (Otto Botz); (16) Integrated fluid concept - optimized technology and service package for users of biodegradable lubricants (Juergen Baer); (17) Utilization of a bio oil sensor to control

  19. Zinc Composite Layers, Incorporating Polymeric Nano-aggregates: Surface Analysis and Electrochemical Behavior

    NARCIS (Netherlands)

    Koleva, D.A.; Zhang, X.; Petrov, P.; Boshkov, N.; Van Breugel, K.; De Wit, J.H.W.; Mol, J.M.C.; Tsvetkova, N.

    2008-01-01

    This study reports on a comparative investigation of the corrosion behavior of zinc (Zn) and nano-composite zinc (ZnC) galvanic layers in 5% NaCl solution. The metallic matrix of the ZnC layers incorporates nano-sized, stabilized polymeric aggregates, formed from the amphiphilic tri-block co-polymer

  20. Biodegradable polylactic acid polymer with nisin for use in antimicrobial food packaging

    Science.gov (United States)

    Biodegradable polylactic acid (PLA) polymer was evaluated for its application as a material for antimicrobial food packaging. PLA films were incorporated with nisin to provide slow release of the encapsulated antimicrobial for control of foodborne pathogens. Antimicrobial activity of PLA/nisin films...

  1. Poly (3-Hydroxyalkanoates): Biodegradable Plastics

    OpenAIRE

    2013-01-01

    During the 1920’s, a polyester called poly (3-hydroxybutyrate) was discovered in bacterial cells. This compound, otherwise known as PHB, is part of a polyester family called polyhydroxyalkanoates (PHAs). Polyhydroxyalkanoates are used as an energy and carbon sto rage compound within certain bacterial cells. Polyhydroxyalkanoates (PHAs) are thermoplastic, biodegradable polyesters synthesized by some bacteria from rene...

  2. Biodegradation kinetics at low concentrations (

    DEFF Research Database (Denmark)

    Toräng, Lars; Albrechtsen, Hans-Jørgen; Nyholm, Niels

    2000-01-01

    Aerobic biodegradation of 2,4-dichlorophenoxyacetic acid (2,4-D) was studied in groundwater added sediment fines. At concentrations at or below 1 mu g/L of 2,4-D degradation kinetic was of true first order without significant growth of specific degraders and with half-life for mineralization...

  3. Biodegradable Pectin/clay Aerogels

    Science.gov (United States)

    Biodegradable, foamlike materials based on renewable pectin and sodium montmorillonite clay were fabricated through a simple, environmentally friendly freeze-drying process. Addition of multivalent cations (Ca2+ and Al3+) resulted in apparent crosslinking of the polymer, and enhancement of aerogel p...

  4. A kinetic model for predicting biodegradation.

    Science.gov (United States)

    Dimitrov, S; Pavlov, T; Nedelcheva, D; Reuschenbach, P; Silvani, M; Bias, R; Comber, M; Low, L; Lee, C; Parkerton, T; Mekenyan, O

    2007-01-01

    Biodegradation plays a key role in the environmental risk assessment of organic chemicals. The need to assess biodegradability of a chemical for regulatory purposes supports the development of a model for predicting the extent of biodegradation at different time frames, in particular the extent of ultimate biodegradation within a '10 day window' criterion as well as estimating biodegradation half-lives. Conceptually this implies expressing the rate of catabolic transformations as a function of time. An attempt to correlate the kinetics of biodegradation with molecular structure of chemicals is presented. A simplified biodegradation kinetic model was formulated by combining the probabilistic approach of the original formulation of the CATABOL model with the assumption of first order kinetics of catabolic transformations. Nonlinear regression analysis was used to fit the model parameters to OECD 301F biodegradation kinetic data for a set of 208 chemicals. The new model allows the prediction of biodegradation multi-pathways, primary and ultimate half-lives and simulation of related kinetic biodegradation parameters such as biological oxygen demand (BOD), carbon dioxide production, and the nature and amount of metabolites as a function of time. The model may also be used for evaluating the OECD ready biodegradability potential of a chemical within the '10-day window' criterion.

  5. Oil recovery with vinyl sulfonic acid-acrylamide copolymers

    Energy Technology Data Exchange (ETDEWEB)

    Norton, C.J.; Falk, D.O.

    1973-12-18

    An aqueous polymer flood containing sulfomethylated alkali metal vinyl sulfonate-acrylamide copolymers was proposed for use in secondary or tertiary enhanced oil recovery. The sulfonate groups on the copolymers sustain the viscosity of the flood in the presence of brine and lime. Injection of the copolymer solution into a waterflooded Berea core, produced 30.5 percent of the residual oil. It is preferred that the copolymers are partially hydrolyzed.

  6. Charge Transport in Conjugated Block Copolymers

    Science.gov (United States)

    Smith, Brandon; Le, Thinh; Lee, Youngmin; Gomez, Enrique

    Interest in conjugated block copolymers for high performance organic photovoltaic applications has increased considerably in recent years. Polymer/fullerene mixtures for conventional bulk heterojunction devices, such as P3HT:PCBM, are severely limited in control over interfaces and domain length scales. In contrast, microphase separated block copolymers self-assemble to form lamellar morphologies with alternating electron donor and acceptor domains, thereby maximizing electronic coupling and local order at interfaces. Efficiencies as high as 3% have been reported in solar cells for one block copolymer, P3HT-PFTBT, but the details concerning charge transport within copolymers have not been explored. To fill this gap, we probed the transport characteristics with thin-film transistors. Excellent charge mobility values for electron transport have been observed on aluminum source and drain contacts in a bottom gate, bottom contact transistor configuration. Evidence of high mobility in ordered PFTBT phases has also been obtained following thermal annealing. The insights gleaned from our investigation serve as useful guideposts, revealing the significance of the interplay between charge mobility, interfacial order, and optimal domain size in organic block copolymer semiconductors.

  7. Thermoreversible copolymer gels for extracellular matrix.

    Science.gov (United States)

    Vernon, B; Kim, S W; Bae, Y H

    2000-07-01

    To improve the properties of a reversible synthetic extracellular matrix based on a thermally reversible polymer, copolymers of N-isopropylacrylamide and acrylic acid were prepared in benzene with varying contents of acrylic acid (0 to 3%) and the thermal properties were evaluated. The poly(N-isopropylacrylamide) and copolymers made with acrylic acid had molecular weights from 0.8 to 1.7 x10(6) D. Differential scanning calorimetry (DSC) showed the high-molecular-weight acrylic acid copolymers had similar onset temperatures to the homopolymers, but the peak width was considerably increased with increasing acrylic acid content. DSC and cloud point measurements showed that polymers with 0 to 3% acrylic acid exhibit a lower critical solution temperature (LCST) transition between 30 degrees and 37 degrees C. In swelling studies, the homopolymer showed significant syneresis at temperatures above 31 degrees C. Copolymers with 1 and 1.5% showed syneresis beginning at 32 degrees and 37 degrees C, respectively. At 37 degrees C the copolymers with 1.5-3% acrylic acid showed little or no syneresis. Due to the high water content and a transition near physiologic conditions (below 37 degrees C), the polymers with 1.5-2.0% acrylic acid exhibited properties that would be useful in the development of a refillable synthetic extracellular matrix. Such a matrix could be applied to several cell types, including islets of Langerhans, for a biohybrid artificial pancreas.

  8. Chain exchange in block copolymer micelles

    Science.gov (United States)

    Lu, Jie; Bates, Frank; Lodge, Timothy

    2014-03-01

    Block copolymer micelles are aggregates formed by self-assembly of amphiphilic copolymers dispersed in a selective solvent, driven by unfavorable interactions between the solvent and the core-forming block. Due to the relatively long chains being subject to additional thermodynamic and dynamic constraints (e.g., entanglements, crystallinity, vitrification), block copolymer micelles exhibit significantly slower equilibration kinetics than small molecule surfactants. As a result, details of the mechanism(s) of equilibration in block copolymer micelles remain unclear. This present works focuses on the chain exchange kinetics of poly(styrene-b-ethylenepropylene) block copolymers in squalane (C30H62) using time-resolved small angle neutron scattering (TR-SANS). A mixture of h-squalane and d-squalane is chosen so that it contrast matches a mixed 50/50 h/d polystyrene micelle core. When the temperature is appropriate and isotopically labeled chains undergo mixing, the mean core contrast with respect to the solvent decreases, and the scattering intensity is therefore reduced. This strategy allows direct probing of chain exchange rate from the time dependent scattering intensity I(q, t).

  9. SCATTERING BY CYCLIC POLYMERS AND COPOLYMERS AT LARGE SCATTERING VECTORS

    NARCIS (Netherlands)

    KOSMAS, M; BENOIT, H; HADZIIOANNOU, G

    1994-01-01

    General formulae allowing the evaluation of the form factors of cyclic block copolymers are established and graphs for cyclic copolymers of the form (A-B)(N) are shown. When N is large, the linear and the cyclic copolymer have the same behaviour. It is possible to extend at large angle an analytical

  10. Adsorption of graft copolymers onto silica and titania.

    NARCIS (Netherlands)

    Bijsterbosch, H.D.; Cohen Stuart, M.A.; Fleer, G.J.

    1998-01-01

    The adsorption of graft copolymers of poly(acrylamide) (PAAm, backbone) and poly(ethylene oxide) (PEO, side chains) from aqueous solution onto silica and titania was studied with reflectometry. Two high-molar-mass copolymers were used with different PEO graft densities (10 and 18% w/w PEO in copolym

  11. 21 CFR 181.32 - Acrylonitrile copolymers and resins.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Acrylonitrile copolymers and resins. 181.32 Section... Ingredients § 181.32 Acrylonitrile copolymers and resins. (a) Acrylonitrile copolymers and resins listed in... of the vinyl chloride resin) resin—for use only in contact with oleomargarine. (iv)...

  12. 21 CFR 175.210 - Acrylate ester copolymer coating.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Acrylate ester copolymer coating. 175.210 Section... COATINGS Substances for Use as Components of Coatings § 175.210 Acrylate ester copolymer coating. Acrylate ester copolymer coating may safely be used as a food-contact surface of articles intended for...

  13. 21 CFR 177.1350 - Ethylene-vinyl acetate copolymers.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Ethylene-vinyl acetate copolymers. 177.1350 Section... Basic Components of Single and Repeated Use Food Contact Surfaces § 177.1350 Ethylene-vinyl acetate copolymers. Ethylene-vinyl acetate copolymers may be safely used as articles or components of...

  14. Novel biodegradable α-TCP/poly(amino acid) composite artificial lamina following spinal surgery for prevention of intraspinal scar adhesion.

    Science.gov (United States)

    Ran, Bo; Song, Yue-Ming; Liu, Hao; Liu, Li-Min; Gong, Quan; Li, Tao; Zeng, Jian-Cheng; Yuan, Hai-Feng

    2011-12-01

    Biodegradable copolymer α-TCP/poly(amino acid) composite artificial lamina was prepared and used in goat cervical vertebra resection repair. Cervical 4 was removed by laminectomy, and a vertebra defect of 27 × 9 mm was made. α-TCP/poly(amino acid) composite artificial lamina was inserted in the test group. The efficiency of the copolymer during repair and reconstruction of the goats' vertebra was tested by using X-ray, CT scanning, and histological and biomechanical measurements. In the 24 weeks following the operation, the artificial lamina refrained from shifting, and no dural adhesion pressure was observed. In contrast, the control group suffered from infiltration of soft tissue in the spinal canal, dural pressure and α-TCP/poly(amino acid) degradation. In conclusion, α-TCP/poly(amino acid) composite artificial lamina can significantly prevent scar tissue from infiltrating the spinal canal.

  15. Biodegradable polyurethane nanocomposites containing dexamethasone for ocular route

    Energy Technology Data Exchange (ETDEWEB)

    Rodrigues da Silva, Gisele [Federal University of Sao Joao Del Rei, School of Pharmacy, Divinopolis, Minas Gerais (Brazil); Silva-Cunha, Armando da [Federal University of Minas Gerais, School of Pharmacy, Belo Horizonte, Minas Gerais (Brazil); Behar-Cohen, Francine [INSERM, Physiopathology of ocular diseases: Therapeutic innovations, Institut des Cordeliers, Paris (France); Laboratoire d' Innovations Therapeutiques, Fondation Rothschild, Paris (France); Universite Rene Descartes, Hotel Dieu University Hospital, Paris (France); Ayres, Eliane [Federal University of Minas Gerais, Department of Metallurgical and Materials Engineering, Belo Horizonte, Minas Gerais (Brazil); Orefice, Rodrigo L., E-mail: rorefice@demet.ufmg.br [Federal University of Minas Gerais, Department of Metallurgical and Materials Engineering, Belo Horizonte, Minas Gerais (Brazil)

    2011-03-12

    The treatment of posterior segment ocular diseases, such as uveitis, by using eye drops and oral drugs is usually not effective due to the body's natural barriers to drug penetration. In this study, ocular implants to treat uveitis were synthesized by incorporating dexamethasone acetate, an important type of corticoid used in the treatment of some uveitis, into a biodegradable polyurethane containi clay nanoparticles. Biodegradable polyurethane nanocomposites having poly(caprolactone) oligomers as soft segments were obtained by delaminating clay particles within a polyurethane aqueous dispersion. The drug was incorporated into the polymer by dispersing it in the waterborne polyurethane followed by a drying step. Nanoparticles derived from clay were demonstrated to be able to tailor the mechanical properties of polyurethanes to achieve values that can match the properties of ocular soft tissues. Infrared spectra (FTIR) showed that the presence of clay particles was able to change the microphase separation process typical of polyurethanes. X-ray diffraction and small angle x-ray scattering (SAXS) results were explored to show that the incorporation of both dexamethasone acetate and nanocomponents derived from clay led to a less defined two-phase polyurethane. The presence of clay nanoparticles increased the rate of drug release measured in vitro. Human retinal pigment epithelial cells (ARPE-19) were cultured in contact with polyurethanes and polyurethane nanocomposites, and the viability of them (evaluated by using MTT assay after 7 days) showed that no toxic components were released from polyurethanes containing no drugs during the test.

  16. Nanoscale Ionic Aggregate Morphology in Zwitterionic Copolymers

    Science.gov (United States)

    Choi, Jae-Hong; Huyck, Rebecca; Salas-de La Cruz, David; Long, Timothy E.; Winey, Karen I.

    2009-03-01

    The morphology of two different zwitterionic copolymers, poly(sulfobetaine methacrylate-ran-butyl acrylate), and poly(sulfobetaine methacrylamide-ran-butyl acrylate) are investigated as a function of the mol % content of SBMA (7 and 9 mol %) and SBMAm (6, 10 and 13 mol %), respectively. In both copolymers, X-ray scattering results show a new structure in the material arising from ionic aggregates. The sizes of the ionic aggregates are obtained through the scattering model. The sizes of the ionic aggregates increase as the ion content increases. The application of scanning transmission electron microscopy to the study of ionomer morphology has enabled direct, model-independent visualization of the ionic aggregates. The correlation between X-ray scattering results and the real space imaging for morphology of these zwitterionic copolymers will be presented.

  17. Functionalization of Block Copolymer Vesicle Surfaces

    Directory of Open Access Journals (Sweden)

    Wolfgang Meier

    2011-01-01

    Full Text Available In dilute aqueous solutions certain amphiphilic block copolymers self-assemble into vesicles that enclose a small pool of water with a membrane. Such polymersomes have promising applications ranging from targeted drug-delivery devices, to biosensors, and nanoreactors. Interactions between block copolymer membranes and their surroundings are important factors that determine their potential biomedical applications. Such interactions are influenced predominantly by the membrane surface. We review methods to functionalize block copolymer vesicle surfaces by chemical means with ligands such as antibodies, adhesion moieties, enzymes, carbohydrates and fluorophores. Furthermore, surface-functionalization can be achieved by self-assembly of polymers that carry ligands at their chain ends or in their hydrophilic blocks. While this review focuses on the strategies to functionalize vesicle surfaces, the applications realized by, and envisioned for, such functional polymersomes are also highlighted.

  18. Polyhydroxyalkanoate-based natural synthetic hybrid copolymer films: A small-angle neutron scattering study

    Science.gov (United States)

    Foster, L. John R.; Knott, Robert; Sanguanchaipaiwong, Vorapat; Holden, Peter J.

    2006-11-01

    Polyhydroxyalkanoates have attracted attention as biodegradable alternatives to conventional thermoplastics and as biomaterials. Through modification of their biosynthesis using Pseudomonas oleovorans, we have manipulated the material properties of these biopolyesters and produced a natural-synthetic hybrid copolymer of polyhydroxyoctanoate- block-diethylene glycol (PHO- b-DEG). A mixture of PHO and PHO-DEG were solvent cast from analytical grade chloroform and analysed using small-angle neutron scattering. A scattering pattern, easily distinguished above the background, was displayed by the films with a diffraction ring at q∼0.12 Å -1. This narrow ring of intensity is suggestive of a highly ordered system. Analysis of the diffraction pattern supported this concept and showed a d-spacing of approximately 50 Å. In addition, conformation of the hybrid polymer chains can be manipulated to support their self-assembly into ordered microporous films.

  19. Graft Copolymers of Maleic Anhydride and Its Isostructural Analogues: High Performance Engineering Materials

    CERN Document Server

    Rzayev, Zakir M O

    2011-01-01

    This review summarizes the main advances published over the last 15 years outlining the different methods of grafting, including reactive extruder systems, surface modification, grafting and graft copolymerization of synthetic and natural polymers with maleic anhydride and its isostructural analogues such as maleimides and maleates, and anhydrides, esters and imides of citraconic and itaconic acids, derivatives of fumaric acid, etc. Special attention is spared to the grafting of conventional and non-conventional synthetic and natural polymers, including biodegradable polymers, mechanism of grafting and graft copolymerization, in situ grafting reactions in melt by reactive extrusion systems, in solutions and solid state (photo- and plasma-induced graftings), and H-bonding effect in the reactive blend processing. The structural phenomena, unique properties and application areas of these copolymers and their various modifications and composites as high performance engineering materials have been also described.

  20. Dynamics of Block Copolymer Nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Mochrie, Simon G. J.

    2014-09-09

    A detailed study of the dynamics of cadmium sulfide nanoparticles suspended in polystyrene homopolymer matrices was carried out using X-ray photon correlation spectroscopy for temperatures between 120 and 180 °C. For low molecular weight polystyrene homopolymers, the observed dynamics show a crossover from diffusive to hyper-diffusive behavior with decreasing temperatures. For higher molecular weight polystyrene, the nanoparticle dynamics appear hyper-diffusive at all temperatures studied. The relaxation time and characteristic velocity determined from the measured hyper-diffusive dynamics reveal that the activation energy and underlying forces determined are on the order of 2.14 × 10-19 J and 87 pN, respectively. We also carried out a detailed X-ray scattering study of the static and dynamic behavior of a styrene– isoprene diblock copolymer melt with a styrene volume fraction of 0.3468. At 115 and 120 °C, we observe splitting of the principal Bragg peak, which we attribute to phase coexistence of hexagonal cylindrical and cubic double- gyroid structure. In the disordered phase, above 130 °C, we have characterized the dynamics of composition fluctuations via X-ray photon correlation spectroscopy. Near the peak of the static structure factor, these fluctuations show stretched-exponential relaxations, characterized by a stretching exponent of about 0.36 for a range of temperatures immediately above the MST. The corresponding characteristic relaxation times vary exponentially with temperature, changing by a factor of 2 for each 2 °C change in temperature. At low wavevectors, the measured relaxations are diffusive with relaxation times that change by a factor of 2 for each 8 °C change in temperature.

  1. Co-polymer Films for Sensors

    Science.gov (United States)

    Ryan, Margaret A. (Inventor); Homer, Margie L. (Inventor); Yen, Shiao-Pin S. (Inventor); Kisor, Adam (Inventor); Jewell, April D. (Inventor); Shevade, Abhijit V. (Inventor); Manatt, Kenneth S. (Inventor); Taylor, Charles (Inventor); Blanco, Mario (Inventor); Goddard, William A. (Inventor)

    2012-01-01

    Embodiments include a sensor comprising a co-polymer, the co-polymer comprising a first monomer and a second monomer. For some embodiments, the first monomer is poly-4-vinyl pyridine, and the second monomer is poly-4-vinyl pyridinium propylamine chloride. For some embodiments, the first monomer is polystyrene and the second monomer is poly-2-vinyl pyridinium propylamine chloride. For some embodiments, the first monomer is poly-4-vinyl pyridine, and the second monomer is poly-4-vinyl pyridinium benzylamine chloride. Other embodiments are described and claimed.

  2. Polaronic Tunnelling in Organic Triblock Copolymers

    Institute of Scientific and Technical Information of China (English)

    LIU De-Sheng; ZHANG Da-Cheng; XIE Shi-Jie; MEI Liang-Mo

    2005-01-01

    @@ Polaron tunnelling is studied in xPA/nPPP/xPA (PA for polyacetylene and PPP poly (p-phenylene)) triblock copolymer, which has a well-barrier-well structure. An extended tight-binding Hamiltonian including external electric field is adopted. Without electric field, the injected electrons would not extend over the whole copolymer chain but instead be confined in the segments of PA. This is different from the behaviour of the traditional semiconductors. It is found that the polaron can transfer to the potential barrier-PPP segment when the applied electric field reaches a certain value. The critical polaron tunnelling electric fields depend upon the lengths of PPP segments.

  3. Ordering phenomena in ABA triblock copolymer gels

    DEFF Research Database (Denmark)

    Reynders, K.; Mischenko, N.; Kleppinger, R.

    1997-01-01

    Temperature and concentration dependencies of the degree of order in ABA triblock copolymer gels are discussed. Two factors can influence the ordering phenomena: the conformation of the midblocks (links of the network) and the polydispersity of the endblock domains (nodes of the network). The lat......Temperature and concentration dependencies of the degree of order in ABA triblock copolymer gels are discussed. Two factors can influence the ordering phenomena: the conformation of the midblocks (links of the network) and the polydispersity of the endblock domains (nodes of the network...

  4. Studies in reactive extrusion processing of biodegradable polymeric materials

    Science.gov (United States)

    Balakrishnan, Sunder

    Various reaction chemistries such as Polymerization, Polymer cross-linking and Reactive grafting were investigated in twin-screw extruders. Poly (1,4-dioxan-2-one) (PPDX) was manufactured in melt by the continuous polymerization of 1,4-dioxan-2-one (PDX) monomer in a twin-screw extruder using Aluminum tri-sec butoxide (ATSB) initiator. Good and accurate control over molecular weight was obtained by controlling the ratio of monomer to initiator. A screw configuration consisting of only conveying elements was used for the polymerization. The polymerization reaction was characterized by a monomer-polymer dynamic equilibrium, above the melting temperature of the polymer, limiting the equilibrium conversion to 78-percent. Near complete (˜100-percent) conversion was obtained on co-polymerizing PDX monomer with a few mol-percent (around 8-percent) Caprolactone (CL) monomer in a twin-screw extruder using ATSB initiator. The co-polymers exhibited improved thermal stability with reduction in glass transition temperature. The extruder was modeled as an Axial Dispersed Plug Flow Reactor for the polymerization of CL monomer using Residence Time Distribution (RTD) Analysis. The model provided a good fit to the experimental RTD and conversion data. Aliphatic and aliphatic-aromatic co-polyesters, namely Polycaprolactone (PCL) and Poly butylenes (adipate-co-terephthalate) (Ecoflex) were cross-linked in a twin-screw extruder using radical initiator to form micro-gel reinforced biodegradable polyesters. Cross-linked Ecoflex was further extrusion blended with talc to form blends suitable to be blown into films. A screw configuration consisting of conveying and kneading elements was found to be effective in dispersion of the talc particles (5--10 microns) in the polyester matrix. While the rates of crystallization increased for the talc filled polyester blends, overall crystallinity reduced. Mechanical, tear and puncture properties of films made using the talc filled polyester blends

  5. UV photolysis for accelerating pyridine biodegradation.

    Science.gov (United States)

    Zhang, Yongming; Chang, Ling; Yan, Ning; Tang, Yingxia; Liu, Rui; Rittmann, Bruce E

    2014-01-01

    Pyridine, a nitrogen-containing heterocyclic compound, is slowly biodegradable, and coupling biodegradation with UV photolysis is a potential means to accelerate its biotransformation and mineralization. The initial steps of pyridine biodegradation involve mono-oxygenation reactions that have molecular oxygen and an intracellular electron carrier as cosubstrates. We employed an internal circulation baffled biofilm reactor for pyridine biodegradation following three protocols: direct biodegradation (B), biodegradation after photolysis (P+B), and biodegradation with succinic acid added (B+S). Succinic acid was the main UV-photolysis product from pyridine, and its catabolic oxidation generates internal electron carriers that may accelerate the initial steps of pyridine biodegradation. Compared with direct biodegradation of pyridine (B), the removal rate for the same concentration of photolyzed pyridine (P+B) was higher by 15 to 43%, depending on the initial pyridine concentrations (increasing through the range of 130 to 310 mg/L). Adding succinic acid alone (B+S) gave results similar to P+B, which supports that succinic acid was the main agent for accelerating the pyridine biodegradation rate. In addition, protocols P+B and B+S were similar in terms of increasing pyridine mineralization over 10 h: 84% and 87%, respectively, which were higher than with protocol B (72%). The positive impact of succinic acid-whether added directly or produced via UV photolysis-confirms that its catabolism, which produced intracellular electron carriers, accelerated the initial steps of pyridine biotransformation.

  6. Aerobic biodegradation of a nonylphenol polyethoxylate and toxicity of the biodegradation metabolites.

    Science.gov (United States)

    Jurado, Encarnación; Fernández-Serrano, Mercedes; Núñez-Olea, Josefa; Lechuga, Manuela

    2009-09-01

    In this paper a study was made of the biodegradation of a non-ionic surfactant, a nonylphenol polyethoxylate, in biodegradability tests by monitoring the residual surfactant matter. The influence of the concentration on the extent of primary biodegradation, the toxicity of biodegradation metabolites, and the kinetics of degradation were also determined. The primary biodegradation was studied at different initial concentrations: 5, 25 and 50 mg/L, (at sub-and supra-critical micelle concentration). The NPEO used in this study can be considered biodegradable since the primary biodegradation had already taken place (a biodegradation greater than 80% was found for the different initial concentration tested). The initial concentration affected the shape of the resulting curve, the mean biodegradation rate and the percentage of biodegradation reached (99% in less than 8 days at 5 mg/L, 98% in less than 13 days at 25 mg/L and 95% in 14 days at 50 mg/L). The kinetic model of Quiroga and Sales (1991) was applied to predict the biodegradation of the NPEO. The toxicity value was measured as EC(20) and EC(50). In addition, during the biodegradation process of the surfactant a toxicity analysis was made of the evolution of metabolites generated, confirming that the subproducts of the biodegradation process were more toxic than the original.

  7. Biomimetic triblock copolymer membrane arrays: a stable template for functional membrane proteins

    DEFF Research Database (Denmark)

    Gonzalez-Perez, A.; Jensen, Karin Bagger Stibius; Vissing, Thomas;

    2009-01-01

    , we avoid low molecular weight solvents such as chloroform and toluene, which are strong protein denaturants. The membranes show a low ionic conductance and a long lifetime at room temperature. Contrast phase microscopy shows the presence of a polymer region delimited by a Plateau-Gibbs border similar......It is demonstrated that biomimetic stable triblock copolymer membrane arrays can be prepared using a scaffold containing 64 apertures of 300 μm diameter each. The membranes were made from a stock solution of block copolymers with decane as a solvent using a new deposition method. By using decane...... to what is observed in black lipid membranes. The ion-channel gramicidin A was successfully incorporated into the membrane in a functional form....

  8. Sulfonation and characterization of styrene-indene copolymers for the development of proton conducting polymer membranes

    Directory of Open Access Journals (Sweden)

    Cristiane M. Becker

    2012-01-01

    Full Text Available The aim of this work is to obtain polymer precursors based on styrene copolymers with distinct degrees of sulfonation, as an alternative material for fuel cell membranes. Acetyl sulfate was used to carry out the sulfonation and the performance of the polyelectrolyte was evaluated based on the content of acid polar groups incorporated into the macromolecular chain. Polymeric films were produced by blending the sulfonated styrene-indene copolymer with poly(vinylidene fluoride. The degree of sulfonation of the polymer was strongly affected by the sulfonation reaction parameters, with a direct impact on the ionic exchange capacity and the ionic conductivity of the sulfonated polymers and the membranes obtained from them. The films produced with the blends showed more suitable mechanical properties, although the conductivity of the membranes was still lower than that of commercially available membranes used in fuel cells.

  9. Complete regression of xenograft tumors using biodegradable mPEG-PLA-SN38 block copolymer micelles.

    Science.gov (United States)

    Lu, Lu; Zheng, Yan; Weng, Shuqiang; Zhu, Wenwei; Chen, Jinhong; Zhang, Xiaomin; Lee, Robert J; Yu, Bo; Jia, Huliang; Qin, Lunxiu

    2016-06-01

    7-Ethyl-10-hydroxy-comptothecin (SN38) is an active metabolite of irinotecan (CPT-11) and the clinical application of SN38 is limited by its hydrophobicity and instability. To address these issues, a series of novel amphiphilic mPEG-PLA-SN38-conjugates were synthesized by linking SN38 to mPEG-PLA-SA, and they could form micelles by self-assembly. The effects of mPEG-PLA composition were studied in vitro and in vivo. The mean diameters of mPEG2K-PLA-SN38 micelles and mPEG4K-PLA-SN38 micelles were 10-20nm and 120nm, respectively, and mPEG2K-PLA-SN38 micelles showed greater antitumor efficacy than mPEG4K-PLA-SN38 micelles both in vitro and in vivo. These data suggest that the lengths of mPEG and PLA chains had a major impact on the physicochemical characteristics and antitumor activity of SN38-conjugate micelles.

  10. Molecular Interaction Control in Diblock Copolymer Blends and Multiblock Copolymers with Opposite Phase Behaviors

    Science.gov (United States)

    Cho, Junhan

    2014-03-01

    Here we show how to control molecular interactions via mixing AB and AC diblock copolymers, where one copolymer exhibits upper order-disorder transition and the other does lower disorder-order transition. Linear ABC triblock copolymers possessing both barotropic and baroplastic pairs are also taken into account. A recently developed random-phase approximation (RPA) theory and the self-consistent field theory (SCFT) for general compressible mixtures are used to analyze stability criteria and morphologies for the given systems. It is demonstrated that the copolymer systems can yield a variety of phase behaviors in their temperature and pressure dependence upon proper mixing conditions and compositions, which is caused by the delicate force fields generated in the systems. We acknowledge the financial support from National Research Foundation of Korea and Center for Photofunctional Energy Materials.

  11. Block Copolymers of Ethylene Oxide and Styrene Oxide.New Copolymer Surfactants(Ⅱ)

    Institute of Scientific and Technical Information of China (English)

    Zhuo Yang; David Attwood; Colin Booth

    2003-01-01

    @@ 3.2. Association Number Figure 5 shows the dependence of the weight-average association number (Nw,measured by static light scattering, solution temperature 30 °C) on hydrophobe block length for ES and ESEblock copolymers.

  12. A kind of novel biodegradable hydrogel made from copolymerization of gelatin with polypseudorotaxanes based on {alpha}-CDs

    Energy Technology Data Exchange (ETDEWEB)

    Hou Dandan; Tong Xinming; Yu Huaiqing; Zhang Aiying; Feng Zengguo [School of Materials Science and Engineering, Beijing Institute of Technology, Beijing 100081 (China)

    2007-09-15

    A kind of novel biodegradable supramolecular hydrogel was synthesized via copolymerization of gelatin methacrylamide with photocurable and biodegradable polypseudorotaxanes under UV irradiation. These polypseudorotaxanes were prepared by supramolecular self-assemblies of {alpha}-cyclodextrins threaded onto amphiphilic LA-PEG-LA copolymers end-capped with methacryloyl groups. The hydrogels are injectable, and their structure was characterized in detail with FTIR, {sup 1}H NMR, XRD, TG and DSC techniques. Their swelling behaviour and morphologies were also examined. The analytical results demonstrated that the channel-type crystalline structure of the polypseudorotaxanes remains in the as-obtained hydrogels. Moreover, the SEM pictures showed that the hydrogels having gelatin methacrylamide are more suitable for cell seeding and proliferation than those without gelatin added.

