WorldWideScience

Sample records for styrene block polymers

  1. Blending of styrene-block-butadiene-block-styrene copolymer with sulfonated vinyl aromatic polymers

    NARCIS (Netherlands)

    Ruggeri, Giacomo; Passaglia, Elisa; Giorgi, Ivan; Picchioni, Francesco; Aglietto, Mauro

    2001-01-01

    Different polymers containing sulfonic groups attached to the phenyl rings were prepared by sulfonation of polystyrene (PS) and styrene-block-(ethylene-co-1-butene)-block-styrene (SEBS). The sulfonation degree (SD) was varied between 1 and 20 mol% of the styrene units. Polyphase materials containing

  2. 21 CFR 177.1810 - Styrene block polymers.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Styrene block polymers. 177.1810 Section 177.1810... FOR HUMAN CONSUMPTION (CONTINUED) INDIRECT FOOD ADDITIVES: POLYMERS Substances for Use as Basic Components of Single and Repeated Use Food Contact Surfaces § 177.1810 Styrene block polymers. The styrene...

  3. Mesomorphic structure of poly(styrene)-block-poly(4-vinylpyridine) with oligo(ethylene oxide)sulfonic acid side chains as a model for molecularly reinforced polymer electrolyte

    NARCIS (Netherlands)

    Kosonen, H; Valkama, S; Hartikainen, J; Eerikainen, H; Torkkeli, M; Jokela, K; Serimaa, R; Sundholm, F; ten Brinke, G; Ikkala, O; Eerikäinen, Hannele

    2002-01-01

    We report self-organized polymer electrolytes based on poly(styrene)-block-poly(4-vinylpyridine) (PS-block-P4VP). Liquidlike ethylene oxide (EO) oligomers with sulfonic acid end groups are bonded to the P4VP block, leading to comb-shaped supramolecules with the PS-block-P4VP backbone. Lithium

  4. Biocompatibility of epoxidized styrene-butadiene-styrene block copolymer membrane

    International Nuclear Information System (INIS)

    Yang, Jen Ming; Tsai, Shih Chang

    2010-01-01

    Styrene-butadiene-styrene block copolymer (SBS) membrane was prepared by solution casting method and then was epoxidized with peroxyformic acid generated in situ to yield the epoxidized styrene-butadiene-styrene block copolymer membrane (ESBS). The structure and properties of ESBS were characterized with infrared spectroscopy, Universal Testing Machine, differential scanning calorimetry (DSC), and thermogravimetry analysis (TGA). The performances of contact angle, water content, protein adsorption, and water vapor transmission rate on ESBS membrane were determined. After epoxidation, the hydrophilicity of the membrane increased. The water vapor transmission rate of ESBS membrane is similar to human skin. The biocompatibility of ESBS membrane was evaluated with the cell culture of fibroblasts on the membrane. It revealed that the cells not only remained viable but also proliferated on the surface of the various ESBS membranes and the population doubling time for fibroblast culture decreased.

  5. 40 CFR 721.10151 - Modified styrene, divinylbenzene polymer (generic).

    Science.gov (United States)

    2010-07-01

    ... polymer (generic). 721.10151 Section 721.10151 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.10151 Modified styrene, divinylbenzene polymer (generic). (a) Chemical... as modified styrene, divinylbenzene polymer (PMN P-07-642) is subject to reporting under this section...

  6. Styrene-Based Copolymer for Polymer Membrane Modifications

    OpenAIRE

    Harsha Srivastava; Harshad Lade; Diby Paul; G. Arthanareeswaran; Ji Hyang Kweon

    2016-01-01

    Poly(vinylidene fluoride) (PVDF) was modified with a styrene-based copolymer. The crystalline behavior, phase, thermal stability, and surface morphology of the modified membranes were analyzed. The membrane surface roughness showed a strong dependence on the styrene-acrylonitrile content and was reduced to 34% for a PVDF/styrene-acrylonitrile blend membrane with a 40/60 ratio. The thermal and crystalline behavior confirmed the blend miscibility of both polymers. It was observed in X-ray diffr...

  7. Morphology-properties relationship on nanocomposite films based on poly(styrene-block-diene-block-styrene copolymers and silver nanoparticles

    Directory of Open Access Journals (Sweden)

    2011-02-01

    Full Text Available A comparative study on the self-assembled nanostructured morphology and the rheological and mechanical properties of four different triblock copolymers, based on poly(styrene-block-diene-block-styrene and poly(styrene-block-diene-block-styrene matrices, and of their respective nanocomposites with 1 wt% silver nanoparticles, is reported in this work. In order to obtain well-dispersed nanoparticles in the block copolymer matrix, dodecanethiol was used as surfactant, showing good affinity with both nanoparticles and the polystyrene phase of the matrices as predicted by the solubility parameters calculated based on Hoftyzer and Van Krevelen theory. The block copolymer with the highest PS content shows the highest tensile modulus and tensile strength, but also the smallest elongation at break. When silver nanoparticles treated with surfactant were added to the block copolymer matrices, each system studied shows higher mechanical properties due to the good dispersion and the good interface of Ag nanoparticles in the matrices. Furthermore, it has been shown that semiempirical models such as Guth and Gold equation and Halpin-Tsai model can be used to predict the tensile modulus of the analyzed nanocomposites.

  8. Grafting of poly[(methyl methacrylate)-block-styrene] onto cellulose via nitroxide-mediated polymerization, and its polymer/clay nanocomposite.

    Science.gov (United States)

    Karaj-Abad, Saber Ghasemi; Abbasian, Mojtaba; Jaymand, Mehdi

    2016-11-05

    For the first time, nitroxide-mediated polymerization (NMP) was used for synthesis of graft and block copolymers using cellulose (Cell) as a backbone, and polystyrene (PSt) and poly(methyl metacrylate) (PMMA) as the branches. For this purpose, Cell was acetylated by 2-bromoisobutyryl bromide (BrBiB), and then the bromine group was converted to 4-oxy-2,2,6,6-tetramethylpiperidin-1-oxyl group by a substitution nucleophilic reaction to afford a macroinitiator (Cell-TEMPOL). The macroinitiator obtained was subsequently used in controlled graft and block copolymerizations of St and MMA monomers to yield Cell-g-PSt and Cell-g-(PMMA-b-PSt). The chemical structures of all samples as representatives were characterized by FTIR and (1)H NMR spectroscopies. In addition, Cell-g-(PMMA-b-PSt)/organophilic montmorillonite nanocomposite was prepared through a solution intercalation method. TEM was used to evaluate the morphological behavior of the polymer-clay system. It was demonstrated that the addition of small percent of organophilic montmorillonite (O-MMT; 3wt.%) was enough to improve the thermal stability of the nanocomposite. Copyright © 2016 Elsevier Ltd. All rights reserved.

  9. Microstructure and properties of styrene acrylate polymer cement concrete

    NARCIS (Netherlands)

    Undetermined, U.

    1995-01-01

    The paper systematically describes the evolution of the microstructure of a styrene acrylate polymer cement concrete in relation to its mechanical properties and durability. The results presented and discussed at the present paper involve the interaction of the polymer dispersion with portland

  10. 40 CFR 721.9492 - Polymers of styrene, cyclohexyl methacrylate and substituted methacrylate.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Polymers of styrene, cyclohexyl... Significant New Uses for Specific Chemical Substances § 721.9492 Polymers of styrene, cyclohexyl methacrylate...) The chemical substances identified generically as polymers of styrene, cyclohexyl methacrylate and...

  11. Morphological and physical characterization of poly(styrene-isobutylene-styrene) block copolymers and ionomers thereof

    Science.gov (United States)

    Baugh, Daniel Webster, III

    Poly(styrene-isobutylene-styrene) block copolymers made by living cationic polymerization using a difunctional initiator and the sequential monomer addition technique were analyzed using curve-resolution software in conjunction with high-resolution GPC. Fractional precipitation and selective solvent extraction were applied to a representative sample in order to confirm the identity of contaminating species. The latter were found to be low molecular weight polystyrene homopolymer, diblock copolymer, and higher molecular weight segmented block copolymers formed by intermolecular electrophilic aromatic substitution linking reactions occurring late in the polymerization of the styrene outer blocks. Solvent-cast films of poly(styrene-isobutylene-styrene) (PS-PIB-PS) block copolymers and block ionomers were analyzed using small-angle X-ray scattering (SAXS) and transmission electron microscopy (TEM). Four block copolymer samples with center block molecular weights of 52,000 g/mol and PS volume fractions (o sbPS) ranging from 0.17 to 0.31 were studied. All samples exhibited hexagonally packed cylinders of PS within the PIB matrix. Cylinder spacing was in the range 32 to 36 nm for most samples, while cylinder diameters varied from 14 to 21 nm. Porod analysis of the scattering data indicated the presence of isolated phase mixing and sharp phase boundaries. PS-PIB-PS block copolymers and ionomers therefrom were analyzed using dynamic mechanical analysis (DMA) and tensile testing. The study encompassed five block copolymer samples with similar PIB center blocks with molecular weights of approx52,000 g/mol and PS weight fractions ranging from 0.127 to 0.337. Ionomers were prepared from two of these materials by lightly sulfonating the PS outer blocks. Sulfonation levels varied from 1.7 to 4.7 mol % and the sodium and potassium neutralized forms were compared to the parent block copolymers. Dynamic mechanical analysis (DMA) of the block copolymer films indicated the existence

  12. Characterization of a Poly(styrene-block-methylacrylate-random-octadecylacrylate-block-styrene) Shape Memory ABA Triblock Copolymer

    Science.gov (United States)

    Fei, Pengzhan; Cavicchi, Kevin

    2011-03-01

    A new ABA triblock copolymer of poly(styrene-block- methylacrylate-random-octadecylacrylate-block-styrene) (PS-b- PMA-r-PODA-b-PS) was synthesized by reversible addition fragmentation chain transfer polymerization. The triblock copolymer can generate a three-dimensional, physically crosslinked network by self-assembly, where the glassy PS domains physically crosslink the midblock chains. The side chain crystallization of the polyoctadecylacrylare (PODA) side chain generates a second reversible network enabling shape memory properties. Shape memory tests by uniaxial deformation and recovery of molded dog-bone shape samples demonstrate that shape fixities above 96% and shape recoveries above 98% were obtained for extensional strains up to 300%. An outstanding advantage of this shape memory material is that it can be very easily shaped and remolded by elevating the temperature to 140circ; C, and after remolding the initial shape memory properties are totally recovered by eliminating the defects introduced by the previous deformation cycling.

  13. Evaluation of tri-steps modified styrene-butadiene-styrene block copolymer membrane for wound dressing

    International Nuclear Information System (INIS)

    Yang, Jen Ming; Huang, Huei Tsz

    2012-01-01

    Tri-steps modified styrene-butadiene-styrene block copolymer (SBS) membrane was prepared with epoxidation, ring opening reaction with maleated ionomer and layer-by-layer assembled polyelectrolyte technique. The tri-steps modified SBS membrane was characterized by infrared spectroscopy and X-ray photoelectron spectroscope (XPS). The structures of the modified SBS membranes were identified with methylene blue and azocarmine G. The content of amino group on the surface of the modified membrane was calculated from uptake of an acid dye. The values of the contact angle, water absorption, water vapor transmission rate and the adsorption of fibronectin on the membranes were determined. To evaluate the biocompatibility of the tri-steps modified SBS membrane, the cytotoxicity, antibacterial and growth profile of the cell culture of 3T3 fibroblasts on the membrane were evaluated. The bactericidal activity was found on the modified SBS. From the cell culture of 3T3 fibroblasts on the membrane, it revealed that the cells not only remained viable but also proliferated on the surface of the tri-steps modified SBS membranes. As the membranes are sterile semipermeable with bactericidal activity and transparent allowing wound checks, they can be considered for shallow wound with low exudates. - Highlights: ► Styrene-butadiene-styrene block copolymer (SBS) was modified with tri-steps. ► The tri-steps are epoxidation, ring opening reaction and layer-by-layer assembly. ► Modified SBS membrane for wound dressing is evaluated. ► Membranes are sterile semipermeable with bactericidal activity and transparent. ► Membranes can be considered for shallow wound with low exudates.

  14. Evaluation of tri-steps modified styrene-butadiene-styrene block copolymer membrane for wound dressing

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Jen Ming, E-mail: jmyang@mail.cgu.edu.tw; Huang, Huei Tsz

    2012-08-01

    Tri-steps modified styrene-butadiene-styrene block copolymer (SBS) membrane was prepared with epoxidation, ring opening reaction with maleated ionomer and layer-by-layer assembled polyelectrolyte technique. The tri-steps modified SBS membrane was characterized by infrared spectroscopy and X-ray photoelectron spectroscope (XPS). The structures of the modified SBS membranes were identified with methylene blue and azocarmine G. The content of amino group on the surface of the modified membrane was calculated from uptake of an acid dye. The values of the contact angle, water absorption, water vapor transmission rate and the adsorption of fibronectin on the membranes were determined. To evaluate the biocompatibility of the tri-steps modified SBS membrane, the cytotoxicity, antibacterial and growth profile of the cell culture of 3T3 fibroblasts on the membrane were evaluated. The bactericidal activity was found on the modified SBS. From the cell culture of 3T3 fibroblasts on the membrane, it revealed that the cells not only remained viable but also proliferated on the surface of the tri-steps modified SBS membranes. As the membranes are sterile semipermeable with bactericidal activity and transparent allowing wound checks, they can be considered for shallow wound with low exudates. - Highlights: Black-Right-Pointing-Pointer Styrene-butadiene-styrene block copolymer (SBS) was modified with tri-steps. Black-Right-Pointing-Pointer The tri-steps are epoxidation, ring opening reaction and layer-by-layer assembly. Black-Right-Pointing-Pointer Modified SBS membrane for wound dressing is evaluated. Black-Right-Pointing-Pointer Membranes are sterile semipermeable with bactericidal activity and transparent. Black-Right-Pointing-Pointer Membranes can be considered for shallow wound with low exudates.