  13. Genome-engineered Sinorhizobium meliloti for the production of poly(lactic-co-3-hydroxybutyric) acid copolymer.

    Science.gov (United States)

    Tran, Tam T; Charles, Trevor C

    2016-02-01

    Economically competitive commercial production of biodegradable bioplastics with desirable properties is an important goal. In this study, we demonstrate the use of chromosome engineering of an alternative bacterial host, Sinorhizobium meliloti, for production of the copolymer, poly(lactate-co-3-hydroxybutyrate). Codon-optimized genes for 2 previously engineered enzymes, Clostridium propionicum propionate CoA transferase (Pct532Cp) and Pseudomonas sp. strain MBEL 6-19 polyhydroxyalkanoate (PHA) synthase 1 (PhaC1400Ps6-19), were introduced into S. meliloti Rm1021 by chromosome integration, replacing the native phbC gene. On the basis of phenotypic analysis and detection of polymer product by gas chromatography analysis, synthesis and accumulation of the copolymer was confirmed. The chromosome integrant strain, with the introduced genes under the control of the native phbC promoter, is able to produce over 15% cell dry mass of poly(lactate-co-3-hydroxybutyrate), containing 30 mol% lactate, from growth on mannitol. We were also able to purify the polymer from the culture and confirm the structure by NMR and GC-MS. To our knowledge, this is the first demonstration of production of this copolymer in the Alphaproteobacteria. Further optimization of this system may eventually yield strains that are able to produce economically viable commercial product.

  14. Graft (partially carboxymethylated guar gum-g-poly vinyl sulfonic acid) copolymer: from synthesis to applications.

    Science.gov (United States)

    Yadav, Mithilesh; Srivastav, Abhishek; Verma, Shiv Kumar; Behari, Kunj

    2013-09-12

    The aim of the paper is to study the physico-chemical phenomenon of synthesized graft copolymer (carboxymethylated guar gum-g-vinylsulfonic acid). The reaction optimum conditions for grafting has also been determined by studying the effect of vinylsulfonic acid, hydrogen ion, peroxymonosulphate, glycolic acid concentration and carboxymethylated guar gum along with time and temperature. Experimental results show that maximum grafting has been obtained at 1.8 g dm(-3) concentration of partially carboxymethylated guar gum and 5.3 × 10(-2) mol dm(-3) concentration of vinylsulfonic acid. It has been observed that grafting ratio, add on, conversion, efficiency increase up to 4.0 × 10(-3) mol dm(-3) of hydrogen ion, 4 × 10(-3) mol dm(-3) of glycolic acid, 14 × 10(-3) mol dm(-3) of peroxymonosulphate and 35 °C of temperature. Grafted copolymer has been characterized by FTIR spectroscopy and thermogravimetric analysis. Water swelling, flocculating, metal ion uptake and resistance to biodegradability properties of partially carboxymethylated guar gum-g-vinylsulfonic acid have been determined.

  15. Water transport and clustering behavior in homopolymer and graft copolymer polylactide

    Energy Technology Data Exchange (ETDEWEB)

    Du, An; Koo, Donghun; Theryo, Grayce; Hillmyer, Marc A.; Cairncross, Richard A. (Drexel); (UMM)

    2015-02-19

    Polylactide is a bio-based and biodegradable polymer well-known for its renewable origins. Water sorption and clustering behavior in both a homopolymer polylactide and a graft copolymer of polylactide was studied using the quartz crystal microbalance/heat conduction calorimetry (QCM/HCC) technique. The graft copolymer, poly(1,5-cyclooctadiene-co-5-norbornene-2-methanol-graft-D,L-lactide), contained polylactide chains (95 wt.%) grafted onto a hydrophobic rubbery backbone (5 wt.%). Clustering is an important phenomenon in the study of water transport properties in polymers since the presence of water clusters can affect the water diffusivity. The HCC method using the thermal power signals and Van't Hoff's law were both employed to estimate the water sorption enthalpy. Sorption enthalpy of water in both polymers was determined to be approximately -40 kJ/mol for all water activity levels. Zimm-Lundberg analysis showed that water clusters start to form at a water activity of 0.4. The engaged species induced clustering (ENSIC) model was used to curve fit sorption isotherms and showed that the affinity among water molecules is higher than that between water molecules and polymer chains. All the methods used indicate that clustering of water molecules exists in both polymers.

  16. BIODEGRADABLE COATING FROM AGATHIS ALBA

    Directory of Open Access Journals (Sweden)

    NORYAWATI MULYONO

    2012-11-01

    Full Text Available The adhesive property of copal makes it as a potential coating onto aluminum foil to replace polyethylene. This research aimed to develop copal-based coating. The coating was prepared by extracting the copal in ethyl acetate and dipping the aluminium foil in ethyl acetate soluble extract of copal. The characterization of coating included its thickness, weight, thermal and chemical resistance, and biodegradation. The results showed that the coating thickness and weight increased as the copal concentration and dipping frequency increased. Thermal resistance test showed that the coating melted after being heated at 110°C for 30 min. Copal-based coating wasresistant to acidic solution (pH 4.0, water, and coconut oil, but was deteriorated in detergent 1% (w/v and basic solution (pH 10.0. Biodegradability test using Pseudomonas aeruginosa showed weight reduction of 76.82% in 30 days.

  17. Biomedical Applications of Biodegradable Polyesters

    Directory of Open Access Journals (Sweden)

    Iman Manavitehrani

    2016-01-01

    Full Text Available The focus in the field of biomedical engineering has shifted in recent years to biodegradable polymers and, in particular, polyesters. Dozens of polyester-based medical devices are commercially available, and every year more are introduced to the market. The mechanical performance and wide range of biodegradation properties of this class of polymers allow for high degrees of selectivity for targeted clinical applications. Recent research endeavors to expand the application of polymers have been driven by a need to target the general hydrophobic nature of polyesters and their limited cell motif sites. This review provides a comprehensive investigation into advanced strategies to modify polyesters and their clinical potential for future biomedical applications.

  18. Effect of the macromolecular architecture of biodegradable polyurethanes on the controlled delivery of ocular drugs.

    Science.gov (United States)

    da Silva, Gisele Rodrigues; da Silva Cunha, Armando; Ayres, Eliane; Oréfice, Rodrigo L

    2009-02-01

    Controlled delivery of drugs is a major issue in the treatment of ocular diseases, such as in the treatment of uveitis. In this study, dexamethasone acetate, an important type of corticoid used in the treatment of some uveitis, was incorporated into biodegradable polyurethanes (PU) having different macromolecular architectures. The biodegradable polyurethanes were obtained by preparing PU aqueous dispersions having poly(caprolactone) and/or poly(ethylene glycol) as soft segments. The drug was incorporated into the polymer by dissolving it in the PU aqueous dispersion. FTIR results showed the presence of the drug in the polymer with its original chemical structure. Small angle X-ray scattering (SAXS) results were explored to show that the incorporation of dexamethasone acetate led to the modification of the nanostructure of the polyurethane having only poly(caprolactone) as the soft segment, while the drug did not change significantly the microphase separated structure of PU having both poly(caprolactone) and poly(ethylene glycol) as soft segments. The evaluation of the release of the drug in vitro demonstrated that the obtained biodegradable polyurethanes were well succeeded in delivering dexamethasone acetate at an almost constant rate for 53 weeks. The presence of poly(ethylene glycol) together with poly(caprolactone) as soft segment in biodegradable PU was able to increase the rate of dexamethasone acetate release when compared to the rate of drug release from PU having only poly(caprolactone).

  19. Anaerobic Biodegradation of Detergent Surfactants

    OpenAIRE

    Erich Jelen; Ute Merrettig-Bruns

    2009-01-01

    Detergent surfactantscan be found in wastewater in relevant concentrations. Most of them are known as ready degradable under aerobic conditions, as required by European legislation. Far fewer surfactants have been tested so far for biodegradability under anaerobic conditions. The natural environment is predominantly aerobic, but there are some environmental compartments such as river sediments, sub-surface soil layer and anaerobic sludge digesters of wastewater treatment plants which have str...

  20. Engineering Flame Retardant Biodegradable Nanocomposites

    Science.gov (United States)

    He, Shan; Yang, Kai; Guo, Yichen; Zhang, Linxi; Pack, Seongchan; Davis, Rachel; Lewin, Menahem; Ade, Harald; Korach, Chad; Kashiwagi, Takashi; Rafailovich, Miriam

    2013-03-01

    Cellulose-based PLA/PBAT polymer blends can potentially be a promising class of biodegradable nanocomposites. Adding cellulose fiber reinforcement can improve mechanical properties of biodegradable plastics, but homogeneously dispersing hydrophilic cellulose in the hydrophobic polymer matrix poses a significant challenge. We here show that resorcinol diphenyl phosphates (RDP) can be used to modify the surface energy, not only reducing phase separation between two polymer kinds but also allowing the cellulose particles and the Halloysite clay to be easily dispersed within polymer matrices to achieve synergy effect using melt blending. Here in this study we describe the use of cellulose fiber and Halloysite clay, coated with RDP surfactant, in producing the flame retardant polymer blends of PBAT(Ecoflex) and PLA which can pass the stringent UL-94 V0 test. We also utilized FTIR, SEM and AFM nanoindentation to elucidate the role RDP plays in improving the compatibility of biodegradable polymers, and to determine structure property of chars that resulted in composites that could have optimized mechanical and thermal properties. Supported by Garcia Polymer Center and NSF Foundation.

  1. Gyroid Membranes made from Nanoporous Blck Copolymers

    DEFF Research Database (Denmark)

    Szewczykowski, Piotr Plzemystaw; Vigild, Martin Etchells; Ndoni, Sokol;

    2007-01-01

    of the membrane and its nanoporosity is e.g. obtained by cross-linking the majority blocks and selectively etching the minority blocks. Here we report on ultrafiltration membranes prepared from a 1,2-polybutadiene-b-polydimethylsiloxane diblock copolymer with gyroid structure. Different experimental methods...

  2. Substrate tolerant direct block copolymer nanolithography

    DEFF Research Database (Denmark)

    Li, Tao; Wang, Zhongli; Schulte, Lars

    2016-01-01

    simplifies the main stream BC lithography process, showing a broad substrate tolerance and allowing for efficient pattern transfer over wafer scale. PDMS-rich poly(styrene-b-dimethylsiloxane) (PS-b-PDMS) copolymers are directly applied on substrates including polymers, silicon and graphene. A single oxygen...

  3. LEDs based on conjugated PPV block copolymers

    NARCIS (Netherlands)

    Brouwer, H.J.; Hilberer, A.; Krasnikov, V.V.; Werts, M.; Wildeman, J.; Hadziioannou, G.

    1997-01-01

    A way to control the bandgap in semi-conducting polymers is by preparing polymers with a partially conjugated backbone. In our laboratory, three conjugated copolymers containing PPV trimers as light emitting chromophores have been synthesized, which emit in the blue, green and orange wavelength regi

  4. Chiral Block Copolymer Structures for Metamaterial Applications

    Science.gov (United States)

    2015-01-27

    MONITOR’S REPORT NUMBER(S) AOARD-114078 12. DISTRIBUTION/AVAILABILITY STATEMENT Distribution A: Approved for public release. Distribtion is...researchers focused o synthesis and processing, morphology and physical characterization of chiral block copolymer (BCP) materials. Such materials a...developed a platform process technology that can fabricate novel netwo morphologies from initial bicontinuous cubic phases through supergroup/subgroup

  5. Helical Ordering in Chiral Block Copolymers

    Science.gov (United States)

    Zhao, Wei; Hong, Sung Woo; Chen, Dian; Grason, Gregory; Russell, Thomas

    2012-02-01

    Introducing molecular chirality into the segments of block copolymers can influence the nature of the resultant morphology. Such an effect was found for poly(styrene-b-L-lactide) (PS-b-PLLA) diblock copolymers where hexagonally packed PLLA helical microdomains (H* phase) form in a PS matrix. However, molecular ordering of PLLA within the helical microdomains and the transfer of chirality from the segmental level to the mesoscale is still not well understood. We developed a field theoretic model to describe the interactions between segments of chiral blocks, which have the tendency to form a ``cholesteric'' texture. Based on the model, we calculated the bulk morphologies of chiral AB diblock copolymers using self-consistent field theory (SCFT). Experiments show that the H* phase only forms when microphase separation between PS and PLLA block happens first and crystallization of PLLA block is suppressed or happens within confined microdomain. Hence, crystalline ordering is not necessary for H* phase formation. The SCFT offers the chance to explore the range of thermodynamic stability of helical structures in the phase diagram of chiral block copolymer melts, by tuning parameters not only like the block segregation strength and composition, but also new parameters such as the ratio between preferred helical pitch to the radius of gyration and the Frank elastic constant for inter-segment distortions.

  6. CONJUGATED BLOCK-COPOLYMERS FOR ELECTROLUMINESCENT DIODES

    NARCIS (Netherlands)

    Hilberer, A; Gill, R.E; Herrema, J.K; Malliaras, G.G; Wildeman, J.; Hadziioannou, G

    1995-01-01

    In this article we review results obtained in our laboratory on the design and study of new light-emitting polymers. We are interested in the synthesis and characterisation of block copolymers with regularly alternating conjugated and non conjugated sequences. The blocks giving rise to luminescence

  7. Nylon 46-polytetramethylene oxide segmented block copolymers

    NARCIS (Netherlands)

    Gaymans, R.J.; Schwering, P.; Haan, de J.L.

    1989-01-01

    Block copolymers were synthesized from amine-terminated polytetramethylene oxide (PMTO) (Mw 800 and 1130) and polyamide 4,6 salt. First prepolymers were prepared at 200–210°C in the presence of a solvent (pyrrolidone). The prepolymers were postcondensed at 255°C (where possible in the solid state) t

  8. Block copolymer/ferroelectric nanoparticle nanocomposites

    Science.gov (United States)

    Pang, Xinchang; He, Yanjie; Jiang, Beibei; Iocozzia, James; Zhao, Lei; Guo, Hanzheng; Liu, Jin; Akinc, Mufit; Bowler, Nicola; Tan, Xiaoli; Lin, Zhiqun

    2013-08-01

    Nanocomposites composed of diblock copolymer/ferroelectric nanoparticles were formed by selectively constraining ferroelectric nanoparticles (NPs) within diblock copolymer nanodomains via judicious surface modification of ferroelectric NPs. Ferroelectric barium titanate (BaTiO3) NPs with different sizes that are permanently capped with polystyrene chains (i.e., PS-functionalized BaTiO3NPs) were first synthesized by exploiting amphiphilic unimolecular star-like poly(acrylic acid)-block-polystyrene (PAA-b-PS) diblock copolymers as nanoreactors. Subsequently, PS-functionalized BaTiO3 NPs were preferentially sequestered within PS nanocylinders in the linear cylinder-forming polystyrene-block-poly(methyl methacrylate) (PS-b-PMMA) diblock copolymer upon mixing the BaTiO3 NPs with PS-b-PMMA. The use of PS-b-PMMA diblock copolymers, rather than traditional homopolymers, offers the opportunity for controlling the spatial organization of PS-functionalized BaTiO3 NPs in the PS-b-PMMA/BaTiO3 NP nanocomposites. Selective solvent vapor annealing was utilized to control the nanodomain orientation in the nanocomposites. Vertically oriented PS nanocylinders containing PS-functionalized BaTiO3 NPs were yielded after exposing the PS-b-PMMA/BaTiO3 NP nanocomposite thin film to acetone vapor, which is a selective solvent for PMMA block. The dielectric properties of nanocomposites in the microwave frequency range were investigated. The molecular weight of PS-b-PMMA and the size of BaTiO3 NPs were found to exert an apparent influence on the dielectric properties of the resulting nanocomposites.Nanocomposites composed of diblock copolymer/ferroelectric nanoparticles were formed by selectively constraining ferroelectric nanoparticles (NPs) within diblock copolymer nanodomains via judicious surface modification of ferroelectric NPs. Ferroelectric barium titanate (BaTiO3) NPs with different sizes that are permanently capped with polystyrene chains (i.e., PS-functionalized BaTiO3NPs) were

  9. Nanopatterned block copolymers for use as vascular biomaterials

    Science.gov (United States)

    Silverstein, Joshua S.

    Manipulation of surface topography or chemistry has been a growing trend in efforts to enhance the properties of medical devices. Understanding the interactions of biomolecules with nanoengineered surfaces is vital to assess the safety and efficacy of devices that incorporate these structures. In this dissertation, a model block copolymer (BCP) system based on poly(styrene)-block-poly(1,2-butadiene) was systematically modified using photochemical thiol-ene chemistry. Poly(1,2-butadiene) molecular weight and thiol-ene ratios were systematically varied based on a model monomer, boc-cysteamine, to determine the efficiency of the reaction. The results demonstrate the polydispersity index of modified BCPs significantly increased when low thiol-ene ratios were employed and sometimes induced gelation of the reacted polymers. Using a tenfold excess of thiol, functionalizations between 60-90% were obtained for an acid, amine, amide, and a pharmaceutical with a pendant thiol. Calorimetry showed a 30-60 °C increase in the glass transition temperature of the daughter polymers. Subsequently, films were cast from solvents found suitable to forming self-assembled BCP thin films. The synthetic and processing approach allows for the formation of nanopatterned block copolymer films with controlled chemistries from a single source material. The BCPs were further characterized using water contact angle measurements and atomic force microscopy in liquid. Significantly decreased contact angles were caused by selective swelling of charged BCP domains. Protein (fibrinogen, albumin, cytochrome C, immunoglobulin G) adsorption experiments were conducted under static and dynamic conditions with a quartz crystal microbalance with dissipation. The results indicate that nanopatterned chemistry and experimental conditions strongly impact adsorption dynamics. Adsorption behavior was dependent both on protein structure and the characteristics of the surface. Depending on the structural stability

  10. A review of plastic waste biodegradation.

    Science.gov (United States)

    Zheng, Ying; Yanful, Ernest K; Bassi, Amarjeet S

    2005-01-01

    With more and more plastics being employed in human lives and increasing pressure being placed on capacities available for plastic waste disposal, the need for biodegradable plastics and biodegradation of plastic wastes has assumed increasing importance in the last few years. This review looks at the technological advancement made in the development of more easily biodegradable plastics and the biodegradation of conventional plastics by microorganisms. Additives, such as pro-oxidants and starch, are applied in synthetic materials to modify and make plastics biodegradable. Recent research has shown that thermoplastics derived from polyolefins, traditionally considered resistant to biodegradation in ambient environment, are biodegraded following photo-degradation and chemical degradation. Thermoset plastics, such as aliphatic polyester and polyester polyurethane, are easily attacked by microorganisms directly because of the potential hydrolytic cleavage of ester or urethane bonds in their structures. Some microorganisms have been isolated to utilize polyurethane as a sole source of carbon and nitrogen source. Aliphatic-aromatic copolyesters have active commercial applications because of their good mechanical properties and biodegradability. Reviewing published and ongoing studies on plastic biodegradation, this paper attempts to make conclusions on potentially viable methods to reduce impacts of plastic waste on the environment.

  11. Biodegradation of high molecular weight polylactic acid

    Science.gov (United States)

    Stloukal, Petr; Koutny, Marek; Sedlarik, Vladimir; Kucharczyk, Pavel

    2012-07-01

    Polylactid acid seems to be an appropriate replacement of conventional non-biodegradable synthetic polymer primarily due to comparable mechanical, thermal and processing properties in its high molecular weight form. Biodegradation of high molecular PLA was studied in compost for various forms differing in their specific surface area. The material proved its good biodegradability under composting conditions and all investigated forms showed to be acceptable for industrial composting. Despite expectations, no significant differences in resulting mineralizations were observed for fiber, film and powder sample forms with different specific surface areas. The clearly faster biodegradation was detected only for the thin coating on porous material with high specific surface area.

  12. Biodegradable materials as foundry moulding sands binders

    Directory of Open Access Journals (Sweden)

    K. Major - Gabryś

    2015-07-01

    Full Text Available The aim of this article is to show the possibility of using biodegradable materials as part of the composition of foundry moulding and core sand binders. Research shows that moulding sands with biodegradable materials selected as binders are not only less toxic but are also better suited to mechanical reclamation than moulding sands with phenol-furfuryl resin. The use of biodegradable materials as additives to typical synthetic resins can result in their decreased toxicity and improved ability to reclamation as well as in accelerated biodegradation of binding material leftovers of mechanical reclamation.

  13. Generation of Microcellular Biodegradable Polycaprolactone Foams in Supercritical Carbon Dioxide

    Institute of Scientific and Technical Information of China (English)

    Xu Qun; Ren Xian-wen; Chang Yu-ning; Yu Long; Wang Jing-wu

    2004-01-01

    Present now the application of microcellular polymeric materials in biomedical field is growing rapidly, as that of guided tissue regeneration and cell transplantation. As far as guided tissue regeneration is concerned, porous implants are used as size selective membrane to promote the growth of a special tissue in a healing site. Ideally, the implant should be inherently biocompatible,have well-defined cell size and be resorbable with appropriate biodegradation rates.Poly(a-caprolactone) (PCL) is a kind of materials suit for the demands above. PCL is biocompatible and biodegradable aliphatic polyester which is nontoxic for living organisms and bioresorbable after a period of implantation. Because of its unique combination of biocompatibility, permeability and biodegradability, PCL and some of its copolymer with lactides and glycolide have been widely applied in medicine as artificial skin, artificial bone and containers for sustained drug release.Goel and Beckman have reported a new method to generate microcellular poly(methy l methacrylate) foams in which the samples are saturated with CO2 under a series of supercritical (SC)conditions, and then the system is rapidly depressurized to atmospheric pressure at constant temperature. Unlike traditional methods, it reduces glass-transition temperature (Tg) of the mixture to below the experimental temperature rather than directly heat the system above Tg. In this process of nucleation, no phase separation occurs as well as no phase boundary meets, so the cellular structure of the foam can be retained better.In this work, we have generated PCL foams by using supercritical CO2. Because of the low glass transition temperature (Tg = -60 ℃) of PCL far below the ice point, the experimental temperature in our study is much higher than Tg, which is different from the studies by others before. A series of variable factors on the foam structure as saturation temperature, saturation pressure, saturation time and depressurization

  14. Electrospun biodegradable polymers loaded with bactericide agents

    Directory of Open Access Journals (Sweden)

    Ramaz Katsarava

    2016-03-01

    Full Text Available Development of materials with an antimicrobial activity is fundamental for different sectors, including medicine and health care, water and air treatment, and food packaging. Electrospinning is a versatile and economic technique that allows the incorporation of different natural, industrial, and clinical agents into a wide variety of polymers and blends in the form of micro/nanofibers. Furthermore, the technique is versatile since different constructs (e.g. those derived from single electrospinning, co-electrospinning, coaxial electrospinning, and miniemulsion electrospinning can be obtained to influence the ability to load agents with different characteristics and stability and to modify the release behaviour. Furthermore, antimicrobial agents can be loaded during the electrospinning process or by a subsequent coating process. In order to the mitigate burst release effect, it is possible to encapsulate the selected drug into inorganic nanotubes and nanoparticles, as well as in organic cyclodextrine polysaccharides. In the same way, processes that involve covalent linkage of bactericide agents during surface treatment of electrospun samples may also be considered. The present review is focused on more recent works concerning the electrospinning of antimicrobial polymers. These include chitosan and common biodegradable polymers with activity caused by the specific load of agents such as metal and metal oxide particles, quaternary ammonium compounds, hydantoin compounds, antibiotics, common organic bactericides, and bacteriophages.

  15. Biodegradable mesoporous delivery system for biomineralization precursors

    Science.gov (United States)

    Yang, Hong-ye; Niu, Li-na; Sun, Jin-long; Huang, Xue-qing; Pei, Dan-dan; Huang, Cui; Tay, Franklin R

    2017-01-01

    Scaffold supplements such as nanoparticles, components of the extracellular matrix, or growth factors have been incorporated in conventional scaffold materials to produce smart scaffolds for tissue engineering of damaged hard tissues. Due to increasing concerns on the clinical side effects of using large doses of recombinant bone-morphogenetic protein-2 in bone surgery, it is desirable to develop an alternative nanoscale scaffold supplement that is not only osteoinductive, but is also multifunctional in that it can perform other significant bone regenerative roles apart from stimulation of osteogenic differentiation. Because both amorphous calcium phosphate (ACP) and silica are osteoinductive, a biodegradable, nonfunctionalized, expanded-pore mesoporous silica nanoparticle carrier was developed for loading, storage, and sustained release of a novel, biosilicification-inspired, polyamine-stabilized liquid precursor phase of ACP for collagen biomineralization and for release of orthosilicic acid, both of which are conducive to bone growth. Positively charged poly(allylamine)-stabilized ACP (PAH-ACP) could be effectively loaded and released from nonfunctionalized expanded-pore mesoporous silica nanoparticles (pMSN). The PAH-ACP released from loaded pMSN still retained its ability to infiltrate and mineralize collagen fibrils. Complete degradation of pMSN occurred following unloading of their PAH-ACP cargo. Because PAH-ACP loaded pMSN possesses relatively low cytotoxicity to human bone marrow-derived mesenchymal stem cells, these nanoparticles may be blended with any osteoconductive scaffold with macro- and microporosities as a versatile scaffold supplement to enhance bone regeneration. PMID:28182119

  16. 生物降解型防污涂料的制备%Preparation of Biodegradation Antifouling Coatings

    Institute of Scientific and Technical Information of China (English)

    余浩杰; 桂泰江; 肖玲; 王科; 于雪艳; 陈正涛; 张华庆

    2012-01-01

    介绍了生物降解型防污涂料用树脂的合成及生物降解型低铜、无铜防污涂料的制备进展情况,讨论了可降解嵌段共聚物树脂的性能、生物降解型防污涂料防污剂及颜填料、助剂的选择及其性能。经过实海挂板检验,初步验证此生物降解型防污涂料具有一定的防污效果,能抑制海洋污损生物的生长。%This paper introduces the synthesis of biodegradation antifouling coatings resin and the preparation progress of biodegradation low copper and copper-free antifouling coatings; discusses the properties of biodegradable block copolymer resin and the selection and the properties of biodegradation antifouling agents, pigments and additives. After panel immersion test, it is validated preliminarily that the antifouling coatings have certain antifouling effect and can inhibit the growth of marine fouling organisms.

  17. Determination of the specific interaction between sulfonylurea-incorporated polymer and rat islets.

    Science.gov (United States)

    Park, Keun-Hong; Song, Soo Chang; Akaike, Toshihiro

    2002-03-01

    A SU derivative, mimicking glibenclamide in chemical structure, was synthesized to incorporate it into a water-soluble polymeric backbone as a biospecific and stimulating polymer for insulin secretion. The ability of insulin secretion was examined with different glucose concentrations (3.3 and 11.6 mM). Although the vinylated SU did not exhibit significant activity compared to the control, the SU-incorporated copolymer could enhance insulin secretion as much as or more than glibenclamide did. In this study, a polymer fluorescence-labeled with rodamine-B isothiocyanate was used to visualize the interactions and we found that the labeled polymer was strongly absorbed to rat islets, probably due to its specific interaction mediated by SU receptors on the cell membrane. To verify the specific interaction between the SU (K+ channel closer)-incorporated copolymer and rat islets, cells were pretreated with diazoxide, an agonist of ATP-sensitive K+ channels (K+ channel opener), before adding the incorporated polymer to the cell culture medium. This treatment suppressed the action of SUs on rat islets. A confocal laser microscopic study further confirmed this interaction. The results of this study provided evidence that the SU-incorporated copolymer stimulates insulin secretion through specific interactions of SU moieties in the polymer with rat islets.

  18. Analysis of the mechanical properties and characterization by solid state 13C NMR of recycled EVA copolymer/silica composites

    Directory of Open Access Journals (Sweden)

    Giovanni Chaves Stael

    2005-09-01

    Full Text Available The incorporation of micrometer sized silica particles on poly (ethylene-co-vinyl acetate - EVA - residues from the footwear industry was evaluated. The effects of the processing parameters - temperature and mixing ratio - on the mechanical behavior of molded plates of neat recycled EVA and EVA/silica composites were also investigated. The mechanical properties measured by the tensile test, the fractographic analysis by scanning electron microscopy (SEM, and the 13C Nuclear Magnetic Resonance (NMR showed a reduced EVA to silica compatibility. Therefore, incorporation of untreated silica to recycled EVA copolymer produced a slight decrease on the mechanical performance of EVA/silica composites in respect to neat EVA copolymer. The NMR analysis also shows that the crosslinking process on recycled EVA may be occurring at the carbonyl group.

  19. Fracture mechanics and statistical modeling of ternary blends of polylactide/ethylene-acrylate copolymer /wood-flour composites

    Science.gov (United States)

    Afrifah, Kojo Agyapong

    This study examined the mechanisms of toughening the brittle bio-based poly(lactic acid) (PLA) with a biodegradable rubbery impact modifier to develop biodegradable and cost effective PLA/wood-flour composites with improved impact strength, toughness, high ductility, and flexibility. Semicrystalline and amorphous PLA grades were impact modified by melt blending with an ethylene-acrylate copolymer (EAC) impact modifier. EAC content was varied to study the effectiveness and efficiency of the impact modifier in toughening the semicrystalline and amorphous grades of the PLA. Impact strength was used to assess the effectiveness and efficiency of the EAC in toughening the blends, whereas the toughening mechanisms were determined with the phase morphologies and the miscibilities of the blends. Subsequent tensile property analyses were performed on the most efficiently toughened PLA grade. Composites were made from PLA, wood flour of various particle sizes, and EAC. Using two-level factorial design the interaction between wood flour content, wood flour particle size, and EAC content and its effect on the mechanical properties of the PLA/wood-flour composites was statistically studied. Numerical optimization was also performed to statistically model and optimize material compositions to attain mechanical properties for the PLA/wood-flour composites equivalent to at least those of unfilled PLA. The J-integral method of fracture mechanics was applied to assess the crack initiation (Jin) and complete fracture (J f) energies of the composites to account for imperfections in the composites and generate data useful for engineering designs. Morphologies of the fractured surfaces of the composites were analyzed to elucidate the failure and toughening mechanisms of the composites. The EAC impact modifier effectively improved the impact strength of the PLA/EAC blends, regardless of the PLA type. However, the EAC was more efficient in the semicrystalline grades of PLA compared to the

  20. Here today, gone tomorrow: biodegradable soft robots

    Science.gov (United States)

    Rossiter, Jonathan; Winfield, Jonathan; Ieropoulos, Ioannis

    2016-04-01

    One of the greatest challenges to modern technologies is what to do with them when they go irreparably wrong or come to the end of their productive lives. The convention, since the development of modern civilisation, is to discard a broken item and then procure a new one. In the 20th century enlightened environmentalists campaigned for recycling and reuse (R and R). R and R has continued to be an important part of new technology development, but there is still a huge problem of non-recyclable materials being dumped into landfill and being discarded in the environment. The challenge is even greater for robotics, a field which will impact on all aspects of our lives, where discards include motors, rigid elements and toxic power supplies and batteries. One novel solution is the biodegradable robot, an active physical machine that is composed of biodegradable materials and which degrades to nothing when released into the environment. In this paper we examine the potential and realities of biodegradable robotics, consider novel solutions to core components such as sensors, actuators and energy scavenging, and give examples of biodegradable robotics fabricated from everyday, and not so common, biodegradable electroactive materials. The realisation of truly biodegradable robots also brings entirely new deployment, exploration and bio-remediation capabilities: why track and recover a few large non-biodegradable robots when you could speculatively release millions of biodegradable robots instead? We will consider some of these exciting developments and explore the future of this new field.

  1. Primary biodegradation of petroleum hydrocarbons in seawater

    Energy Technology Data Exchange (ETDEWEB)

    Comber, M.I.H.; Den Haan, K.H.; Djemel, N.; Eadsforth, C.V.; King, D.; Paumen, M.L.; Parkerton, T.; Dmytrasz, B.

    2012-12-15

    This report describes primary biodegradation experiments performed to determine the persistence of higher molecular weight petroleum hydrocarbons in seawater. Results from the biodegradation experiments show that the majority of tested petroleum hydrocarbons have half-lives in seawater less than 60 days.

  2. Biodegradation of aliphatic and aromatic polycarbonates.

    Science.gov (United States)

    Artham, Trishul; Doble, Mukesh

    2008-01-01

    Polycarbonate is one of the most widely used engineering plastics because of its superior physical, chemical, and mechanical properties. Understanding the biodegradation of this polymer is of great importance to answer the increasing problems in waste management of this polymer. Aliphatic polycarbonates are known to biodegrade either through the action of pure enzymes or by bacterial whole cells. Very little information is available that deals with the biodegradation of aromatic polycarbonates. Biodegradation is governed by different factors that include polymer characteristics, type of organism, and nature of pretreatment. The polymer characteristics such as its mobility, tacticity, crystallinity, molecular weight, the type of functional groups and substituents present in its structure, and plasticizers or additives added to the polymer all play an important role in its degradation. The carbonate bond in aliphatic polycarbonates is facile and hence this polymer is easily biodegradable. On the other hand, bisphenol A polycarbonate contains benzene rings and quaternary carbon atoms which form bulky and stiff chains that enhance rigidity. Even though this polycarbonate is amorphous in nature because of considerable free volume, it is non-biodegradable since the carbonate bond is inaccessible to enzymes because of the presence of bulky phenyl groups on either side. In order to facilitate the biodegradation of polymers few pretreatment techniques which include photo-oxidation, gamma-irradiation, or use of chemicals have been tested. Addition of biosurfactants to improve the interaction between the polymer and the microorganisms, and blending with natural or synthetic polymers that degrade easily, can also enhance the biodegradation.