  15. Thermodynamics of coil-hyperbranched poly(styrene-b-acrylated epoxidized soybean oil) block copolymers

    Science.gov (United States)

    Lin, Fang-Yi; Hohmann, Austin; Hernández, Nacú; Cochran, Eric

    Here we present the phase behavior of a new type of coil-hyperbranched diblock copolymer: poly(styrene- b-acrylated epoxidized soybean oil), or PS-PAESO. PS-PAESO is an example of a biorenewable thermoplastic elastomer (bio-TPE). To date, we have shown that bio-TPEs can be economical commercial substitutes for their petrochemically derived analogues--such as poly(styrene- b-butadiene- b-styrene) (SBS)--in a range of applications including pressure sensitive adhesives and bitumen modification. From a polymer physics perspective, PS-PAESO is an interesting material in that it couples a linear coil-like block with a highly branched block. Thus in contrast to the past five decades of studies on linear AB diblock copolymers, coil-hyperbranched block copolymers are relatively unknown to the community and can be expected to deviate substantially from the standard ``universal'' phase behavior in the AB systems. To explore these new materials, we have constructed a library of PS-PAESO materials spanning a range of molecular weight and composition values. The phase transition behavior and the morphology information will be interpreted by isochronal temperature scanning in dynamic shear rheology, small angle X-ray scattering and the corresponding transmission electron microscopy.

  16. -Styrene)

    KAUST Repository

    Sutisna, Burhannudin

    2017-10-04

    Membranes are prepared by self-assembly and casting of 5 and 13 wt% poly(styrene-b-butadiene-b-styrene) (PS-b-PB-b-PS) copolymers solutions in different solvents, followed by immersion in water or ethanol. By controlling the solution-casting gap, porous films of 50 and 1 µm thickness are obtained. A gradient of increasing pore size is generated as the distance from the surface increased. An ordered porous surface layer with continuous nanochannels can be observed. Its formation is investigated, by using time-resolved grazing incident small angle X-ray scattering, electron microscopy, and rheology, suggesting a strong effect of the air-solution interface on the morphology formation. The thin PS-b-PB-b-PS ordered films are modified, by promoting the photolytic addition of thioglycolic acid to the polybutadiene groups, adding chemical functionality and specific transport characteristics on the preformed nanochannels, without sacrificing the membrane morphology. Photomodification increases fivefold the water permeance to around 2 L m(-2) h(-1) bar(-1) , compared to that of the unmodified one. A rejection of 74% is measured for methyl orange in water. The membranes fabrication with tailored nanochannels and chemical functionalities can be demonstrated using relatively lower cost block copolymers. Casting on porous polyacrylonitrile supports makes the membranes even more scalable and competitive in large scale.

  17. Modification of poly(styrene-block-butadiene-block-styrene) [SBS] with phosphorus containing fire retardants

    DEFF Research Database (Denmark)

    Chernyy, Sergey; Ullah, Saif; Jomaas, Grunde

    2015-01-01

    An elaborate survey of the chemical modification methods for endowing highly flammable SBS with increased fire resistant properties by means of chemical modification of the polymer backbone with phosphorus containing fire retardant species is presented. Optimal conditions for free radical addition...

  18. -Styrene)

    KAUST Repository

    Sutisna, Burhannudin; Polymeropoulos, George; Musteata, Valentina-Elena; Sougrat, Rachid; Smilgies, Detlef-M.; Peinemann, Klaus-Viktor; Hadjichristidis, Nikolaos; Nunes, Suzana Pereira

    2017-01-01

    Membranes are prepared by self-assembly and casting of 5 and 13 wt% poly(styrene-b-butadiene-b-styrene) (PS-b-PB-b-PS) copolymers solutions in different solvents, followed by immersion in water or ethanol. By controlling the solution-casting gap

  19. Chitosan/polyanion surface modification of styrene-butadiene-styrene block copolymer membrane for wound dressing.

    Science.gov (United States)

    Yang, Jen Ming; Yang, Jhe-Hao; Huang, Huei Tsz

    2014-01-01

    The surface of styrene-butadiene-styrene block copolymer (SBS) membrane is modified with tri-steps in this study. At first, two step modified SBS membrane (MSBS) was prepared with epoxidation and ring opening reaction with maleated ionomer. Then chitosan was used as the polycation electrolyte and sodium alginate, poly(γ-glutamic acid) (PGA) and poly(aspartic acid) (PAsp) were selected as polyanion electrolytes to deposit on the surfaces of MSBS membrane by the layer-by-layer self-assembly (LbL) deposition technique to get three [chitosan/polyanion] LbL modified SBS membranes, ([CS/Alg], [CS/PGA] and [CS/PAsp]). From the quantitative XPS analysis and water contact angle measurement, it is found that the order of wettability and the content of functional group percentages of COO(-) and OCN on the three [CS/polyanion] systems are [CS/Alg]>[CS/PGA]>[CS/PAsp]. Performances of water vapor transmission rates, fibronectin adsorption, antibacterial assessment and 3T3 fibroblast cell growth on [CS/Alg], [CS/PGA] and [CS/PAsp] membranes were also evaluated. With the evaluation of water vapor transmission rate, these [CS/Alg], [CS/PGA] and [CS/PAsp] membranes are sterile semipermeable with water evaporation at about 82±8g/day·m(2). It is found that the amount of fibronectin adsorption on the three [CS/polyanion] systems is significantly determined by the sum of the functional group of COO(-) and OCN on the surfaces of [CS/Alg], [CS/PGA] and [CS/PAsp] systems. The results are inverse with the sum of the functional group of COO(-) and OCN on the three [CS/polyanion]. From the cytotoxicity test and cell adhesion and proliferation assay of 3T3 fibroblasts on the three [CS/polyanion] systems, it revealed that the cells not only remained viable but they also proliferated on the surfaces of [CS/Alg], [CS/PGA] and [CS/PAsp]. The bactericidal activity was found on [CS/Alg], [CS/PGA] and [CS/PAsp]. The transport of bacterial through these [CS/polyanion] membranes was also conducted

  20. 78 FR 20032 - Styrene-Ethylene-Propylene Block Copolymer; Tolerance Exemption

    Science.gov (United States)

    2013-04-03

    ...-Ethylene-Propylene Block Copolymer; Tolerance Exemption AGENCY: Environmental Protection Agency (EPA... for residues of styrene-ethylene-propylene block copolymer (CAS Reg. No. 108388-87-0) when used as an...-ethylene-propylene block copolymer on food or feed commodities. DATES: This regulation is effective April 3...

  1. Polymers and block copolymers of fluorostyrenes by ATRP

    DEFF Research Database (Denmark)

    Hvilsted, Søren; Borkar, Sachin; Abildgaard, Lillian

    2002-01-01

    Fully or partly fluorinated polymers have many desirable and intriguing properties. In the framework of a larger program on design and control of new functional block copolymers we recently employed the Atom Transfer Radical Polymerization (ATRP) protocol on 2,3,4,5,6-pentafluorostyrene (FS). We...... materials based on 2,3,5,6-tetrafiuoro-4-methoxy-styrene (TFMS). TFMS homopolymers as well as diblock copolymers with FS are produced by ATRP. Both types of novel polymers were subsequently demethylated and different side chains introduced on the resulting hydroxy sites....

  2. Synthesis by ATRP of triblock copolymers with densely grafted styrenic end blocks from a polyisobutylene macroinitiator

    DEFF Research Database (Denmark)

    Truelsen, Jens Høg; Kops, Jørgen; Pedersen, Walther Batsberg

    2000-01-01

    A macroinitiator was prepared from a triblock copolymer of polyisobutylene (PIB) with end blocks of poly(p-methylstyrene) (P(p-MeS)) by bromination to obtain initiating bromomethyl groups for atom transfer radical polymerization (ATRP). Controlled polymerization of styrene and p-acetoxystyrene yi......A macroinitiator was prepared from a triblock copolymer of polyisobutylene (PIB) with end blocks of poly(p-methylstyrene) (P(p-MeS)) by bromination to obtain initiating bromomethyl groups for atom transfer radical polymerization (ATRP). Controlled polymerization of styrene and p...

  3. SYNTHESIS OF STYRENE-METHYL METHACRYLATE BLOCK COPOLYMER BY POLYAZOAMIDE AS INITIATOR

    Institute of Scientific and Technical Information of China (English)

    WANG Zhongyi; WEI Jeqing

    1996-01-01

    Polyazoamide(PAA) was used as initiator to prepare block copolymer P(MMA-b-St) by free radical polymerization. The fraction of block copolymer was about 50%. The structure of the block-copolymer was characterized by IR and the results of 1H-NMR and GPC showed that the content of the block and the molecular weight (-Mw) of the prepolymer and block copolymer could be controlled by varying the mol ratio of styrene/PAA and MMA/prepolymer. DSC and TEM results revealed that the block copolymer has two separated glass transition temperatures and phase separation within the domain structure.

  4. Synthesis and gas permeability of block copolymers composed of poly(styrene-co-acrylonitrile) and polystyrene blocks

    Czech Academy of Sciences Publication Activity Database

    Lokaj, Jan; Brožová, Libuše; Holler, Petr; Pientka, Zbyněk

    2002-01-01

    Roč. 67, č. 2 (2002), s. 267-278 ISSN 0010-0765 R&D Projects: GA ČR GA203/99/0572 Institutional research plan: CEZ:AV0Z4050913 Keywords : azeotropic styrene-acrylonitrile copolymers * block copolymers * nitroxide-mediated copolymerization Subject RIV: CD - Macromolecular Chemistry Impact factor: 0.848, year: 2002

  5. Adhesion and adhesion changes at the copper metal-(acrylonitrile-butadiene-styrene) polymer interface

    NARCIS (Netherlands)

    Kisin, S.; Varst, van der P.G.T.; With, de G.

    2007-01-01

    It is known that the adhesive strength of metallic films on polymer substrates often changes in the course of time. To study this effect in more detail, the adhesion energy of sputtered and galvanically strengthened copper coatings on acrylonitrile–butadiene–styrene polymer substrate was determined

  6. Solubilization of docetaxel in poly(ethylene oxide)-block-poly(butylene/styrene oxide) micelles.

    Science.gov (United States)

    Elsabahy, Mahmoud; Perron, Marie-Eve; Bertrand, Nicolas; Yu, Ga-Er; Leroux, Jean-Christophe

    2007-07-01

    Poly(ethylene oxide)-block-poly(styrene oxide) (PEO-b-PSO) and PEO-b-poly(butylene oxide) (PEO-b-PBO) of different chain lengths were synthesized and characterized for their self-assembling properties in water by dynamic/static light scattering, spectrofluorimetry, and transmission electron microscopy. The resulting polymeric micelles were evaluated for their ability to solubilize and protect the anticancer drug docetaxel (DCTX) from degradation. The drug release kinetics as well as the cytotoxicity of the loaded micelles were assessed in vitro. All polymers formed micelles with a highly viscous core at low critical association concentrations (hydrolysis under accelerated stability testing conditions. Only PEO-b-PBO bearing 24 BO units afforded significant protection against degradation. In vitro, DCTX was released slower from the latter micelles, but all formulations possessed a similar cytotoxic effect against PC-3 prostate cancer cells. These data suggest that PEO-b-P(SO/BO) micelles could be used as alternatives to conventional surfactants for the solubilization of taxanes.

  7. Studies on atom transfer radical polymerization of acrylates and styrenes with controlled polymeric block structures

    OpenAIRE

    Ibrahim, Khalid

    2006-01-01

    Atom transfer radical polymerization (ATRP) was applied to homo and block copolymerization of vinyl monomers methacrylates, acrylates, and styrene with iron (FeCl2.4H2O) as the transition metal in most cases. As complexing ligand either a commercially available ligand (triphenyl phosphine) (PPh3) or synthetic aliphatic amines were used. As initiators, methyl 2-bromopropionate, ethyl 2-bromoisobutyrate, α,α-dichloroacetophenone, and poly(ethylene oxide) macroinitiator were employed. Block ...

  8. State of mixing of deuterated and non-deuterated block polymer chains

    International Nuclear Information System (INIS)

    Hasegawa, Hirokazu; Hashimoto, Takeji

    1984-01-01

    Prior to the small-angle neutron scattering study on the conformation of block polymer chains in the domain space, the state of mixing of two block polymers, an ordinary polystyrene-polyisoprene diblock polymer and a poly(deuterated styrene)-polyisoprene diblock polymer with a different molecular weight and composition, was investigated by a small-angle X-ray scattering (SAXS) technique. Only one kind of domain structure was observed for each blend, and the domain spacings obtained by SAXS were proportional to the two-thirds power of the number-average molecular weight of the blends (reduced to non-deuterated block polymer). The volume fractions of polystyrene domain in the blends evaluated by computer simulation of SAXS profiles well agreed with the values estimated from blend composition. All these facts suggest the molecular mixing of the two block polymers in the domain space. (author)

  9. Effect of casting solvents on the properties of styrene-butadiene-styrene block copolymers studied by positron annihilation techniques

    International Nuclear Information System (INIS)

    Djermouni, B.; Ache, H.J.

    1980-01-01

    The positron annihilation technique was used to study the properties of styrene-butadiene-styrene block copolymers obtained by casting them in four different solvents: toluene, carbon tetrachloride, ethyl acetate, and methyl ethyl ketone. The positron annihilation rates plotted as a function of temperature show in all films irregularities at -70 and +85 0 C which were attributed to the onset of motions in the polybutadiene and polystyrene domaines, respectively. In addition to that, two irregularities were observed at -14 and +10 0 C if a poor solvent, such as ethyl acetate or methyl ethyl ketone, was used, while films cast in a good solvent such as toluene or carbon tetrachloride show only one additional irregularity on the lambda 2 -T curves at -14 0 C. The latter results were explained in terms of the interfacial model by assuming that these irregularities correspond to the glass transition of interlayer phases between the pure polystyrene and the pure polybutadiene phases. The one which shows the irregularity at -14 0 C could be the phase in which polybutadiene is the major component, while the transition at +10 0 C can be attributed to a phase in which polystyrene is the dominating factor

  10. Reduced graphene oxide/hydroxylated styrene-butadiene-styrene tri-block copolymer electroconductive nanocomposites: Preparation and properties

    Energy Technology Data Exchange (ETDEWEB)

    Xiong, Yuanqin; Xie, Yanyan [Institute of Polymer Science and Engineering, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082 (China); Zhang, Fan [College of Chemistry and Chemical Engineering, Jishou University, Jishou 416000 (China); Ou, Encai; Jiang, Zhuojuan; Ke, Lili; Hu, Ding [Institute of Polymer Science and Engineering, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082 (China); Xu, Weijian, E-mail: weijianxu59@gmail.com [Institute of Polymer Science and Engineering, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082 (China)

    2012-08-20

    Highlights: Black-Right-Pointing-Pointer RGO/HO-SBS nanocomposites are prepared successfully. Black-Right-Pointing-Pointer The introduction of -OH improves the compatibility between RGO and HO-SBS. Black-Right-Pointing-Pointer RGO disperse homogeneously and form a compact continuous network in matrix (HO-SBS). Black-Right-Pointing-Pointer The percolation threshold of the nanocomposites is of 0.2-0.5 wt% (0.09-0.23 vol%) and its conductivity is up to 1.3 S/m. - Abstract: Flexible and electroconductive nanocomposites based on reduced graphene oxide (RGO) and hydroxylated styrene-butadiene-styrene tri-block copolymer (HO-SBS) were prepared by solution blending method. By the introduction of the groups of -OH and >C=O onto SBS, the compatibility between RGO and SBS was enhanced. Field emission scanning electron microscopy (FE-SEM) and high-resolution transmission electron microscopy (HR-TEM) showed that RGO dispersed homogeneously and formed a compact continuous network in matrix (HO-SBS). The addition of RGO improved the thermal stability of the RGO/HO-SBS nanocomposites while slightly lowered the mechanical property. Moreover, RGO gave the nanocomposites a maximum electrical conductivity up to 1.3 S/m.

  11. Determination of styrene migration from food-contact polymers into margarine, using azeotropic distillation and headspace gas chromatography.

    Science.gov (United States)

    Varner, S L; Breder, C V; Fazio, T

    1983-09-01

    Migration studies were conducted to determine the quantity of styrene that migrates from polymers into fatty foods, specifically margarine. Azeotropic distillation was used to isolate styrene from the margarine. Headspace gas chromatography with a Chromosorb 104 column and a flame ionization detector was used for quantitation. The quantitation limit for the method was about 25 ppb (wt/wt) styrene in margarine. On the average, greater than 90% of the styrene was recovered. Several commercial margarines were examined. The method and results of the migration studies are presented. There was no detectable migration of styrene into margarine.

  12. 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.

  13. Inducing β Phase Crystallinity in Block Copolymers of Vinylidene Fluoride with Methyl Methacrylate or Styrene

    Directory of Open Access Journals (Sweden)

    Nahal Golzari

    2017-07-01

    Full Text Available Block copolymers of poly(vinylidene fluoride (PVDF with either styrene or methyl methacrylate (MMA were synthesized and analyzed with respect to the type of the crystalline phase occurring. PVDF with iodine end groups (PVDF-I was prepared by iodine transfer polymerization either in solution with supercritical CO2 or in emulsion. To activate all iodine end groups Mn2(CO10 is employed. Upon UV irradiation Mn(CO5 radicals are obtained, which abstract iodine from PVDF-I generating PVDF radicals. Subsequent polymerization with styrene or methyl methacrylate (MMA yields block copolymers. Size exclusion chromatography and NMR results prove that the entire PVDF-I is converted. XRD, FT-IR, and differential scanning calorimetry (DSC analyses allow for the identification of crystal phase transformation. It is clearly shown that the original α crystalline phase of PVDF-I is changed to the β crystalline phase in case of the block copolymers. For ratios of the VDF block length to the MMA block length ranging from 1.4 to 5 only β phase material was detected.

  14. 76 FR 77709 - Butyl acrylate-methacrylic acid-styrene polymer; Tolerance Exemption

    Science.gov (United States)

    2011-12-14

    ...This regulation establishes an exemption from the requirement of a tolerance for residues of 2-Propenoic acid, 2-methyl-, polymer with butyl 2-propenoate and ethenylbenzene (CAS Reg. No. 25036-16-2); also known as butyl acrylate-methacrylic acid-styrene polymer when used as an inert ingredient in a pesticide chemical formulation. Momentive Performance Materials submitted a petition to EPA under the Federal Food, Drug, and Cosmetic Act (FFDCA), requesting an exemption from the requirement of a tolerance. This regulation eliminates the need to establish a maximum permissible level for residues of 2-Propenoic acid, 2-methyl-, polymer with butyl 2-propenoate and ethenylbenzene on food or feed commodities.

  15. Functional Nanoporous Polymers from Block Copolymer Precursors

    DEFF Research Database (Denmark)

    Guo, Fengxiao

    Abstract Self-assembly of block copolymers provides well-defined morphologies with characteristic length scales in the nanometer range. Nanoporous polymers prepared by selective removal of one block from self-assembled block copolymers offer great technological promise due to their many potential...... 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......, where living anionic polymerization and atom transfer radical polymerization (ATRP) are combined to synthesize a polydimethylsiloxane-b-poly(tert-butyl acrylate)-b-polystyrene (PDMS-b-PtBA-b-PS) triblock copolymer precursor. By using either anhydrous hydrogen fluoride or trifluoroacetic acid, PtBA block...

  16. Separation of Poly(styrene-block-t-butyl methacrylate) Copolymers by Various Liquid Chromatography Techniques

    Science.gov (United States)

    Šmigovec Ljubič, Tina; Pahovnik, David; Žigon, Majda; Žagar, Ema

    2012-01-01

    The separation of a mixture of three poly(styrene-block-t-butyl methacrylate) copolymers (PS-b-PtBMA), consisting of polystyrene (PS) blocks of similar length and t-butyl methacrylate (PtBMA) blocks of different lengths, was performed using various chromatographic techniques, that is, a gradient liquid chromatography on reversed-phase (C18 and C8) and normal-phase columns, a liquid chromatography under critical conditions for polystyrene as well as a fully automated two-dimensional liquid chromatography that separates block copolymers by chemical composition in the first dimension and by molar mass in the second dimension. The results show that a partial separation of the mixture of PS-b-PtBMA copolymers can be achieved only by gradient liquid chromatography on reversed-phase columns. The coelution of the two block copolymers is ascribed to a much shorter PtBMA block length, compared to the PS block, as well as a small difference in the length of the PtBMA block in two of these copolymers, which was confirmed by SEC-MALS and NMR spectroscopy. PMID:22489207

  17. Directed self-assembly of poly(styrene)-block-poly(acrylic acid) copolymers for sub-20nm pitch patterning

    Science.gov (United States)

    Cheng, Jing; Lawson, Richard A.; Yeh, Wei-Ming; Jarnagin, Nathan D.; Peters, Andrew; Tolbert, Laren M.; Henderson, Clifford L.

    2012-03-01

    Directed self-assembly (DSA) of block copolymers is a promising technology for extending the patterning capability of current lithographic exposure tools. For example, production of sub-40 nm pitch features using 193nm exposure technologies is conceivably possible using DSA methods without relying on time consuming, challenging, and expensive multiple patterning schemes. Significant recent work has focused on demonstration of the ability to produce large areas of regular grating structures with low numbers of defects using self-assembly of poly(styrene)-b-poly(methyl methacrylate) copolymers (PS-b-PMMA). While these recent results are promising and have shown the ability to print pitches approaching 20 nm using DSA, the ability to advance to even smaller pitches will be dependent upon the ability to develop new block copolymers with higher χ values and the associated alignment and block removal processes required to achieve successful DSA with these new materials. This paper reports on work focused on identifying higher χ block copolymers and their associated DSA processes for sub-20 nm pitch patterning. In this work, DSA using polystyrene-b-polyacid materials has been explored. Specifically, it is shown that poly(styrene)-b-poly(acrylic acid) copolymers (PS-b-PAA) is one promising material for achieving substantially smaller pitch patterns than those possible with PS-b-PMMA while still utilizing simple hydrocarbon polymers. In fact, it is anticipated that much of the learning that has been done with the PS-b-PMMA system, such as development of highly selective plasma etch block removal procedures, can be directly leveraged or transferred to the PS-b-PAA system. Acetone vapor annealing of PS-b-PAA (Mw=16,000 g/mol with 50:50 mole ratio of PS:PAA) and its self-assembly into a lamellar morphology is demonstrated to generate a pattern pitch size (L0) of 21 nm. The χ value for PS-b-PAA was estimated from fingerprint pattern pitch data to be approximately 0.18 which

  18. Nanostructuration of self-assembled poly(styrene-b-isoprene-b-styrene) block copolymer thin films in a highly oriented pyrolytic graphite substrate

    Energy Technology Data Exchange (ETDEWEB)

    Zalakain, Inaki; Ramos, Jose Angel; Fernandez, Raquel; Etxeberria, Haritz; Mondragon, Inaki, E-mail: inaki.mondragon@ehu.e

    2011-01-03

    Highly oriented pyrolitic graphite (HOPG) is a useful substrate to visualize epitaxial formation due to its crystallographic structure. The morphology of a poly(styrene-b-isoprene-b-styrene) block copolymer thin film on a HOPG substrate was investigated by atomic force microscopy. Block copolymer domains generated a morphology with triangular regularity. This arrangement was induced by the HOPG substrate structure due to van der Waals attraction between the HOPG {pi}-conjugated system and aromatic ring of polystyrene domains. However, increasing the film thickness, the substrate effect on the surface morphology decreased. As a consequence, film surfaces showed the coexistence of different structures such as highly aligned cylinders and perforated lamellae. When film thickness exceeded a threshold value, the substrate did not have effect in the surface arrangements and the surface showed a similar morphology to that existing in bulk.

  19. Syntheses and Post-Polymerization Modifications of Well-Defined Styrenic Polymers Containing Three-Membered Heterocyclic Functionalities

    Science.gov (United States)

    McLeod, David Charles

    Macromolecules that contain electrophilic moieties, such as benzyl halides, activated esters, and epoxides, will readily undergo efficient nucleophilic substitution reactions with a wide variety of compounds under mild conditions, and are therefore ideally suited to act as "universal" precursors to functional materials. Epoxide-containing polymers derived from the radical polymerization of commercially-available glycidyl methacrylate are often employed in this role; however, methacrylic polymers suffer from certain limitations as a result of the incorporated ester groups, which are not stabile in the presence of strong nucleophiles, acids, bases, or esterase enzymes. Styrenic polymers that do not contain labile carbonyl moieties are usually the precursors of choice when high chemical stability is desired in the end product, but the production of functional materials from epoxide-containing styrenic polymers is relatively unexplored. In this dissertation, improved methods were developed for synthesizing 4-vinylphenyloxirane (4VPO) and 4-vinylphenyl glycidyl ether (4VPGE), two of the better-known epoxide-containing styrenic monomers, in high-yield and purity. Well-defined, epoxide-containing styrenic polymers with targeted molecular weights, narrow molecular weight distributions, and controlled architectures (specifically, linear and star-shaped homopolymers, as well as linear block copolymers with styrene) were produced from 4VPO and 4VPGE for the first time using reversible-deactivation radical polymerization techniques, such as low-catalyst-concentration atom transfer radical polymerization (LCC ATRP) and reversible addition-fragmentation chain-transfer (RAFT) polymerization. The robust nature and utility of poly4VPO and poly4VPGE were then demonstrated by the efficient, ring-opening modification of the pendant epoxide groups with a structurally- and functionally-diverse array of alcohols under acidic conditions at ambient temperature. The macromolecular

  20. Investigation on physical behavior of styrene wood-polymer in different concentrations of monomer

    Directory of Open Access Journals (Sweden)

    maryam ghorbani

    2016-09-01

    Full Text Available This research was conducted to study the effect of different concentrations of styrene lumen monomer on the physical properties of beech wood. Physical test samples were prepared according to ASTM-D1037 standard and treated with vacuum-pressure method at five concentration levels; 0, 40, 60, 80 and 100 percent of soluble monomer. For polymerization, treated samples were heated in oven for two 24-hour period at 90 and 103ºC respectively. Monomer and polymer absorption, density variation, water absorption, swelling and anti-swelling efficiency (ASE were determined. According to the results, Monomer and polymer absorption were increment by monomer concentration increase, and they were reported 38.2% and 26% in highest level. With polymer absorption enhancement, density of wood increased from 0/63g/cm³ in control to 0/91g/cm³ in the highest monomer concentration level that reduces pores in wood-polymer structure. Absorbed polymer enhancement decreased hydrophilicity and dimensional changes of treated samples, so that water absorption and swelling volume of the samples saturated with 100% concentration of monomer were decreased 64% and 45.3% after the longest immersion time. Highest Anti-swelling efficiency of Styrene-saturated samples was determined 56.15% in the maximum concentration level of treatment.