  3. Nylon biodegradation by lignin-degrading fungi.

    OpenAIRE

    Deguchi, T; Kakezawa, M; Nishida, T

    1997-01-01

    The biodegradation of nylon by lignin-degrading fungi was investigated. The fungus IZU-154 significantly degraded nylon-66 membrane under ligninolytic conditions. Nuclear magnetic resonance analysis showed that four end groups, CHO, NHCHO, CH3, and CONH2, were formed in the biodegraded nylon-66 membranes, suggesting that nylon-66 was degraded oxidatively.

  4. Biodegradation of Crystal Violet by Agrobacterium radiobacter

    DEFF Research Database (Denmark)

    Parshetti, G.K.; Parshetti, S.G.; Telke, A.A.

    2011-01-01

    and phenol. We proposed the hypothetical metabolic pathway of Crystal Violet biodegradation by A. radiobacter. Phytotoxicity and microbial toxicity study showed that Crystal Violet biodegradation metabolites were less toxic to bacteria (A. radiobacter, P. aurugenosa and A. vinelandii) contributing to soil...

  5. Current trends in biodegradable polyhydroxyalkanoates.

    Science.gov (United States)

    Chanprateep, Suchada

    2010-12-01

    The microbial polyesters known as polyhydroxyalkanoates (PHAs) positively impact global climate change scenarios by reducing the amount of non-degradable plastic used. A wide variety of different monomer compositions of PHAs has been described, as well as their future prospects for applications where high biodegradability or biocompatibility is required. PHAs can be produced from renewable raw materials and are degraded naturally by microorganisms that enable carbon dioxide and organic compound recycling in the ecosystem, providing a buffer to climate change. This review summarizes recent research on PHAs and addresses the opportunities as well as challenges for their place in the global market.

  6. Enhanced Mechanical Properties and Corrosion Behavior of Biodegradable Mg-Zn/HA Composite

    Science.gov (United States)

    Salleh, Emee Marina; Zuhailawati, Hussain; Ramakrishnan, Sivakumar; Dhindaw, Brij Kumar

    2017-03-01

    Magnesium (Mg) and its alloys have shown potential for use in the biomedical industry due to their excellent biological performance and biodegradability in the bioenvironment. Thus, the aim of the present study was to develop a reliable biodegradable hard tissue substituent. Biodegradable and bioactive Mg-Zinc (Zn) reinforced by hydroxyapatite (HA) composite was prepared using mechanically alloyed Mg-6.5 wt pct Zn and pure HA powders as starting materials. Various HA contents (i.e., 5, 10, 15, and 20 wt pct) were introduced in forming the Mg-Zn/HA composite. The effect of bioactive HA incorporation in biodegradable Mg-6.5 wt pct Zn alloy matrix on mechanical and biodegradation properties as well as microstructural observation was investigated. As measured by the Williamson-Hall formula, the Mg crystallite size of the sintered composites containing 5, 10, 15, and 20 wt pct HA were 36.76, 29.08, 27.93, and 27.31 nm, respectively. According to X-ray diffraction (XRD) analysis, there was no new crystalline phase formed during milling, indicating that no mechanochemical reactions between Mg-Zn alloy and HA occurred. The -1.70 V shifted significantly toward the passive position of the plain Mg-6.5 wt pct Zn alloy and Mg-Zn/10 wt pct HA composite, which were -1.50 and -1.46 V, respectively, indicating that the Mg-Zn/10 wt pct HA composite was least susceptible to corrosion in the bioenvironment.

  7. Responsive copolymers for enhanced petroleum recovery. Quarterly technical progress report, December 22, 1993--March 21, 1994

    Energy Technology Data Exchange (ETDEWEB)

    McCormick, C.; Hester, R.

    1994-06-01

    The overall goal of this research is the development of advanced water-soluble copolymers for use in enhanced oil recovery. This report summarizes technical progress for the following tasks: advanced copolymer synthesis; and characterization of molecular structure of copolymers.

  8. Surface modification of polyacrylonitrile co-polymer membranes using pulsed direct current nitrogen plasma

    Energy Technology Data Exchange (ETDEWEB)

    Pal, Dipankar; Neogi, Sudarsan; De, Sirshendu, E-mail: sde@che.iitkgp.ernet.in

    2015-12-31

    Low temperature plasma treatment using pulsed direct current discharge of nitrogen gas was employed to enhance hydrophilicity of the polyacrylonitrile co-polymer membranes. The membranes were characterized in terms of morphology, structure, hydrophilicity, and membrane performance. Properties and functional groups on the surface of polyacrylonitrile co-polymer membranes were investigated by contact angle, scanning electron microscopy, Fourier transform infrared and X-ray photoelectron spectroscopy. Effects of plasma conditions, namely, pulsed voltage, duty cycle and treatment time on increase in membrane hydrophilicity were studied. Permeability of treated membrane was increased by 47% and it was retained up to 70 days. Surface etching due to plasma treatment was confirmed by weight loss of the treated membranes. Due to surface etching, average pore size increased and rejection of 200 kDa polyethylene glycol decreased to about 70% for the treated membrane. Oxygen and nitrogen functional groups were responsible for surface hydrophilicity. - Highlights: • Surface modification of polyacrylonitrile co-polymer membranes by pulsed direct current nitrogen plasma • Hydrophilic functional groups incorporated on the membrane surface • Significant enhancement of the permeability and wettability of the membranes • Water contact angle increased with storage time and finally stabilized.

  9. Synthesis of comb-like copolymers from renewable resources: Itaconic anhydride, stearyl methacrylate and lactic acid

    Science.gov (United States)

    Shang, Shurui

    The synthesis and properties of comb-like copolymers and ionomers derived from renewable resources: itaconic anhydride (ITA), stearyl methacrylate (SM) and lactic acid (LA) are described. The copolymers based on ITA and SM (ITA-SM) were nearly random with a slight alternating tendency. The copolymers exhibited a nanophase-separated morphology, with the stearate side-chains forming a bilayer, semi-crystalline structure. The crystalline side-chains suppressed molecular motion of the main-chain, so that a glass transition temperature (Tg) was not resolved unless the ITA concentration was sufficiently high so that Tg > the melting point (Tm). The softening point and modulus of the copolymers increased with the increasing ITA concentration, but the thermal stability decreased. The ITA moiety along the main chain of the copolymers was neutralized with metal acetates to produce Na-, Ca- and Zn- random ionomers with comb-like architectures. In general, the incorporation of the ionic groups increased the Tg and suppressed the crystallinity of the side-chain packing. Ionomers with high SM side-chain density had two competing driving forces for self-assembled nano-phase separation: ionic aggregation and side-chain crystalline packing. Upon neutralization, a morphological transition from semi-crystalline lamella to spherical ionic aggregation was observed by small angle X-ray scattering (SAXS) analysis and transmission electron microscopy (TEM). Thermomechanical analysis revealed an increasing resistance to penetration deformation with an increasing degree of neutralization and an apparent rubbery plateau was observed above Tg. A controlled transesterification of PLA in glassware was an effective way to prepare a methacrylate functionalized PLA macromonomer with controlled molecular weight, which was used to synthesize a variety of copolymers. The copolymerization of this functionalized PLA macromonomer with ITA totally suppressed the side-chain crystallinity for the PLA chain

  10. COMPOSITIONAL HETEROGENEITY OF ETHYLENE OXIDE-BUTYLENE TEREPHTHALATE SEGMENTED COPOLYMER

    Institute of Scientific and Technical Information of China (English)

    De-zhu Ma; Dong-sheng Li; Ming-chuan Zhao; Mo-zhen Wang; Ran Ye; Xiao-lie Luo

    1999-01-01

    A series of ethylene oxide-butylene terephthalate (EOBT) segmented copolymers with different soft segment length and hard segment content were synthesized. The compositional heterogeneity was studied by solvent extraction. The results show that the compositional heterogeneity increases when soft segment length and hard segment content increase. The compositional heterogeneity is also reflected in the crystallization behavior and morphology of soft and hard segment in EOBT segmented copolymer. The more compositional heterogeneous the EOBT segmented copolymer is, the more different the morphology and the crystallization behavior between separated fractions. Compared with ethylene oxide-ethylene terephthalate (EOET) segmented copolymer, compositional heterogeneity in EOBT segmented copolymer is weaker. But the compositional heterogeneity in EOBT segmented copolymer with long soft segment and high hard segment content is still obvious.

  11. Biodegradable polymers for electrospinning: towards biomedical applications.

    Science.gov (United States)

    Kai, Dan; Liow, Sing Shy; Loh, Xian Jun

    2014-12-01

    Electrospinning has received much attention recently due to the growing interest in nano-technologies and the unique material properties. This review focuses on recent progress in applying electrospinning technique in production of biodegradable nanofibers to the emerging field of biomedical. It first introduces the basic theory and parameters of nanofibers fabrication, with focus on factors affecting the morphology and fiber diameter of biodegradable nanofibers. Next, commonly electrospun biodegradable nanofibers are discussed, and the comparison of the degradation rate of nanoscale materials with macroscale materials are highlighted. The article also assesses the recent advancement of biodegradable nanofibers in different biomedical applications, including tissue engineering, drug delivery, biosensor and immunoassay. Future perspectives of biodegradable nanofibers are discussed in the last section, which emphasizes on the innovation and development in electrospinning of hydrogels nanofibers, pore size control and scale-up productions.

  12. Biodegradation and toxicological evaluation of lubricant oils

    Directory of Open Access Journals (Sweden)

    Ivo Shodji Tamada

    2012-12-01

    Full Text Available The aim of this work was to compare different toxicity levels of lubricant oils. The tests were performed using the earthworm (Eisenia andrei, arugula seeds (Eruca sativa and lettuce seeds (Lactuca sativa, with three types of contaminants (mineral lubricant oil, synthetic lubricant oil and used lubricant oil for various biodegradation periods in the soil. The toxicity tests indirectly measured the biodegradation of the contaminants. The samples were analyzed at t0, t60, t120 and t180 days of biodegradation. The used lubricant oil was proved very toxic in all the tests and even after biodegradation its toxicity was high. The mineral and synthetic oils were biodegraded efficiently in the soil although their toxicity did not disappear completely after 180 days.

  13. Design of 3D scaffolds for tissue engineering testing a tough polylactide-based graft copolymer

    Energy Technology Data Exchange (ETDEWEB)

    Dorati, R., E-mail: rossella.dorati@unipv.it [Department of Drug Sciences, University of Pavia, V.le Taramelli 12, 27100 Pavia (Italy); Center for Tissue Engineering (CIT), University of Pavia, Via Ferrata 1, 27100 Pavia (Italy); Colonna, C. [Department of Drug Sciences, University of Pavia, V.le Taramelli 12, 27100 Pavia (Italy); Center for Tissue Engineering (CIT), University of Pavia, Via Ferrata 1, 27100 Pavia (Italy); Tomasi, C. [C.S.G.I., Department of Chemistry, Division of Physical Chemistry, University of Pavia, V.le Taramelli 16 I, 27100 Pavia (Italy); Genta, I. [Department of Drug Sciences, University of Pavia, V.le Taramelli 12, 27100 Pavia (Italy); Center for Tissue Engineering (CIT), University of Pavia, Via Ferrata 1, 27100 Pavia (Italy); Bruni, G. [C.S.G.I., Department of Chemistry, Division of Physical Chemistry, University of Pavia, V.le Taramelli 16 I, 27100 Pavia (Italy); Conti, B. [Department of Drug Sciences, University of Pavia, V.le Taramelli 12, 27100 Pavia (Italy); Center for Tissue Engineering (CIT), University of Pavia, Via Ferrata 1, 27100 Pavia (Italy)

    2014-01-01

    as biodegradable biomaterial for TE. • The tough PLA graft copolymer resulted to being suitable for the preparation of 2D film and 3D scaffold. • The tough LMP-3055 polymer resulted to being a suitable substrate for cell seeding and proliferation.

  14. TOPICAL REVIEW: Multifunctional nanoassemblies of block copolymers for future cancer therapy

    Science.gov (United States)

    Cabral, Horacio; Kataoka, Kazunori

    2010-02-01

    Nanoassemblies from amphiphilic block copolymers are promising nanomedicine platforms for cancer diagnosis and therapy due to their relatively small size, high loading capacity of drugs, controlled drug release, in vivo stability and prolonged blood circulation. Recent clinical trials with self-assembled polymeric micelles incorporating anticancer drugs have shown improved antitumor activity and decreased side effects encouraging the further development of nanoassemblies for drug delivery. This review summarizes recent approaches considering stimuli-responsive, multifunctionality and more advanced architectures, such as vesicles or worm-like micelles, for tumor-specific drug and gene delivery.

  15. Metal nanodot arrays fabricated via seed-mediated electroless plating with block copolymer thin film scaffolding.

    Science.gov (United States)

    Komiyama, Hideaki; Iyoda, Tomokazu; Sanji, Takanobu

    2015-10-02

    We present an alternative approach to fabricating hexagonally arranged nanodot arrays of various metals by seed-mediated electroless plating with a cylinder-forming block copolymer thin film, PEO-b-PMA(Az), as a scaffold. Metal ions were selectively incorporated into PEO cylinders, followed by their reduction to metal and the etching of the scaffold to obtain highly ordered seed arrays of Au, Pd, and Pt. Nanodot arrays of the target metals (Au, Ag, and Ni) were selectively grown on the seed with their highly ordered arrangement by electroless plating. We studied the fabrication processes' suitability for control of the nanodot array size, as well as the plasmonic properties thereof.

  16. Imide/Arylene Ether Copolymers Containing Phosphine Oxide

    Science.gov (United States)

    Jensen, Brian J.; Partos, Richard D.

    1993-01-01

    Phosphine oxide groups react with oxygen to form protective phosphate surface layers. Series of imide/arylene ether block copolymers containing phosphine oxide units in backbone synthesized and characterized. In comparison with commercial polyimide, these copolymers display better resistance to etching by oxygen plasma. Tensile strengths and tensile moduli greater than those of polyarylene ether homopolymer. Combination of properties makes copolymers attractive for films, coatings, adhesives, and composite matrices where resistance to atomic oxygen needed.

  17. Development of a High-Frequency Multilayer Copolymer Acoustic Projector

    Science.gov (United States)

    1994-03-31

    Vinylidene Fluoride/Trifluoroethylene Copolymers in Relation to Their Structures," Japanese Journal of Applied Physics , vol. 103, 1987, p. 554. 4. R. AI... Journal of Applied Physics , vol. 21, 1982, p. L455. 17. K. Rittenmyer, *Report on the Electromechanical Evaluation of PVDF Copolymer Materials," U. S...Ohigashi and K. Koga, "Ferroelectric Copolymers of Vinylidene Fluoride and Trifluoroethylene with a Large Electromechanical Coupling Factor,* Japanese

  18. Formation of Anisotropic Block Copolymer Gels

    Science.gov (United States)

    Liaw, Chya Yan; Shull, Kenneth; Henderson, Kevin; Joester, Derk

    2011-03-01

    Anisotropic, fibrillar gels are important in a variety of processes. Biomineralization is one example, where the mineralization process often occurs within a matrix of collagen or chitin fibers that trap the mineral precursors and direct the mineralization process. We wish to replicate this type of behavior within block copolymer gels. Particularly, we are interested in employing gels composed of cylindrical micelles, which are anisotropic and closely mimic biological fibers. Micelle geometry is controlled in our system by manipulating the ratio of molecular weights of the two blocks and by controlling the detailed thermal processing history of the copolymer solutions. Small-Angle X-ray Scattering and Dynamic Light Scattering are used to determine the temperature dependence of the gel formation process. Initial experiments are based on a thermally-reversible alcohol-soluble system, that can be subsequently converted to a water soluble system by hydrolysis of a poly(t-butyl methacrylate) block to a poly (methacrylic acid) block. MRSEC.

  19. Rapid ordering of block copolymer thin films

    Science.gov (United States)

    Majewski, Pawel W.; Yager, Kevin G.

    2016-10-01

    Block-copolymers self-assemble into diverse morphologies, where nanoscale order can be finely tuned via block architecture and processing conditions. However, the ultimate usage of these materials in real-world applications may be hampered by the extremely long thermal annealing times—hours or days—required to achieve good order. Here, we provide an overview of the fundamentals of block-copolymer self-assembly kinetics, and review the techniques that have been demonstrated to influence, and enhance, these ordering kinetics. We discuss the inherent tradeoffs between oven annealing, solvent annealing, microwave annealing, zone annealing, and other directed self-assembly methods; including an assessment of spatial and temporal characteristics. We also review both real-space and reciprocal-space analysis techniques for quantifying order in these systems.

  20. Nanostructured Polysulfone-Based Block Copolymer Membranes

    KAUST Repository

    Xie, Yihui

    2016-05-01

    The aim of this work is to fabricate nanostructured membranes from polysulfone-based block copolymers through self-assembly and non-solvent induced phase separation. Block copolymers containing polysulfone are novel materials for this purpose providing better mechanical and thermal stability to membranes than polystyrene-based copolymers, which have been exclusively used now. Firstly, we synthesized a triblock copolymer, poly(tert-butyl acrylate)-b-polsulfone-b-poly(tert-butyl acrylate) through polycondensation and reversible addition-fragmentation chain-transfer polymerization. The obtained membrane has a highly porous interconnected skin layer composed of elongated micelles with a flower-like arrangement, on top of the graded finger-like macrovoids. Membrane surface hydrolysis was carried out in a combination with metal complexation to obtain metal-chelated membranes. The copper-containing membrane showed improved antibacterial capability. Secondly, a poly(acrylic acid)-b-polysulfone-b-poly(acrylic acid) triblock copolymer obtained by hydrolyzing poly(tert-butyl acrylate)-b-polsulfone-b-poly(tert-butyl acrylate) formed a thin film with cylindrical poly(acrylic acid) microdomains in polysulfone matrix through thermal annealing. A phase inversion membrane was prepared from the same polymer via self-assembly and chelation-assisted non-solvent induced phase separation. The spherical micelles pre-formed in a selective solvent mixture packed into an ordered lattice in aid of metal-poly(acrylic acid) complexation. The space between micelles was filled with poly(acrylic acid)-metal complexes acting as potential water channels. The silver0 nanoparticle-decorated membrane was obtained by surface reduction, having three distinct layers with different particle sizes. Other amphiphilic copolymers containing polysulfone and water-soluble segments such as poly(ethylene glycol) and poly(N-isopropylacrylamide) were also synthesized through coupling reaction and copper0-mediated

  1. Mechanism of Molecular Exchange in Copolymer Micelles

    Science.gov (United States)

    Choi, Soo-Hyung; Lodge, Timothy; Bates, Frank

    2010-03-01

    Compared to thermodynamic structure, much less has been known about the kinetics of block copolymer micelles which should underlay the attainment of thermodynamic equilibrium. In this presentation, molecular exchange between spherical micelles formed by isotopically labeled diblock copolymers was investigated using time-resolved small-angle neutron scattering. Two pairs of structurally matched poly(styrene-b-ethylene-alt-propylene) (PS-PEP) were synthesized and dispersed in isotopic mixture of squalane, highly selective to PEP block. Each pair includes polymers with fully deuterated (dPS-PEP) and a normal (hPS-PEP) PS blocks. Temperature dependence of the micelle exchange rate R(t) is consistent with melt dynamics for the core polymer. Furthermore, R(t) is significantly sensitive to the core block length N due to the thermodynamic penalty associated with ejecting a core block into the solvent. This hypersensitivity, combined with modest polydispersity in N, leads to an approximately logarithmic decay in R(t).

  2. Effect of Rubberwood Content on Biodegradability of Poly(butylene succinate Biocomposites

    Directory of Open Access Journals (Sweden)

    Hemhong Anankaphong

    2015-01-01

    Full Text Available Poly(butylene succinate (PBS biocomposites incorporated with rubberwood powder (RWP were fabricated with various RWP weight fractions (i.e., 0 to 40% wt by injection moulding process. The soil burial test was employed to examine the biodegradability of such biocomposites under outdoor environment for 60 days. The physical appearance, percentage weight loss, chemical structure, and mechanical properties before and after the soil burial test were determined. Apparent changes in physical appearance of the biocomposites from optical micrographs were detected in terms of surface morphology and colour. The percentage of crystallinity of PBS/RWP biocomposites was studied by the X-ray diffraction (XRD technique, and the XRD pattern revealed a decrease in percentage of crystallinity due to enhancing RWP weight fractions. This may be attributed to a presence of rubberwood powders providing more disordered molecular chain arrangement of PBS matrix and also an agglomeration of the rubberwood powder content at greater concentration as seen in SEM micrographs. With increasing RWP weight fractions and burial time, the results exhibited a considerable change in chemical structure (essentially ester linkage due to biodegradation mechanism of PBS, relatively greater percentage weight loss, and a substantial decrease in flexural properties. Consequently, the results indicate that incorporating RWP enhances biodegradability of PBS/RWP biocomposites; that is, the biodegradation rate of biocomposites increases with increasing RWP weight fractions and burial time.

  3. Parallel Computing Properties of Tail Copolymer Chain

    Directory of Open Access Journals (Sweden)

    Hong Li

    2013-08-01

    Full Text Available The properties of a AB diblock copolymer chain are calculated by Monte Carlo methods. Monomer A contacting to the surface has an adsorption energy E=-1 and monomer B E= 0. The polymer chain is simulated by self-avoiding walk in simple cubic lattice. The adsorption properties and the conformation properties of the polymer chain are computed by using message passing interface (MPI. The speedup is close to linear speedup by parallel computing independent samples.    

  4. Nanostructured Block Copolymer Coatings for Biofouling Inhibition

    Science.gov (United States)

    2015-06-30

    biofouling program contractors. 15. SUBJECT TERMS antifouling; coatings; block copolymers; IR nanoscale imaging ; biocides 16. SECURITY CLASSIFICATION OF...diagnostics and drug delivery. In our scanned probe microscopy studies on collaborator coatings and marine organisms, we have provided teamwork . We have...Studies of Organisms on model fouiants: • H. elegans studies 3. Testing of other contractor materials 4. Imaging technology. We applied our organic

  5. Synthesis and Biodegradation of St-g-poly(MMA-co-VAc) Initiated by Manganic Pyrophosphate

    Institute of Scientific and Technical Information of China (English)

    ZHU Lin-hui; CHEN Mi-feng; JI Yan; XIA Hai-ping; DING Ma-tai

    2004-01-01

    Methyl methacrylate (MMA) and vinyl acetate (VAc) were grafted onto corn starch with manganic pyrophosphate { [Mn(H2P2O7)3]3-} as the initiator and water as the reaction medium. The influences of reaction conditions, including pH value, initiator concentration, monomer concentration and its composition, on percent grafting and grafting efficiency were investigated. The graft copolymer was characterized by means of IR spectroscopy, scanning electron micrograph(SEM) and 1H NMR spectroscopy. The biodegradation experiment showed that the degradation of corn starch-g-poly(MMA-co-VAc) was mainly from starch. However,after poly VAc in the side chain was transformed into poly vinyl alcohol(PVA), both starch and the grafted side chain could be degraded completely.

  6. Influence of Methacrylic-Acrylic Copolymer Composition on Plasticiser-free Optode Films for pH Sensors

    Directory of Open Access Journals (Sweden)

    Musa Ahmad

    2003-03-01

    Full Text Available In this work we have examined the use of plasticiser-free polymeric films incorporating a proton selective chromoionophore for optical pH sensor. Four types of methacrylic-acrylic copolymers containing different compositions of n-butyl acrylate (nBA and methyl methacrylate (MMA were synthesised for use as optical sensor films. The copolymers were mixed with appropriate amounts of chromoionophore (ETH5294 and a lipophilic salt before spin coated on glass slides to form films for the evaluation of pH response using spectrophotometry. Co-polymer films with high nBA content gave good response and the response time depended on the film thickness. A preliminary evaluation of the optical films of high nBA content with pHs from 2 - 14 showed distinguishable responses from pH 5 - 9. However, the adhesion of the pH sensitive film was good for copolymers with higher content of MMA but not for films with high nBA.

  7. Effect of Small Molecule Osmolytes on the Self-Assembly and Functionality of Globular Protein-Polymer Diblock Copolymers

    Energy Technology Data Exchange (ETDEWEB)

    Thomas, Carla S.; Xu, Liza; Olsen, Bradley D. [MIT

    2013-12-05

    Blending the small molecule osmolytes glycerol and trehalose with the model globular protein–polymer block copolymer mCherry-b-poly(N-isopropyl acrylamide) (mCherry-b-PNIPAM) is demonstrated to improve protein functionality in self-assembled nanostructures. The incorporation of either additive into block copolymers results in functionality retention in the solid state of 80 and 100% for PNIPAM volume fractions of 40 and 55%, respectively. This represents a large improvement over the 50–60% functionality observed in the absence of any additive. Furthermore, glycerol decreases the thermal stability of block copolymer films by 15–20 °C, while trehalose results in an improvement in the thermal stability by 15–20 °C. These results suggest that hydrogen bond replacement is responsible for the retention of protein function but suppression or enhancement of thermal motion based on the glass transition of the osmolyte primarily determines thermal stability. While both osmolytes are observed to have a disordering effect on the nanostructure morphology with increasing concentration, this effect is less pronounced in materials with a larger polymer volume fraction. Glycerol preferentially localizes in the protein domains and swells the nanostructures, inducing disordering or a change in morphology depending on the PNIPAM coil fraction. In contrast, trehalose is observed to macrophase separate from the block copolymer, which results in nanodomains becoming more disordered without changing significantly in size.

  8. Synthesis of Amphiphilic Dextran-Poly(Lactide) Copolymer and Their Nanoparticles as Doxorubicin Delivery Systems%葡聚糖-聚乳酸接枝共聚物的合成及其药物载体输送系统

    Institute of Scientific and Technical Information of China (English)

    孙继红; 温丽利; 吴雁; 王欢; 李彦威

    2013-01-01

    合成葡聚糖-聚乳酸接枝共聚物,并以此为载体,选择盐酸阿霉素为模型药物,利用纳米沉淀法和双乳法构建出了载药纳米粒子,并通过透射电镜(scanning electron microscope,TEM)、动态光散射(dynamic light scattering,DLS)、紫外(UV-vis)对其形貌、粒径及包封率进行了表征,结果表明:不同共聚物/药物比例会影响载药纳米粒子的粒径、粒径分布及包封率.此外,载药纳米粒子的体外释放实验表明:在弱碱条件(pH=7.4)下的释放速度比在弱酸条件(pH=5.0)下的慢,说明释放介质的pH对其释放性能有较大影响,有利于药物在肿瘤细胞中的控释.%Novel biodegradable amphiphilic copolymer nanoparticles based on dextran and poly(lactide)have been prepared.To estimate the feasibility as drug carriers,an anti-tumor model drug doxorubicin (DOX) was successfully incorporated into polymeric nanoparticles by double emulsion (DE) and nanoprecipitation (NP) methods.The DOX-loaded nanoparticles were confirmed by dynamic light scattering (DLS),transmission electron microscopy (TEM) and ultraviolet (UV) absorption spectrometry.The DOX-loaded nanoparticle size,size distribution and encapsulation efficiency (EE)were influenced by the feed weight ratio of the copolymer to DOX.In addition,in vitro release experiments exhibited the release behavior was affected by pH of release media.The DOX-loaded nanoparticles release slower in pH 7.4 than in pH 5.0 buffer.The dextran-co-PLA polymeric nanoparticles can be useful as drug carriers for anti-tumor drug delivery.

  9. Intimately coupling of photolysis accelerates nitrobenzene biodegradation, but sequential coupling slows biodegradation

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Lihui [Department of Environmental Science and Engineering, College of Life and Environmental Science, Shanghai Normal University, Shanghai 200234 (China); Zhang, Yongming, E-mail: zhym@shnu.edu.cn [Department of Environmental Science and Engineering, College of Life and Environmental Science, Shanghai Normal University, Shanghai 200234 (China); Bai, Qi; Yan, Ning; Xu, Hua [Department of Environmental Science and Engineering, College of Life and Environmental Science, Shanghai Normal University, Shanghai 200234 (China); Rittmann, Bruce E. [Swette Center for Environmental Biotechnology, Biodesign Institute, Arizona State University, Tempe, AZ 85287-5701 (United States)

    2015-04-28

    Highlights: • Intimately coupled UV photolysis accelerated nitrobenzene biodegradation. • NB biodegradation was slowed by accumulation of nitrophenol. • Oxalic acid was a key product of UV photolysis. • Oxalic acid accelerated biodegradation of nitrobenzene and nitrophenol by a co-substrate effect. • Intimate coupling of UV and biodegradation accentuated the benefits of oxalic acid. - Abstract: Photo(cata)lysis coupled with biodegradation is superior to photo(cata)lysis or biodegradation alone for removal of recalcitrant organic compounds. The two steps can be carried out sequentially or simultaneously via intimate coupling. We studied nitrobenzene (NB) removal and mineralization to evaluate why intimate coupling of photolysis with biodegradation was superior to sequential coupling. Employing an internal circulation baffled biofilm reactor, we compared direct biodegradation (B), biodegradation after photolysis (P + B), simultaneous photolysis and biodegradation (P&B), and biodegradation with nitrophenol (NP) and oxalic acid (OA) added individually and simultaneously (B + NP, B + OA, and B + NP + OA); NP and OA were NB’s main UV-photolysis products. Compared with B, the biodegradation rate P + B was lower by 13–29%, but intimately coupling (P&B) had a removal rate that was 10–13% higher; mineralization showed similar trends. B + OA gave results similar to P&B, B + NP gave results similar to P + B, and B + OA + NP gave results between P + B and P&B, depending on the amount of OA and NP added. The photolysis product OA accelerated NB biodegradation through a co-substrate effect, but NP was inhibitory. Although decreasing the UV photolysis time could minimize the inhibition impact of NP in P + B, P&B gave the fastest removal of NB by accentuating the co-substrate effect of OA.

  10. Antimicrobial activity of allyl isothiocyanate used to coat biodegradable composite films as affected by storage and handling conditions

    Science.gov (United States)

    We evaluated the effects of storage and handling conditions on the antimicrobial activity of biodegradable composite films (polylactic acid and sugar beet pulp) coated with allyl isothiocyanate (AIT). Polylactic acid (PLA) and chitosan were incorporated with AIT and coated on one side of the film. T...

  11. Biodegradable Poly(butylene succinate Composites Reinforced by Cotton Fiber with Silane Coupling Agent

    Directory of Open Access Journals (Sweden)

    Masahiro Funabashi

    2013-01-01

    Full Text Available In this study, the use of cotton fiber (CF as a filler in poly(butylene succinate (PBS and the effect of silane treatment on the mechanical properties, thermal stability, and biodegradability of PBS/CF composites are investigated. The results showed that the tensile strength of PBS was improved (15%–78% with the incorporation of CF (10–40 wt% and was further increased (25%–118% when CF was treated with a silane coupling agent. Scanning electron microscopy (SEM observation of the fracture surfaces of PBS/CF composites showed that there was slight improvement in fiber-matrix compatibility. Thermogravimetric (TG analysis showed that the thermal stability of the composites was lower than that of neat PBS and decreased with increasing filler loading. The biobased carbon content of the composites increased with increasing CF content. The incorporation of CF (with and without silane treatment in PBS significantly increased the biodegradation rate of the composites.

  12. Combined Delivery of Let-7b MicroRNA and Paclitaxel via Biodegradable Nanoassemblies for the Treatment of KRAS Mutant Cancer.

    Science.gov (United States)

    Dai, Xin; Fan, Wei; Wang, Yingzhe; Huang, Lijie; Jiang, Ying; Shi, Lei; Mckinley, DeAngelo; Tan, Wen; Tan, Chalet

    2016-02-01

    In the present study, we synthesized a novel cationic copolymer composed of polyethylene glycol 5000 (PEG5K), vitamin E (VE), and diethylenetriamine (DET) at 1:4:20 molar ratio. The resulting PEG5K-VE4-DET20 copolymer formed nanoassemblies when mixed with the neutral PEG5K-VE4 copolymer at 1:8 weight ratio, which were investigated as the nanocarriers for combined delivery of paclitaxel and let-7b mimic. We found that the PEG5K-VE4-DET20 nanoassemblies could entrap paclitaxel for an extended period and burst release the drug in the presence of cathepsin B, demonstrating the biodegradability of the copolymers. At N/P ratio of 12:1, the PEG5K-VE4-DET20 nanoassemblies formed stable polyplexes with let-7b mimic, which were efficiently taken up by tumor cells and underwent endosomal escape. In non-small cell lung cancer A549 cells that harbor mutant KRAS, paclitaxel and let-7b mimic-loaded nanoassemblies (N-PTX/let-7b) markedly potentiated the cytotoxicity of paclitaxel, induced apoptosis, and diminished the invasiveness of tumor cells. In mice bearing subcutaneous A549 xenografts, intravenous administration of N-PTX/let-7b retarded tumor growth more efficaciously than Taxol. Our study demonstrates the promise of the PEG5K-VE4-DET20 nanoassemblies for concurrent delivery of hydrophobic drugs and miRNA mimics.