  1. Theoretical aspects of gradient reversed-phase high performance liquid chromatography of styrene-butylacrylate block copolymers

    NARCIS (Netherlands)

    Kolarova, L.; Jandera, P.; Vonk, E.C.; Claessens, H.A.

    2004-01-01

    Butylacrylate – styrene co-polymers prepared by atom transfer radical polymeratization were separated on an octadecyl silica column by gradient elution with tetrahydrofuran in water, up to the molar masses 10,000. In reversed-phase high performance liquid chromatography (RP-HPLC), the retention of

  2. Pyrolysis gas chromatographic study of homo polymers and copolymers of chlorotrifluoroethylene and styrene

    International Nuclear Information System (INIS)

    Rizvi, M.; Munir, A.

    1993-01-01

    Polymer degradation reactions have always been important for the development of thermally stable polymers. Among different available techniques, pyrolysis gas chromatography (PGC) has been used frequently to establish thermal stability and the plausible mechanism of degradation reactions. In the present work, homo polymers of chlorotrifluoroethylene (CTFE) and styrene and their copolymers were studied by PGC/IR for separation and identification of degraded products and to understand the degradation mechanism. Besides monomers, C/sub 2/H/sub 4/, C/sub 2/H/sub 2/, SiF/sub 4/, C/sub 6/H/sub 6/ C/sub 3/F/sub 5/Cl, C/sub 7/H sub 8/, C/sub 8/H/sub 10/ are the observed pyrolysis products. Mechanism for different degradation reactions have also been studied. (author)

  3. Free volume dependence on electrical properties of Poly (styrene co-acrylonitrile)/Nickel oxide polymer nanocomposites

    Science.gov (United States)

    Ningaraju, S.; Hegde, Vinayakaprasanna N.; Prakash, A. P. Gnana; Ravikumar, H. B.

    2018-04-01

    Polymer nanocomposites of Poly (styrene co-acrylonitrile)/Nickel Oxide (PSAN/NiO) have been prepared. The increased free volume sizes up to 0.4 wt% of NiO loading indicates overall reduction in packing density of polymer network. The decreased o-Ps lifetime (τ3) at higher concentration of NiO indicates improved interfacial interaction between the surface of NiO nanoparticles and side chain of PSAN polymer matrix. The increased AC/DC conductivity at lower wt% of NiO loading demonstrates increased number of electric charge carriers/mobile ions and their mobility. The increased dielectric constant and dielectric loss up to 0.4 wt% of NiO loading suggests the increased dipoles polarization.

  4. Preparation and drug-loading properties of Fe3O4/Poly(styrene-co-acrylic acid) magnetic polymer nanocomposites

    International Nuclear Information System (INIS)

    Lu, Wensheng; Shen, Yuhua; Xie, Anjian; Zhang, Weiqiang

    2013-01-01

    Fe 3 O 4 /poly(styrene-co-acrylic acid) magnetic polymer nanocomposites were synthesized by the dispersion polymerization method using styrene as hard monomer, acrylic acid as functional monomer, Fe 3 O 4 nanoparticles modified with oleic acid as core, and poly(styrene-co-acrylic acid) as shell. Drug-loading properties of magnetic polymer nanocomposites with curcumin as a model drug were also studied. The results indicated that magnetic polymer nanocomposites with monodisperse were obtained, the particle size distribution was 50–120 nm, and the average size was about 100 nm. The contents of poly(styrene-co-acrylic acid) and Fe 3 O 4 nanoparticles in magnetic polymer nanocomposites were 74% and 24.7%, respectively. The drug-loading capacity and entrapment efficiency were 2.5% and 44.4%, respectively. The saturation magnetization of magnetic polymer nanocomposites at 300 K was 20.2 emu/g without coercivity and remanence. The as-prepared magnetic polymer nanocomposites have not only lots of functional carboxyl groups but also stronger magnetic response, which might have potential applications in drug carrier and targeted drug release

  5. TUNG OIL BASED MONOMER FOR THERMOSETTING POLYMERS: SYNTHESIS, CHARACTERIZATION AND COPOLYMERIZATION WITH STYRENE

    Directory of Open Access Journals (Sweden)

    Chengguo Liu,

    2011-11-01

    Full Text Available A tung oil (TO based monomer for rigid thermosetting polymer was synthesized, characterized, and copolymerized with styrene in this study. Tung oil was alcoholyzed with pentaerythritol (PER to get tung oil pentaerythritol alcoholysis products (TOPER, and the optimized conditions were explored according to the yields of TOPER analyzed by gas chromatography-mass spectrometry (GC-MS. The resulting alcoholysis products were maleinated to form tung oil maleate half ester (TOPERMA, and the reaction conditions were determined by monitoring the reaction extents of TOPER and maleic anhydride (MA with 1HNMR spectroscopy. The TO alcoholysis and maleinization reaction products were characterized by IR, 1HNMR, and electrospray ionization-mass spectrometry (ESI-MS techniques. At last, the TOPERMA mixture was cured with styrene (St, and the initiator tert-butyl peroxy benzoate (TPB. Differential scanning calorimetry (DSC was employed to characterize the curing process. Mechanical properties of the cured TOPERMA/St resin further confirmed the best procedure for the maleinization reaction. The loading of TO reached about 30% weight of the resulting thermosetting polymer. This promising material from renewable resources can be a potential substitution for petroleum products when used as sheet molding compounds.

  6. Poly(vinylpyridine-co-styrene) based in situ cross-linked gel polymer electrolyte for lithium-ion polymer batteries

    International Nuclear Information System (INIS)

    Oh, Sijin; Kim, Dong Wook; Lee, Changjin; Lee, Myong-Hoon; Kang, Yongku

    2011-01-01

    A gel polymer electrolyte (GPE) was successfully prepared by means of an in situ cross-linking reaction of poly(2-vinylpyridine-co-styrene) and oligo(ethylene oxide) with epoxide functional groups at 65 °C without using a polymerization initiator. A stable gel polymer electrolyte could be obtained by adding only 1% of a polymer gelator. The ionic conductivity of the GPE containing 99 wt% of liquid electrolyte was measured to be ca. 10 −2 S/cm at the ambient temperature. The ionic conductivity of the resulting GPE was comparable to that of a pure liquid electrolyte. The electrochemical stability window of the prepared gel polymer electrolytes was measured to be 5.2 V. The test cell carried a discharge capacity of 133.2 mAh/g at 0.1 C and showed good cycling performance with negligible capacity fading after the 200th cycle, maintaining 99.5% coulombic efficiency throughout 200 cycles. The resulting gel polymer electrolyte prepared by in situ thermal cross-linking without a polymerization initiator holds promise for application to on the high power lithium-ion polymer batteries.

  7. Microbial production of the aromatic building-blocks (S)-styrene oxide and (R)-1,2-phenylethanediol from renewable resources.

    Science.gov (United States)

    McKenna, Rebekah; Pugh, Shawn; Thompson, Brian; Nielsen, David R

    2013-12-01

    (S)-Styrene oxide and (R)-1,2-phenylethanediol are chiral aromatic molecular building blocks used commonly as precursors to pharmaceuticals and other specialty chemicals. Two pathways have been engineered in Escherichia coli for their individual biosynthesis directly from glucose. The novel pathways each constitute extensions of the previously engineered styrene pathway, developed by co-expressing either styrene monooxygenase (SMO) or styrene dioxygenase (SDO) to convert styrene to (S)-styrene oxide and (R)-1,2-phenylethanediol, respectively. StyAB from Pseudomonas putida S12 was determined to be the most effective SMO. SDO activity was achieved using NahAaAbAcAd of Pseudomonas sp. NCIB 9816-4, a naphthalene dioxygenase with known broad substrate specificity. Production of phenylalanine, the precursor to both pathways, was systematically enhanced through a number of mutations, most notably via deletion of tyrA and over-expression of tktA. As a result, (R)-1,2-phenylethanediol reached titers as high as 1.23 g/L, and at 1.32 g/L (S)-styrene oxide titers already approach their toxicity limit. As with other aromatics, product toxicity was strongly correlated with a model of membrane accumulation and disruption. This study additionally demonstrates that greater flux through the styrene pathway can be achieved if its toxicity is addressed, as achieved in this case by reacting styrene to less toxic products. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Surfactant-Free RAFT Emulsion Polymerization of Styrene Using Thermoresponsive macroRAFT Agents: Towards Smart Well-Defined Block Copolymers with High Molecular Weights

    Directory of Open Access Journals (Sweden)

    Steffen Eggers

    2017-12-01

    Full Text Available The combination of reversible addition–fragmentation chain transfer (RAFT and emulsion polymerization has recently attracted much attention as a synthetic tool for high-molecular-weight block copolymers and their micellar nano-objects. Up to recently, though, the use of thermoresponsive polymers as both macroRAFT agents and latex stabilizers was impossible in aqueous media due to their hydrophobicity at the usually high polymerization temperatures. In this work, we present a straightforward surfactant-free RAFT emulsion polymerization to obtain thermoresponsive styrenic block copolymers with molecular weights of around 100 kDa and their well-defined latexes. The stability of the aqueous latexes is achieved by adding 20 vol % of the cosolvent 1,4-dioxane (DOX, increasing the phase transition temperature (PTT of the used thermoresponsive poly(N-acryloylpyrrolidine (PAPy macroRAFT agents above the polymerization temperature. Furthermore, this cosolvent approach is combined with the use of poly(N,N-dimethylacrylamide-block-poly(N-acryloylpiperidine-co-N-acryloylpyrrolidine (PDMA-b-P(APi-co-APy as the macroRAFT agent owning a short stabilizing PDMA end block and a widely adjustable PTT of the P(APi-co-APy block in between 4 and 47 °C. The temperature-induced collapse of the latter under emulsion polymerization conditions leads to the formation of RAFT nanoreactors, which allows for a very fast chain growth of the polystyrene (PS block. In dynamic light scattering (DLS, as well as cryo-transmission electron microscopy (cryoTEM, moreover, all created latexes indeed reveal a high (temperature stability and a reversible collapse of the thermoresponsive coronal block upon heating. Hence, this paper pioneers a versatile way towards amphiphilic thermoresponsive high-molecular-weight block copolymers and their nano-objects with tailored corona switchability.

  9. Radiation-induced crosslinking of poly(styrene–butadiene–styrene) block copolymers and their sulfonation

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Sun-Young [Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, 29 Geumgu-gil, Jeongeup-si, Jeollabuk-do 580-185 (Korea, Republic of); Department of Chemical and Biomolecular Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 120-749 (Korea, Republic of); Song, Ju-Myung; Sohn, Joon-Yong [Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, 29 Geumgu-gil, Jeongeup-si, Jeollabuk-do 580-185 (Korea, Republic of); Shul, Yong-Gun [Department of Chemical and Biomolecular Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 120-749 (Korea, Republic of); Shin, Junhwa, E-mail: shinj@kaeri.re.kr [Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, 29 Geumgu-gil, Jeongeup-si, Jeollabuk-do 580-185 (Korea, Republic of)

    2013-12-01

    Highlights: • The c-SBS films were prepared using a gamma ray or electron beam. • The crosslinking degree of the c-SBS films were increased with the irradiation dose. • The prepared c-SBS films were sulfonated with various concentration of CSA. • The sulfonation of the c-SBS film is largely dependent on the concentration of CSA. • The sulfonation process is progressed from the surface to the inner part of c-SBS film. -- Abstract: Several crosslinked poly(styrene–butadiene–styrene) (c-SBS) block copolymer films were prepared using a gamma ray or electron beam with various irradiation doses and the prepared c-SBS film was then subjected to sulfonation using a chlorosulfonic acid (CSA) solution to introduce a sulfonic acid group. To estimate the degree of crosslinking, the gel fractions and FT-IR spectra of the c-SBS films were used and the results indicate that the degree of crosslinking is increased with an increase in the radiation dose. The surface morphology and mechanical property of the c-SBS films were observed using SEM and UTM instruments, respectively. The sulfonated c-SBS films were investigated by measuring the ion exchange capacity (IEC) and by observing the cross-sectional distribution patterns of sulfonic acid group using an SEM-EDX instrument. The IEC and SEM-EDX studies indicate that the sulfonated c-SBS membranes can be successfully prepared through the radiation crosslinking of the SBS film and the subsequent sulfonation with a diluted CSA solution.

  10. Membrane protein extraction and purification using styrene-maleic acid (SMA) copolymer: effect of variations in polymer structure.

    Science.gov (United States)

    Morrison, Kerrie A; Akram, Aneel; Mathews, Ashlyn; Khan, Zoeya A; Patel, Jaimin H; Zhou, Chumin; Hardy, David J; Moore-Kelly, Charles; Patel, Roshani; Odiba, Victor; Knowles, Tim J; Javed, Masood-Ul-Hassan; Chmel, Nikola P; Dafforn, Timothy R; Rothnie, Alice J

    2016-12-01

    The use of styrene-maleic acid (SMA) copolymers to extract and purify transmembrane proteins, while retaining their native bilayer environment, overcomes many of the disadvantages associated with conventional detergent-based procedures. This approach has huge potential for the future of membrane protein structural and functional studies. In this investigation, we have systematically tested a range of commercially available SMA polymers, varying in both the ratio of styrene and maleic acid and in total size, for the ability to extract, purify and stabilise transmembrane proteins. Three different membrane proteins (BmrA, LeuT and ZipA), which vary in size and shape, were used. Our results show that several polymers, can be used to extract membrane proteins, comparably to conventional detergents. A styrene:maleic acid ratio of either 2:1 or 3:1, combined with a relatively small average molecular mass (7.5-10 kDa), is optimal for membrane extraction, and this appears to be independent of the protein size, shape or expression system. A subset of polymers were taken forward for purification, functional and stability tests. Following a one-step affinity purification, SMA 2000 was found to be the best choice for yield, purity and function. However, the other polymers offer subtle differences in size and sensitivity to divalent cations that may be useful for a variety of downstream applications. © 2016 The Author(s); published by Portland Press Limited on behalf of the Biochemical Society.

  11. Chitosan/polyanion surface modification of styrene–butadiene–styrene block copolymer membrane for wound dressing

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Jen Ming, E-mail: jmyang@mail.cgu.edu.tw [Department of Chemical and Materials Engineering, Chang Gung University, Kwei-Shan, Tao-Yuan 333, Taiwan (China); Yang, Jhe-Hao [Department of Electronic Engineering, Chang Gung University, Kwei-Shan, Tao-Yuan 333, Taiwan (China); Huang, Huei Tsz [Department of Chemical and Materials Engineering, Chang Gung University, Kwei-Shan, Tao-Yuan 333, Taiwan (China)

    2014-01-01

    The surface of styrene–butadiene–styrene block copolymer (SBS) membrane is modified with tri-steps in this study. At first, two step modified SBS membrane (MSBS) was prepared with epoxidation and ring opening reaction with maleated ionomer. Then chitosan was used as the polycation electrolyte and sodium alginate, poly(γ-glutamic acid) (PGA) and poly(aspartic acid) (PAsp) were selected as polyanion electrolytes to deposit on the surfaces of MSBS membrane by the layer-by-layer self-assembly (LbL) deposition technique to get three [chitosan/polyanion] LbL modified SBS membranes, ([CS/Alg], [CS/PGA] and [CS/PAsp]). From the quantitative XPS analysis and water contact angle measurement, it is found that the order of wettability and the content of functional group percentages of COO{sup −} and -O=C-N- on the three [CS/polyanion] systems are [CS/Alg] > [CS/PGA] > [CS/PAsp]. Performances of water vapor transmission rates, fibronectin adsorption, antibacterial assessment and 3T3 fibroblast cell growth on [CS/Alg], [CS/PGA] and [CS/PAsp] membranes were also evaluated. With the evaluation of water vapor transmission rate, these [CS/Alg], [CS/PGA] and [CS/PAsp] membranes are sterile semipermeable with water evaporation at about 82 ± 8 g/day · m{sup 2}. It is found that the amount of fibronectin adsorption on the three [CS/polyanion] systems is significantly determined by the sum of the functional group of COO{sup −} and -O=C-N- on the surfaces of [CS/Alg], [CS/PGA] and [CS/PAsp] systems. The results are inverse with the sum of the functional group of COO{sup −} and -O=C-N- on the three [CS/polyanion]. From the cytotoxicity test and cell adhesion and proliferation assay of 3T3 fibroblasts on the three [CS/polyanion] systems, it revealed that the cells not only remained viable but they also proliferated on the surfaces of [CS/Alg], [CS/PGA] and [CS/PAsp]. The bactericidal activity was found on [CS/Alg], [CS/PGA] and [CS/PAsp]. The transport of bacterial through

  12. Blends of Styrene-Butadiene-Styrene Triblock Copolymer with Random Styrene-Maleic Anhydride Copolymers

    NARCIS (Netherlands)

    Piccini, Maria Teresa; Ruggeri, Giacomo; Passaglia, Elisa; Picchioni, Francesco; Aglietto, Mauro

    2002-01-01

    Blends of styrene-butadiene-styrene triblock copolymer (SBS) with random styrene-maleic anhydride copolymers (PS-co-MA), having different MA content, were prepared in a Brabender Plastigraph mixer. The presence of polystyrene (PS) blocks in the SBS copolymer and the high styrene content (93 and 86

  13. Poly(Acrylic Acid-b-Styrene) Amphiphilic Multiblock Copolymers as Building Blocks for the Assembly of Discrete Nanoparticles

    Science.gov (United States)

    Greene, Anna C.; Zhu, Jiahua; Pochan, Darrin J.; Jia, Xinqiao; Kiick, Kristi L.

    2011-01-01

    In order to expand the utility of current polymeric micellar systems, we have developed amphiphilic multiblock copolymers containing alternating blocks of poly(acrylic acid) and poly(styrene). Heterotelechelic poly(tert-butyl acrylate-b-styrene) diblock copolymers containing an α-alkyne and an ω-azide were synthesized by atom transfer radical polymerization (ATRP), allowing control over the molecular weight while maintaining narrow polydispersity indices. The multiblock copolymers were constructed by copper-catalyzed azide-alkyne cycloaddition of azide-alkyne end functional diblock copolymers which were then characterized by 1H NMR, FT-IR and SEC. The tert-butyl moieties of the poly(tert-butyl acrylate-b-styrene) multiblock copolymers were easily removed to form the poly(acrylic acid-b-styrene) multiblock copolymer ((PAA-PS)9), which contained up to 9 diblock repeats. The amphiphilic multiblock (PAA-PS)9 (Mn = 73.3 kg/mol) was self-assembled by dissolution into tetrahydrofuran and extensive dialysis against deionized water for 4 days. The critical micelle concentration (CMC) for (PAA-PS)9 was determined by fluorescence spectroscopy using pyrene as a fluorescent probe and was found to be very low at 2 × 10-4 mg/mL. The (PAA-PS)9 multiblock was also analyzed by dynamic light scattering (DLS) and transmission electron microscopy (TEM). The hydrodynamic diameter of the particles was found to be 11 nm. Discrete spherical particles were observed by TEM with an average particle diameter of 14 nm. The poly(acrylic acid) periphery of the spherical particles should allow for future conjugation of biomolecules. PMID:21552373

  14. Mechanical properties of weakly segregated block copolymers : 1. Synergism on tensile properties of poly(styrene-b-n-butylmethacrylate) diblock copolymers

    NARCIS (Netherlands)

    Weidisch, R.; Michler, G.H.; Fischer, H.; Arnold, M.; Hofmann, S.; Stamm, M.

    1999-01-01

    Mechanical properties of poly(styrene-b-n-butylmethacrylate) diblock copolymers, PS-b-PBMA, with different lengths of the polystyrene block were investigated. The copolymers display a composition range where the tensile strength of the block copolymers exceeds the values of the corresponding

  15. Morphological investigation of polydisperse asymmetric block copolymer systems of poly(styrene) and poly(methacrylic acid) in the strong segregation regime

    DEFF Research Database (Denmark)

    Asad Ayoubi, Mehran; Zhu, Kaizheng; Nyström, Bo

    2013-01-01

    Samples of compositionally (highly) asymmetric diblock copolymers and, also, mixtures of diblock and triblock copolymers (the latter obtained as end-coupling products of two diblock molecules of the mixture), composed of (a) monodisperse majority block(s) of poly(styrene) (PS) and a polydisperse...

  16. Nanostructured Double Hydrophobic Poly(Styrene-b-Methyl Methacrylate) Block Copolymer Membrane Manufactured Via Phase Inversion Technique

    KAUST Repository

    Karunakaran, Madhavan; Shevate, Rahul; Peinemann, Klaus-Viktor

    2016-01-01

    In this paper, we demonstrate the formation of nanostructured double hydrophobic poly(styrene-b-methyl methacrylate) (PS-b-PMMA) block copolymer membranes via state-of-the-art phase inversion technique. The nanostructured membrane morphologies are tuned by different solvent and block copolymer compositions. The membrane morphology has been investigated using FESEM, AFM and TEM. Morphological investigation shows the formation of both cylindrical and lamellar structures on the top surface of the block copolymer membranes. The PS-b-PMMA having an equal block length (PS160K-b-PMMA160K) exhibits both cylindrical and lamellar structures on the top layer of the asymmetric membrane. All membranes fabricated from PS160K-b-PMMA160K shows an incomplete pore formation in both cylindrical and lamellar morphologies during the phase inversion process. However, PS-b-PMMA (PS135K-b-PMMA19.5K) block copolymer having a short PMMA block allowed us to produce open pore structures with ordered hexagonal cylindrical pores during the phase inversion process. The resulting PS-b-PMMA nanostructured block copolymer membranes have pure water flux from 105-820 l/m2.h.bar and 95% retention of PEG50K

  17. Nanostructured Double Hydrophobic Poly(Styrene-b-Methyl Methacrylate) Block Copolymer Membrane Manufactured Via Phase Inversion Technique

    KAUST Repository

    Karunakaran, Madhavan

    2016-03-11

    In this paper, we demonstrate the formation of nanostructured double hydrophobic poly(styrene-b-methyl methacrylate) (PS-b-PMMA) block copolymer membranes via state-of-the-art phase inversion technique. The nanostructured membrane morphologies are tuned by different solvent and block copolymer compositions. The membrane morphology has been investigated using FESEM, AFM and TEM. Morphological investigation shows the formation of both cylindrical and lamellar structures on the top surface of the block copolymer membranes. The PS-b-PMMA having an equal block length (PS160K-b-PMMA160K) exhibits both cylindrical and lamellar structures on the top layer of the asymmetric membrane. All membranes fabricated from PS160K-b-PMMA160K shows an incomplete pore formation in both cylindrical and lamellar morphologies during the phase inversion process. However, PS-b-PMMA (PS135K-b-PMMA19.5K) block copolymer having a short PMMA block allowed us to produce open pore structures with ordered hexagonal cylindrical pores during the phase inversion process. The resulting PS-b-PMMA nanostructured block copolymer membranes have pure water flux from 105-820 l/m2.h.bar and 95% retention of PEG50K

  18. Bond Characteristics of Macro Polypropylene Fiber in Cementitious Composites Containing Nanosilica and Styrene Butadiene Latex Polymer

    Directory of Open Access Journals (Sweden)

    Jae-Woong Han

    2015-01-01

    Full Text Available This study evaluated the bond properties of polypropylene (PP fiber in plain cementitious composites (PCCs and styrene butadiene latex polymer cementitious composites (LCCs at different nanosilica contents. The bond tests were evaluated according to JCI SF-8, in which the contents of nanosilica in the cement were 0, 2, 4, 6, 8, and 10 wt%, based on cement weight. The addition of nanosilica significantly affected the bond properties between macro PP fiber and cementitious composites. For PCCs, the addition of 0–2 wt% nanosilica enhanced bond strength and interface toughness, whereas the addition of 4 wt% or more reduced bond strength and interface toughness. The bond strength and interfacial toughness of LCCs also increased with the addition of up to 6% nanosilica. The analysis of the relative bond strength showed that the addition of nanosilica affects the bond properties of both PCC and LCC. This result was confirmed via microstructural analysis of the macro PP fiber surface after the bond tests, which revealed an increase in scratches due to frictional forces and fiber tearing.

  19. Synthesis of Ethylene Bis-stearamide for Acrylonitrile-Butadiene-Styrene Polymer

    Directory of Open Access Journals (Sweden)

    M.A. Sayyadnejad

    2009-12-01

    Full Text Available Ethylene bis-stearamide is one of the important acrylonitrile-butadiene-styrene (ABS( polymer additives, which is used as lubricant, slip agent and mold release agent. In this research, ethylene bis-stearamide for ABS application was synthesized using stearic acid and ethylene diamine under reflux condition. Refluxing prevented ethylenediamine from evaporation and thus the initial molar ratio was maintained unchanged. The other role of refluxing was to prevent the oxidation of ethylene diamine by removal of oxygen which might have been present inside the reactor. The synthesized samples were characterized by Fourier transform infrared spectroscopy (FTIR(, total acid number and melting point. The total acid number of the synthesized samples in the lab, bench scale 1 kg( and pilot scale 30 kg( were 6.5, 8.7 and 8.6 mgKOH/g, respectively, and their melting points were in 141-144 °C range. It was found that total acid number values of samples are inversely proportional with reaction time. The longer the reaction time, the higher was the total acid number and sample purity. Compounding was carried out using ABS containing synthesized and reference ethylene bis-stearamide and the physical-mechanical properties of the samples were measured. The obtained results showed that, the measured properties such as melt flow index, impact resistance, softening temperature, heat deflection temperature, tensile strength and hardness for the compound prepared using synthesized ethylene bis-stearamide match very well with those of reference compound.