  13. Biodegradable and compostable alternatives to conventional plastics.

    Science.gov (United States)

    Song, J H; Murphy, R J; Narayan, R; Davies, G B H

    2009-07-27

    Packaging waste forms a significant part of municipal solid waste and has caused increasing environmental concerns, resulting in a strengthening of various regulations aimed at reducing the amounts generated. Among other materials, a wide range of oil-based polymers is currently used in packaging applications. These are virtually all non-biodegradable, and some are difficult to recycle or reuse due to being complex composites having varying levels of contamination. Recently, significant progress has been made in the development of biodegradable plastics, largely from renewable natural resources, to produce biodegradable materials with similar functionality to that of oil-based polymers. The expansion in these bio-based materials has several potential benefits for greenhouse gas balances and other environmental impacts over whole life cycles and in the use of renewable, rather than finite resources. It is intended that use of biodegradable materials will contribute to sustainability and reduction in the environmental impact associated with disposal of oil-based polymers. The diversity of biodegradable materials and their varying properties makes it difficult to make simple, generic assessments such as biodegradable products are all 'good' or petrochemical-based products are all 'bad'. This paper discusses the potential impacts of biodegradable packaging materials and their waste management, particularly via composting. It presents the key issues that inform judgements of the benefits these materials have in relation to conventional, petrochemical-based counterparts. Specific examples are given from new research on biodegradability in simulated 'home' composting systems. It is the view of the authors that biodegradable packaging materials are most suitable for single-use disposable applications where the post-consumer waste can be locally composted.

  14. Biodegradable Metals From Concept to Applications

    CERN Document Server

    Hermawan, Hendra

    2012-01-01

    This book in the emerging research field of biomaterials covers biodegradable metals for biomedical applications. The book contains two main parts where each of them consists of three chapters. The first part introduces the readers to the field of metallic biomaterials, exposes the state of the art of biodegradable metals, and reveals its application for cardiovascular implants. It includes some fundamental aspects to give basic understanding on metals for further review on the degradable ones is covered in chapter one. The second chapter introduces the concept of biodegradable metals, it's st

  15. Different strategies to improve the functionality of biodegradable films based on starch and other polymers

    OpenAIRE

    2016-01-01

    [EN] In the present Doctoral Thesis, different strategies to improve functional properties of starch films for food packaging applications were analysed: study of the effect of amylose:amylopectin ratio, blend with other polymers poly(vinyl alcohol) (PVA), and incorporation of different fillers (rice bran and cellulose nanocrystals-CNCs) and antimicrobial agents (neem oil-N, oregano essential oil-O and silver nanoparticles-AgNPs). Likewise, a biodegradation study of the films as affected by a...

  16. Bending Modulus of Elasticity of the Press Forming Composite Material from Bagasse Fiber and Biodegradable Resin

    OpenAIRE

    柴田, 信一; 曹, 勇; 福本, 功; Shibata, Shin-ichi; Cao, Yong; Fukumoto, Isao

    2005-01-01

    Bending modulus of elasticity of the composite material from bagasse fiber (remains after sugar cane squeezed) and biodegradable resin was investigated in view of the content of bagasse fiber and the fiber length. The result was validated by short fiber strengthen theory. The result is as followings. Bending modulus of elasticity increased with increasing the content of bagasse fiber. The increase of Bending modulus of elasticity is predicted by short fiber strengthen theory incorporated with...

  17. Porous Hydroxyapatite Scaffold with Three-Dimensional Localized Drug Delivery System Using Biodegradable Microspheres

    Science.gov (United States)

    2011-03-21

    might be efficiently incorporated with calcium phosphate-based bioceramics using biodegradable polymeric microspheres. Published by Elsevier B.V. 1...induce stem cell differentiation would enhance the flexibility of integration into the surrounding tissue. Since calcium phosphate-based bioceramics ...kinetics and can affect the functionality of the HAp surface. If controlled release from HAp bioceramics is to be achieved, it will require the

  18. Preparation and degradation mechanisms of biodegradable polymer: a review

    Science.gov (United States)

    Zeng, S. H.; Duan, P. P.; Shen, M. X.; Xue, Y. J.; Wang, Z. Y.

    2016-07-01

    Polymers are difficult to degrade completely in Nature, and their catabolites may pollute the environment. In recent years, biodegradable polymers have become the hot topic in people's daily life with increasing interest, and a controllable polymer biodegradation is one of the most important directions for future polymer science. This article presents the main preparation methods for biodegradable polymers and discusses their degradation mechanisms, the biodegradable factors, recent researches and their applications. The future researches of biodegradable polymers are also put forward.

  19. A Photochromic Copolymer Hydrogel Contact Lens: From Synthesis to Application

    Directory of Open Access Journals (Sweden)

    Xiaoli Yang

    2016-01-01

    Full Text Available A photochromic poly(2-hydroxyl-ethyl methacrylate-N-vinylpyrrolidone-spironaphthoxazine hydrogel (p(HEMA-NVP-SPO has been designed and synthesized by free radical polymerization in this work. The chemical and structural information of hydrogels was investigated by IR spectra, equilibrium water content (EWC, and SEM. The IR spectra confirmed successful synthesis of copolymer. The domain of NVP contributed to not only EWC but also inner structure of hydrogel, while SPO had little influence on these properties of hydrogel. The photochromic behaviors of hydrogel including photochromic properties and thermal fading kinetics were systematically studied and compared with hydrogel made by immersing method. Results showed that when SPO was incorporated in hydrogel by polymerization, maximum absorbance wavelength got shorter, and the relaxation half-life became longer. In addition, salicylic acid as a drug model could be loaded into hydrogel by immersing method, and its sustained drug release in a given period was dependent on the characteristics of solution and loading time.

  20. Crystallization Behavior of Copolymer Poly (ethylene terephthalate/isophthalate) (IPET)

    Institute of Scientific and Technical Information of China (English)

    顾书英; 肖茹; 顾利霞

    2001-01-01

    The non-isothermal crystallization kinetics, isothermal crystallization and the morphology of crystals of the copolymer poly (ethylene terephthalate/ isophthalate )(IPET) were studied by DSC and polarized-light microscopy in this paper. DSC results indicate that the glass transition temperature Tg of IPET is slightly lower than that of poly(ethylene terephthalate) (PET), but the melting temperature Tm and the crystallization temperature Tc of PET and IPET have much difference.The difference of Tc between PET and IPET2 is about 7℃, and the difference of Tm between PET and IPET2 is about 16℃. From the kinetics analysis of the crystallization, the crystallization mechanism of all samples is of three-dimension spherulitic growth from instantaneous nuclei and the incorporation of isophthalate (IPA) decreases the crystallization rate of IPET greatly. The isothermal results indicate that the morphologies of PET and IPET crystals are all spherulite, which is in conformity to the results of nonisothermal dynamic crystallization. At the same time,the spherulite of IPET grows slower and has longer incubation time than the spherulite of PET under the same crystallization condition.

  1. Engineered biosynthesis of biodegradable polymers.

    Science.gov (United States)

    Jambunathan, Pooja; Zhang, Kechun

    2016-08-01

    Advances in science and technology have resulted in the rapid development of biobased plastics and the major drivers for this expansion are rising environmental concerns of plastic pollution and the depletion of fossil-fuels. This paper presents a broad view on the recent developments of three promising biobased plastics, polylactic acid (PLA), polyhydroxyalkanoate (PHA) and polybutylene succinate (PBS), well known for their biodegradability. The article discusses the natural and recombinant host organisms used for fermentative production of monomers, alternative carbon feedstocks that have been used to lower production cost, different metabolic engineering strategies used to improve product titers, various fermentation technologies employed to increase productivities and finally, the different downstream processes used for recovery and purification of the monomers and polymers.

  2. Enhancing relative permittivity by incorporating PDMS-PEG multiblock copolymers in binary polymer blends

    DEFF Research Database (Denmark)

    A Razak, Aliff Hisyam; Szabo, Peter; Skov, Anne Ladegaard

    Polydimethylsiloxane (PDMS) elastomers are well-known to be soft and highly stretchable, yet they never achieve maximum elongation when utilised as dielectric elastomers, simply because their dielectric permittivity remains rather low. Conversely, polyethyleneglycols (PEG) are not stretchable...

  3. Improving dielectric permittivity by incorporating PDMS-PEG block copolymer into PDMS network

    DEFF Research Database (Denmark)

    A Razak, Aliff Hisyam; Szabo, Peter; Skov, Anne Ladegaard

    Polydimethylsiloxane (PDMS) is well-known to cause hydrophobic surfaces due to their low surface energy as well as they possess low conductivity and extremely low glass transition temperature 1. On the other hand, polyethyleneglycol (PEG) behaves hydrophilic and is a highly conductive polymer...

  4. Sustained Release of Antibacterial Lipopeptides from Biodegradable Polymers against Oral Pathogens

    Science.gov (United States)

    Eckhard, Lea H.; Houri-Haddad, Yael; Sol, Asaf; Zeharia, Rotem; Shai, Yechiel; Beyth, Shaul; Domb, Abraham J.

    2016-01-01

    The development of antibacterial drugs to overcome various pathogenic species, which inhabit the oral cavity, faces several challenges, such as salivary flow and enzymatic activity that restrict dosage retention. Owing to their amphipathic nature, antimicrobial peptides (AMPs) serve as the first line of defense of the innate immune system. The ability to synthesize different types of AMPs enables exploitation of their advantages as alternatives to antibiotics. Sustained release of AMPs incorporated in biodegradable polymers can be advantageous in maintaining high levels of the peptides. In this study, four potent ultra-short lipopeptides, conjugated to an aliphatic acid chain (16C) were incorporated in two different biodegradable polymers: poly (lactic acid co castor oil) (PLACO) and ricinoleic acid-based poly (ester-anhydride) (P(SA-RA)) for sustained release. The lipopeptide and polymer formulations were tested for antibacterial activity during one week, by turbidometric measurements of bacterial outgrowth, anti-biofilm activity by live/dead staining, biocompatibility by hemolysis and XTT colorimetric assays, mode of action by fluorescence-activated cell sorting (FACS) and release profile by a fluorometric assay. The results show that an antibacterial and anti-biofilm effect, as well as membrane disruption, can be achieved by the use of a formulation of lipopeptide incorporated in biodegradable polymer. PMID:27606830

  5. 21 CFR 177.1310 - Ethylene-acrylic acid copolymers.

    Science.gov (United States)

    2010-04-01

    ... (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) INDIRECT FOOD ADDITIVES: POLYMERS Substances for Use as... this section are not applicable to ethylene-acrylic acid copolymers used in food-packaging adhesives... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Ethylene-acrylic acid copolymers. 177.1310...

  6. 21 CFR 177.1980 - Vinyl chloride-propylene copolymers.

    Science.gov (United States)

    2010-04-01

    ... (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) INDIRECT FOOD ADDITIVES: POLYMERS Substances for Use as... applicable to vinyl chloride-propylene copolymers used in food-packaging adhesives complying with § 175.105... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Vinyl chloride-propylene copolymers....

  7. Surface morphology of PS-PDMS diblock copolymer films

    DEFF Research Database (Denmark)

    Andersen, T.H.; Tougaard, S.; Larsen, N.B.

    2001-01-01

    Spin coated thin films (∼400 Å) of poly(styrene)–poly(dimethylsiloxane) (PS–PDMS) diblock copolymers have been investigated using X-ray Photoelectron Spectroscopy and Atomic Force Microscopy. Surface segregation of the poly(dimethylsiloxane) blocks was studied for five diblock copolymers which...

  8. From Block Copolymers to Nano-porous Materials

    DEFF Research Database (Denmark)

    Vigild, Martin Etchells; Ndoni, Sokol; Berg, Rolf Henrik

    2003-01-01

    Quantitative etching of the polydimethylsiloxane block in a series of polystyrene-polydimethylsiloxane (PS-PDMS) block copolymers is reported. Reacting the block copolymer with anhydrous hydrogen fluoride (HF) renders a nanoporous material with the remaining PS maintaining the original morphology...

  9. Alternation and tunable composition in hydrogen bonded supramolecular copolymers.

    Science.gov (United States)

    Felder, Thorsten; de Greef, Tom F A; Nieuwenhuizen, Marko M L; Sijbesma, Rint P

    2014-03-07

    Sequence control in supramolecular copolymers is limited by the selectivity of the associating monomer end groups. Here we introduce the use of monomers with aminopyrimidinone and aminohydroxynaphthyridine quadruple hydrogen bonding end groups, which both homodimerize, but form even stronger heterodimers. These features allow the formation of supramolecular copolymers with a tunable composition and a preference for alternating sequences.

  10. Self-assembled materials from thermosensitive and biohybrid block copolymers

    NARCIS (Netherlands)

    de Graaf, A.J.

    2012-01-01

    In this research, several block copolymers were synthesized and characterized with regard to possible pharmaceutical applications. All block copolymers were thermosensitive and self-assembled at 37 °C into structures like micelles and hydrogels, which can be used for innovative drug delivery purpose

  11. Hierarchical structure formation in supramolecular comb-shaped block copolymers

    NARCIS (Netherlands)

    Hofman, Anton; ten Brinke, Gerrit; Loos, Katja

    2016-01-01

    Block copolymers are known to spontaneously form ordered structures at the nano-to mesoscale. Although the number of different morphologies is rather limited in diblock copolymer systems, their phase behavior becomes increasingly more complex with each additional building block. Synthesis of such al

  12. Morphological studies on block copolymer modified PA 6 blends

    Science.gov (United States)

    Poindl, M.; Bonten, C.

    2014-05-01

    Recent studies show that compounding polyamide 6 (PA 6) with a PA 6 polyether block copolymers made by reaction injection molding (RIM) or continuous anionic polymerization in a reactive extrusion process (REX) result in blends with high impact strength and high stiffness compared to conventional rubber blends. In this paper, different high impact PA 6 blends were prepared using a twin screw extruder. The different impact modifiers were an ethylene propylene copolymer, a PA PA 6 polyether block copolymer made by reaction injection molding and one made by reactive extrusion. To ensure good particle matrix bonding, the ethylene propylene copolymer was grafted with maleic anhydride (EPR-g-MA). Due to the molecular structure of the two block copolymers, a coupling agent was not necessary. The block copolymers are semi-crystalline and partially cross-linked in contrast to commonly used amorphous rubbers which are usually uncured. The combination of different analysis methods like atomic force microscopy (AFM), transmission electron microscopy (TEM) and scanning electron microscopy (SEM) gave a detailed view in the structure of the blends. Due to the partial cross-linking, the particles of the block copolymers in the blends are not spherical like the ones of ethylene propylene copolymer. The differences in molecular structure, miscibility and grafting of the impact modifiers result in different mechanical properties and different blend morphologies.

  13. Antimicrobial activity of poly(acrylic acid) block copolymers

    Energy Technology Data Exchange (ETDEWEB)

    Gratzl, Günther, E-mail: guenther.gratzl@jku.at [Johannes Kepler University Linz, Institute for Chemical Technology of Organic Materials, Altenberger Str. 69, 4040 Linz (Austria); Paulik, Christian [Johannes Kepler University Linz, Institute for Chemical Technology of Organic Materials, Altenberger Str. 69, 4040 Linz (Austria); Hild, Sabine [Johannes Kepler University Linz, Institute of Polymer Science, Altenberger Str. 69, 4040 Linz (Austria); Guggenbichler, Josef P.; Lackner, Maximilian [AMiSTec GmbH and Co. KG, Leitweg 13, 6345 Kössen, Tirol (Austria)

    2014-05-01

    The increasing number of antibiotic-resistant bacterial strains has developed into a major health problem. In particular, biofilms are the main reason for hospital-acquired infections and diseases. Once formed, biofilms are difficult to remove as they have specific defense mechanisms against antimicrobial agents. Antimicrobial surfaces must therefore kill or repel bacteria before they can settle to form a biofilm. In this study, we describe that poly(acrylic acid) (PAA) containing diblock copolymers can kill bacteria and prevent from biofilm formation. The PAA diblock copolymers with poly(styrene) and poly(methyl methacrylate) were synthesized via anionic polymerization of tert-butyl acrylate with styrene or methyl methacrylate and subsequent acid-catalyzed hydrolysis of the tert-butyl ester. The copolymers were characterized via nuclear magnetic resonance spectroscopy (NMR), size-exclusion chromatography (SEC), Fourier transform infrared spectroscopy (FTIR), elemental analysis, and acid–base titrations. Copolymer films with a variety of acrylic acid contents were produced by solvent casting, characterized by atomic force microscopy (AFM) and tested for their antimicrobial activity against Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa. The antimicrobial activity of the acidic diblock copolymers increased with increasing acrylic acid content, independent of the copolymer-partner, the chain length and the nanostructure. - Highlights: • Acrylic acid diblock copolymers are antimicrobially active. • The antimicrobial activity depends on the acrylic acid content in the copolymer. • No salts, metals or other antimicrobial agents are needed.

  14. Synthesis of Functional Block Copolymers Carrying One Poly( p -phenylenevinylene) and One Nonconjugated Block in a Facile One-Pot Procedure

    KAUST Repository

    Menk, Florian

    2016-02-29

    Block copolymers composed of a MEH-PPV block and a nonconjugated functional block (molecular weights between 5 and 90 kg/mol) were synthesized in a facile one-pot procedure via ROMP. This one-pot procedure permits the synthesis of numerous block copolymers with little effort. Amphiphilic block copolymers were obtained via incorporation of oxanorbornene carrying a PEG side chain as well as via postpolymerization modification of a reactive ester carrying norbornene derivative with methoxypoly(ethylene glycol)amine. These amphiphilic block copolymers can be self-assembled into micelles exhibiting different sizes (60-95 nm), morphologies (micelles or fused, caterpillar-like micelles), and optical properties depending on the polymer composition and the micellization procedure. Furthermore, the reactive ester carrying block copolymers enabled the introduction of anchor groups which facilitated the preparation of nanocomposites with CdSe/CdZnS core-shell QDs. The obtained composites were studied using time-resolved photoluminescence measurements. The results revealed an increased interaction based on an accelerated decay of the QD emission for composites as compared to the mixture of the QDs with unfunctionalized polymers. © 2016 American Chemical Society.

  15. Absorption ability and kinetics of a liquid electrolyte in PVDF-HFP copolymer containing or not SiO 2

    Science.gov (United States)

    Caillon-Caravanier, M.; Claude-Montigny, B.; Lemordant, D.; Bosser, G.

    Gel polymer electrolytes have been prepared from PVDF-HFP copolymer with various silica contents incorporating Gamma valerolactone (VL) or VL/EC (80/20 in mole) (EC: ethylene carbonate) solutions of lithium bis(trifluoromethane sulfone) imide (LiTFSI). The influence of temperature, salt content and silica addition on the kinetics of absorption and wettability of the copolymer has been investigated. An empirical model, taking into account gel swelling during the absorption allows us to relate, at constant temperature, the wetting time and the volumetric fraction of trapped electrolyte, which is a critical factor for ionic conductivity of the gel. Increasing the silica content in the dry copolymer increases the porosity and consequently the rate of absorption and thus the amount of incorporated liquid phase at saturation. To a lower extent, an increase in the temperature of absorption has the same effects. The prepared gels have good mechanicals properties and conductivities. As an example, a gel of composition: PVDF- HFP/ SiO2/ VL/ EC/ LiTFSI of molar percentages 36/6.7/42/10.5/4.8 exhibits a conductivity of 2.9 mS cm - 1 at 293 K.

  16. Banana fiber-reinforced biodegradable soy protein composites

    Institute of Scientific and Technical Information of China (English)

    Rakesh Kumar; Veena Choudhary; Saroj Mishra; Ik Varma

    2008-01-01

    Banana fiber,a waste product of banana cultivation,has been used to prepare banana fiber reinforced soy protein composites. Alkali modified banana fibers were characterized in terms of density,denier and crystallinity index. Fourier transformed infrared spectroscopy (FTIR),scanning electron microscopy (SEM) and thermogravimetric analysis (TGA) were also performed on the fibers. Soy protein composites were prepared by incorporating different volume fractions of alkali,treated and untreated fibers into soy protein isolate (SPI) with different amounts of glycerol (25%,50%) as plasticizer.Composites thus prepared were characterized in terms of mechanical properties,SEM and water resistance.The results indicate that at 0.3 volume fraction,tensile strength and modulus of alkali treated fiber reinforced soy protein composites increased to 82% and 963%,respectively,compared to soy protein film without fibers.Water resistance of the composites increased significantly with the addition of glutaraldehyde which acts as crosslinking agent. Biodegradability of the composites has also been tested in the contaminated environment and the composites were found to be 100% biodegradable.

  17. Biodegradable polyoxyethylenated pentaerythritol quaternary esters as oil spill dispersants

    Energy Technology Data Exchange (ETDEWEB)

    El-Sayed Abdel-Raouf, Manar [Egyptian Petroleum Research Institute, Cairo (Egypt). Petroleum Application Dept.

    2012-03-15

    Four polyoxyethylenated pentaerythritol (PE) ester surfactants have been synthesized. The molecular weights of these surfactants were calculated and evaluated experimentally by GPC and confirmed by calculations based on {sup 1}H-NMR. Also, their HLB values were calculated by Griffin formula. The surface tension and thermodynamic properties of the surfactants were obtained from surface tension measurements at different temperatures (298-318 K). It was found that the minimum area/surfactant molecule (A{sub min}) for the investigated surfactants increased with increasing the molecular weight of the incorporated ethylene oxide. The thermodynamic parameters of micellization ({delta}G{sub mic,} {delta}H{sub mic} and {delta}S{sub mic}) and that for adsorption ({delta}G{sub ad,} {delta}H{sub ad} and {delta}S{sub ad}) were also calculated. The more negative Gibbs free energy of adsorption values than those of micellization suggest that these surfactants favor adsorption than micellization. This finding is utilized for monitoring their dispersancy power. It was found that the water solubility of the prepared surfactants is correlated to their HLB values. Furthermore, the biodegradability of the prepared compounds was studied at different conditions in order to investigate their usability as oil spill dispersants. The data revealed that PE200-C12 had maximum dispersion efficiency and it was completely biodegraded after 8 days. (orig.)

  18. Phyllosphere yeasts rapidly break down biodegradable plastics.

    Science.gov (United States)

    Kitamoto, Hiroko K; Shinozaki, Yukiko; Cao, Xiao-Hong; Morita, Tomotake; Konishi, Masaaki; Tago, Kanako; Kajiwara, Hideyuki; Koitabashi, Motoo; Yoshida, Shigenobu; Watanabe, Takashi; Sameshima-Yamashita, Yuka; Nakajima-Kambe, Toshiaki; Tsushima, Seiya

    2011-11-29

    The use of biodegradable plastics can reduce the accumulation of environmentally persistent plastic wastes. The rate of degradation of biodegradable plastics depends on environmental conditions and is highly variable. Techniques for achieving more consistent degradation are needed. However, only a few microorganisms involved in the degradation process have been isolated so far from the environment. Here, we show that Pseudozyma spp. yeasts, which are common in the phyllosphere and are easily isolated from plant surfaces, displayed strong degradation activity on films made from poly-butylene succinate or poly-butylene succinate-co-adipate. Strains of P. antarctica isolated from leaves and husks of paddy rice displayed strong degradation activity on these films at 30°C. The type strain, P. antarctica JCM 10317, and Pseudozyma spp. strains from phyllosphere secreted a biodegradable plastic-degrading enzyme with a molecular mass of about 22 kDa. Reliable source of biodegradable plastic-degrading microorganisms are now in our hands.

  19. PREPARATION AND SURFACE PROPERTIES OF ACRYLIC COPOLYMERS CONTAINING FLUORINATED MONOMERS

    Institute of Scientific and Technical Information of China (English)

    Tai-jiang Gui; Hao Wei; Ying Zhao; Xiu-lin Wang; Du-jin Wang; Duan-fu Xu

    2006-01-01

    A series of copolymers comprising butylmethacrylate, styrene, butylacrylate, hydroxypropyl acrylate and perfluoroalkyl methacrylate were synthesized by the free radical polymerization using BPO as an initiator. The surface property of the copolymer films was subsequently characterized. The contact angle measurements and energy dispersive analysis of X-ray (EDAX) show that the length and content ofperfluoroalkyl side chains in the copolymers are crucial for the preparation of the film with low surface energy. At a given content of fluorinated monomers in the copolymers, the longer the perfluoroalkyl side chain, the larger the water contact angle of the copolymer films will be. On the other hand, the higher the content of fluorinated monomers, the lower the surface energy is. The water contact angle increases with the increase of the fluorinated monomer content and reaches a plateau at 3 wt% of fluorinated monomer content.

  20. Multicompartment Micelles From π-Shaped ABC Block Copolymers

    Institute of Scientific and Technical Information of China (English)

    XIA Jun; ZHONG Chong-Li

    2007-01-01

    Dissipative particle dynamics simulations were performed on the morphology and structure of multicompartment micelles formed from n-shaped ABC block copolymers in water. The influences of chain architectures were studied in a systematic way, and a rich variety of morphologies were observed, such as spherical, wormlike,X-shaped, Y-shaped, ribbon-like, layered rod-like, layered disk-like, as well as network morphologies. The simulations show that the distance between the two grafts plays an important role in control of the morphology. Since π-shaped ABC block copolymers can be reduced to linear ABC and star ABC block copolymers, they are good model copolymers for studying the self-assembly of complex block copolymers into micelles. The knowledge obtained in this work as well as the new morphologies identified provide useful information for future rational design and synthesis of novel multicompartment micelles.

  1. Sulfomethylated graft copolymers of xanthan gum and polyacrylamide

    Energy Technology Data Exchange (ETDEWEB)

    Cottrell, I.W.; Empey, R.A.; Racciato, J.S.

    1978-08-08

    A water-soluble anionic graft copolymer of xanthan gum and polyacrylamide is described in which at least part of the amide function of the acrylamide portion of the copolymer is sulfomethylated and the xanthan gum portion of the copolymer is unreacted with formaldehyde. The copolymer is sulfomethylated by reaction with formaldehyde and sodium metabisulfite. The formaldehyde does not cause any appreciable cross-linking between hydroxyl groups of the xanthan moieties. The sulfomethylation of the acrylamido group takes place at temperatures from 35 to 70 C. The pH is 10 or higher, typically from 12 to 13. The degree of anionic character may be varied by adjusting the molar ratio of formaldehyde and sodium metabisulfite with respect to the copolymer. 10 claims.

  2. Structure and Mechanical Properties of Ethylene-butene Copolymers

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The crystallinity of ethylene-butene copolymers prepared by copolymerization of ethylene and butene in the presence of a new highly active catalyst was studied by means of DSC, WAXD and DMA. The results show that the melting temperature, the crystallinity and the crystallite size decreased with increasing the content of butene in the copolymers. The copolymers have a high degree of branching, the butene segments are mainly in the amorphous regions of the copolymers, while the polyethylene sequence forms crystal phase acting as crosslinking bondage between the molecules at room temperature. The ethylene-butene copolymers have a low modulus, a low stress and a high strain analogous to the stress-strain behavior of non-cross thermoplastic elastomer.

  3. Mechanical behaviour׳s evolution of a PLA-b-PEG-b-PLA triblock copolymer during hydrolytic degradation.

    Science.gov (United States)

    Breche, Q; Chagnon, G; Machado, G; Girard, E; Nottelet, B; Garric, X; Favier, D

    2016-07-01

    PLA-b-PEG-b-PLA is a biodegradable triblock copolymer that presents both the mechanical properties of PLA and the hydrophilicity of PEG. In this paper, physical and mechanical properties of PLA-b-PEG-b-PLA are studied during in vitro degradation. The degradation process leads to a mass loss, a decrease of number average molecular weight and an increase of dispersity index. Mechanical experiments are made in a specific experimental set-up designed to create an environment close to in vivo conditions. The viscoelastic behaviour of the material is studied during the degradation. Finally, the mechanical behaviour is modelled with a linear viscoelastic model. A degradation variable is defined and included in the model to describe the hydrolytic degradation. This variable is linked to physical parameters of the macromolecular polymer network. The model allows us to describe weak deformations but become less accurate for larger deformations. The abilities and limits of the model are discussed.

  4. Star-shaped copolymer grafted PEI and REDV as a gene carrier to improve migration of endothelial cells.

    Science.gov (United States)

    Lv, Juan; Hao, Xuefang; Li, Qian; Akpanyung, Mary; Nejjari, Abdelilah; Neve, Agnaldo Luis; Ren, Xiangkui; Feng, Yakai; Shi, Changcan; Zhang, Wencheng

    2017-01-17

    In this work, a biodegradable star-shaped copolymer poly(lactide-co-3(S)-methyl-morpholine-2,5-dione)6 (Star-(PLMD)6) was synthesized via ring-opening polymerization (ROP), and subsequently a gene carrier Star-PLMD-g-PEI-g-PEG-CREDVW was prepared by grafting polyethyleneimine (PEI), polyethylene glycol (PEG) and targeting peptide REDV onto Star-(PLMD)6. This gene carrier could form stable micelles to condense pEGFP-ZNF580 through electrostatic interaction. The resulting complexes were biocompatible and showed high efficiency in gene delivery. In addition, these complexes exhibited high selectivity for endothelial cells (ECs), high transfection efficiency and enhanced migration of ECs. The protein level of ZNF580 expression was significantly high (up to 85%), while the control group was only 51%. This combination of degradability, targeting ligand and star-structure strategy exhibits a significant advantage in transfection efficiency and migration of ECs.

  5. The use of biodegradable mulch for tomato and broccoli production: Crop yield and quality, mulch deterioration, and growers' perceptions

    Science.gov (United States)

    Cowan, Jeremy Scott

    Biodegradable mulch may offer the benefits of polyethylene mulch for crop production with the added benefit of biodegradability. Four studies were carried out in Mount Vernon, WA to evaluate biodegradable mulch for tomato (Solanum lycopersicum L.) and broccoli (Brassica oleracea var. italica) production. The first study compared four biodegradable mulch treatments: BioAgri, BioTelo, WeedGuardPlus (cellulose product), and SB-PLA-10/11/12 (experimental, non-woven fabric), to polyethylene mulch and bare ground in high tunnels and in the open field for tomato yield and fruit quality over three growing seasons. Biodegradable plastic films produced yields and fruit quality comparable to polyethylene. Moreover, high tunnels increased total and marketable fruit weight five and eight times, respectively, compared to the open field. The second study quantified relationships among visual assessment parameters and mulch mechanical properties. Visual assessments and mechanical property tests of polyethylene, BioAgri, BioTelo, WeedGuardPlus, and SB-PLA-10/11/12, were made over three growing seasons. Regression analyses found the strongest relationship overall (r2 = 0.41) to be between the percent of initial breaking force in the machine direction and log 10 of percent visual deterioration. However, evaluating mulch products individually and increasing sample frequency are recommended for future research. The third study evaluated three biodegradable mulch products, BioAgri, Crown 1, and SB-PLA-11, after soil-incorporation. The average area of recovered mulch fragments decreased for all mulch products over time. The number of mulch fragments initially increased for all mulch products, with the greatest number of Crown 1 and BioAgri fragments recovered 132 and 299 days after incorporation, respectively. At 397 days after soil-incorporation, the total area of recovered fragments of Crown 1 and BioAgri was 0% and 34% of the theoretical maximum area, respectively. The fourth study

  6. Electric field stimulation through a biodegradable polypyrrole-co-polycaprolactone substrate enhances neural cell growth.

    Science.gov (United States)

    Nguyen, Hieu T; Sapp, Shawn; Wei, Claudia; Chow, Jacqueline K; Nguyen, Alvin; Coursen, Jeff; Luebben, Silvia; Chang, Emily; Ross, Robert; Schmidt, Christine E

    2014-08-01

    Nerve guidance conduits (NGCs) are FDA-approved devices used to bridge gaps across severed nerve cables and help direct axons sprouting from the proximal end toward the distal stump. In this article, we present the development of a novel electrically conductive, biodegradable NGC made from a polypyrrole-block-polycaprolactone (PPy-PCL) copolymer material laminated with poly(lactic-co-glycolic acid) (PLGA). The PPy-PCL has a bulk conductivity ranging 10-20 S/cm and loses 40 wt % after 7 months under physiologic conditions. Dorsal root ganglia (DRG) grown on flat PPy-PCL/PLGA material exposed to direct current electric fields (EF) of 100 mV/cm for 2 h increased axon growth by 13% (± 2%) toward either electrode of a 2-electrode setup, compared with control grown on identical substrates without EF exposure. Alternating current increased axon growth by 21% (±3%) without an observable directional preference, compared with the same control group. The results from this study demonstrate PLGA-coated PPy-PCL is a unique biodegradable material that can deliver substrate EF stimulation to improve axon growth for peripheral nerve repair.

  7. Transport of nonlinearly biodegradable contaminants in aquifers

    OpenAIRE

    Keijzer, H.

    2001-01-01

    This thesis deals with the transport behavior of nonlinearly biodegradable contaminants in aquifers. Such transport occurs during in situ bioremediation which is based on the injection of an electron acceptor or electron donor. The main interests in this thesis are the mutual influences of underlying processes, i.e. transport, adsorption and biodegradation, and their influence on in situ bioremediation performance. To gain insight in these influences, the processes in a homogeneous aquifer ar...