  20. Impact of styrenic polymer one-step hyper-cross-linking on volatile organic compound adsorption and desorption performance.

    Science.gov (United States)

    Ghafari, Mohsen; Atkinson, John D

    2018-06-05

    A novel one-step hyper-cross-linking method, using 1,2-dichloroethane (DCE) and 1,6-dichlorohexane (DCH) cross-linkers, expands the micropore volume of commercial styrenic polymers. Performance of virgin and modified polymers was evaluated by measuring hexane, toluene, and methyl-ethyl-ketone (MEK) adsorption capacity, adsorption/desorption kinetics, and desorption efficiency. Hyper-cross-linked polymers have up to 128% higher adsorption capacity than virgin polymers at P/P 0  = 0.05 due to micropore volume increases up to 330%. Improvements are most pronounced with the DCE cross-linker. Hyper-cross-linking has minimal impact on hexane adsorption kinetics, but adsorption rates for toluene and MEK decrease by 6-41%. Desorption rates decreased (3-36%) for all materials after hyper-cross-linking, with larger decreases for DCE hyper-cross-linked polymers due to smaller average pore widths. For room temperature desorption, 20-220% more adsorbate remains in hyper-cross-linked polymers after regeneration compared to virgin materials. DCE hyper-cross-linked polymers have 13-92% more residual adsorbate than DCH counterparts. Higher temperatures were required for DCE hyper-cross-linked polymers to completely desorb VOCs compared to the DCH hyper-cross-linked and virgin counterparts. Results show that the one-step hyper-cross-linking method for modifying styrenic polymers improves adsorption capacity because of added micropores, but decreases adsorption/desorption kinetics and desorption efficiency for large VOCs due to a decrease in average pore width. Copyright © 2018 Elsevier B.V. All rights reserved.

  1. Direct Synthesis of Polymer Nanotubes by Aqueous Dispersion Polymerization of a Cyclodextrin/Styrene Complex.

    Science.gov (United States)

    Chen, Xi; Liu, Lei; Huo, Meng; Zeng, Min; Peng, Liao; Feng, Anchao; Wang, Xiaosong; Yuan, Jinying

    2017-12-22

    A one-step synthesis of nanotubes by RAFT dispersion polymerization of cyclodextrin/styrene (CD/St) complexes directly in water is presented. The resulted amphiphilic PEG-b-PS diblock copolymers self-assemble in situ into nanoparticles with various morphologies. Spheres, worms, lamellae, and nanotubes were controllably obtained. Because of the complexation, the swelling degree of polystyrene (PS) blocks by free St is limited, resulting in limited mobility of PS chains. Consequently, kinetically trapped lamellae and nanotubes were obtained instead of spherical vesicles. During the formation of nanotubes, small vesicles first formed at the ends of the tape-like lamellae, then grew and fused into nanotubes with a limited chain rearrangement. The introduction of a host-guest interaction based on CDs enables the aqueous dispersion polymerization of water-immiscible monomers, and produces kinetically trapped nanostructures, which could be a powerful technique for nanomaterials synthesis. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Effect of mineral acid on polymer produced during radiation-induced grafting of styrene monomer

    International Nuclear Information System (INIS)

    Garnett, J.L.; Jankiewicz, S.V.; Sangster, D.F.

    1982-01-01

    The inclusion of mineral acid in a solution of styrene in methanol subjected to 60 Co γ irradiation markedly enhances the yield of monomer grafted to cellulose and other radiation grafting systems. Results were reported from a preliminary investigation into the mechanism of this acid effect through a study of the action of acid during the solution polymerization process. It was found that the presence of acid in a monomer solution such as styrene in 1, 4-dioxan led to an enhancement in the homopolymer yield of styrene; and it was showed that the acid also effected the number-average molecular weight of this homopolymer. 1 figure, 4 tables

  3. Resonance energy transfer from quinolinone modified polystyrene-block-poly(styrene-alt-maleic anhydride) copolymer to terbium(III) metal ions

    Energy Technology Data Exchange (ETDEWEB)

    Výprachtický, Drahomír, E-mail: vyprachticky@imc.cas.cz [Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, Heyrovský Sq. 2, 162 06 Prague 6 (Czech Republic); Mikeš, František [New York University Polytechnic School of Engineering, Polymer Research Institute, 6 MetroTech Center, Brooklyn, NY 11201 (United States); Lokaj, Jan; Pokorná, Veronika; Cimrová, Věra [Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, Heyrovský Sq. 2, 162 06 Prague 6 (Czech Republic)

    2015-04-15

    Polystyrene-block-poly(styrene-alt-maleic anhydride) was synthesized by nitroxide mediated radical polymerization and modified with 7-amino-4-methylquinolin-2(1H)-one (I) and methanol. The formed block polymer ligand contained a quinolinone fluorophore (Ω) and carboxyl (III) or sodium carboxylate (IV) binding sites. The ligand-to-metal resonance energy transfer (RET) and ligand binding properties of [III–Tb{sup 3+}] and [IV–Tb{sup 3+}] complexes were investigated by steady-state and time-resolved luminescence spectroscopy in tetrahydrofuran/methanol and/or tetrahydrofuran/deuterated methanol mixtures and compared with those of a low-molecular-weight model ligand, i.e. the sodium salt of N-(4-methyl-2-oxo-1,2-dihydroquinolin-7-yl)succinamic acid (II). The long-lived emission intensities of Tb{sup 3+} at 490, 545, 585, and 620 nm corresponding to the {sup 5}D{sub 4}→{sup 7}F{sub 6}, {sup 5}D{sub 4}→{sup 7}F{sub 5}, {sup 5}D{sub 4}→{sup 7}F{sub 4}, and {sup 5}D{sub 4}→{sup 7}F{sub 3} transitions, respectively, were strongly increased by the addition of ligands in the order [II-Tb{sup 3+}]⪡[III-Tb{sup 3+}]<[IV-Tb{sup 3+}]. The efficiency of energy transfer (E) was evaluated from the emission intensity of the donor (Ω) in the presence or absence of the acceptor (Tb{sup 3+}) depending on the acceptor concentration and ligand neutralization. It was concluded that the macromolecular ligand structural properties (polymer coil and supramolecular structures, e.g. micelles) were responsible for the increase in RET. The time-resolved luminescence measurements revealed that the binding affinity of the ligands II, III, and IV increased in the order IIblock polymer (donor) for Tb{sup 3+} (acceptor) luminescence was developed. • Efficient donor–acceptor resonance energy transfer (RET) was found out. • Macromolecular (polymer coil) structure caused a powerful RET and also a supramacromolecular (micelles) structure

  4. Controlled radical copolymerization of styrene and maleic anhydride and the synthesis of novel polyolefin-based block copolymers by reversible addition-fragmentation chain-transfer (RAFT) polymerization

    NARCIS (Netherlands)

    Brouwer, de J.A.M.; Schellekens, M.A.J.; Klumperman, B.; Monteiro, M.J.; German, A.L.

    2000-01-01

    Reversible addn.-fragmentation chain transfer (RAFT) was applied to the copolymn. of styrene and maleic anhydride. The product had a low polydispersity and a predetd. molar mass. Novel, well-defined polyolefin-based block copolymers were prepd. with a macromol. RAFT agent prepd. from a com.

  5. Preparation and drug-loading properties of Fe{sub 3}O{sub 4}/Poly(styrene-co-acrylic acid) magnetic polymer nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Wensheng [School of Chemistry and Chemical Engineering, Anhui University, Hefei 230039 (China); Coordination Chemistry Institute, School of Chemistry and Chemical Engineering and Life Science, Chaohu University, Chaohu 238000 (China); Shen, Yuhua, E-mail: s_yuhua@163.com [School of Chemistry and Chemical Engineering, Anhui University, Hefei 230039 (China); Xie, Anjian [School of Chemistry and Chemical Engineering, Anhui University, Hefei 230039 (China); Zhang, Weiqiang [School of Chemistry and Chemical Engineering, Anhui University, Hefei 230039 (China); Coordination Chemistry Institute, School of Chemistry and Chemical Engineering and Life Science, Chaohu University, Chaohu 238000 (China)

    2013-11-15

    Fe{sub 3}O{sub 4}/poly(styrene-co-acrylic acid) magnetic polymer nanocomposites were synthesized by the dispersion polymerization method using styrene as hard monomer, acrylic acid as functional monomer, Fe{sub 3}O{sub 4} nanoparticles modified with oleic acid as core, and poly(styrene-co-acrylic acid) as shell. Drug-loading properties of magnetic polymer nanocomposites with curcumin as a model drug were also studied. The results indicated that magnetic polymer nanocomposites with monodisperse were obtained, the particle size distribution was 50–120 nm, and the average size was about 100 nm. The contents of poly(styrene-co-acrylic acid) and Fe{sub 3}O{sub 4} nanoparticles in magnetic polymer nanocomposites were 74% and 24.7%, respectively. The drug-loading capacity and entrapment efficiency were 2.5% and 44.4%, respectively. The saturation magnetization of magnetic polymer nanocomposites at 300 K was 20.2 emu/g without coercivity and remanence. The as-prepared magnetic polymer nanocomposites have not only lots of functional carboxyl groups but also stronger magnetic response, which might have potential applications in drug carrier and targeted drug release.

  6. RANDOM COPOLYMER BLENDS OF STYRENE, PARA-FLUORO STYRENE AND ORTHO-FLUORO STYRENE

    NARCIS (Netherlands)

    OUDHUIS, AACM; TENBRINKE, G; KARASZ, FE

    1993-01-01

    This study completes the investigation of the phase behaviour of polymer blends involving styrene (S), ortho-fluoro styrene (oFS) and para-fluoro styrene (pFS). As before, due to the proximity of the glass transition temperatures of most blends investigated, the miscibility or immiscibility is

  7. Preparation of candidate reference materials for the determination of phosphorus containing flame retardants in styrene-based polymers.

    Science.gov (United States)

    Roth, Thomas; Urpi Bertran, Raquel; Latza, Andreas; Andörfer-Lang, Katrin; Hügelschäffer, Claudia; Pöhlein, Manfred; Puchta, Ralph; Placht, Christian; Maid, Harald; Bauer, Walter; van Eldik, Rudi

    2015-04-01

    Candidate reference materials (RM) for the analysis of phosphorus-based flame retardants in styrene-based polymers were prepared using a self-made mini-extruder. Due to legal requirements of the current restriction for the use of certain hazardous substances in electrical and electronic equipment, focus now is placed on phosphorus-based flame retardants instead of the brominated kind. Newly developed analytical methods for the first-mentioned substances also require RMs similar to industrial samples for validation and verification purposes. Hence, the prepared candidate RMs contained resorcinol-bis-(diphenyl phosphate), bisphenol A bis(diphenyl phosphate), triphenyl phosphate and triphenyl phosphine oxide as phosphorus-based flame retardants. Blends of polycarbonate and acrylonitrile-co-butadiene-co-styrene as well as blends of high-impact polystyrene and polyphenylene oxide were chosen as carrier polymers. Homogeneity and thermal stability of the candidate RMs were investigated. Results showed that the candidate RMs were comparable to the available industrial materials. Measurements by ICP/OES, FTIR and NMR confirmed the expected concentrations of the flame retardants and proved that analyte loss and degradation, respectively, was below the uncertainty of measurement during the extrusion process. Thus, the candidate RMs were found to be suitable for laboratory use.

  8. Solvothermal Vapor Annealing of Lamellar Poly(styrene)-block-poly(d,l-lactide) Block Copolymer Thin Films for Directed Self-Assembly Application.

    Science.gov (United States)

    Cummins, Cian; Mokarian-Tabari, Parvaneh; Andreazza, Pascal; Sinturel, Christophe; Morris, Michael A

    2016-03-01

    Solvothermal vapor annealing (STVA) was employed to induce microphase separation in a lamellar forming block copolymer (BCP) thin film containing a readily degradable block. Directed self-assembly of poly(styrene)-block-poly(d,l-lactide) (PS-b-PLA) BCP films using topographically patterned silicon nitride was demonstrated with alignment over macroscopic areas. Interestingly, we observed lamellar patterns aligned parallel as well as perpendicular (perpendicular microdomains to substrate in both cases) to the topography of the graphoepitaxial guiding patterns. PS-b-PLA BCP microphase separated with a high degree of order in an atmosphere of tetrahydrofuran (THF) at an elevated vapor pressure (at approximately 40-60 °C). Grazing incidence small-angle X-ray scattering (GISAXS) measurements of PS-b-PLA films reveal the through-film uniformity of perpendicular microdomains after STVA. Perpendicular lamellar orientation was observed on both hydrophilic and relatively hydrophobic surfaces with a domain spacing (L0) of ∼32.5 nm. The rapid removal of the PLA microdomains is demonstrated using a mild basic solution for the development of a well-defined PS mask template. GISAXS data reveal the through-film uniformity is retained following wet etching. The experimental results in this article demonstrate highly oriented PS-b-PLA microdomains after a short annealing period and facile PLA removal to form porous on-chip etch masks for nanolithography application.

  9. Supramolecular Assemblies from Poly(styrene-block-poly(4-vinylpyridine Diblock Copolymers Mixed with 6-Hydroxy-2-naphthoic Acid

    Directory of Open Access Journals (Sweden)

    Jean-François Gohy

    2013-06-01

    Full Text Available Supramolecular assemblies involving interaction of a small organic molecule, 2-hydroxy-6-Naphthoic acid (HNA, with poly(styrene-block-poly(4-vinylpyridine (PS-b-P4VP diblock copolymers are utilized to obtain micellar structures in solution, nanostructured thin films on flat substrates and, finally, nanoporous thin films. The formation of hydrogen bonds between HNA and the poly(4-vinylpyridine (P4VP blocks is confirmed by spectroscopic measurements. The accordingly P4VP/HNA hydrogen-bonded complexes are poorly soluble in 1,4-dioxane, resulting in the formation of micellar structures with a P4VP/HNA core and a polystyrene (PS corona. Those micelles have been spin-coated onto silicon wafers, resulting in nanostructured thin films consisting of P4VP/HNA dot-like features embedded in a PS matrix. The morphology of those films has been tuned by solvent annealing. Selective dissolution of HNA by methanol results in the formation of a nanoporous thin film. The P4VP/HNA nanodomains have been also cross-linked by borax, and the thin films have been further dissolved in a good solvent for PS, leading to micelles with a structure reminiscent of the thin films.

  10. Morphology and mechanical properties of polypropylene/polystyrene blends compatibilized with styrene-butadiene block copolymers

    Czech Academy of Sciences Publication Activity Database

    Fortelný, Ivan; Minkova, L. I.; Kotek, Jiří; Lapčíková, Monika; Michálková, Danuše

    2012-01-01

    Roč. 52, č. 1 (2012), s. 191-204 ISSN 0032-3888 R&D Projects: GA ČR GA106/06/0729; GA AV ČR IAA200500903 Institutional research plan: CEZ:AV0Z40500505 Keywords : polymer blends * compatibilization * morphology Subject RIV: JI - Composite Materials Impact factor: 1.243, year: 2012

  11. Oligomers and Polymers Based on Pentacene Building Blocks

    Science.gov (United States)

    Lehnherr, Dan; Tykwinski, Rik R.

    2010-01-01

    Functionalized pentacene derivatives continue to provide unique materials for organic semiconductor applications. Although oligomers and polymers based on pentacene building blocks remain quite rare, recent synthetic achievements have provided a number of examples with varied structural motifs. This review highlights recent work in this area and, when possible, contrasts the properties of defined-length pentacene oligomers to those of mono- and polymeric systems.

  12. Functional polymers as nanoscopic building blocks

    International Nuclear Information System (INIS)

    Hernandez-Lopez, J.L.; Bauer, R.E.; Chang, W.-S.; Glasser, G.; Grebel-Koehler, D.; Klapper, M.; Kreiter, M.; Leclaire, J.; Majoral, J.-P.; Mittler, S.; Muellen, K.; Vasilev, K.; Weil, T.; Wu, J.; Zhu, T.; Knoll, W.

    2003-01-01

    Polyphenylene dendrimers are introduced as polymeric building blocks--with a strictly monodisperse particle size distribution within the nanometer range--for the construction of nanostructured materials and devices. The possibility for the introduction of different functionalities in the core, the scaffold or the periphery of the dendrimers offer their use as interesting modules for photonic, electronic or bioactive structures and supramolecular functional assemblies. Thus, dendrimers complement the available set of nanoscopic building blocks made from metals, e.g., Au nanoclusters and semiconductors, e.g., luminescent quantum dots. In a first set of experiments, we describe the fabrication of multilayer architectures using dendrimers with chargeable groups at the surface. This way, the polyelectrolyte deposition technique can be applied for the construction of hybrid layered assemblies with a control of the internal supramolecular structure at the nanometer level. Surface plasmon field-enhanced fluorescence spectroscopy is used to monitor the luminescent properties of dendrimers with a phthalocyanine core integrated into such a multilayer assembly. AFM and SEM micrographs demonstrate the use of surface-functionalized dendrimers (exposing sulfur groups at the periphery) in combination with Au nanoparticles for the controlled assembly of hybrid aggregates as nanoscopic functional devices

  13. Copolymerization of carbon monoxide and styrene catalyzed by resin-supported palladium polymer

    Directory of Open Access Journals (Sweden)

    2007-02-01

    Full Text Available Polyketone was prepared by the copolymerization of carbon monoxide (CO and styrene (ST catalyzed by o-phenylenediamine resin-supported palladium acetate. Effects of each catalytic system component such as 2,2’-bipyridine, 1,4-quinone and p-toluene-sulphonate on the copolymerization were investigated. The resin-supported catalyst and the copolymerization product were characterized by infrared spectroscopy (IR, differential scanning calorimetry (DSC, thermogravimetry (TG, X-ray photoelectron spectroscopy (XPS, Scanning Electron Microscopy (SEM. Results indicated that the resin-supported catalyst has excellent catalytic property. Furthermore, partial catalytic activity was maintained after the catalyst was used for five times.

  14. Microbial production of building block chemicals and polymers.

    Science.gov (United States)

    Lee, Jeong Wook; Kim, Hyun Uk; Choi, Sol; Yi, Jongho; Lee, Sang Yup

    2011-12-01

    Owing to our increasing concerns on the environment, climate change, and limited natural resources, there has recently been considerable effort exerted to produce chemicals and materials from renewable biomass. Polymers we use everyday can also be produced either by direct fermentation or by polymerization of monomers that are produced by fermentation. Recent advances in metabolic engineering combined with systems biology and synthetic biology are allowing us to more systematically develop superior strains and bioprocesses for the efficient production of polymers and monomers. Here, we review recent trends in microbial production of building block chemicals that can be subsequently used for the synthesis of polymers. Also, recent successful cases of direct one-step production of polymers are reviewed. General strategies for the production of natural and unnatural platform chemicals are described together with representative examples. Copyright © 2011 Elsevier Ltd. All rights reserved.

  15. Star polymers by ATRP of styrene and acrylates employing multifunctional initiators

    DEFF Research Database (Denmark)

    Jankova, Katja Atanassova; Bednarek, Melania; Hvilsted, Søren

    2005-01-01

    -bromoisobutyrates or 2-bromopropionates as obtained by reaction with acid bromides. Star polystyrene (PS) is produced by using these macroinitiators and neat styrene in a controlled manner by ATRP at 110 degrees C, employing the catalytic system CuBr and bipyridine. M. up to 51,000 associated with narrow molecular...... weight distributions (PDI degrade thermally in nitrogen in a two-step process in which the first low-temperature step involves...... scission of the ester linkages and the second step corresponds to the normal PS degradation. Star poly(methyl acrylates) with various cores are likewise prepared in a controlled manner by ATRP of methyl acrylate in bulk and in solution at 6080 degrees C with the 1,1,4,7,7-pentamethyldiethylene triamine...

  16. Oligomers and Polymers Based on Pentacene Building Blocks

    Directory of Open Access Journals (Sweden)

    Dan Lehnherr

    2010-04-01

    Full Text Available Functionalized pentacene derivatives continue to provide unique materials for organic semiconductor applications. Although oligomers and polymers based on pentacene building blocks remain quite rare, recent synthetic achievements have provided a number of examples with varied structural motifs. This review highlights recent work in this area and, when possible, contrasts the properties of defined-length pentacene oligomers to those of mono- and polymeric systems.

  17. 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.

  18. Effects of solvent evaporation conditions on solvent vapor annealed cylinder-forming block polymer thin films

    Science.gov (United States)

    Grant, Meagan; Jakubowski, William; Nelson, Gunnar; Drapes, Chloe; Baruth, A.

    Solvent vapor annealing is a less time and energy intensive method compared to thermal annealing, to direct the self-assembly of block polymer thin films. Periodic nanostructures have applications in ultrafiltration, magnetic arrays, or other structures with nanometer dimensions, driving its continued interest. Our goal is to create thin films with hexagonally packed, perpendicular aligned cylinders of poly(lactide) in a poly(styrene) matrix that span the thickness of the film with low anneal times and low defect densities, all with high reproducibility, where the latter is paramount. Through the use of our computer-controlled, pneumatically-actuated, purpose-built solvent vapor annealing chamber, we have the ability to monitor and control vapor pressure, solvent concentration within the film, and solvent evaporation rate with unprecedented precision and reliability. Focusing on evaporation, we report on two previously unexplored areas, chamber pressure during solvent evaporation and the flow rate of purging gas aiding the evaporation. We will report our exhaustive results following atomic force microscopy analysis of films exposed to a wide range of pressures and flow rates. Reliably achieving well-ordered films, while occurring within a large section of this parameter space, was correlated with high-flow evaporation rates and low chamber pressures. These results have significant implications on other methods of solvent annealing, including ``jar'' techniques.

  19. Novel styrene polymers functionalized with phosphorus-nitrogen containing molecules: Synthesis and properties

    Energy Technology Data Exchange (ETDEWEB)

    Tai Qilong [State Key Laboratory of Fire Science, University of Science and Technology of China and USTC-CityU Joint Advanced Research Centre, Suzhou (China); Department of Building and Construction, City University of Hong Kong and USTC-CityU Joint Advanced Research Centre, Suzhou (China); Suzhou Key Laboratory of Urban Public Safety, Suzhou Institute of University of Science and Technology of China, Suzhou (China); Song Lei [State Key Laboratory of Fire Science, University of Science and Technology of China and USTC-CityU Joint Advanced Research Centre, Suzhou (China); Hu Yuan, E-mail: yuanhu@ustc.edu.cn [State Key Laboratory of Fire Science, University of Science and Technology of China and USTC-CityU Joint Advanced Research Centre, Suzhou (China); Suzhou Key Laboratory of Urban Public Safety, Suzhou Institute of University of Science and Technology of China, Suzhou (China); Yuen, Richard K.K., E-mail: Richard.Yuen@cityu.edu.hk [Department of Building and Construction, City University of Hong Kong and USTC-CityU Joint Advanced Research Centre, Suzhou (China); Feng Hao; Tao Youji [State Key Laboratory of Environmental Adaptability for Industrial Products, China National Electric Apparatus Research Institute, Guangzhou 510300 (China)

    2012-05-15

    Highlights: Black-Right-Pointing-Pointer Novel styrene copolymers were successfully synthesized and well characterized. Black-Right-Pointing-Pointer The copolymers have good optical transparency. Black-Right-Pointing-Pointer The copolymers exhibited much lower flammability. - Abstract: A phosphorus and nitrogen-containing compound with high phosphorus content, AC{sub 2}NP{sub 2}, was firstly synthesized by the Kabachnik-Fields reaction and followed by esterification with acryloyl chloride. The synthesized comonomer was then incorporated into different amounts of polystyrene via radical solution polymerization. The copolymers were well characterized using Fourier transform infrared (FTIR), UV/vis spectrophotometer, nuclear magnetic resonance (NMR), gel permeation chromatography (GPC), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), microscale combustion calorimeter (MCC) and LOI. The results showed that the AC{sub 2}NP{sub 2} was easily incorporated into the backbone of polystyrene, and the copolymers prepared have high transparency. The glass transition temperature (T{sub g}) of the copolymers was decreased with increasing the AC{sub 2}NP{sub 2} content, due to the introduction of much more flexible molecular chain. The TGA results revealed that the introduction of AC{sub 2}NP{sub 2} units slightly decreased the initial decomposition temperatures, but significantly improved the thermal stability of copolymers at high temperature regions under both nitrogen and air atmosphere. Furthermore, all the copolymers exhibited much lower flammability as compared with virgin polystyrene.

  20. Self-assembly behavior of poly(fluorenyl styrene)-block-poly(2-vinyl pyridine) and their blends with single wall carbon nanotubes (SWCNT)

    Science.gov (United States)

    Mezzenga, Raffaele; Li, Chaoxu; Hsu, Jung-Ching; Chen, Wen-Chang; Sugiyama, Kenji; Hirao, Akira

    2010-03-01

    We describe a supramolecular strategy to disperse carbon nanotubes in block copolymer matrices. To achieve the desired functions and morphologies, comb-type architectures in which one and two fluorene units attached on the styrene ring of polystyrene-block-poly(2-vinyl pyridine) were studied. Depending on the pendant fluorene units, the block ratio, the casting solvent and thermal annealing history, multiple morphologies were found. The phase diagram, compared to PS-b-P2VP, was interpreted in terms of the conformational asymmetry arising from grafting of fluorene units of variable lengths. Hydrogen bonds between COOH-SWCNT and P2VP favor miscibility of SWCNT within P2VP domains and the blending of these two components is reflected both on the final morphologies and on the electron conductivity of the blends.

  1. Transparent Wood Smart Windows: Polymer Electrochromic Devices Based on Poly(3,4-Ethylenedioxythiophene):Poly(Styrene Sulfonate) Electrodes.