  8. Ball Powder Production Wastewater Biodegradation Support Studies

    Science.gov (United States)

    1989-02-01

    Any unusual removal criteria (NO3, toxic compound, etc.): * None 9 Type of wastewater treated: Dairy ( whey and grease) 1 Design basis for scale-up... WASTEWATER BIODEGRADATION SUPPORT STUDIES (TASK ORDER NO. 11) February 1989 Contract No. DAAK11-85-D-0008 w MAR 2 9 1983 Prepared by: Arthur D...United States Army Toxic and Hazardous Materials Agency February 1989 I Ball Powder Production Wastewater Pilot-Scale £ Biodegradation Support Studies I

  9. Mechano-responsive hydrogels crosslinked by reactive block copolymer micelles

    Science.gov (United States)

    Xiao, Longxi

    Hydrogels are crosslinked polymeric networks that can swell in water without dissolution. Owing to their structural similarity to the native extracelluar matrices, hydrogels have been widely used in biomedical applications. Synthetic hydrogels have been designed to respond to various stimuli, but mechanical signals have not incorporated into hydrogel matrices. Because most tissues in the body are subjected to various types of mechanical forces, and cells within these tissues have sophisticated mechano-transduction machinery, this thesis is focused on developing hydrogel materials with built-in mechano-sensing mechanisms for use as tissue engineering scaffolds or drug release devices. Self-assembled block copolymer micelles (BCMs) with reactive handles were employed as the nanoscopic crosslinkers for the construction of covalently crosslinked networks. BCMs were assembled from amphiphilic diblock copolymers of poly(n-butyl acrylate) and poly(acrylic acid) partially modified with acrylate. Radical polymerization of acrylamide in the presence of micellar crosslinkers gave rise to elastomeric hydrogels whose mechanical properties can be tuned by varying the BCM composition and concentration. TEM imaging revealed that the covalently integrated BCMs underwent strain-dependent reversible deformation. A model hydrophobic drug, pyrene, loaded into the core of BCMs prior to the hydrogel formation, was dynamically released in response to externally applied mechanical forces, through force-induced reversible micelle deformation and the penetration of water molecules into the micelle core. The mechano-responsive hydrogel has been studied for tissue repair and regeneration purposes. Glycidyl methacrylate (GMA)-modified hyaluronic acid (HA) was photochemically crosslinked in the presence of dexamethasone (DEX)-loaded crosslinkable BCMs. The resultant HA gels (HAxBCM) contain covalently integrated micellar compartments with DEX being sequestered in the hydrophobic core. Compared

  10. Incorporating Feminist Standpoint Theory

    DEFF Research Database (Denmark)

    Ahlström, Kristoffer

    2005-01-01

    As has been noted by Alvin Goldman, there are some very interesting similarities between his Veritistic Social Epistemology (VSE) and Sandra Harding’s Feminist Standpoint Theory (FST). In the present paper, it is argued that these similarities are so significant as to motivate an incorporation...

  11. Differentiating leucine incorporation of

    NARCIS (Netherlands)

    Yokokawa, T.; Sintes, E.; de Corte, D.; Olbrich, K.; Herndl, G.J.

    2012-01-01

    The abundance (based on catalyzed reporter deposition-fluorescence in situ hybrid ization, CARD-FISH) and leucine incorporation rates of Archaea and Bacteria were determined throughout the water column in the eastern Atlantic. Bacteria dominated throughout the water column, although their contributi

  12. Small domain-size multiblock copolymer electrolytes

    Energy Technology Data Exchange (ETDEWEB)

    Pistorino, Jonathan; Eitouni, Hany Basam

    2016-09-20

    New block polymer electrolytes have been developed which have higher conductivities than previously reported for other block copolymer electrolytes. The new materials are constructed of multiple blocks (>5) of relatively low domain size. The small domain size provides greater protection against formation of dendrites during cycling against lithium in an electrochemical cell, while the large total molecular weight insures poor long range alignment, which leads to higher conductivity. In addition to higher conductivity, these materials can be more easily synthesized because of reduced requirements on the purity level of the reagents.

  13. Preparation of Impact and Weather Resistant Copolymer

    Institute of Scientific and Technical Information of China (English)

    LIANG Tao

    2001-01-01

    @@ Synthesis method of the resin is that crosslinked polybutyl acrylate latex is used as base latex. Styrene (St) and acrylonitrile (AN) are grafted onto polybutyl acrylate latex particle and turn into core-shell copolymer. The resin is a good resin's impact modifier. There are study of influence regularity about additive emulsifier, initiator, monomer concentration, the ratio of St to AN, chain transfer to graft polymerization. A kind of core-shell resin used as impact modifier is obtained. (A) Preparation of Crosslinked Butyl Acrylate Rubber Latex

  14. Preparation of Impact and Weather Resistant Copolymer

    Institute of Scientific and Technical Information of China (English)

    LIANG; Tao

    2001-01-01

    Synthesis method of the resin is that crosslinked polybutyl acrylate latex is used as base latex. Styrene (St) and acrylonitrile (AN) are grafted onto polybutyl acrylate latex particle and turn into core-shell copolymer. The resin is a good resin's impact modifier. There are study of influence regularity about additive emulsifier, initiator, monomer concentration, the ratio of St to AN, chain transfer to graft polymerization. A kind of core-shell resin used as impact modifier is obtained. (A) Preparation of Crosslinked Butyl Acrylate Rubber Latex  ……

  15. Manufacturing of biodegradable polyurethane scaffolds based on polycaprolactone using a phase separation method: physical properties and in vitro assay

    Directory of Open Access Journals (Sweden)

    Asefnejad A

    2011-10-01

    Full Text Available Azadeh Asefnejad1, Mohammad Taghi Khorasani2, Aliasghar Behnamghader3, Babak Farsadzadeh1, Shahin Bonakdar4 1Department of Biomedical Engineering, Science and Research Branch, Islamic Azad University, Tehran, Iran; 2Iran Polymers and Petrochemical Institute, Tehran, Iran; 3Materials and Energy Research Center, Tehran, Iran; 4National Cell Bank of Iran, Pasteur Institute of Iran, Tehran, Iran Background: Biodegradable polyurethanes have found widespread use in soft tissue engineering due to their suitable mechanical properties and biocompatibility. Methods: In this study, polyurethane samples were synthesized from polycaprolactone, hexamethylene diisocyanate, and a copolymer of 1,4-butanediol as a chain extender. Polyurethane scaffolds were fabricated by a combination of liquid–liquid phase separation and salt leaching techniques. The effect of the NCO:OH ratio on porosity content and pore morphology was investigated. Results: Scanning electron micrographs demonstrated that the scaffolds had a regular distribution of interconnected pores, with pore diameters of 50–300 µm, and porosities of 64%–83%. It was observed that, by increasing the NCO:OH ratio, the average pore size, compressive strength, and compressive modulus increased. L929 fibroblast and chondrocytes were cultured on the scaffolds, and all samples exhibited suitable cell attachment and growth, with a high level of biocompatibility. Conclusion: These biodegradable polyurethane scaffolds demonstrate potential for soft tissue engineering applications. Keywords: polyurethane, tissue engineering, biodegradable, fibroblast cells

  16. Biodegradability of Chlorinated Anilines in Waters

    Institute of Scientific and Technical Information of China (English)

    CHAO WANG; GUAN-GHUA LU; YAN-JIE ZHOU

    2007-01-01

    Objective To identify the bacteria tolerating chlorinated anilines and to study the biodegradability of o-chloroaniline and its coexistent compounds. Methods Microbial community of complex bacteria was identified by plate culture observation techniques and Gram stain method. Bacterial growth inhibition test was used to determine the tolerance of complex bacteria to toxicant. Biodegradability of chlorinated anilines was determined using domesticated complex bacteria as an inoculum by shaking-flask test. Results The complex bacteria were identified, consisting of Xanthomonas, Bacillus alcaligenes,Acinetobacter, Pseudomonas, and Actinomycetaceae nocardia. The obtained complex bacteria were more tolerant to o-chloroaniline than mixture bacteria in natural river waters. The effects of exposure concentration and inoculum size on the biodegradability of o-chloroaniline were analyzed, and the biodegradation characteristics of single o-chloroaniline and 2,4-dichloroaniline were compared with the coexistent compounds. Conclusion The biodegradation rates can be improved by decreasing concentration of compounds and increasing inoculum size of complex bacteria. When o-chloroaniline coexists with aniline, the latter is biodegraded prior to the former, and as a consequence the metabolic efficiency of o-chloroaniline is improved with the increase of aniline concentration. Meanwhile, when o-chloroaniline coexists with 2,4-dichloroaniline, the metabolic efficiency of 2,4-dichloroaniline is markedly improved.

  17. Immersed multilayer biodegradable ureteral stent with reformed biodegradation: An in vitro experiment.

    Science.gov (United States)

    Yang, Ganggang; Xie, Hua; Huang, Yichen; Lv, Yiqing; Zhang, Mingqing; Shang, Yafeng; Zhou, Junmei; Wang, Liping; Wang, Jin-Ye; Chen, Fang

    2017-03-01

    Objective The aim of this study was to develop a novel immersed multilayer biodegradable ureteral stent with reformed biodegradation and evaluate it in vitro. Methods Poly(glycolic-co-lactic acid) (PGLA), microsphere zein and BaSO4 were employed to produce a multilayer biodegradable stent using immersion technology. Tests of the biodegradable stents and conventional control stents were conducted in human urine in vitro to evaluate the biodegradable properties. The biocompatibility was assessed by the morphology and proliferation of urine-derived cells cultured with extracted media from the biodegradable stent and a latex material positive control. Results An immersed multilayer biodegradable stent was successfully produced. It began to degrade in week 2 and was fully degraded by week 4. The mass loss ratio in the first 2 weeks was low (approximately 10.0% at 1 week, 20.0% at 2 weeks) and increased after 3 weeks (approximately 70%) to the end of testing. During the first 2 weeks, the radial compression load performances of the biodegradable stents were better than those of the control stents with statistically significant differences ( p = 0.00, p = 0.01) and the tensile strengths were lower in the biodegradable stents than those in the control stents throughout the experiment. SEM showed that the stents degraded layer by layer from the outer to the inner wall. The influences on the cells of extracted medium from the biodegradable stents were morphologically slight and lower than 10% in relative growth rates. Conclusions This preliminary study demonstrates that the immersed multilayer biodegradable ureteral stent has good radial compression and biocompatible performance and can be degraded in vitro within 4 weeks in a moderate manner.

  18. Novel docetaxel-loaded nanoparticles based on PCL-Tween 80 copolymer for cancer treatment

    Directory of Open Access Journals (Sweden)

    Mei L

    2011-11-01

    Full Text Available Yuandong Ma1,2*, Yi Zheng1,2*, Xiaowei Zeng1-3*, Liqin Jiang4, Hongbo Chen1,2, Ranyi Liu5, Laiqiang Huang1,2, Lin Mei1,21School of Life Sciences, Tsinghua University, Beijing, 2Division of Life and Health Sciences, Graduate School at Shenzhen, Tsinghua University, Shenzhen, Guangdong, 3Materials and Environment Experimental Center, Department of Materials Science and Engineering, Qinhuangdao Branch, Northeastern University, Qinhuangdao, 4Insitute of Biomedical Engineering, Peking Union Medical College, Chinese Academy of Medical Sciences, Tianjin, 5State Key Laboratory of Oncology in South China, Sun Yat-sen University Cancer Center, Guangzhou, People’s Republic of China *These authors contributed equally to this workBackground: The formulation of docetaxel available for clinical use (Taxotere® contains a high concentration of polysorbate 80 (Tween 80. After incorporation of Tween 80 into poly-ε-caprolactone (PCL-Tween 80 copolymer, the relative amount of Tween 80 should be decreased and the advantages of PCL and Tween 80 should be combined.Methods: A novel PCL-Tween 80 copolymer was synthesized from ε-caprolactone and Tween 80 in the presence of stannous octoate as a catalyst via ring opening polymerization. Two types of nanoparticle formulation were made from commercial PCL and a self-synthesized PCL-Tween 80 copolymer using a modified solvent extraction/evaporation method.Results: The nanoparticles were found by field emission scanning electron microscopy to have a spherical shape and be 200 nm in diameter. The copolymers could encapsulate 10% of the drug in the nanoparticles and release 34.9% of the encapsulated drug over 28 days. PCL-Tween 80 nanoparticles could be internalized into the cells and had higher cellular uptake than the PCL nanoparticles. The drug-loaded PCL-Tween 80 nanoparticles showed better in vitro cytotoxicity towards C6 cancer cells than commercial Taxotere at the same drug concentration.Conclusion: Nanoparticles

  19. 21 CFR 177.1360 - Ethylene-vinyl acetate-vinyl alcohol copolymers.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Ethylene-vinyl acetate-vinyl alcohol copolymers... acetate-vinyl alcohol copolymers. Ethylene-vinyl acetate-vinyl alcohol copolymers (CAS Reg. No. 26221-27-2... accordance with the following prescribed conditions: (a) Ethylene-vinyl acetate-vinyl alcohol copolymers...

  20. Research Progress of Electrospun Biodegradable Synthetic Polymer Fibers%可降解合成高分子静电纺纤维的研究进展

    Institute of Scientific and Technical Information of China (English)

    江乙逵; 赖明河; 陈向标; 陈海宏

    2012-01-01

    The principle of electrospinning and the research progress of biodegradable synthetic polymer nanofibers prepared by electrospinning were introduced. The research progress of several major electrospun biodegradable synthetic polymer fibers such as poly-carboxylic acid, polylactic acid, polycaprolactone and their copolymers, etc was mainly described. The important application in biomedical field was pointedout.%介绍了静电纺丝的原理及利用静电纺丝方法制备生物可降解合成高分子纳米纤维的最新研究进展,主要讲述聚羧基乙酸、聚乳酸、聚己内酯及其共聚物等几种主要的生物可降解合成高分子电纺纤维的研究进展,并指出它们在生物医学领域的重要应用.

  1. Conjugated Polymer Chains Confined in Vertical Nanocylinders of a Block-Copolymer Film: Preparation, Characterization, and Optoelectronic Function

    KAUST Repository

    Dong, Ban Xuan

    2013-01-15

    Hybrid materials composed of phase-separated block copolymer films and conjugated polymers of the phenylenevinylene family (PPV) are prepared. The PPV chains are embedded in vertical cylinders of nanometer diameter in the block-copolymer films. The cylinders span continuously the whole film thickness of 70 nm. Incorporation of the PPV chains into the one-dimensional cylinders leads to modified photoluminescence spectra and to large absorption anisotropy. The hybrid films show electroluminescence from the PPV chains in a simple light-emitting device at minute doping concentrations, and also exhibit a factor of 19 increase in electron transport efficiency along the single PPV chains. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Effect of Comonomer Ethylene on Plateau Modulus of Crystalline Ethylene-propylene Random Copolymer with Broad Molecular Weight Distribution

    Institute of Scientific and Technical Information of China (English)

    丁健; 徐日炜; 丁雪佳; 余鼎声

    2005-01-01

    Ethylene-propylene random copolymer with ultra-high molecular weight (UHPPR) and broad molecular weight distribution (MWD) was prepared with Ziegler-Natta catalyst. The viscoelastic behavior of UHPPR has been investigated by means of oscillatory rheometer at 180, 200 and 220℃. The loss modulus (G"""") curves of 180 and 200℃ present a pronounced maximum at 38.10 and 84.70r/s, respectively, For the first time, this makes it possible to directly determine the plateau modulus ( GN0 ) of crystalline ethylene-propylene random copolymer with broad MWD in a certain experimental temperature G""""(w) curve. The plateau modulus of UHPPR is 4.51×105 and 3.67×105 Paat 180 and 200℃ respectively, increasing with random incorporation of comonomer ethylene into the molecular chains and being independent of molecular weight.

  3. Novel 'nano in nano' composites for sustained drug delivery: biodegradable nanoparticles encapsulated into nanofiber non-wovens.

    Science.gov (United States)

    Beck-Broichsitter, Moritz; Thieme, Marcel; Nguyen, Juliane; Schmehl, Thomas; Gessler, Tobias; Seeger, Werner; Agarwal, Seema; Greiner, Andreas; Kissel, Thomas

    2010-12-08

    Novel 'nano in nano' composites consisting of biodegradable polymer nanoparticles incorporated into polymer nanofibers may efficiently modulate drug delivery. This is shown here using a combination of model compound-loaded biodegradable nanoparticles encapsulated in electrospun fibers. The dye coumarin 6 is used as model compound for a drug in order to simulate drug release from loaded poly(lactide-co-glycolide) nanoparticles. Dye release from the nanoparticles occurs immediately in aqueous solution. Dye-loaded nanoparticles which are encapsulated by electrospun polymer nanofibers display a significantly retarded release.

  4. Processing and characterization of novel biobased and biodegradable materials

    Science.gov (United States)

    Pilla, Srikanth

    Human society has benefited tremendously from the use of petroleum-based plastics. However, there are growing concerns with their adverse environmental impacts and volatile costs attributed to the skyrocketing oil prices. Additionally most of the petroleum-based polymers are non-biodegradable causing problems about their disposal. Thus, during the last couple of decades, scientists ail over the world have been focusing on developing new polymeric materials that are biobased and biodegradable, also termed as green plastics . This study aims to develop green materials based on polylactide (PLA) biopolymer that can be made from plants. Although PLA can provide important advantages in terms of sustainability and biodegradability, it has its own challenges such as high cost, brittleness, and narrow processing window. These challenges are addressed in this study by investigating both new material formulations and processes. To improve the material properties and control the material costs, PLA was blended with various fillers and modifiers. The types of fillers investigated include carbon nanotube (CNT) nanoparticles and various natural fibers such as pine-wood four, recycled-wood fibers and flax fiber. Using natural fibers as fillers for PLA can result in fully biodegradable and eco-friendly biocomposites. Also due to PLA's sensitivity to moisture and temperature, molecular degradation can occur during processing leading to inferior material properties. To address this issue, one of the approaches adopted by this study was to incorporate a multifunctional chain-extender into PLA, which increased the molecular weight of PLA thereby improving the material properties. To improve the processability and reduce the material cost, both microcellular injection molding and extrusion processes have been studied. The microcellular technology allows the materials to be processed at a lower temperature, which is attractive for thermo- and moisture-sensitive materials like PLA. They

  5. Biodegradable and Biocompatible Systems Based on Hydroxyapatite Nanoparticles

    Directory of Open Access Journals (Sweden)

    Pau Turon

    2017-01-01

    Full Text Available Composites of hydroxyapatite (HAp are widely employed in biomedical applications due to their biocompatibility, bioactivity and osteoconductivity properties. In fact, the development of industrially scalable hybrids at low cost and high efficiency has a great impact, for example, on bone tissue engineering applications and even as drug delivery systems. New nanocomposites constituted by HAp nanoparticles and synthetic or natural polymers with biodegradable and biocompatible characteristics have constantly been developed and extensive works have been published concerning their applications. The present review is mainly focused on both the capability of HAp nanoparticles to encapsulate diverse compounds as well as the preparation methods of scaffolds incorporating HAp. Attention has also been paid to the recent developments on antimicrobial scaffolds, bioactive membranes, magnetic scaffolds, in vivo imaging systems, hydrogels and coatings that made use of HAp nanoparticles.

  6. Facilitated Transport of Ethylene in Poly (Amide 12-Block Tetramethylenoxide) Copolymer/AgBF4 Membranes Containing Silver (I) and Copper (I) Ions as Carriers

    Science.gov (United States)

    Ben Hamouda, Sofiane; Trong Nguyen, Quang; Langevin, Dominique; Roudesli, Sadok

    Metal-incorporated poly(amide 12-block-tetramethylenoxide) (PA12-co-PTMO) copolymer was used for studying facilitated transport of olefines through new composite membranes. The metals incorporated were silver {Ag(I)} and copper {Cu(I)}. Tests were carried out at room temperature (25±2°C) to determine the selectivity and permeability of these membranes to ethylene and ethane gas. The membranes prepared by mixing in solution the copolymer with silver (AgBF4) or copper (CuBF4) salt show a ethylene/ethane selectivity much higher than that of pure PA12-co-PTMO. The membranes were also characterized by Fourier Transform Infra Red (FTIR) spectroscopy and Scanning Electron Microscopy (SEM) in order to understand the structural feature responsible for the observed behaviour. The IRFT spectrum indicate that Ag+ and Cu+ ions are developing interactions with the copolymer. The permeation results obtained with copper containing membranes show that CuBF4 salt introduction in the copolymer tends to reduce ethane permeability. This phenomenon is explained by a diminution of the free volume caused by a decrease of the interchain distance due to the formation of metal ions-polymer matrix complexes. At the same time, for ethylene, the decrease in permeability observed at low salt content is recouped rapidly, when the salt content increases, by a dramatic increase of the permeability which attains 10 times that of the pure PA12-co-PTMO. This behaviour is attributed to the facilitated transport mechanism of the ethylene molecules able to develop specific interactions with the incorporated metal ions. It results from these two antagonistic phenomena a multiplication by 18 of the ethylene/ethane selectivity of the pure copolymer when the CuBF4 content of the composite attains 60%.

  7. Amphiphilic star block copolymers as gene carrier Part I: Synthesis via ATRP using calix[4]resorcinarene-based initiators and characterization

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Anna; Xue, Yan; Wei, Dafu [Shanghai Key Laboratory of Advanced Polymeric Materials, Key Laboratory for Ultrafine Materials of Ministry of Education, School of Materials Science and Engineering, East China University of Science and Technology, Shanghai 200237 (China); Guan, Yong, E-mail: yguan@ecust.edu.cn [Shanghai Key Laboratory of Advanced Polymeric Materials, Key Laboratory for Ultrafine Materials of Ministry of Education, School of Materials Science and Engineering, East China University of Science and Technology, Shanghai 200237 (China); Xiao, Huining [Department of Chemical Engineering, University of New Brunswick, Fredericton, New Brunswick, Canada E3B 5A3 (Canada)

    2013-01-01

    In this work, a cationic star polymer [poly(2-dimethylamino)ethyl methacrylate (PDMAEMA)] was prepared via atom transfer radical polymerization (ATRP), using brominated calix[4]resorcinarene as an initiator. Hydrophobic moieties, methyl methacrylate (MMA) and butyl acrylate (BA), were further incorporated via 'one-pot' method. Well-defined eight-armed star block copolymers bearing hydrophilic blocks inside and hydrophobic blocks outside were synthesized. The molecular weight, particle size, electrophoretic mobility and apparent charge density were determined by gel permeation chromatography (GPC), dynamic light scattering (DLS), phase analysis light scattering (PALS) and colloidal titration, respectively. The zeta potentials and apparent charge densities of the products exhibited the characteristics of polyelectrolyte. The incorporation of hydrophobic moieties generated electrostatic screening effect. The as-synthesized amphiphilic star copolymer is promising as a thermo-sensitive gene carrier for gene therapy. Highlights: Black-Right-Pointing-Pointer Amphiphilic cationic star block copolymers with well-controlled structures were prepared via ATRP. Black-Right-Pointing-Pointer The molecular structures and properties of the initiator and copolymers were systematically characterized. Black-Right-Pointing-Pointer The products exhibited the positive charged character, and hydrophobic moieties generated electrostatic screening effect.

  8. Self-Assembled Cationic Biodegradable Nanoparticles from pH-Responsive Amino-Acid-Based Poly(Ester Urea Urethane)s and Their Application As a Drug Delivery Vehicle.

    Science.gov (United States)

    He, Mingyu; Potuck, Alicia; Kohn, Julie C; Fung, Katharina; Reinhart-King, Cynthia A; Chu, Chih-Chang

    2016-02-01

    The objective of this study is to develop a new family of biodegradable and biologically active copolymers and their subsequent self-assembled cationic nanoparticles as better delivery vehicles for anticancer drugs to achieve the synergism between the cytotoxicity effects of the loaded drugs and the macrophage inflammatory response of the delivery vehicle. This family of cationic nanoparticles was formulated from a new family of amphiphilic cationic Arginine-Leucine (Arg-Leu)-based poly(ester urea urethane) (Arg-Leu PEUU) synthesized from four building blocks (amino acids, diols, glycerol α-monoallyl ether, and 1,6 hexamethylene diisocyanate). The chemical, physical, and biological properties of Arg-Leu PEUU biomaterials can be tuned by controlling the feed ratio of the four building blocks. The Arg-Leu PEUU copolymers have weight-average molecular weights from 13.4 to 16.8 kDa and glass-transition temperatures from -3.4 to -4.6 °C. The self-assembled cationic nanoparticles (Arg-Leu PEUU NPs) were prepared using a facile dialysis method. Arg-Leu PEUU NPs have average diameters ranging from 187 to 272 nm, show good biocompatibility with 3T3 fibroblasts, and they support bovine aortic endothelial cell (BAEC) proliferation and adhesion. Arg-Leu PEUU NPs also enhanced the macrophages' production of tumor necrosis factor-α (TNF-α) and nitric oxide (NO), but produced relatively low levels of interleukin-10 (IL-10), and therefore, the antitumor activity of macrophages might be enhanced. Arg-Leu PEUU NPs were taken up by HeLa cells after 4 h of incubation. The in vitro hemolysis assay showed the cationic Arg-Leu PEUU NPs increased their chance of endosomal escape at a more acidic pH. Doxorubicin (DOX) was successfully incorporated into the Arg-Leu PEUU NPs, and the DOX-loaded Arg-Leu PEUU NPs exhibited a pH-dependent drug release profile with accelerated release kinetics in a mild acidic condition. The DOX-loaded 6-Arg-4-Leu-4 A/L-2/1 NPs showed higher HeLa cell

  9. The heat-chill method for preparation of self-assembled amphiphilic poly(ε-caprolactone)-poly(ethylene glycol) block copolymer based micellar nanoparticles for drug delivery.

    Science.gov (United States)

    Payyappilly, Sanal Sebastian; Dhara, Santanu; Chattopadhyay, Santanu

    2014-04-07

    A new method is developed for preparation of amphiphilic block copolymer micellar nanoparticles and investigated as a delivery system for celecoxib, a hydrophobic model drug. Biodegradable block copolymers of poly(ethylene glycol) (PEG) and poly(ε-caprolactone) (PCL) were synthesized by ring opening copolymerization and characterized thoroughly using FTIR, (1)H NMR and GPC. The block copolymer was dispersed in distilled water at 60 °C and then it was chilled in an ice bath for the preparation of the micellar nanoparticles. Polymers self-assembled to form micellar nanoparticles (HR-TEM, DLS and DSC. The cytotoxicity of the polymer micellar nanoparticles was investigated against HaCaT cell lines. The study of celecoxib release from the micellar nanoparticles was carried out to assess their suitability as a drug delivery vehicle. Addition of the drug to the system at low temperature is an added advantage of this method compared to the other temperature assisted nanoparticle preparation techniques. In a nutshell, polymer micellar nanoparticles prepared using the heat-chill method are believed to be promising for the controlled drug release system of labile drugs, which degrade in toxic organic solvents and at higher temperatures.

  10. Controlling Structure in Sulfonated Block Copolymer Membranes

    Science.gov (United States)

    Truong, Phuc; Stein, Gila; Strzalka, Joe

    2015-03-01

    In many ionic block copolymer systems, the strong incompatibility between ionic and non-ionic segments will trap non-equilibrium structures in the film, making it difficult to engineer the optimal domain sizes and transport pathways. The goal of this work is to establish a framework for controlling the solid-state structure of sulfonated pentablock copolymer membranes. They have ABCBA block sequence, where A is poly(t-butyl styrene), B is poly(hydrogenated isoprene), and C is poly(styrene sulfonate). To process into films, the polymer is dissolved in toluene/n-propanol solvent mixtures, where the solvent proportions and the polymer loading were both varied. Solution-state structure was measured with small angle X-ray scattering (SAXS). We detected micelles with radii that depend on the solvent composition and polymer loading. Film structure was measured with grazing-incidence SAXS, which shows (i) domain periodicity is constant throughout film thickness; (ii) domain periodicity depends on solvent composition and polymer loading, and approximately matches the micelle radii in solutions. The solid-state packing is consistent with a hard sphere structure factor. Results suggest that solid-state structure can be tuned by manipulating the solution-state self-assembly.

  11. Chain exchange in triblock copolymer micelles

    Science.gov (United States)

    Lu, Jie; Lodge, Timothy; Bates, Frank

    2015-03-01

    Block polymer micelles offer a host of technological applications including drug delivery, viscosity modification, toughening of plastics, and colloidal stabilization. Molecular exchange between micelles directly influences the stability, structure and access to an equilibrium state in such systems and this property recently has been shown to be extraordinarily sensitive to the core block molecular weight in diblock copolymers. The dependence of micelle chain exchange dynamics on molecular architecture has not been reported. The present work conclusively addresses this issue using time-resolved small-angle neutron scattering (TR-SANS) applied to complimentary S-EP-S and EP-S-EP triblock copolymers dissolved in squalane, a selective solvent for the EP blocks, where S and EP refer to poly(styrene) and poly(ethylenepropylene), respectively. Following the overall SANS intensity as a function of time from judiciously deuterium labelled polymer and solvent mixtures directly probes the rate of molecular exchange. Remarkably, the two triblocks display exchange rates that differ by approximately ten orders of magnitude, even though the solvophobic S blocks are of comparable size. This discovery is considered in the context of a model that successfully explains S-EP diblock exchange dynamics.

  12. Nanocomposites of Polyacrylic Acid Nanogels and Biodegradable Polyhydroxybutyrate for Bone Regeneration and Drug Delivery

    Directory of Open Access Journals (Sweden)

    Mikael Larsson

    2014-01-01

    Full Text Available Biodegradable cell scaffolds and local drug delivery to stimulate cell response are currently receiving much scientific attention. Here we present a nanocomposite that combines biodegradation with controlled release of lithium, which is known to enhance bone growth. Nanogels of lithium neutralized polyacrylic acid were synthesized by microemulsion-templated polymerization and were incorporated into a biodegradable polyhydroxybutyrate (PHB matrix. Nanogel size was characterized using dynamic light scattering, and the nanocomposites were characterized with regard to structure using scanning electron microscopy, mechanical properties using tensile testing, permeability using tritiated water, and lithium release in PBS using a lithium specific electrode. The nanogels were well dispersed in the composites and the mechanical properties were good, with a decrease in elastic modulus being compensated by increased tolerance to strain in the wet state. Approximately half of the lithium was released over about three hours, with the remaining fraction being trapped in the PHB for subsequent slow release during biodegradation. The prepared nanocomposites seem promising for use as dual functional scaffolds for bone regeneration. Here lithium ions were chosen as model drug, but the nanogels could potentially act as carriers for larger and more complex drugs, possibly while still carrying lithium.

  13. MOLECULAR DESIGN SYNTHESIS AND PROPERTIES OF SIX KINDS OF MULTIPHASE (STYRENE-ETHYLENE OXIDE) COPOLYMERS

    Institute of Scientific and Technical Information of China (English)

    XIE Hongquan; ZHOU Peiguang; SUN Wenbo; XIA Jun; LIU Jin; XIE Dong

    1991-01-01

    @@ Multiphase copolymers of styrene (S) and ethylene oxide (EO) are amphiphilic,because of the hydrophobic and amorphous polystyrene (PS) segments and the hydrophilic and crystalline polyoxyethylene (PEO). They have many uses including polymeric surfactants, electrostatic charge reducers, compatibilizer in polymer blending, phase transfer catalysts or solid polymer electrolytes. These copolymers include different types of block copolymers, graft copolymers and star-shaped block copolymers.

  14. 可降解多元氨基酸共聚物/磷酸钙复合材料椎间融合器植入山羊颈椎即刻稳定性的生物力学评价%Biomechanical Evaluation of Immediate Stability of Biodegradable Multi-amino Acid Copolymer/Tri-calcium Phosphate Composite Interbody Cages in a Goat Cervical Spine Model

    Institute of Scientific and Technical Information of China (English)

    周春光; 宋跃明; 屠重棋; 段宏; 裴福兴; 严永刚; 李鸿

    2011-01-01

    设计制备可降解多元氨基酸共聚物/磷酸钙复合材料椎间融合器 (MAACP /T CP Cage),探讨其对山羊颈椎C3-4融合术后的即刻稳定作用.首先对正常山羊颈椎进行测试,之后将27个标本随机分为3组,这样实验共有4组:A组:MAACP/TCP Cage组(n=9); B组:钛合金Cage组(n=9);C组:三面皮质髂骨组(n=9);D组:正常对照组 (n=27).切除颈3/4椎间盘后植入以上内植物,采用非破坏刚度法进行前屈、后伸、侧屈和旋转的生物力学测定,由此计算出各组活动范围(ROM)及相对刚度,并行比较.与正常对照组相比,MAACP/TCP Cage植入后,颈3-4节段屈曲和左、右侧屈的ROM下降,相对刚度提高(P<0 05);与髂骨组相比,MAACP/TCP Cage植入后,颈3-4节段后伸、屈曲和左、右侧屈的ROM低于髂骨组,相对刚度高于髂骨组(P<0 05);与钛合金Cage组相比,M AACP/TCP Cage植入后,颈3-4节段屈曲、后伸和左、右侧屈的ROM及相对刚度无明显差别( P>0 05),而旋转的ROM高于钛合金Cage组,相对刚度低于钛合金Cage组(P<0 05).结论:MAACP/TCP Cage可为山羊颈椎椎间融合提供足够的初始生物力学稳定性.%A new kind of Interbody Cage made of multi-amino acid copolymer/ tri-calcium phosphate ( MAACP/TCP)composite was designed, and the purpose of this study was to evaluate immediate stability of MAACP/TCP Cage in a goat cervical spine model (C3-4). After the motion segment C3-4 was tested intact, 27 goat cervical spines were divided into three groups randomly. There were four groups : group A : MAACP/TCP Cage group(n= 9) , group B: titanium Cage group(n= 9) .group C: autologous tricortical iliac crest bone group (n= 9) and group D: intact group(n =27). Different Cage groups were implanted after complete discectomy (C3-4) was performed. Then they were tested in flexion, extension, axial rotation. and lateral bending with a nondestructive stiffness method. The range of motion (ROM) and relative stiffness were

  15. Biomechanical Challenges to Polymeric Biodegradable Stents.

    Science.gov (United States)

    Soares, Joao S; Moore, James E

    2016-02-01

    Biodegradable implants have demonstrated clinical success in simple applications (e.g., absorbable sutures) and have shown great potential in many other areas of interventional medicine, such as localized drug delivery, engineered tissue scaffolding, and structural implants. For endovascular stenting and musculoskeletal applications, they can serve as temporary mechanical support that provides a smooth stress-transfer from the degradable implant to the healing tissue. However, for more complex device geometries, in vivo environments, and evolving load-bearing functions, such as required for vascular stents, there are considerable challenges associated with the use of biodegradable materials. A biodegradable stent must restore blood flow and provide support for a predictable appropriate period to facilitate artery healing, and subsequently, fail safely and be absorbed in a controllable manner. Biodegradable polymers are typically weaker than metals currently employed to construct stents, so it is difficult to ensure sufficient strength to keep the artery open and alleviate symptoms acutely while keeping other design parameters within clinically acceptable ranges. These design challenges are serious, given the general lack of understanding of biodegradable polymer behavior and evolution in intimal operating conditions. The modus operandi is mainly empirical and relies heavily on trial-and-error methodologies burdened by difficult, resource-expensive, and time-consuming experiments. We are striving for theoretical advancements systematizing the empirical knowledge into rational frameworks that could be cast into in silico tools for simulation and product development optimization. These challenges are evident when one considers that there are no biodegradable stents on the US market despite more than 30 years of development efforts (and currently only a couple with CE mark). This review summarizes previous efforts at implementing biodegradable stents, discusses the

  16. Synthesis and properties of polystyrene/polydimethylsiloxane graft copolymers

    Institute of Scientific and Technical Information of China (English)

    Wu Ningjing; Huang Likan; Zheng Anna

    2006-01-01

    Polystyrene-graft-polydimethylsiloxane (PS-g-PDMS) copolymers with different PDMS content were synthesized by the radical bulk copolymerization of PDMS macromonomer and styrene.The copolymers were characterized by Fourier transform infrared (FT-IR),1H-nuclear magnetic resonance (NMR),thermogravimetric analysis (TGA),dynamic mechanical analysis (DMA),transmission electron microscopy (TEM) and the mechanical properties of the copolymers were also carried out.It was indicated that the notched impact strength and elongation at break of the polymers increased with the increase of PDMS content.The thermal stability of PS-g-PDMS is better than that of PS.

  17. Self-assembled antimicrobial and biocompatible copolymer films on titanium.

    Science.gov (United States)

    Pfaffenroth, Cornelia; Winkel, Andreas; Dempwolf, Wibke; Gamble, Lara J; Castner, David G; Stiesch, Meike; Menzel, Henning

    2011-11-10

    Copolymers of 4-vinyl-N-hexylpyridinium bromide and dimethyl(2-methacryloyloxyethyl) phosphonate self-assemble to form ultrathin layers on titanium surfaces that show antimicrobial activity, and biocompatibility. The copolymer layers are characterized by contact angle measurements, ellipsometry and XPS. Antibacterial activity is assessed by investigation of adherence of S. mutans. Biocompatibility is rated based on human gingival fibroblast adhesion and proliferation. By balancing the opposing effects of the chemical composition on biocompatibility and antimicrobial activity, copolymer coatings are fabricated that are able to inhibit the growth of S. mutans on the surface but still show attachment of gingival fibroblasts, and therefore might prevent biofilm formation on implants.

  18. Phase Transition Induced by Small Molecules in Confined Copolymer Films

    Institute of Scientific and Technical Information of China (English)

    ZHOU Ling

    2007-01-01

    We investigate the phase transition induced by small molecules in confined copolymer films by using density functional theory.It is found that the addition of small molecules can effectively promote the phase separation of copolymers.In a symmetric diblock copolymer film,the affinity and concentration of small molecules play an important role in the structure transjtions.The disordered-lamellar transitions lamellar-lamellar transitions and the re-entrant transitions of the same structures are observed.Our results have potential applications in the fabrication of new functional materials.

  19. STUDY ON SOLID STATE POLYCONDENSATION OF POLYETHYLENE TEREPHTHALATE COPOLYMERS

    Institute of Scientific and Technical Information of China (English)

    WU Rongrui; DENG Yuan; HUANG Guanbao; DENG Jianyuan; LI Huiping

    1994-01-01

    The kinetic data of solid state polycondensation of PET and its copolymers are determined.It is shown that the reaction rate of copolycondensation is higher than that of PET polycondensation, and increases with the comonomers content. But the reaction rate of copolycondensation in melt state of this kind of copolymers is lower than that of PET. It is considered that the chemical reactivity of comonomer is the main factor which affect the polycondensation in melt state,whereas the aggregative structure of the polymer is the main factor in solid state. The crystallinity and crystallite size of the copolymers have been measured by X-ray method.

  20. Synthesis of amphiphilic diblock copolymer for surface modification of Ethylene-Norbornene copolymers

    DEFF Research Database (Denmark)

    Levinsen, Simon; Svendsen, Winnie Edith; Horsewell, Andy

    2014-01-01

    The aim of this work is to produce polymer modifiers in order to develop hydrophilic polymeric surfaces for use in microfluidics. The use of hydrophilic polymers in microfluidics will have many advantages e.g. preventing protein absorbance. Here we present an amphiphilic diblock copolymer......-norbornene copolymer TOPAS. Through matching of the radius of gyration for the model polymer and TOPAS the miscibility was achieved. The poly(ethylene-1-butene) polymer was synthesized from a hydrogenated anionic polymerized polybutadiene polymer. As hydrophilic block poly(ethylene oxide) was subsequently added also...... with anionic polymerization. Recent miscibility results between the model polymer and TOPAS will be presented, as well ongoing efforts to study the hydrophilic surface....

  1. Synthesis, Properties and Applications of Biodegradable Polymers Derived from Diols and Dicarboxylic Acids: From Polyesters to Poly(ester amides

    Directory of Open Access Journals (Sweden)

    Angélica Díaz

    2014-04-01

    Full Text Available Poly(alkylene dicarboxylates constitute a family of biodegradable polymers with increasing interest for both commodity and speciality applications. Most of these polymers can be prepared from biobased diols and dicarboxylic acids such as 1,4-butanediol, succinic acid and carbohydrates. This review provides a current status report concerning synthesis, biodegradation and applications of a series of polymers that cover a wide range of properties, namely, materials from elastomeric to rigid characteristics that are suitable for applications such as hydrogels, soft tissue engineering, drug delivery systems and liquid crystals. Finally, the incorporation of aromatic units and α-amino acids is considered since stiffness of molecular chains and intermolecular interactions can be drastically changed. In fact, poly(ester amides derived from naturally occurring amino acids offer great possibilities as biodegradable materials for biomedical applications which are also extensively discussed.

  2. pH-responsive biodegradable micelles based on acid-labile polycarbonate hydrophobe: synthesis and triggered drug release.

    Science.gov (United States)

    Chen, Wei; Meng, Fenghua; Li, Feng; Ji, Shun-Jun; Zhong, Zhiyuan

    2009-07-13

    pH-responsive biodegradable micelles were prepared from block copolymers comprising of a novel acid-labile polycarbonate hydrophobe and poly(ethylene glycol) (PEG). Two new cyclic aliphatic carbonate monomers, mono-2,4,6-trimethoxybenzylidene-pentaerythritol carbonate (TMBPEC, 2a) and mono-4-methoxybenzylidene-pentaerythritol carbonate (MBPEC, 2b) were designed and successfully synthesized via a two-step procedure. The ring-opening polymerization of 2a or 2b in the presence of methoxy PEG in dichloromethane at 50 °C using zinc bis[bis(trimethylsilyl)amide] as a catalyst yielded the corresponding block copolymers PEG-PTMBPEC (3a) or PEG-PMBPEC (3b) with low polydispersities (PDI 1.03-1.04). The copolymerization of D,L-lactide (DLLA) and 2a under otherwise the same conditions could also proceed smoothly to afford PEG-P(TMBPEC-co-DLLA) (3c) block copolymer. These block copolymers readily formed micelles in water with sizes of about 120 nm as determined by dynamic light scattering (DLS). The hydrolysis of the acetals of the polycarbonate was investigated using UV/vis spectroscopy. The results showed that the acetals of micelles 3a, while stable at pH 7.4 are prone to rapid hydrolysis at mildly acidic pH of 4.0 and 5.0, with a half-life of 1 and 6.5 h, respectively. The acetal hydrolysis resulted in significant swelling of micelles, as a result of change of hydrophobic polycarbonate to hydrophilic polycarbonate. In comparison, the acetals of PMBPEC of micelles 3b displayed obviously slower hydrolysis at the same pH. Both paclitaxel and doxorubicin could be efficiently encapsulated into micelles 3a achieving high drug loading content (13.0 and 11.7 wt %, respectively). The in vitro release studies showed clearly a pH dependent release behavior, that is, significantly faster drug release at mildly acidic pH of 4.0 and 5.0 compared to physiological pH. These pH-responsive biodegradable micelles are promising as smart nanovehicles for targeted delivery of anticancer drugs.

  3. Biodegradable mesoporous delivery system for biomineralization precursors

    Directory of Open Access Journals (Sweden)

    Yang HY

    2017-01-01

    Full Text Available Hong-ye Yang,1 Li-na Niu,2 Jin-long Sun,2 Xue-qing Huang,3 Dan-dan Pei,4 Cui Huang,1 Franklin R Tay5 1The State Key Laboratory Breeding Base of Basic Science of Stomatology, Key Laboratory for Oral Biomedicine Ministry of Education, School and Hospital of Stomatology, Wuhan University, Wuhan, Hubei, People’s Republic of China; 2State Key Laboratory of Military Stomatology, National Clinical Research Center for Oral Diseases, Shaanxi Key Laboratory of Oral Diseases, Department of Prosthodontics, School of Stomatology, The Fourth Military Medical University, Xi’an, Shaanxi, People’s Republic of China; 3Department of Prosthodontics, Guanghua School and Hospital of Stomatology, Guangdong Key Laboratory of Stomatology, Yat-sen University, Guangzhou, Guangdong, People’s Republic of China; 4Department of Prosthodontics, College of Stomatology, Xi’an Jiaotong University, Xi’an, Shaanxi, People’s Republic of China; 5Department of Endodontics, College of Dental Medicine, Augusta University, Augusta, GA, USA Abstract: Scaffold supplements such as nanoparticles, components of the extracellular matrix, or growth factors have been incorporated in conventional scaffold materials to produce smart scaffolds for tissue engineering of damaged hard tissues. Due to increasing concerns on the clinical side effects of using large doses of recombinant bone-morphogenetic protein-2 in bone surgery, it is desirable to develop an alternative nanoscale scaffold supplement that is not only osteoinductive, but is also multifunctional in that it can perform other significant bone regenerative roles apart from stimulation of osteogenic differentiation. Because both amorphous calcium phosphate (ACP and silica are osteoinductive, a biodegradable, nonfunctionalized, expanded-pore mesoporous silica nanoparticle carrier was developed for loading, storage, and sustained release of a novel, biosilicification-inspired, polyamine-stabilized liquid precursor phase of ACP

  4. Biodegradable compounds: Rheological, mechanical and thermal properties

    Science.gov (United States)

    Nobile, Maria Rossella; Lucia, G.; Santella, M.; Malinconico, M.; Cerruti, P.; Pantani, R.

    2015-12-01

    Recently great attention from industry has been focused on biodegradable polyesters derived from renewable resources. In particular, PLA has attracted great interest due to its high strength and high modulus and a good biocompatibility, however its brittleness and low heat distortion temperature (HDT) restrict its wide application. On the other hand, Poly(butylene succinate) (PBS) is a biodegradable polymer with a low tensile modulus but characterized by a high flexibility, excellent impact strength, good thermal and chemical resistance. In this work the two aliphatic biodegradable polyesters PBS and PLA were selected with the aim to obtain a biodegradable material for the industry of plastic cups and plates. PBS was also blended with a thermoplastic starch. Talc was also added to the compounds because of its low cost and its effectiveness in increasing the modulus and the HDT of polymers. The compounds were obtained by melt compounding in a single screw extruder and the rheological, mechanical and thermal properties were investigated. The properties of the two compounds were compared and it was found that the values of the tensile modulus and elongation at break measured for the PBS/PLA/Talc compound make it interesting for the production of disposable plates and cups. In terms of thermal resistance the compounds have HDTs high enough to contain hot food or beverages. The PLA/PBS/Talc compound can be, then, considered as biodegradable substitute for polystyrene for the production of disposable plates and cups for hot food and beverages.

  5. Development of mold for biodegradable materials

    Energy Technology Data Exchange (ETDEWEB)

    Japitana, F.H.; Jabrica, A.M. [Metals Industry Research and Develeopment Center, Manila (Philippines). Dept. of Science and Technology; Komatsu, M. [Komatsu Consulting Engineer Office, Iwaki City, Fukushima (Japan); Takeuchi, Y. [Osaka Univ., Osaka (Japan). Dept. of Mechanical Engineering

    2008-07-01

    The improper disposal of non-biodegradable plastics adversely affect global environmental factors, principles of sustainability, industrial ecology and ecoefficiency. Therefore, a new generation of bio-based polymeric products has been developed. These polylactides (PLA), cellulose esters, starch plastics and polyhydroxyalkanoates (PHAs) are made from renewable natural resources and are biodegradable. They meet environmental conditions and can compete with their petrochemical counterparts. Among them, PLA is particularly attractive as a sustainable alternative to synthetic polymers and a potential candidate for the fabrication of biocomposites. Certain blends have proved successful in medical implants, sutures and drug delivery systems because of their capacity to dissolve away with time. However, widespread use of PLA is limited because of cost. Biodegradable plastic products are currently 6 to 10 times more expensive than traditional plastics. Environmentalists argue that the cheaper price of traditional plastics does not reflect their true cost when their impact is considered. This paper presented a solution to reduce the production cost of biodegradable plastics. In particular, it described a newly developed plastic injection mold for biodegradable materials which can produce a scrapless product. The system reduces processing time because it is not necessary to remove any gating or runners after the injection process. Takeout robots ensure that the quality of the product is maintained. 12 figs.

  6. Bio-Degradable Plastics Impact On Environment

    Directory of Open Access Journals (Sweden)

    T.SUBRAMANI

    2014-06-01

    Full Text Available The potential of biodegradable polymers and more particularly that of polymers obtained from renewable resources such as the polysaccharides (e.g., starch have long been recognized. However, these biodegradable polymers have been largely used in some applications (e.g., food industry and have not found extensive applications in the packaging industries to replace conventional plastic materials, although they could be an interesting way to overcome the limitation of the petrochemical resources in the future. The fossil fuel and gas could be partially replaced by greener agricultural sources, which should participate in the reduction of CO2 emissions. Bio-based and biodegradable plastics can form the basis for environmentally preferable, sustainable alternative to current materials based exclusively on petroleum feed stocks. These bio-based materials offer value in the sustainability/life-cycle equation by being a part of the biological carbon cycle, especially as it relates to carbon-based polymeric materials such as plastics, water soluble polymers and other carbon based products like lubricants, biodiesel, and detergents. Identification and quantification of bio based content uses radioactive C-14 signature. Biopolymers are generally capable of being utilized by living matter (biodegraded, and so can be disposed in safe and ecologically sound ways through disposal processes (waste management like composting, soil application, and biological wastewater treatment. Single use, short-life, disposable products can be engineered to be bio-based and biodegradable.

  7. The effects of biodegradation on the compositions of aromatic hydrocarbons and maturity indicators in biodegraded oils from Liaohe Basin

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    By the aid of GC-MS technique,a series of sequentially biodegraded oils from Liaohe Basin have been analyzed. The results show that the concentrations and relative compositions of various aromatic compounds in the biodegraded crude oils will change with increasing biodegradation degree. The concentrations of alkyl naphthalenes,alkyl phenanthrenes,alkyl dibenzothiophene are decreased,and the concentration of triaromatic steroids will increase with increasing biodegradation degree in biodegraded oils. Those phenomena indicate that various aromatic compounds are more easily biodegraded by bacteria like other kinds of hydrocarbons such as alkanes,but different series of aromatic compounds have a varied ability to resistant to biodegradation. The ratios of dibenzothiophene to phenenthrene(DBTH/P) and methyl dibenzothiophene to methyl phenanthrene(MDBTH/MP) are related to the features of depositional environment for source rocks such as redox and ancient salinity. However,in biodegraded oils,the two ratios increase quickly with the increase of the biodegradation degree,indicating that they have lost their geochemical significance. In this case,they could not be used to evaluate the features of depositional environment. Methyl phenanthrene index,methyl phenanthrene ratio and methyl dibenzoyhiophene ratio are useful aromatic maturity indicators for the crude oils and the source rocks without vitrinite. But for biodegraded oils,those aromatic maturity indicators will be affected by biodegradation and decrease with the increase of the biodegradation degree. Therefore,those aromatic molecular maturity indicators could not be used for biodegraded oils.

  8. Biodegradability of degradable plastic waste.

    Science.gov (United States)

    Agamuthu, P; Faizura, Putri Nadzrul

    2005-04-01

    Plastic waste constitutes the third largest waste volume in Malaysian municipal solid waste (MSW), next to putrescible waste and paper. The plastic component in MSW from Kuala Lumpur averages 24% (by weight), whereas the national mean is about 15%. The 144 waste dumps in the country receive about 95% of the MSW, including plastic waste. The useful life of the landfills is fast diminishing as the plastic waste stays un-degraded for more than 50 years. In this study the compostability of polyethylene and pro-oxidant additive-based environmentally degradable plastics (EDP) was investigated. Linear low-density polyethylene (LLDPE) samples exposed hydrolytically or oxidatively at 60 degrees C showed that the abiotic degradation path was oxidative rather than hydrolytic. There was a weight loss of 8% and the plastic has been oxidized as shown by the additional carbonyl group exhibited in the Fourier transform infra red (FTIR) Spectrum. Oxidation rate seemed to be influenced by the amount of pro-oxidant additive, the chemical structure and morphology of the plastic samples, and the surface area. Composting studies during a 45-day experiment showed that the percentage elongation (reduction) was 20% for McD samples [high-density polyethylene, (HDPE) with 3% additive] and LL samples (LLDPE with 7% additive) and 18% reduction for totally degradable plastic (TDP) samples (HDPE with 3% additive). Lastly, microbial experiments using Pseudomonas aeroginosa on carbon-free media with degradable plastic samples as the sole carbon source, showed confirmatory results. A positive bacterial growth and a weight loss of 2.2% for degraded polyethylene samples were evident to show that the degradable plastic is biodegradable.

  9. Confined assembly of asymmetric block-copolymer nanofibers via multiaxial jet electrospinning.

    Science.gov (United States)

    Kalra, Vibha; Lee, Jung Hun; Park, Jay Hoon; Marquez, Manuel; Joo, Yong Lak

    2009-10-01

    Multiaxial (triaxial/coaxial) electrospinning is utilized to fabricate block copolymer (poly(styrene-b-isoprene), PS-b-PI) nanofibers covered with a silica shell. The thermally stable silica shell allows post-fabrication annealing of the fibers to obtain equilibrium self-assembly. For the case of coaxial nanofibers, block copolymers with different isoprene volume fractions are studied to understand the effect of physical confinement and interfacial interaction on self-assembled structures. Various confined assemblies such as co-existing cylinders and concentric lamellar rings are obtained with the styrene domain next to the silica shell. This confined assembly is then utilized as a template to guide the placement of functional nanoparticles such as magnetite selectively into the PI domain in self-assembled nanofibers. To further investigate the effect of interfacial interaction and frustration due to the physically confined environment, triaxial configuration is used where the middle layer of the self-assembling material is sandwiched between the innermost and outermost silica layers. The results reveal that confined block-copolymer assembly is significantly altered by the presence and interaction with both inner and outer silica layers. When nanoparticles are incorporated into PS-b-PI and placed as the middle layer, the PI phase with magnetite nanoparticles migrates next to the silica layers. The migration of the PI phase to the silica layers is also observed for the blend of PS and PS-b-PI as the middle layer. These materials not only provide a platform to further study the effect of confinement and wall interactions on self-assembly but can also help develop an approach to fabricate multilayered, multistructured nanofibers for high-end applications such as drug delivery.

  10. Study of rheological properties in modified random propylene-ethylene copolymer

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Sivelton G.; Otaguro, Harumi; Lima, Luis F.C.P.; Lugao, Ademar B. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil). Centro de Quimica e Meio Ambiente], E-mail: sgsantos@ipen.br; Artel, Beatriz W.H. [Empresa Brasileira de Radiacao Ltda (EMBRARAD), Cotia, SP (Brazil)

    2007-07-01

    The random copolymer of propylene and ethylene (RP) presents exceptional transparency and brightness; possess low transference of odor and flavor showing better relation of rigidity/impact than homopolymer of polypropylene (PP). Due to the existence of units of ethylene this copolymer has distinct characteristics than PP of the same melt flow rate, improving its processability and allowing the use in processes such as: injection and blow molding and thermoforming of the plates. In the case of the thermoforming, the melt conventional polypropylene has the tendency to collapse during the process. It is well known, that the incorporation of a second monomer diminishes drastically the melting point of the sample up to 5 deg C changing its rheological characteristic and processing conditions. Therefore, the aim of the present work is to modify the random copolymer of propylene-ethylene with melt flow of 10 g/10 min and check its properties. In this process gamma irradiation technique was used to induce chemical changes in RP in the presence of Tri-allyl-cyanurate (TAC), with concentration ranging from 0 to 5.0 mmol/100 g of the pure resin. All samples had been characterized adequately with respect to rheological properties as: viscosity at low shear rate, storage and loss modulus, as well as, the evaluation of molecular mass distribution from zero shear viscosity value ({eta}0). The improvements in the rheological properties and processability had been evaluated in term of its performance during the thermoforming vacuum process. The modified samples showed a good performance during the thermoforming process. This behavior was observed exactly when the monomer concentration increase, except in the case of 5.0 mmol, where the sample tores during thermoforming, probably due to the high degree of ramification and branching in polymer chain. (author)

  11. Photophysical characterization of pyrromethene 597 laser dye in cross-linked silicon-containing organic copolymers

    Energy Technology Data Exchange (ETDEWEB)

    Tyagi, A.; Agua, D. del [Institut II - Experimentelle und Angewandte Physik, Universitaet Regensburg, Universitaetsstrasse 31, 93053 Regensburg (Germany); Penzkofer, A. [Institut II - Experimentelle und Angewandte Physik, Universitaet Regensburg, Universitaetsstrasse 31, 93053 Regensburg (Germany)], E-mail: alfons.penzkofer@physik.uni-regensburg.de; Garcia, O.; Sastre, R. [Instituto de Ciencia y Tecnologia de Polimeros, CSIC, Juan de la Cierva 3, 28006 Madrid (Spain); Costela, A.; Garcia-Moreno, I. [Instituto de Quimica Fisica ' Rocasolano' , CSIC, Serrano 119, 28006 Madrid (Spain)

    2007-12-06

    Samples of the dipyrromethene-BF{sub 2} dye PM597 incorporated in copolymers of 3-trimethoxysilylpropyl 2-methylprop-2-enoate (TMSPMA, number of polymerizable CC double bonds: {kappa} = 1) with 2-(2-methylprop-2-enoyloxy)ethyl 2-methylprop-2-enoate (EGDMA, {kappa} = 2), [2-(hydroxymethyl)-3-prop-2-(prop-2-enoyloxymethyl)propyl] prop-2-enoate (PETA, {kappa} = 3), and [3-prop-2-enoyloxy-2,2-bis(prop-2-2-enoyloxymethyl)propyl]prop-2-enoate (PETRA, {kappa} = 4) are characterized. The fluorescence quantum distributions, fluorescence quantum yields, degrees of fluorescence polarization, and fluorescence lifetimes are measured. The radiative lifetimes are calculated from fluorescence lifetime and quantum yield. Absorption coefficient spectra are determined from transmission measurements. Absolute absorption cross-section spectra and dye concentrations are obtained by calibration to the radiative lifetimes and to saturable absorptions. Excited-state absorption cross-sections at 527 nm are determined by saturable absorption measurements. The photo-degradation is studied under cw laser excitation conditions and quantum yields of photo-degradation are extracted. The excited-state absorption cross-sections were found to be rather small, and the photo-stability turned out to be high (up to 3 million excitation cycles before degradation) making this class of dipyrromethene dye-doped polymers attractive active laser media. Structural and thermo-mechanical properties of the materials have been determined by Fourier transform infrared spectroscopy, differential scanning calorimetry, thermogravimetry, densitometry, and refractometry. They improve with increasing inter-crossing (copolymerization of TMSPMA with PETA and PETRA). The laser properties of the PM597 doped copolymers were evaluated by transverse pumping with 6 ns laser pulses at 532 nm. The best laser materials resulted to be the 7:3 and 9:1 TMSPMA-monomer copolymers.

  12. Small angle neutron scattering study on the aggregation behaviour of PEO–PPO–PEO copolymers in the presence of a hydrophobic diol

    Indian Academy of Sciences (India)

    B Bharatiya; V K Aswal; P Bahadur

    2008-11-01

    Small angle neutron scattering (SANS) measurements on aqueous solutions of four polyethylene oxide–polypropylene oxide–polyethylene oxide block copolymers (commercially known as Pluronic®)F88, P85, F127 and P123 in the presence of hydrophobic C14Diol (also known as Surfynol® 104) reveal information on micellization, micellar size and micellar transitions. While most hydrophilic F88 (with least PPO/PEO ratio) remained unimers in water at 30◦ C, other copolymers formed micellar solutions. Surfynol® 104 is sparingly soluble in water to only about ∼ 0.1 wt%, but on addition to pluronic solution, it gets incorporated in the micellar region of block copolymer which leads to increase in aggregation number and transformation of spherical to ellipsoidal micelles. The added diol-induced micellization in F88, though hydrophilic copolymers F88 and F127 did not show any appreciable micellar growth or shape changes as observed for P85 and P123 (which are comparatively more hydrophobic). The SANS results on copolymer pairs with same molecular weight PPO but different % PEO (viz. F88 and P85, F127 and P123) and with same molecular weight PEO but different PPO (F88 and F127) reveal that the copolymer with large PPO/PEO ratio facilitate micellar transition in the presence of diol. An increase in temperature and presence of added electrolyte (sodium chloride) in the solution further enhances these effects. The micellar parameters for these systems were found out using available software and are reported.

  13. Introduction of environmentally degradable parameters to evaluate the biodegradability of biodegradable polymers.

    Directory of Open Access Journals (Sweden)

    Wenbin Guo

    Full Text Available Environmentally Degradable Parameter ((EdK is of importance in the describing of biodegradability of environmentally biodegradable polymers (BDPs. In this study, a concept (EdK was introduced. A test procedure of using the ISO 14852 method and detecting the evolved carbon dioxide as an analytical parameter was developed, and the calculated (EdK was used as an indicator for the ultimate biodegradability of materials. Starch and polyethylene used as reference materials were defined as the (EdK values of 100 and 0, respectively. Natural soil samples were inoculated into bioreactors, followed by determining the rates of biodegradation of the reference materials and 15 commercial BDPs over a 2-week test period. Finally, a formula was deduced to calculate the value of (EdK for each material. The (EdK values of the tested materials have a positive correlation to their biodegradation rates in the simulated soil environment, and they indicated the relative biodegradation rate of each material among all the tested materials. Therefore, the (EdK was shown to be a reliable indicator for quantitatively evaluating the potential biodegradability of BDPs in the natural environment.

  14. Cell proliferation by silk gut incorporating FGF-2 protein microcrystals.

    Science.gov (United States)

    Kotani, Eiji; Yamamoto, Naoto; Kobayashi, Isao; Uchino, Keiro; Muto, Sayaka; Ijiri, Hiroshi; Shimabukuro, Junji; Tamura, Toshiki; Sezutsu, Hideki; Mori, Hajime

    2015-06-08

    Silk gut processed from the silk glands of the silkworm could be an ideal biodegradable carrier for cell growth factors. We previously demonstrated that polyhedra, microcrystals of Cypovirus 1 polyhedrin, can serve as versatile carrier proteins. Here, we report the generation of a transgenic silkworm that expresses polyhedrin together with human basic fibroblast growth factor (FGF-2) in its posterior silk glands to utilize silk gut as a proteinaceous carrier to protect and slowly release active cell growth factors. In the posterior silk glands, polyhedrin formed polyhedral microcrystals, and FGF-2 became encapsulated within the polyhedra due to a polyhedron-immobilization signal. Silk gut powder prepared from posterior silk glands containing polyhedron-encapsulated FGF-2 stimulated the phosphorylation of p44/p42 MAP kinase and induced the proliferation of serum-starved NIH3T3 cells by releasing bioactive FGF-2. Even after a one-week incubation at 25 °C, significantly higher biological activity of FGF-2 was observed for silk gut powder incorporating polyhedron-encapsulated FGF-2 relative to silk gut powder with non-encapsulated FGF-2. Our results demonstrate that posterior silk glands incorporating polyhedron-encapsulated FGF-2 are applicable to the preparation of biodegradable silk gut, which can protect and release FGF-2 that is produced in a virus- and serum-free expression system with significant application potential.

  15. Block copolymer templated etching on silicon.

    Science.gov (United States)

    Qiao, Yinghong; Wang, Dong; Buriak, Jillian M

    2007-02-01

    The use of self-assembled polymer structures to direct the formation of mesoscopic (1-100 nm) features on silicon could provide a fabrication-compatible means to produce nanoscale patterns, supplementing conventional lithographic techniques. Here we demonstrate nanoscale etching of silicon, applying standard aqueous-based fluoride etchants, to produce three-dimensional nanoscale features with controllable shapes, sizes, average spacing, and chemical functionalization. The block copolymers serve to direct the silicon surface chemistry by controlling the spatial location of the reaction as well as concentration of reagents. The interiors of the resulting etched nanoscale features may be selectively functionalized with organic monolayers, metal nanoparticles, and other materials, leading to a range of ordered arrays on silicon.

  16. Concentration Dependent Structure of Block Copolymer Solutions

    Science.gov (United States)

    Choi, Soohyung; Bates, Frank S.; Lodge, Timothy P.

    2015-03-01

    Addition of solvent molecules into block copolymer can induce additional interactions between the solvent and both blocks, and therefore expands the range of accessible self-assembled morphologies. In particular, the distribution of solvent molecules plays a key role in determining the microstructure and its characteristic domain spacing. In this study, concentration dependent structures formed by poly(styrene-b-ethylene-alt-propylene) (PS-PEP) solution in squalane are investigated using small-angle X-ray scattering. This reveals that squalane is essentially completely segregated into the PEP domains. In addition, the conformation of the PS block changes from stretched to nearly fully relaxed (i.e., Gaussian conformation) as amounts of squalane increases. NRF

  17. Amphiphilic copolymers for fouling-release coatings

    DEFF Research Database (Denmark)

    Noguer, Albert Camós; Olsen, Stefan Møller; Hvilsted, Søren

    Polydimethylsiloxane (PDMS) resins are extensively used as binder in fouling-release coatings due to the low critical surface energy and low elastic modulus of PDMS. These properties result in poor adhesion of the fouling organisms, which are therefore detached by hydrodynamic forces during...... navigation [1,2,3]. Other compounds are usually mixed together with the binder (e.g. silica and pigments) in order to improve the mechanical, thixotropic and visual properties of the coatings. It has ben shown, however, that these ingredients have a negative effect on the fouling-release properties...... of the coatings [1,2,4]. Together with the PDMS-system, non-reactive polymers have been used to improve the fouling-release properties of the coatings. Initially, hydrophobic siloxane-based polymers were used, which aimed to increase the hydrophobicity of the PDMS surface [5,6]. However, copolymers comprising...

  18. Biodegradable nanoparticles for gene therapy technology

    Energy Technology Data Exchange (ETDEWEB)

    Hosseinkhani, Hossein, E-mail: hosseinkhani@mail.ntust.edu.tw; He, Wen-Jie [National Taiwan University of Science and Technology (Taiwan Tech), Graduate Institute of Biomedical Engineering (China); Chiang, Chiao-Hsi [School of Pharmacy, National Defense Medical Center (China); Hong, Po-Da [National Taiwan University of Science and Technology (Taiwan Tech), Graduate Institute of Biomedical Engineering (China); Yu, Dah-Shyong [Nanomedicine Research Center, National Defense Medical Center (China); Domb, Abraham J. [The Hebrew University of Jerusalem, Institute of Drug Research, School of Pharmacy, Faculty of Medicine, Center for Nanoscience and Nanotechnology and The Alex Grass Center for Drug Design and Synthesis (Israel); Ou, Keng-Liang [College of Oral Medicine, Taipei Medical University, Research Center for Biomedical Devices and Prototyping Production (China)

    2013-07-15

    Rapid propagations in materials technology together with biology have initiated great hopes in the possibility of treating many diseases by gene therapy technology. Viral and non-viral gene carriers are currently applied for gene delivery. Non-viral technology is safe and effective for the delivery of genetic materials to cells and tissues. Non-viral systems are based on plasmid expression containing a gene encoding a therapeutic protein and synthetic biodegradable nanoparticles as a safe carrier of gene. Biodegradable nanoparticles have shown great interest in drug and gene delivery systems as they are easy to be synthesized and have no side effect in cells and tissues. This review provides a critical view of applications of biodegradable nanoparticles on gene therapy technology to enhance the localization of in vitro and in vivo and improve the function of administered genes.

  19. Biodegradable Materials for Bone Repairs: A Review

    Institute of Scientific and Technical Information of China (English)

    Lili Tan; Xiaoming Yu; Peng Wan; Ke Yang

    2013-01-01

    With attractive research and development of biomaterials,more and more opportunities have been brought to the treatments of human tissue repairs.The implant is usually no need to exist in the body accompanied with the recovery or regeneration of the tissue lesions,and the long-term effect of exotic substance to human body should be reduced as lower as possible.For this purpose,biodegradable materials,including polymers,magnesium alloys and ceramics,have attracted much attention for medical applications due to their biodegradable characters in body environment.This paper in turn introduces these three different types of widely studied biodegradable materials as well as their advantages as implants in applications for bone repairs.Relevant history and research progresses are summarized.

  20. Novel biodegradable nanocarriers for enhanced drug delivery.

    Science.gov (United States)

    Gagliardi, Mariacristina

    2016-12-01

    With the refinement of functional properties, the interest around biodegradable materials, in biorelated applications and, in particular, in their use as controlled drug-delivery systems, increased in the last decades. Biodegradable materials are an ideal platform to obtain nanoparticles for spatiotemporal controlled drug delivery for the in vivo administration, thanks to their biocompatibility, functionalizability, the control exerted on delivery rates and the complete degradation. Their application in systems for cancer treatment, brain and cardiovascular diseases is already a consolidated practice in research, while the bench-to-bedside translation is still late. This review aims at summarizing reported applications of biodegradable materials to obtain drug-delivery nanoparticles in the last few years, giving a complete overview of pros and cons related to degradable nanomedicaments.

  1. Biodegradation of resorcinol by Pseudomonas sp.

    Directory of Open Access Journals (Sweden)

    Nader Hajizadeh

    2016-11-01

    Full Text Available Objective: To investigate the ability of Pseudomonas sp. isolated from East Azarbaijan, Iran in bioremediation of resorcinol. Methods: Resorcinol biodegradation was evaluated using spectrophotometry and confirmed by gas chromatography-mass spectroscopy. Results: This isolate was able to remove up to 37.12% of resorcinol from contaminated water. Reusability experiments had confirmed the biodegradation process which produced seven intermediate compounds. These intermediates were characterized by gas chromatographymass spectroscopy technique. The products of resorcinol biodegradation were apparently 1, 4-cyclohexadiene, nonadecene, 2-heptadecanone, 1-isopropyl-2-methoxy-4-methylbenzene, hexadecanoic acid, 9-octadecenoic acid, phenol and 5-methyl-2-(1-methylethyl. Conclusions: The findings revealed that Pseudomonas sp. is able to degrade resorcinol. Because of being an indigenous organism, this isolate is more compatible with the climate of the northwest region of Iran and possibly will be used for degradation of other similar aromatic compounds.

  2. Biodegradation of resorcinol byPseudomonas sp.

    Institute of Scientific and Technical Information of China (English)

    Nader Hajizadeh; Najibeh Shirzad; Ali Farzi; Mojtaba Salouti; Azra Momeni

    2016-01-01

    ABSTRACT Objective:To investigate the ability ofPseudomonas sp. isolated from East Azarbaijan, Iran in bioremediation of resorcinol. Methods: Resorcinol biodegradation was evaluated using spectrophotometry and confirmed by gas chromatography-mass spectroscopy. Results:This isolate was able to remove up to 37.12% of resorcinol from contaminated water. Reusability experiments had confirmed the biodegradation process which produced seven intermediate compounds. These intermediates were characterized by gas chromatography-mass spectroscopy technique. The products of resorcinol biodegradation were apparently 1, 4-cyclohexadiene, nonadecene, 2-heptadecanone, 1-isopropyl-2-methoxy-4-methylbenzene, hexadecanoic acid, 9-octadecenoic acid, phenol and 5-methyl-2-(1-methylethyl). Conclusions: The findings revealed thatPseudomonas sp. is able to degrade resorcinol. Because of being an indigenous organism, this isolate is more compatible with the climate of the northwest region of Iran and possibly will be used for degradation of other similar aromatic compounds.

  3. Biodegradation of malachite green by Ochrobactrum sp.

    Science.gov (United States)

    Vijayalakshmidevi, S R; Muthukumar, Karuppan

    2014-02-01

    This study presents the biodegradation of malachite green (MG), a triphenylmethane dye, using a novel microorganism isolated from textile effluent contaminated environment. The organism responsible for degradation was identified as Ochrobactrum sp JN214485 by 16S rRNA analysis. The effect of operating parameters such as temperature, pH, immobilized bead loading, and initial dye concentration on % degradation was studied, and their optimal values were found to be 30 °C, 6, 20 g/L and 100 mg/L, respectively. The analysis showed that the extracellular enzymes were responsible for the degradation. The biodegradation of MG was confirmed by UV-visible spectroscopic and FTIR analysis. The phytotoxicity test concluded that the degradation products were less toxic compared to MG. The kinetics of biodegradation was studied and the activation energy was found to be 10.65 kcal/mol.

  4. Biodegradable Polymers and Stem Cells for Bioprinting.

    Science.gov (United States)

    Lei, Meijuan; Wang, Xiaohong

    2016-04-29

    It is imperative to develop organ manufacturing technologies based on the high organ failure mortality and serious donor shortage problems. As an emerging and promising technology, bioprinting has attracted more and more attention with its super precision, easy reproduction, fast manipulation and advantages in many hot research areas, such as tissue engineering, organ manufacturing, and drug screening. Basically, bioprinting technology consists of inkjet bioprinting, laser-based bioprinting and extrusion-based bioprinting techniques. Biodegradable polymers and stem cells are common printing inks. In the printed constructs, biodegradable polymers are usually used as support scaffolds, while stem cells can be engaged to differentiate into different cell/tissue types. The integration of biodegradable polymers and stem cells with the bioprinting techniques has provided huge opportunities for modern science and technologies, including tissue repair, organ transplantation and energy metabolism.

  5. Biodegradable Polymers and Stem Cells for Bioprinting

    Directory of Open Access Journals (Sweden)

    Meijuan Lei

    2016-04-01

    Full Text Available It is imperative to develop organ manufacturing technologies based on the high organ failure mortality and serious donor shortage problems. As an emerging and promising technology, bioprinting has attracted more and more attention with its super precision, easy reproduction, fast manipulation and advantages in many hot research areas, such as tissue engineering, organ manufacturing, and drug screening. Basically, bioprinting technology consists of inkjet bioprinting, laser-based bioprinting and extrusion-based bioprinting techniques. Biodegradable polymers and stem cells are common printing inks. In the printed constructs, biodegradable polymers are usually used as support scaffolds, while stem cells can be engaged to differentiate into different cell/tissue types. The integration of biodegradable polymers and stem cells with the bioprinting techniques has provided huge opportunities for modern science and technologies, including tissue repair, organ transplantation and energy metabolism.

  6. Single-layer electroluminescent devices based on fluorene-1H-pyrazolo[3,4-b]quinoxaline co-polymers

    Science.gov (United States)

    Pokladko-Kowar, Monika; Danel, Andrzej; Chacaga, Łukasz

    2013-11-01

    A fluorene based copolymer was synthesized for electroluminescent application. To the main chain of polymer the nitrogen heterocyclic, 1H-pyrazolo[3,4-b]quinoxaline, unit was introduced. The incorporation of this derivative tuned the emission from the blue to yellow-green one. A simple, single layered device was fabricated with the configuration ITO/PEDOT/co-poly-FLU-PQX/Ca/Mg.

  7. Nanopatterned articles produced using surface-reconstructed block copolymer films

    Energy Technology Data Exchange (ETDEWEB)

    Russell, Thomas P.; Park, Soojin; Wang, Jia-Yu; Kim, Bokyung

    2016-06-07

    Nanopatterned surfaces are prepared by a method that includes forming a block copolymer film on a substrate, annealing and surface reconstructing the block copolymer film to create an array of cylindrical voids, depositing a metal on the surface-reconstructed block copolymer film, and heating the metal-coated block copolymer film to redistribute at least some of the metal into the cylindrical voids. When very thin metal layers and low heating temperatures are used, metal nanodots can be formed. When thicker metal layers and higher heating temperatures are used, the resulting metal structure includes nanoring-shaped voids. The nanopatterned surfaces can be transferred to the underlying substrates via etching, or used to prepare nanodot- or nanoring-decorated substrate surfaces.

  8. BARRIER PROPERTY AND STRUCTURE OF ACRYLONITRILE/ACRYLIC COPOLYMERS

    Institute of Scientific and Technical Information of China (English)

    YANG Zhenghua; LI Yuesheng

    1997-01-01

    A series of acrylonitrile (AN) copolymers with methyl acrylate (MA) or ethyl acrylate (EA) as comonomer (5-23 wt%) was prepared by free-radical copolymerization. The permeability coefficients of the copolymers to oxygen and carbon dioxide were measured at 1.0 MPa and at 30 ℃, and those to water vapor also measured at 100% relative humidity and at 30 ℃. All the AN/acrylic copolymers are semicrystalline. As the acrylate content increase, the permeability coefficients of the copolymers to oxygen and carbon dioxide are increased progressively, but those to water vapor are decreased progressively. The gas permeability coefficients of the polymers were correlated with free-volume fractions or the ratio of free volume to cohesive energy.

  9. Opto-electronic devices from block copolymers and their oligomers.

    NARCIS (Netherlands)

    Hadziioannou, G

    1997-01-01

    This paper presents research activities towards the development of polymer materials and devices for optoelectronics, An approach to controlling the conjugation length and transferring the luminescence properties of organic molecules to polymers through black copolymers containing well-defined conju

  10. Thermal analytical study of polyamide copolymer/Surlyn Ionomers Blends

    Energy Technology Data Exchange (ETDEWEB)

    Qin, C.; Ding, Y.P. [Baxter Healthcare Corp., Round Lake, IL (United States)

    1993-12-31

    Thermal analytical technique was used as a screening method to study polyamide(Nylon)/ethylene-co-methacrylic acid copolymer-based ionomer(Surlyn)blends. The retardation of crystallization process from molten state of Nylon-12 by the existence of the ionomer was observed, but the crystallization of Nylon-12 can not be thwarted even at high concentration of ionomers. Zinc ionomers shows stronger effect than sodium ionomers. A Nylon copolymer, polyamide-6,6-co-polyamide-6,10, was used to blend with different ionomers and the crystallization process from molten state of Nylon copolymer could be thwarted at high concentration of zinc ionomer even at very cooling rate. Interesting cold crystallization behavior of polyamide copolymer was observed during second DSC heating cycle in the temperature range of the melting process of ionomer.

  11. HPMA and HEMA copolymer bead interactions with eukaryotic cells

    Directory of Open Access Journals (Sweden)

    Cristina D. Vianna-Soares

    2004-09-01

    Full Text Available Two different hydrophilic acrylate beads were prepared via aqueous suspension polymerization. Beads produced of a hydroxypropyl methacrylate (HPMA and ethyleneglycol methacrylate (EDMA copolymer were obtained using a polyvinyl alcohol suspending medium. Copolymers of 2hydroxyethyl methacrylate (HEMA, methyl methacrylate (MMA and ethyleneglycol methacrylate (EDMA beads were obtained using magnesium hydroxide as the suspending agent. Following characterization by scanning electron microscopy (SEM, nitrogen sorption analysis (NSA and mercury intrusion porosimetry (MIP, the beads were cultured with monkey fibroblasts (COS7 to evaluate their ability to support cell growth, attachment and adhesion. Cell growth behavior onto small HPMA/EDMA copolymer beads and large HEMA/MMA/EDMA copolymer beads is evaluated regarding their hidrophilicity/hidrophobicity and surface roughness.

  12. Synthesis of Polyacrylate/Polysiloxane Copolymer and Its Damping Performance

    Institute of Scientific and Technical Information of China (English)

    夏宇正; 石淑先; 焦书科; 李素青

    2003-01-01

    The copolymer of polyacrylate/polysiloxane for vibration damping materials was synthesized through emulsion polymerization. The effects of the amount of methyl methacrylate (MMA),polysiloxane containing vinyl, initiator and emulsifier on the conversion, stability of polyacrylate/polysiloxane emulsion were discussed when the emulsion was prepared by pre-emulsifying half continuous method. The graft copolymer has good vibration damping performance. The widest glass transition region of the copolymer spans 100℃, and the highest value of tanδ reached 2.0. The glass transition of the samples was examined by dynamic mechanical analysis (DMA). The vibration damping performance of the graft copolymer was affected by the amount of poly-vinyl dimethylsiloxane (PVMS).

  13. 21 CFR 177.1950 - Vinyl chloride-ethylene copolymers.

    Science.gov (United States)

    2010-04-01

    ... the production of such basic copolymers. The optional adjuvant substances required in the production... is cooled and an equal volume of acetone is added. (e) The solution is titrated with 0.005 N...

  14. Composition fluctuations in homopolymer blends and diblock copolymers

    DEFF Research Database (Denmark)

    Frielinghaus, H.; Mortensen, K.; Almdal, K.

    2000-01-01

    The thermal composition fluctuations of a deuterogenous polystyrene/polyethyleneoxide (dPS/PEO) homopolymer blend and corresponding diblock copolymer have been investigated by small angle neutron scattering (SANS). The measured susceptibilities could be described by theories, which take strong...

  15. Thermal Stability of Poly (acrylonitrile-methyl acrylate) Copolymers

    Institute of Scientific and Technical Information of China (English)

    HAN Na; ZHANG Xing-xiang; WANG Xue-chen

    2008-01-01

    Poly (acrylonitrile-methyl acrylate) copolymer was synthesized by water depositing polymerization and has a typical feed ratio of 85/15. And then 1 - 3 wt% lauryl alcohol maleic anhydride (LAM) was adopted as stabilizer to mix with the acrylonitrile based copolymer. The mixtures were characterized by using Fourier Transform Infrared Spectroscopy (FTIR), Nuclear Magnetic Resonance (1H NMR ), Gel Permeation Chromatography ( GPC ), Differential Scanning Calorimetry (DSC), optic microscope and Ubbelohde viscosimetryr etc. The melting point (Tm) and glass transition temperature (Tg) of the 85/15 AN/MA copolymer mixed with LAM all decrease with the increase of stabilizer content. The lowest Tg and Tm were 116.1 ℃ and 209. 1℃ respectively at the heating rate of 100℃/min when the content of LAM is 2 wt%. The 85°/15 AN/MA copolymer mixed with 1 - 3 w t% LAM possess good thermal stability up to 30 min at 220 ℃.

  16. Synthesis of CO2 Copolymer Based Polyurethane Foams

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    CO2-copolymer based polyurethane foams were synthesized and characterized in this paper. The foams were found to have higher strength and lower heat of combustion than the conventional polyether polyurethane foams. They may find wide applications in many fields.

  17. Preparation and modification of itaconic anhydride–methyl methacrylate copolymers

    Directory of Open Access Journals (Sweden)

    MILOS B. MILOVANOVIC

    2007-12-01

    Full Text Available The free radical copolymerisation of itaconic anhydride and methyl methacrylate in solution was studied at 60 °C. The copolymer composition was determined by 1H-NMR spectroscopy and the obtained monomer reactivity ratios were calculated, rITA = 1.35±0.11; rMMA = 0.22±0.22 (by the Fineman–Ross method and rITA = 1.27±0.38; rMMA = 0.10±0.05 (by the Mayo–Lewis method. The synthesised copolymers were modified by reaction with di-n-butyl amine. The copolymer composition after amidation was determined by elemental analysis via the nitrogen content. Amidation of the anhydride units in the copolymers with di-n-butyl amine resulted in complete conversion to itaconamic acid.

  18. Fluctuations, conformational asymmetry and block copolymer phase behaviour

    DEFF Research Database (Denmark)

    Bates, F.S.; Schulz, M.F.; Khandpur, A.K.;

    1994-01-01

    Phase behaviour near the order-disorder transition (ODT) of 58 model hydrocarbon diblock copolymers, representing four different systems, is summarized. Six distinct ordered-state microstructures are reported, including hexagonally modulated lamellae (HML), hexagonally perforated layers (HPL) and...

  19. Multicompartmental Microcapsules from Star Copolymer Micelles

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Ikjun; Malak, Sidney T.; Xu, Weinan; Heller, William T.; Tsitsilianis, Constantinos; Tsukruk, Vladimir V.

    2013-02-26

    We present the layer-by-layer (LbL) assembly of amphiphilic heteroarm pH-sensitive star-shaped polystyrene-poly(2-pyridine) (PSnP2VPn) block copolymers to fabricate porous and multicompartmental microcapsules. Pyridine-containing star molecules forming a hydrophobic core/hydrophilic corona unimolecular micelle in acidic solution (pH 3) were alternately deposited with oppositely charged linear sulfonated polystyrene (PSS), yielding microcapsules with LbL shells containing hydrophobic micelles. The surface morphology and internal nanopore structure of the hollow microcapsules were comparatively investigated for shells formed from star polymers with a different numbers of arms (9 versus 22) and varied shell thickness (5, 8, and 11 bilayers). The successful integration of star unimers into the LbL shells was demonstrated by probing their buildup, surface segregation behavior, and porosity. The larger arm star copolymer (22 arms) with stretched conformation showed a higher increment in shell thickness due to the effective ionic complexation whereas a compact, uniform grainy morphology was observed regardless of the number of deposition cycles and arm numbers. Small-angle neutron scattering (SANS) revealed that microcapsules with hydrophobic domains showed different fractal properties depending upon the number of bilayers with a surface fractal morphology observed for the thinnest shells and a mass fractal morphology for the completed shells formed with the larger number of bilayers. Moreover, SANS provides support for the presence of relatively large pores (about 25 nm across) for the thinnest shells as suggested from permeability experiments. The formation of robust microcapsules with nanoporous shells composed of a hydrophilic polyelectrolyte with a densely packed hydrophobic core based on star amphiphiles represents an intriguing and novel case of compartmentalized microcapsules with an ability to simultaneously store different hydrophilic, charged, and hydrophobic

  20. Histological evaluation of different biodegradable and non-biodegradable membranes implanted subcutaneously in rats

    DEFF Research Database (Denmark)

    Zhao, S; Pinholt, E M; Madsen, J E

    2000-01-01

    Different types of biodegradable membranes have become available for guided tissue regeneration. The purpose of this study was to evaluate histologically three different biodegradable membranes (Bio-Gide, Resolut and Vicryl) and one non-biodegradable membrane (expanded polytetrafluoroethylene/e-PTFE...... that e-PTFE was well tolerated and encapsulated by a fibrous connective tissue capsule. There was capsule formation around Resolut and Vicryl and around Bio-Gide in the early phase there was a wide inflammatory zone already. e-PTFE and Vicryl were stable materials while Resolut and Bio-Gide fragmented...

  1. Soluble Eggshell Mebrane Protein:Antibacterial Property and Biodegradability

    Institute of Scientific and Technical Information of China (English)

    YI Feng; YU Jian; LI Qiang; GUO Zhaoxia

    2007-01-01

    The antibacterial property and biodegradability of soluble eggshell membrane protein (SEP)are reported. Unlike the natural eggshell membrane (ESM), SEP does not possess antibacterial property against E.coli. The biodegradation tests with trypsin show that both ESM and SEP are biodegradable.

  2. Biocompatibility Assessment of PLCL-Sericin Copolymer Membranes Using Wharton’s Jelly Mesenchymal Stem Cells

    Directory of Open Access Journals (Sweden)

    Kewalin Inthanon

    2016-01-01

    Full Text Available Stem cells based tissue engineering requires biocompatible materials, which allow the cells to adhere, expand, and differentiate in a large scale. An ideal biomaterial for clinical application should be free from mammalian products which cause immune reactivities and pathogen infections. We invented a novel biodegradable poly(L-lactic-co-ε-caprolactone-sericin (PLCL-SC copolymer membrane which was fabricated by electrospinning. Membranes with concentrations of 2.5 or 5% (w/v SC exhibited qualified texture characteristics with a noncytotoxic release profile. The hydrophilic properties of the membranes were 35–40% higher than those of a standard PLCL and commercial polystyrene (PS. The improved characteristics of the membranes were due to an addition of new functional amide groups, C=O, N–H, and C–N, onto their surfaces. Degradation of the membranes was controllable, depending on the content proportion of SC. Results of thermogram indicated the superior stability and crystallinity of the membranes. These membranes enhanced human Wharton’s jelly mesenchymal stem cells (hWJMSC proliferation by increasing cyclin A and also promoted cell adhesion by upregulating focal adhesion kinase (FAK. On the membranes, hWJMSC differentiated into a neuronal lineage with the occurrence of nestin. These data suggest that PLCL-SC electrospun membrane represents some properties which will be useful for tissue engineering and medical applications.

  3. Water soluble graft copolymer ({kappa}-carrageenan-g-N-vinyl formamide): preparation, characterization and application

    Energy Technology Data Exchange (ETDEWEB)

    Mishra, M.M.; Yadav, M.; Sand, A.; Tripathy, J.; Behari, K. [University of Allahabad, Allahabad (India). Dept. of Chemistry

    2010-03-25

    {kappa}-Carrageenan-g-N-vinyl formamide was synthesized by free radical initiation using the potassium monopersulphate (PMS)/malonic acid redox pair in an inert atmosphere. The effects of variation of different reactant oil grafting parameters have been studied by varying the concentration. Grafting ratio, add on and conversion showed an increasing trend on increasing the concentration of N-vinyl formamide, malonic acid, kappa-carrageenart and the concentration of PMS from 6 x 10{sup -3} to 22 x 10{sup -3} mol dm{sup -3}. The optimum temperature and time for grafting of N-vinyl formamide onto {kappa}-carrageenan was found to be 40{sup o}C and 120 min, respectively. The metal ion sorption, swelling behaviour, flocculation and resistance to biodegradation properties have been studied. Flocculation capability of {kappa}-carrageenart and {kappa}-carrageenan-g-N-vinyl formamide for both coking and non-coking coals has been studied for the treatment of coal mine waste water. The graft copolymer was characterized by FT-IR spectroscopy and thermogravimetric analysis.

  4. The effect of gamma-radiation on biodegradability of natural FIBER/PP-HMSPP foams: A study of thermal stability and biodegradability

    Energy Technology Data Exchange (ETDEWEB)

    Cardoso, Elizabeth C.L.; Scagliusi, Sandra R.; Lugao, Ademar B., E-mail: eclcardo@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2015-07-01

    This research was carried out to evaluate how gamma-radiation affected PP/HMSPP structural foams reinforced with sugarcane bagasse, in terms of thermal properties, biodegradability and infrared spectrum. Polymers are used in various applications and in different industrial areas providing enormous quantities of wastes in environment, contributing with 20 to 30% of total volume of solid residues. Besides, shortage of plastics resins obtained from oil and natural gas is addressing research and development toward alternative materials; environmental concerning in litter reduction is being directed to renewable polymers for manufacturing of polymeric foams. Biodegradable polymers, a new generation of polymers produced from various natural resources, environmentally safe and friendly, can contribute for pollution reduction, at a low cost. High density structural foams are specially used in civil construction, in replacement of metals, woods and concrete, but contribute for environmental pollution, due to components nature. In this study, it was incorporated sugarcane bagasse in PP/HMSPP polymeric matrix blends. Gamma radiation applied at 50, 100, 150, 200 and 500 kGy doses showed effective for biodegradability induction. TGA analyses pointed toward stability around 205 deg C; decomposition of both cellulose and hemicellulose took place at 310 deg C and above, whereas the degradation of reinforced fibers composites took place above 430 deg C. Infrared spectrum of foams were studied using FTIR, showing no sensitivity to the presence of C = C and C =O functional groups. (author)

  5. Preparation of Porous Biodegradable Polymer and Its Nanocomposites by Supercritical CO2 Foaming for Tissue Engineering

    Directory of Open Access Journals (Sweden)

    Xia Liao

    2012-01-01

    Full Text Available Using supercritical carbon dioxide (scCO2 as an alternative to conventional methods in the preparation of porous biodegradable polymer and polymer/nanocomposites for tissue engineering has attracted increasing interest in recent years due to the absence of using organic solvents and the ability to incorporate thermosensitive biologicals without loss of bioactivity. Additionally, scCO2 can exert a high level of control over porosity and morphology of scaffolds by tuning the processing parameters. This paper describes the newly achievements on the preparation of porous polymer materials using scCO2 foaming technology with focus on the porous biodegradable materials and its nanocomposites relevant to tissue engineering.

  6. Thin Film Assembly of Spider Silk-like Block Copolymers

    Science.gov (United States)

    2011-01-01

    Film Assembly of Spider Silk -like Block Copolymers Sreevidhya T. Krishnaji,†,‡ Wenwen Huang,§ Olena Rabotyagova,†,‡ Eugenia Kharlampieva, ) Ikjun Choi...Received November 26, 2010 We report the self-assembly of monolayers of spider silk -like block copolymers. Langmuir isotherms were obtained for a series of...bioengineered variants of the spider silks , and stable monolayers were generated. Langmuir-Blodgett films were prepared by transferring the monolayers

  7. SYNTHESIS OF A NEW SILICONE-CONTAINING BISMALEIMIDE COPOLYMER RESIN

    Institute of Scientific and Technical Information of China (English)

    KUANG Wenfeng; CAI Xingxian; JIANG Luxia

    1997-01-01

    A copolymer of bismaleimide-diallylbisphenol A-diphenylsilandiol was synthesized and the copolymerization was studied by using N-phenylmaleimide, bisphenol A and diphenylsilandiol as model compounds. The copolymer could be well cured around 200 ℃, and the cured resins had good thermal stability. In the range of 170-210 ℃, a higher curing temperature was favorable to obtain more thermal stable resin by reducing the content of diphenylsilandiol cyclo-homopolymer in resin which would spoil its thermal stability.

  8. Synthesis and characterization of HPMA copolymer-5-FU conjugates

    Institute of Scientific and Technical Information of China (English)

    Fang Yuan; Fu Chen; Qing Yu Xiang; Xuan Qin; Zhi Rong Zhang; Yuan Huang

    2008-01-01

    N-(2-Hydroxypropyl)methacrylamide copolymer-5-fluorouracil (PHPMA-FU)conjugates were synthesized by a novel and simplified synthetic mute,and characterized by UV,FTIR and HPLC analyses.The conjugated content of 5-fluorouracil (5-FU)was 3.41 ± 0.07 wt%.The stabilities of PHPMA-FU conjugates under different conditions were studied.The results showed that HPMA copolymer was a potential carrier for tumor-targeting delivery of 5-FU.

  9. Self-Assembled Antimicrobial and biocompatible copolymer films on Titanium

    OpenAIRE

    2011-01-01

    Biofilm formation on biomedical devices such as dental implants can result in serious infections and finally in device failure. Polymer coatings which provide antimicrobial action to surfaces without compromising the compatibility with human tissue are of great interest. Copolymers of 4-vinyl-N-hexylpyridinium bromide and dimethyl(2-methacryloyloxyethyl) phosphonate are interesting candidates in this respect. These copolymers form ultrathin polycationic layers on titanium surfaces. As the cop...

  10. Biodegradable containers from green waste materials

    Science.gov (United States)

    Sartore, Luciana; Schettini, Evelia; Pandini, Stefano; Bignotti, Fabio; Vox, Giuliano; D'Amore, Alberto

    2016-05-01

    Novel biodegradable polymeric materials based on protein hydrolysate (PH), derived from waste products of the leather industry, and poly(ethylene glycol) diglycidyl ether (PEG) or epoxidized soybean oil (ESO) were obtained and their physico-chemical properties and mechanical behaviour were evaluated. Different processing conditions and the introduction of fillers of natural origin, as saw dust and wood flour, were used to tailor the mechanical properties and the environmental durability of the product. The biodegradable products, which are almost completely manufactured from renewable-based raw materials, look promising for several applications, particularly in agriculture for the additional fertilizing action of PH or in packaging.

  11. MALDI-ToF Analysis of Model Copolymer Blends

    Science.gov (United States)

    Pan, David; Arnould, Mark

    2008-03-01

    MALDI-ToF mass spectrometry was used to determine the composition of a low MW styrene (S) / n-butyl acrylate (nBA) copolymer. Bernoullian chain statistics were used to predict the copolymer distribution and confirm that MALDI-ToF detects the correct composition. The copolymer was blended with a low MW polystyrene homopolymer having the same end group as the copolymer at several levels to determine if MALDI-ToF could be used to calculate the amount of homopolymer by subtracting homopolymer peak areas. It is found that, while MALDI-ToF can be used to monitor the amount of homopolymer blended into the copolymer, the observed increase is always greater than the actual amount added, e.g. up to 13% error. This could be due to the fact that the homopolymer ionizes more efficiently than the low MW copolymer. A model to improve the accuracy of the calculated amount of homopolymer in the blend is discussed.

  12. DNA Island Formation on Binary Block Copolymer Vesicles.

    Science.gov (United States)

    Luo, Qingjie; Shi, Zheng; Zhang, Yitao; Chen, Xi-Jun; Han, Seo-Yeon; Baumgart, Tobias; Chenoweth, David M; Park, So-Jung

    2016-08-17

    Here, we report DNA-induced polymer segregation and DNA island formation in binary block copolymer assemblies. A DNA diblock copolymer of polymethyl acrylate-block-DNA (PMA-b-DNA) and a triblock copolymer of poly(butadiene)-block-poly(ethylene oxide)-block-DNA (PBD-b-PEO-b-DNA) were synthesized, and each was coassembled with a prototypical amphiphilic polymer of poly(butadiene)-block-poly(ethylene oxide) (PBD-b-PEO). The binary self-assembly of PMA-b-DNA and PBD-b-PEO resulted in giant polymersomes with DNA uniformly distributed in the hydrophilic PEO shell. When giant polymersomes were connected through specific DNA interactions, DNA block copolymers migrated to the junction area, forming DNA islands within polymersomes. These results indicate that DNA hybridization can induce effective lateral polymer segregation in mixed polymer assemblies. The polymer segregation and local DNA enrichment have important implications in DNA melting properties, as mixed block copolymer assemblies with low DNA block copolymer contents can still exhibit useful DNA melting properties that are characteristic of DNA nanostructures with high DNA density.

  13. Approaching two-dimensional copolymers: photoirradiation of anthracene- and diaza-anthracene-bearing monomers in Langmuir monolayers.

    Science.gov (United States)

    Payamyar, Payam; Servalli, Marco; Hungerland, Tim; Schütz, Andri P; Zheng, Zhikun; Borgschulte, Andreas; Schlüter, A Dieter

    2015-01-01

    By using structurally similar amphiphilic monomers, it is shown that compressed monolayers of varying amounts of such monomers at the air/water interface can be converted by photo-irradiation into the corresponding covalently connected monolayer sheets. Since one of the monomers carries three anthracene units and the other three 1,8-diaza-anthracene units, the growth reaction is proposed to take place through photochemically achieved [4+4]-cycloaddition between pairs of these units that are co-facially (face-to-face) arranged, to furnish the corresponding covalent dimers. While evidence for both homodimers is amply available, the existence of the heterodimer needs to be established with the help of a model reaction to support the conceptual aspect of this work, copolymerization in two dimensions. The sheet copolymers exhibit substantial robustness in that they can be spanned over 20 × 20 μm(2)-sized holes without rupturing under their own weight. X-ray photoelectron spectroscopy (XPS) studies reveal that the monomers are incorporated into the sheet copolymers according to feed. These results establish existence of the first covalent sheet copolymer, which is considered a step ahead towards novel 2D materials.

  14. Oligomeric Dithienopyrrole-Thienopyrrolodione (DTP-TPD) Donor-Acceptor Copolymer for Organic Photovoltaics: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Hammond, S. R.; Braunecker, W.; Garcia, A.; Larsen, R.; Owczarczyk, Z.; Olson, D.; Ginley, D.

    2011-07-01

    A new donor-acceptor copolymer system based upon a dithienopyrrole (DTP) donor moiety and a thienopyrrolodione (TPD) accepting moiety has been designed and synthesized for organic photovoltaic (OPV) applications. The TPD accepting moiety has recently gained significant attention in the OPV community and is being incorporated into a number of different polymer systems. In contrast, the DTP donor moiety has received only limited attention, likely due in part to synthetic difficulties relating to the monomer. In our hands, the bis(trimethyltin)-DTP monomer was indelibly contaminated with ~5% of the mono-destannylated DTP, which limited the Stille polymerization with the dibromo-TPD monomer (>99% pure) to produce material with Mn ~ 4130 g/mol (PDI = 1.10), corresponding to around eight repeat units. Despite this limitation, UV-visible absorption spectroscopy demonstrates strong absorption for this material with a band gap of ~1.6 eV. Cyclic voltammetry indicates a highest occupied molecular orbital (HOMO) energy level of -5.3 eV, which is much lower than calculations predicted. Initial bulk heterojunction OPV devices fabricated with the fullerene acceptor phenyl C61 butyric acid methyl ester (PCBM) exhibit Voc ~ 700 mV, which supports the deep HOMO value obtained from CV. These results suggest the promise of this copolymer system.

  15. Novel Injectable Pentablock Copolymer Based Thermoresponsive Hydrogels for Sustained Release Vaccines.

    Science.gov (United States)

    Bobbala, Sharan; Tamboli, Viral; McDowell, Arlene; Mitra, Ashim K; Hook, Sarah

    2016-01-01

    The need for multiple vaccinations to enhance the immunogenicity of subunit vaccines may be reduced by delivering the vaccine over an extended period of time. Here, we report two novel injectable pentablock copolymer based thermoresponsive hydrogels made of polyethyleneglycol-polycaprolactone-polylactide-polycaprolactone-polyethyleneglycol (PEG-PCL-PLA-PCL-PEG) with varying ratios of polycaprolactone (PCL) and polylactide (PLA), as single shot sustained release vaccines. Pentablock copolymer hydrogels were loaded with vaccine-encapsulated poly lactic-co-glycolic acid nanoparticles (PLGA-NP) or with the soluble vaccine components. Incorporation of PLGA-NP into the thermoresponsive hydrogels increased the complex viscosity of the gels, lowered the gelation temperature, and minimized the burst release of antigen and adjuvants. The two pentablock hydrogels stimulated both cellular and humoral responses. The addition of PLGA-NP to the hydrogels sustained immune responses for up to 49 days. The polymer with a higher ratio of PCL to PLA formed a more rigid gel, induced stronger immune responses, and stimulated effective anti-tumor responses in a prophylactic melanoma tumor model.

  16. Influence of copolymer composition on the transport properties of conducting copolymers: poly(aniline-co-o-anisidine)

    Indian Academy of Sciences (India)

    S S Umare; A D Borkar; M C Gupta

    2002-06-01

    The effect of different compositions of monomers on the transport properties of copolymers by various techniques such as optical, electrical and magnetic has been investigated and compared with the homopolymers. The UV-visible absorption spectra show a hypsochromic shift with an increase in the o-anisidine content in copolymers indicating a decrease in the extent for conjugation (i.e. an increase in the bandgap). From temperature dependence of electrical conductivity the transport parameters such as charge localization length and average hopping distance are calculated and also the effect of the monomeric composition on the coherence length has been discussed. The magnetic studies show the paramagnetic and diamagnetic nature of homopolymers and copolymers. The X-ray diffraction pattern indicates that the copolymers are of amorphous nature.

  17. Comparative study on the biodegradation and biocompatibility of silicate bioceramic coatings on biodegradable magnesium alloy as biodegradable biomaterial

    Science.gov (United States)

    Razavi, M.; Fathi, M. H.; Savabi, O.; Razavi, S. M.; Hashemibeni, B.; Yazdimamaghani, M.; Vashaee, D.; Tayebi, L.

    2014-03-01

    Many clinical cases as well as in vivo and in vitro assessments have demonstrated that magnesium alloys possess good biocompatibility. Unfortunately, magnesium and its alloys degrade too quickly in physiological media. In order to improve the biodegradation resistance and biocompatibility of a biodegradable magnesium alloy, we have prepared three types of coating include diopside (CaMgSi2O6), akermanite (Ca2MgSi2O6) and bredigite (Ca7MgSi4O16) coating on AZ91 magnesium alloy through a micro-arc oxidation (MAO) and electrophoretic deposition (EPD) method. In this research, the biodegradation and biocompatibility behavior of samples were evaluated in vitro and in vivo. The in vitro analysis was performed by cytocompatibility and MTT-assay and the in vivo test was conducted on the implantation of samples in the greater trochanter of adult rabbits. The results showed that diopside coating has the best bone regeneration and bredigite has the best biodegradation resistance compared to others.

  18. Stable material modication with polymers incorporation for broad application in microfabrication

    DEFF Research Database (Denmark)

    Mednova, Olga

    The aim of this thesis is to improve SU-8 fracture resistance in order to eliminate micro crack formation during fabrication of microelectromechanical system (MEMS). An amphiphilic block copolymer incorporation, as an efficient method of material toughening without changing its original properties......, is successfully applied. The novelty of the study consists in design and synthesis of the most optimal copolymer composition, which can self-assemble in SU-8 resin. In the first part of the thesis, solubility prediction with the Hansen Solubility Parameters method is described in details and poly(ethyl ethylene...... analytical techniques. The second part of the thesis describes modified SU-8 blends. Thermal stability, structural organization, components interaction, hardness and brittleness of the composites are described. Finally, lithographic properties of modified SU-8 blends have been tested. Commercial SU-8...

  19. Immediate implant placement using a biodegradable barrier, polyhydroxybutyrate-hydroxyvalerate reinforced with polyglactin 910. An experimental study in dogs

    DEFF Research Database (Denmark)

    Gotfredsen, K; Nimb, L; Hjørting-Hansen, E

    1994-01-01

    extracted bilaterally. Each dog had 4 Astra Dental Implants placed directly into the fresh extraction sockets. The top of the fixtures was placed at the same level as the top of the buccal cortical bone. The two implants in the right side were covered with the hydrolyzable polyester material......The purpose of this study was to evaluate the use of a biodegradable membrane of polyhydroxybutyrate-hydroxyvalerate copolymer reinforced with polyglactin 910 fibers, as an occlusive barrier over implants placed into fresh extraction sockets. Ten dogs had the 3rd and 4th mandibular premolars...... (polyhydroxybutyrate-hydroxyvalerate reinforced with polyglactin 910 fibers; PHB-HV/PG), and the 2 implants in the left side were controls without occlusive membranes. Soft tissue dehiscences were registered for half of the implants in the test side but were not noted in the control side. The histomorphological...

  20. The research and preparation of a bi-layer biodegradable external sheath with directional drug release profiles for vein graft

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Zhenjie, E-mail: lawson3001@gmail.com [Department of Surgery, Sir Run Run Shaw Hospital, Zhejiang University, Hangzhou (China); Institute of Vascular Surgery, Fudan University, Shanghai (China); Department of Surgery, University of Wisconsin-Madison, WI (United States); Guo, Zhenying [Department of Pathology, Zhejiang Cancer Hospital, Hangzhou (China); Si, Yi [Department of Surgery, University of Wisconsin-Madison, WI (United States); Zhang, Xiangman; Shi, Zhenyu [Institute of Vascular Surgery, Fudan University, Shanghai (China); Chen, Feng [College of Chemical Engineering and Material Science, Zhejiang University of Technology, Hangzhou (China); Fu, Weiguo [Institute of Vascular Surgery, Fudan University, Shanghai (China)

    2013-11-01

    External sheath has been suggested for autologous vein grafts to inhibit neointimal hyperplasia and prevent anastomosis stricture. In this study, we prepared a bi-layer biodegradable paclitaxel-loaded sheaths with a synthetic copolymer poly(ethylene carbonate-ε-caprolactone) at room temperature. The bi-layer drug release profiles of the Paclitaxel-loaded (PTX-loaded) sheath significantly slow down the paclitaxel (PTX) release rates and result in a directional drug release way. Moreover, the nanofibrous layer of PTX-loaded poly(EC-CL) sheaths reduced the cytotoxicity and provided a better support for fibroblast adhesion and proliferation than the PTX-loaded layer of the sheaths. Thus, this study demonstrates that the bi-layer PTX-loaded poly(EC-CL) sheath with directional drug release profiles have a promising application for vein graft to against neointimal hyperplasia and anastomotic stricture.

  1. LOW DENSITY POLYETHYLENE/CLAY NANOCOMPOSITES MODIFIED BY ETHYLENE COPOLYMERS: EFFECTS OF FUNCTIONALIZED SEGMENTS ON MORPHOLOGY

    Institute of Scientific and Technical Information of China (English)

    Bo Xu; Yi-hu Song; Yong-gang ShangGuan; Qiang Zheng

    2006-01-01

    Melt extrusion was used to prepare binary nanocomposites of ethylene copolymers and organoclay and trinary nanocomposites of low-density polyethylene (LDPE), ethylene copolymer and organoclay. X-ray diffraction (XRD) and transmission electron microscopy (TEM) were used to analyze the structure of the clay phase and the morphology of the nanocomposites. Influences of the comonomer in the copolymer and the content of the copolymer on the morphology of the resulting nanocomposites were discussed. The binary and the trinary composites may form intercalated or exfoliated structures depending on the interaction between the copolymer and the clay layers and the content of the copolymer.

  2. Real-time monitoring of the penetration of amphiphilic acrylate copolymer in leather using a fluorescent copolymer as tracer.

    Science.gov (United States)

    Du, Jin-Xia; Shi, Lu; Peng, Bi-Yu

    2015-12-01

    A fluorescent tracer, poly (acrylic-co-stearyl acrylate-co-3-acryloyl fluorescein) [poly (AA-co-SA-co-Ac-Flu)], used for real-time monitoring the penetration of amphiphilic acrylate copolymer, poly (acrylic-co-stearyl acrylate) [poly (AA-co-SA)], in leather was synthesized by radical polymerization of acrylic, stearyl acrylate and fluorescent monomer, 3-acryloyl fluorescein (Ac-Flu). The structure, molecular weight, introduced fluorescent group content and fluorescent characteristics of the fluorescent tracer and target copolymer, amphiphilic acrylate copolymer, were also characterized. The results show that the tracer presents the similar structural characteristics to the target and enough fluorescence intensity with 1.68 wt % of the fluorescent monomer introduced amount. The vertical section of the leather treated with the target copolymer mixing with 7% of the tracer exhibits evident fluorescence, and the change of fluorescence intensity along with the vertical section with treating time increasing can reflect the penetration depth of the target copolymer. The introduction of the fluorescent group in polymer structure through copolymerization with a limited amount of fluorescent monomer, Ac-Flu, is an effective way to make a tracer to monitor the penetration of the target in leather, which provides a new thought for the penetration research of syntans such as vinyl copolymer materials in leather manufacture.

  3. Preparation of epoxy resin copolymers with low luminous decay%低光衰环氧树脂共聚物的制备

    Institute of Scientific and Technical Information of China (English)

    冯钠; 张小扉; 张桂霞; 陈涛; 王旭

    2011-01-01

    Copolymers of epoxy resin grafted by hydroxy-terminated silicone(EP-g-HTPDMS) with low luminous decay were prepared by graft condensation polymerization from EP and HTPDMS. The structure of the EP-g-HTPDMS copolymers was characterized by Fourier transform infrared spectroscopy(FTIR) and therm ogravimetric(TG) analysis. The EP-g-HTPDMS copolymers were applied to package of light-emitting diode, and its optical properties were studied by luminous decay and refractive index test. The mechanical properties and micro-morphology of the copolymers were analyzed by hardness tester and scanning electron microscope(SEM). The results indicate that HTPDMS is successfully incorporated into EP molecular chain.Adding HTPDMS has unobvious effect on the refractive index of the copolymers. When HTPDMS mass content is less than 9%, the relative light output of the EP-g-HTPDMS copolymers is higher than that of unmodified EP and luminous decay reduces significantly. The hardness of the copolymers decreases with increasing HTPDMS mass content. The introduction of HTPDMS makes the copolymer exhibit the features of tough fracture, lowers the internal stress in the system and improves the resistance to cracking.%采用接枝缩聚的方法,将端羟基硅酮(HTPDMS)与环氧树脂(EP)反应,制备低光衰HTPDMS接枝EP(EP-g-HTPDMS)共聚物.利用傅里叶变换红外光谱和热重分析表征其结构,并将制备的EP-g-HTPDMS共聚物应用于发光二级管封装,通过测试光衰和折射率分析其光学性能,同时利用硬度测试仪和扫描电子显微镜研究其力学性能和微观结构.结果表明:HTPDMS成功接枝在EP分子链中;引入HTPDMS对共聚物折射率的影响并不明显,当w(HTPDMS)小于9%时,共聚物的相对输出功率均高于EP,光衰明显降低;随着w(HTPDMS)增加,共聚物的硬度减小;引入HTPDMS使共聚物断面呈韧性断裂,体系的内应力降低,抗开裂性能得到改善.

  4. Biodegradable starch-based polymeric materials

    Science.gov (United States)

    Suvorova, Anna I.; Tyukova, Irina S.; Trufanova, Elena I.

    2000-05-01

    The effects of low-molecular-weight additives, temperature and mechanical action on the structure and properties of starch are discussed. Special attention is given to mixtures of starch with synthetic polymers, e.g., co-polymers of ethylene with vinyl acetate, vinyl alcohol, acrylic acid, cellulose derivatives and other natural polymers. These mixtures can be used in the development of novel environmentally safe materials (films, coatings, packaging materials) and various articles for short-term use. The bibliography includes 105 references.

  5. Biodegradability of leathers through anaerobic pathway.

    Science.gov (United States)

    Dhayalan, K; Fathima, N Nishad; Gnanamani, A; Rao, J Raghava; Nair, B Unni; Ramasami, T

    2007-01-01

    Leather processing generates huge amounts of both solid and liquid wastes. The management of solid wastes, especially tanned leather waste, is a challenging problem faced by tanners. Hence, studies on biodegradability of leather become imperative. In this present work, biodegradability of untanned, chrome tanned and vegetable tanned leather under anaerobic conditions has been addressed. Two different sources of anaerobes have been used for this purpose. The effect of detanning as a pretreatment method before subjecting the leather to biodegradation has also been studied. It has been found that vegetable tanned leather leads to more gas production than chrome tanned leather. Mixed anaerobic isolates when employed as an inoculum are able to degrade the soluble organics of vegetable tanned material and thus exhibit an increased level of gas production during the initial days, compared to the results of the treatments that received the anaerobic sludge. With chrome tanned materials, there was not much change in the volume of the gas produced from the two different sources. It has been found that detanning tends to improve the biodegradability of both types of leathers.

  6. Natural Biodegradation of Phenolic Compounds in Groundwater

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    A combination of field data and theoretical approaches is used to assess the natural attenuation and status of a complex plume of phenolic compounds (phenol, cresols, xylenols) in a deep, consolidated, UK Permo-Triassic sandstone aquifer. Biodegradation of the phenolic compounds at concentrations up to 12500mg·L-1 is occurring under aerobic, NO-3-reducing, Mn/Fe-reducing, SO2-4-reducing and methanogenic conditions in the aquifer, with the accumulation of inorganic and organic metabolites in the plume. An electron and carbon balance for the plume suggests that only 6% of the source term has been degraded in 50 years. The residual contaminant mass in the plume significantly exceeds estimates of electron acceptor inputs, indicating that the plume will grow. Two detailed vertical profiles through the plume show that contaminant distributions are controlled more by source history than by biodegradation processes. Microbiological and mass balance studies show that biodegradation is greatest at the plume fringe where contaminant concentrations are diluted by transverse mixing. Active bacterial populations exist throughout the plume but biodegradation is inhibited in the plume core by high contaminant concentrations. Stable isotope studies show that SO2-4-reduction is particularly sensitive to contaminant concentration. The aquifer is not oxidant-deficient but natural attenuation of the phenolic compounds in this system is limited by toxicity from the pollutant load and the bioavailability of electron acceptors. Natural attenuation of these contaminants will increase only after increased dilution of the plume.

  7. Enhancement of 4-chlorophenol biodegradation using glucose

    Energy Technology Data Exchange (ETDEWEB)

    Tarighian, Alireza; Hill, Gordon; Headley, John [Division of Environmental Engineering, University of Saskatchewan, 105 Maintenance Road, S7N 5C5, Saskatoon, SK (Canada); Pedras, Soledad [Department of Chemistry, University of Saskatchewan, 110 Science Place, S7N 5C9, Saskatoon, SK (Canada)

    2003-03-01

    Toxic, xenobiotic chemicals present challenging problems for the environment since they are normally resistant to biodegradation. Sometimes it is possible to induce biodegradation activity by the use of growth cosubstrates. In this study, pure solutions and binary mixtures of glucose, phenol and 4-chlorophenol have been metabolized in batch cultures by a pure strain of Pseudomonas putida. Following a lag period during which slow growth and low production of biomass occurred, phenol was metabolized according to the Monod model. Glucose was also metabolized according to the Monod model but exponential growth commenced immediately after inoculation with no noticeable lag phase. Biokinetic behavior for growth on a mixture of phenol and glucose paralleled the behavior on individual substrates with simultaneous consumption of both substrates. 4-chlorophenol was not consumed as a sole substrate by Pseudomonas putida but was consumed as a cometabolite with either glucose or phenol acting as the primary growth cosubstrate. Surprisingly, glucose was found to be the superior growth cosubstrate, suggesting that inexpensive sugars can be used to enhance the biodegradation of chlorophenol-contaminated sites. Glucose and the excreted metabolic products of the biodegradation process, including a bright yellow pigment, demonstrated negligible toxicity towards Artemia salina, unlike the phenol and 4-chlorophenol substrates. (orig.)

  8. Transport of nonlinearly biodegradable contaminants in aquifers

    NARCIS (Netherlands)

    Keijzer, H.

    2001-01-01

    This thesis deals with the transport behavior of nonlinearly biodegradable contaminants in aquifers. Such transport occurs during in situ bioremediation which is based on the injection of an electron acceptor or electron donor. The main interests in this thesis are the mutual influences of underlyin

  9. Neuronal growth and differentiation on biodegradable membranes.

    Science.gov (United States)

    Morelli, Sabrina; Piscioneri, Antonella; Messina, Antonietta; Salerno, Simona; Al-Fageeh, Mohamed B; Drioli, Enrico; De Bartolo, Loredana

    2015-02-01

    Semipermeable polymeric membranes with appropriate morphological, physicochemical and transport properties are relevant to inducing neural regeneration. We developed novel biodegradable membranes to support neuronal differentiation. In particular, we developed chitosan, polycaprolactone and polyurethane flat membranes and a biosynthetic blend between polycaprolactone and polyurethane by phase-inversion techniques. The biodegradable membranes were characterized in order to evaluate their morphological, physicochemical, mechanical and degradation properties. We investigated the efficacy of these different membranes to promote the adhesion and differentiation of neuronal cells. We employed as model cell system the human neuroblastoma cell line SHSY5Y, which is a well-established system for studying neuronal differentiation. The investigation of viability and specific neuronal marker expression allowed assessment that the correct neuronal differentiation and the formation of neuronal network had taken place in vitro in the cells seeded on different biodegradable membranes. Overall, this study provides evidence that neural cell responses depend on the nature of the biodegradable polymer used to form the membranes, as well as on the dissolution, hydrophilic and, above all, mechanical membrane properties. PCL-PU membranes exhibit mechanical properties that improve neurite outgrowth and the expression of specific neuronal markers.

  10. Fabrication of Environmentally Biodegradable Lignin Nanoparticles

    NARCIS (Netherlands)

    Frangville, C.; Rutkevicius, M.; Richter, A.P.; Velev, O.D.; Stoyanov, S.D.; Paunov, V.N.

    2012-01-01

    We developed a method for the fabrication of novel biodegradable nanoparticles (NPs) from lignin which are apparently non-toxic for microalgae and yeast. We compare two alternative methods for the synthesis of lignin NPs which result in particles of very different stability upon change of pH. The fi

  11. Fate and biodegradability of sulfonated aromatic amines

    NARCIS (Netherlands)

    Tan, N.C.G.; Leeuwen, van A.; Voorthuizen, van E.M.; Slenders, P.; Prenafeta, F.X.; Temmink, H.; Lettinga, G.; Field, J.A.

    2005-01-01

    Ten sulfonated aromatic amines were tested for their aerobic and anaerobic biodegradability and toxicity potential in a variety of environmental inocula. Of all the compounds tested, only two aminobenzenesulfonic acid (ABS) isomers, 2- and 4-ABS, were degraded. The observed degradation occurred only

  12. Biodegradation of Guanidinium By Aquatic Microorganisms.

    Science.gov (United States)

    1985-12-01

    Linear Alkylbenzene Sulfonates . Appl. Microbiol. 30:922-929. 21. Pfaender, F.K. and G.W. Bartholomew. 1982. Measurement of Aquatic Biodegradation Rates by...incubation, after which time its disappearance became linear , and it could no longer be detected by the 20th day. Results for an identical water sample

  13. Nanoparticle carriers based on copolymers of poly( l-aspartic acid co- l-lactide)-1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine for drug delivery

    Science.gov (United States)

    Han, Siyuan; Wang, Huan; Liang, Xingjie; Hu, Liming; Li, Min; Wu, Yan

    2011-09-01

    A novel poly( l-aspartic) derivative (PAL-DPPE) containing polylactide and 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine (DPPE) segments has been successfully synthesized. The chemical structures of the copolymers were confirmed by Fourier-transform infrared spectroscopy (FTIR), NMR (1H NMR, 13C NMR, 31P NMR), and thermogravimetric analysis (TGA). Fluorescence spectroscopy, dynamic light scattering (DLS), and transmission electron microscopy (TEM) confirmed the formation of micelles of the PAL-DPPE copolymers. In order to estimate the feasibility as novel drug carriers, an anti-tumor model drug doxorubicin (DOX) was incorporated into polymeric micelles by double emulsion and nanoprecipitation method. The DOX-loaded micelle size, size distribution, and encapsulation efficiency (EE) were influenced by the feed weight ratio of the copolymer to DOX. In addition, in vitro release experiments of the DOX-loaded PAL-DPPE micelles exhibited that faster release in pH 5.0 than their release in pH 7.4 buffer. The poly( l-aspartic) derivative copolymer was proved to be an available carrier for the preparation of micelles for anti-tumor drug delivery.

  14. Nanoparticle carriers based on copolymers of poly(l-aspartic acid co-l-lactide)-1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine for drug delivery

    Energy Technology Data Exchange (ETDEWEB)

    Han Siyuan; Wang Huan; Liang Xingjie [National Center for Nanoscience and Technology, Laboratory of Nanobiomedicine and Nanosafety, Division of Nanomedicine and Nanobiology (China); Hu Liming, E-mail: huliming@bjut.edu.cn [Beijing University of Technology, College of Life Science and Bioengineering (China); Li Min; Wu Yan, E-mail: wuy@nanoctr.cn [National Center for Nanoscience and Technology, Laboratory of Nanobiomedicine and Nanosafety, Division of Nanomedicine and Nanobiology (China)

    2011-09-15

    A novel poly(l-aspartic) derivative (PAL-DPPE) containing polylactide and 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine (DPPE) segments has been successfully synthesized. The chemical structures of the copolymers were confirmed by Fourier-transform infrared spectroscopy (FTIR), NMR ({sup 1}H NMR, {sup 13}C NMR, {sup 31}P NMR), and thermogravimetric analysis (TGA). Fluorescence spectroscopy, dynamic light scattering (DLS), and transmission electron microscopy (TEM) confirmed the formation of micelles of the PAL-DPPE copolymers. In order to estimate the feasibility as novel drug carriers, an anti-tumor model drug doxorubicin (DOX) was incorporated into polymeric micelles by double emulsion and nanoprecipitation method. The DOX-loaded micelle size, size distribution, and encapsulation efficiency (EE) were influenced by the feed weight ratio of the copolymer to DOX. In addition, in vitro release experiments of the DOX-loaded PAL-DPPE micelles exhibited that faster release in pH 5.0 than their release in pH 7.4 buffer. The poly(l-aspartic) derivative copolymer was proved to be an available carrier for the preparation of micelles for anti-tumor drug delivery.

  15. Hydrogen Bonding-Mediated Microphase Separation during the Formation of Mesoporous Novolac-Type Phenolic Resin Templated by the Triblock Copolymer, PEO-b-PPO-b-PEO

    Directory of Open Access Journals (Sweden)

    Wei-Cheng Chu

    2013-11-01

    Full Text Available After blending the triblock copolymer, poly(ethylene oxide-b-propylene oxide-b-ethylene oxide (PEO-b-PPO-b-PEO with novolac-type phenolic resin, Fourier transform infrared spectroscopy revealed that the ether groups of the PEO block were stronger hydrogen bond acceptors for the OH groups of phenolic resin than were the ether groups of the PPO block. Thermal curing with hexamethylenetetramine as the curing agent resulted in the triblock copolymer being incorporated into the phenolic resin, forming a nanostructure through a mechanism involving reaction-induced microphase separation. Mild pyrolysis conditions led to the removal of the PEO-b-PPO-b-PEO triblock copolymer and formation of mesoporous phenolic resin. This approach provided a variety of composition-dependent nanostructures, including disordered wormlike, body-centered-cubic spherical and disorder micelles. The regular mesoporous novolac-type phenolic resin was formed only at a phenolic content of 40–60 wt %, the result of an intriguing balance of hydrogen bonding interactions among the phenolic resin and the PEO and PPO segments of the triblock copolymer.

  16. Biodegradation of acetanilide herbicides acetochlor and butachlor in soil.

    Science.gov (United States)

    Ye, Chang-ming; Wang, Xing-jun; Zheng, He-hui

    2002-10-01

    The biodegradation of two acetanilide herbicides, acetochlor and butachlor in soil after other environmental organic matter addition were measured during 35 days laboratory incubations. The herbicides were applied to soil alone, soil-SDBS (sodium dodecylbenzene sulfonate) mixtures and soil-HA (humic acid) mixtures. Herbicide biodegradation kinetics were compared in the different treatment. Biodegradation products of herbicides in soil alone samples were identified by GC/MS at the end of incubation. Addition of SDBS and HA to soil decreased acetochlor biodegradation, but increased butachlor biodegradation. The biodegradation half-life of acetochlor and butachlor in soil alone, soil-SDBS mixtures and soil-HA mixtures were 4.6 d, 6.1 d and 5.4 d and 5.3 d, 4.9 d and 5.3 d respectively. The biodegradation products were hydroxyacetochlor and 2-methyl-6-ethylaniline for acetochlor, and hydroxybutachlor and 2,6-diethylaniline for butachlor.

  17. Development of biodegradable materials; balancing degradability and performance

    Energy Technology Data Exchange (ETDEWEB)

    Mayer, J.M.; Allen, A.L.; Dell, P.A.; McCassie, J.E.; Shupe, A.E.; Stenhouse, P.J. Stenhouse, Welch, E.A.; Kaplan, D.L. [Army Natick Research Development, MA (United States)

    1993-12-31

    The development of biodegradable materials suitable for packaging must take into consideration various performance criteria such as mechanical and barrier properties, as well as rate of biodegradability in given environments. Individual or blended biopolymer films were obtained commercially or blown into film in the laboratory and tested for tensile strength, ultimate elongation and oxygen barrier. These films were then subjected to accelerated marine biodegradation tests as well as simulated marine respirometry. Starch/ethylene vinyl alcohol films exhibited good mechanical and excellent oxygen barrier properties, but were very slow to biodegrade in the simulated and excellent oxygen barrier properties, but were very slow to biodegrade in the simulated marine environment. Polyhydroxyalkanoates had good mechanical properties, average oxygen barrier and good biodegradability. Data indicate that performance and biodegradability of packaging can be tailored to needs by combining individual biopolymers in different proportions in blends and laminates.

  18. Nanostructure controlled sustained delivery of human growth hormone using injectable, biodegradable, pH/temperature responsive nanobiohybrid hydrogel

    Science.gov (United States)

    Singh, Narendra K.; Nguyen, Quang Vinh; Kim, Bong Sup; Lee, Doo Sung

    2015-02-01

    The clinical efficacy of a therapeutic protein, the human growth hormone (hGH), is limited by its short plasma half-life and premature degradation. To overcome this limitation, we proposed a new protein delivery system by the self-assembly and intercalation of a negatively charged hGH onto a positively charged 2D-layered double hydroxide nanoparticle (LDH). The LDH-hGH ionic complex, with an average particle size of approximately 100 nm, retards hGH diffusion. Nanobiohybrid hydrogels (PAEU/LDH-hGH) were prepared by dispersing the LDH-hGH complex into a cationic pH- and temperature-sensitive injectable PAEU copolymer hydrogel to enhance sustained hGH release by dual ionic interactions. Biodegradable copolymer hydrogels comprising poly(β-amino ester urethane) and triblock poly(ε-caprolactone-lactide)-poly(ethylene glycol)-poly-(ε-caprolactone-lactide) (PCLA-PEG-PCLA) were synthesized and characterized. hGH was self-assembled and intercalated onto layered LDH nanoparticles through an anion exchange technique. X-ray diffraction and zeta potential results showed that the LDH-hGH complex was prepared successfully and that the PAEU/LDH-hGH nanobiohybrid hydrogel had a disordered intercalated nanostructure. The biocompatibility of the nanobiohybrid hydrogel was confirmed by an in vitro cytotoxicity test. The in vivo degradation of pure PAEU and its nanobiohybrid hydrogels was investigated and it showed a controlled degradation of the PAEU/LDH nanobiohybrids compared with the pristine PAEU copolymer hydrogel. The LDH-hGH loaded injectable hydrogels suppressed the initial burst release of hGH and extended the release period for 13 days in vitro and 5 days in vivo. The developed nanohybrid hydrogel has the potential for application as a protein carrier to improve patient compliance.The clinical efficacy of a therapeutic protein, the human growth hormone (hGH), is limited by its short plasma half-life and premature degradation. To overcome this limitation, we proposed a new

  19. Shape memory rubber bands & supramolecular ionic copolymers

    Science.gov (United States)

    Brostowitz, Nicole

    subject covered in this dissertation is supra-molecular ionic copolymers. Supramolecular interactions are non-covalent; e.g. hydrogen bonding, ionic interactions, van der Waals forces. Supramolecular interactions in polymers can be used to tailor the thermo-mechanical properties by controlling bond association and dissociation. Recent research has focused on hydrogen bonded systems due to established synthesis mechanisms. Reversibility of the supramolecular interactions can be triggered by environmental changes. Ionic interactions would provide greater bond strength and more control over operating conditions. Research has been limited on ionic copolymers due to complicated synthesis methods needed to include functionalization. Low molecular weight polymers were synthesized by atom transfer radical polymerization with post polymerization conversion to phosphonium end-groups. Both polystyrene and poly(methyl acrylate) were investigated with similar reaction conditions. Chromatography measured the molecular weight and indicated a low polydispersity consistent with controlled reactions. Copolymers were formed by interfacial mixing of the cationic polymers with multifunctional, anionic oligomers. Oligomers containing sulfonate groups were used to create linear or three-dimensional polymer networks. NMR and rheology was used to characterize the presence and effect of ionic groups when compared to the neat polymer.

  20. Fouling release nanostructured coatings based on PDMS-polyurea segmented copolymers

    KAUST Repository

    Fang, Jason

    2010-05-01

    The bulk and surface characteristics of a series of coatings based on PDMS-polyurea segmented copolymers were correlated to their fouling release performance. Incorporation of polyurea segments to PDMS backbone gives rise to phase separation with the extensively hydrogen bonded hard domains creating an interconnected network that imparts mechanical rigidity. Increasing the compositional complexity of the system by including fluorinated or POSS-functionalized chain extenders or through nanoclay intercalation, confers further thermomechanical improvements. In analogy to the bulk morphology, the surface topography also reflects the compositional complexity of the materials, displaying a wide range of motifs. Investigations on settlement and subsequent removal of Ulva sporelings on those nanostructured surfaces indicate that the work required to remove the microorganisms is significantly lower compared to coatings based on standard PDMS homopolymer. All in all, the series of materials considered in this study demonstrate advanced fouling release properties, while exhibiting superior mechanical properties and, thus, long term durability. © 2010 Elsevier Ltd.