    Science.gov (United States)

    Lang, Augustus W; Li, Yuanyuan; De Keersmaecker, Michel; Shen, D Eric; Österholm, Anna M; Berglund, Lars; Reynolds, John R

    2018-03-09

    Transparent wood composites, with their high strength and toughness, thermal insulation, and excellent transmissivity, offer a route to replace glass for diffusely transmitting windows. Here, conjugated-polymer-based electrochromic devices (ECDs) that switch on-demand are demonstrated using transparent wood coated with poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) as a transparent conducting electrode. These ECDs exhibit a vibrant magenta-to-clear color change that results from a remarkably colorless bleached state. Furthermore, they require low energy and power inputs of 3 mWh m -2 at 2 W m -2 to switch due to a high coloration efficiency (590 cm 2  C -1 ) and low driving voltage (0.8 V). Each device component is processed with high-throughput methods, which highlights the opportunity to apply this approach to fabricate mechanically robust, energy-efficient smart windows on a large scale. © 2018 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

  2. Penelitian “polymer blend” high styrene rubber dengan karet alam untuk “sponnge middle sole”

    Directory of Open Access Journals (Sweden)

    Penny Setyowati

    1999-07-01

    Full Text Available The objective of this research was find optimum composision of polymer blend of High Styrene Rubber (HSR and Natural Rubber (SIR 3L for preparation sponge middle sole that save the best fisical properties, strong, flexible, light, stable and thermoplastic properties. The formulation of rubber compound has to be researched as much as 3 formalition MS 1, MS II and MS III with variation of SIR 3L, HSR and HAF black as follows, MS I 70-30-20 phr ; MS II 80-20-30 PHR and MS III 90-10-40 phr . From the fisical test analysis, optimum formulation to be reached at the compound formualtion MS III with result of fisical test as follows : Tensile strength : 0.572 kg/mm2 ; Elongation at break : 204% ; Hardness share A : 55,8 : Density 0,728 gr/cm3 : Tear Resistance : 0,296 kg/mm2 and Compression Set 22,042%.

  3. PREPARATION OF BLOCK COPOLYMERS OF POLY(STYRENE) AND POLY(T-BUTYL ACRYLATE) OF VARIOUS MOLECULAR WEIGHTS AND ARCHITECTURES BY ATOM TRANSFER RADICAL POLYMERIZATION. (R826735)

    Science.gov (United States)

    Block copolymers of polystyrene and poly(t-butyl acrylate) were prepared using atom transfer radical polymerization techniques. These polymers were synthesized with a CuBr/N,N,N,NPredicting the chromatographic retention of polymers: application of the polymer model to poly(styrene/ethylacrylate)copolymers.

    Science.gov (United States)

    Bashir, Mubasher A; Radke, Wolfgang

    2012-02-17

    The retention behavior of a range of statistical poly(styrene/ethylacrylate) copolymers is investigated, in order to determine the possibility to predict retention volumes of these copolymers based on a suitable chromatographic retention model. It was found that the composition of elution in gradient chromatography of the copolymers is closely related to the eluent composition at which, in isocratic chromatography, the transition from elution in adsorption to exclusion mode occurs. For homopolymers this transition takes place at a critical eluent composition at which the molar mass dependence of elution volume vanishes. Thus, similar critical eluent compositions can be defined for statistical copolymers. The existence of a critical eluent composition is further supported by the narrower peak width, indicating that the broad molar mass distribution of the samples does not contribute to the retention volume. It is shown that the existing retention model for homopolymers allows for correct quantitative predictions of retention volumes based on only three appropriate initial experiments. The selection of these initial experiments involves a gradient run and two isocratic experiments, one at the composition of elution calculated from first gradient run and second at a slightly higher eluent strength. Copyright © 2011 Elsevier B.V. All rights reserved.

  4. Synthesis and characterization of sulfonated polymers for ionomeric membranes based on styrene copolymers; Sintese e caracterizacao de precursores sulfonados para membranas polimericas a base de copolimeros estirenicos

    Energy Technology Data Exchange (ETDEWEB)

    Becker, C.M.; Forte, M.M.C.; Amico, S.C. [Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS (Brazil). Escola de Engenharia. Lab. de Materiais Polimericos (LAPOL)], e-mail: crismbecker@yahoo.com.br, e-mail: mmcforte@ufrgs.br, e-mail: amico@ufrgs.br; Vargas, J.V.C. [Universidade Federal do Parana (UFPR), Curitiba, PR (Brazil). Dept. de Engenharia Mecanica], e-mail: jvargas@demec.ufpr.br

    2006-07-01

    Polymer electrolyte membrane fuel cell (PEMFC) have emerged strongly as a viable alternative for power source owing to their high energy efficiency and environmental friendliness. Currently, Nafion is the most frequently used membrane even though it has a high cost. The objective of this work is to synthesize sulfonated polymers, based on styrene copolymers, with different sulfonation degrees as an alternative material for fuel cell membranes. Acetyl sulfate was used to carry out the sulfonation and the resulting polymers were characterized by Fourier Transform Infra-red (FTIR), thermogravimetric analysis (TGA) and degree of substitution or sulfonation (DS). The polyelectrolytes were evaluated regarding their ion exchange capacity (IEC) and conductivity. The results demonstrated that increasing the sulfonic acid content of the polymer results in higher IEC, conductivity and water uptake. (author)

  5. Shape Memory Polymer Composites of Poly(styrene-b-butadiene-b-styrene Copolymer/Liner Low Density Polyethylene/Fe3O4 Nanoparticles for Remote Activation

    Directory of Open Access Journals (Sweden)

    Yongkun Wang

    2016-11-01

    Full Text Available Magnetically sensitive shape memory poly(styrene-b-butadiene-b-styrene copolymer (SBS/liner low density polyethylene (LLDPE composites filled with various contents of Fe3O4 nanoparticles were prepared. The influence of the Fe3O4 nanoparticles content on the thermal properties, mechanical properties, fracture morphology, magnetic behavior, and shape memory effect of SBS/LLDPE/Fe3O4 composites was systematically studied in this paper. The results indicated that homogeneously dispersed Fe3O4 nanoparticles ensured the uniform heat generation and transfer in the alternating magnetic field, and endowed the SBS/LLDPE/Fe3O4 composites with an excellent magnetically responsive shape memory effect. When the shape memory composites were in the alternating magnetic field (f = 60 kHz, H = 21.21 kA·m−1, the best shape recovery ratio reached 99%, the shape retention ratio reached 99.4%, and the shape recovery speed increased significantly with the increment of Fe3O4 nanoparticles. It is anticipated that tagging products with this novel shape memory composite is helpful for the purpose of an intravascular delivery system in Micro-Electro-Mechanical System (MEMS devices.

  6. Block copolymer assisted self-assembly of nanoparticles into Langmuir–Blodgett films: Effect of polymer concentration

    International Nuclear Information System (INIS)

    Martín-García, Beatriz; Velázquez, M. Mercedes

    2013-01-01

    We propose to use the self-assembly ability of a block copolymer to obtain CdSe quantum dots (QDs) structures of different morphology. The methodology proposed consist in transferring mixed Langmuir monolayers of QDs and the polymer poly (styrene-co-maleic anhydride) partial 2 buthoxy ethyl ester cumene terminated, PS-MA-BEE onto mica by the Langmuir–Blodgett (LB) methodology. The morphology of the LB films was analyzed by AFM and TEM measurements. Our results show that it is possible to modulate the self-assembly process by modifying the composition of the mixed Langmuir monolayer precursor of the LB film. The different morphologies are interpreted according to two different dewetting mechanisms, growth of holes and spinodal-like dewetting. The growth of holes dewetting process is driven by gravitatory effects and was observed for LB films obtained by transferring Langmuir monolayer of the smallest elasticity values in which the polymer is in brush conformation. The spinodal dewetting mechanism prevailed when the Langmuir monolayer presents the highest elasticity values. - Graphical abstract: Display Omitted - Highlights: • Effect of the surface composition on the LB films architecture. • QDs/polymer LB films morphology interpreted in terms of dewetting mechanism. • The dewetting mechanism depends on the Langmuir monolayer state

  7. Block copolymer assisted self-assembly of nanoparticles into Langmuir–Blodgett films: Effect of polymer concentration

    Energy Technology Data Exchange (ETDEWEB)

    Martín-García, Beatriz; Velázquez, M. Mercedes, E-mail: mvsal@usal.es

    2013-08-15

    We propose to use the self-assembly ability of a block copolymer to obtain CdSe quantum dots (QDs) structures of different morphology. The methodology proposed consist in transferring mixed Langmuir monolayers of QDs and the polymer poly (styrene-co-maleic anhydride) partial 2 buthoxy ethyl ester cumene terminated, PS-MA-BEE onto mica by the Langmuir–Blodgett (LB) methodology. The morphology of the LB films was analyzed by AFM and TEM measurements. Our results show that it is possible to modulate the self-assembly process by modifying the composition of the mixed Langmuir monolayer precursor of the LB film. The different morphologies are interpreted according to two different dewetting mechanisms, growth of holes and spinodal-like dewetting. The growth of holes dewetting process is driven by gravitatory effects and was observed for LB films obtained by transferring Langmuir monolayer of the smallest elasticity values in which the polymer is in brush conformation. The spinodal dewetting mechanism prevailed when the Langmuir monolayer presents the highest elasticity values. - Graphical abstract: Display Omitted - Highlights: • Effect of the surface composition on the LB films architecture. • QDs/polymer LB films morphology interpreted in terms of dewetting mechanism. • The dewetting mechanism depends on the Langmuir monolayer state.

  8. TEMPO addition into pre-irradiated fluoropolymers and living-radical graft polymerization of styrene for preparation of polymer electrolyte membranes

    Energy Technology Data Exchange (ETDEWEB)

    Sawada, Shin-ichi, E-mail: sawada.shinnichi@jaea.go.j [Conducting Polymer Materials Research Group, Quantum Beam Science Directorate, Japan Atomic Energy Agency (JAEA), 1233 Watanuki, Takasaki, Gunma 370-1292 (Japan); Department of Nuclear Engineering and Management, Graduate School of Engineering, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Suzuki, Akihiro; Terai, Takayuki [Department of Nuclear Engineering and Management, Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Maekawa, Yasunari, E-mail: maekawa.yasunari@jaea.go.j [Conducting Polymer Materials Research Group, Quantum Beam Science Directorate, Japan Atomic Energy Agency (JAEA), 1233 Watanuki, Takasaki, Gunma 370-1292 (Japan)

    2010-04-15

    We prepared proton exchange membranes (PEMs) by 2,2,6,6-tetramethylpiperidinyl-1-oxy (TEMPO)-mediated living-radical graft polymerization (LRGP) of styrene into fluoropolymer films and subsequent sulfonation. Poly(vinylidene fluoride) (PVDF) and poly(ethylene-co-tetrafluoroethylene) (ETFE) films were first irradiated and then treated with TEMPO solutions in various solvents. TEMPO addition was confirmed by the test of styrene grafting into TEMPO-treated films at 60 deg. C, at which the LRGP never proceeds. This test enabled us to differentiate the LRGP from the conventional graft polymerization. In order to gain a deep insight about TEMPO-addition reaction, the TEMPO-penetration behavior into the base polymer films was examined by a permeation experiment and computer simulation. Xylene and dioxane were appropriate solvents for the complete introduction of TEMPO into PVDF and ETFE films, respectively. Then, the LRGP of styrene was performed based on the fully TEMPO-capped films at 125 deg. C with various solvents. By using an alcoholic solvent, the degree of grafting was enhanced and it reached a maximum of 38%. This grafted film was sulfonated to prepare a PEM showing an ion exchange capacity of 2.2 meq/g and proton conductivity of 1.6x10{sup -1} S/cm.

  9. New insights into the effects of styrene-butadiene-styrene polymer modifier on the structure, properties, and performance of asphalt binder: The case of AP-5 asphalt and solvent deasphalting pitch

    Energy Technology Data Exchange (ETDEWEB)

    Nciri, Nader, E-mail: nader.nciri@koreatech.ac.kr [Department of Energy, Materials, and Chemical Engineering, Korea University of Technology and Education, 1600 Chungjeol-ro, Byeongcheon-myeon, Dongnam-gu, Cheonan-City, Chungnam-Province 330-708 (Korea, Republic of); Kim, Namho [Department of Architectural Engineering, Korea University of Technology and Education, 1600 Chungjeol-ro, Byeongcheon-myeon, Dongnam-gu, Cheonan-City, Chungnam-Province 330-708 (Korea, Republic of); Cho, Namjun, E-mail: njuncho@koreatech.ac.kr [Department of Energy, Materials, and Chemical Engineering, Korea University of Technology and Education, 1600 Chungjeol-ro, Byeongcheon-myeon, Dongnam-gu, Cheonan-City, Chungnam-Province 330-708 (Korea, Republic of)

    2017-06-01

    This paper deals with the poorly understood effects of styrene-butadiene-styrene (SBS) copolymer on the bitumen performance. It focuses on determining the impact of various concentrations (e.g., 0, 4, 8, and 12 wt. %) of SBS on the attributes of two types of asphalt namely AP-5 asphalt and solvent deasphalting (SDA) pitch. The unmodified and modified binders were investigated in terms of their chemical compositions, microstructures, thermo-analytical behaviors, and physical properties. The intricate chemical compositions were evaluated by elemental analysis and thin layer chromatography-ionization detection (TLC-FID). Fourier transform infrared (FT-IR) and nuclear magnetic resonance (NMR) spectroscopies, scanning electron microscopy (SEM), and X-ray diffraction (XRD) were utilized to examine the microstructures. Whereas, thermal characteristics were evaluated by thermogravimetric analysis (TGA/DTGA) and differential scanning calorimetry (DSC). The physical behaviors were monitored through the softening point, penetration, viscosity, and ductility tests. The findings showed that the blending of asphalt with different amounts of SBS resulted into different rheological behaviors. This was reflected from the difference in the SARA (i.e., saturates, aromatics, resins, and asphaltenes) compositions and colloidal instability indexes of the modified asphalts. SEM exhibited a continuous asphalt phase with distributed SBS particles, a continuous polymer phase with distributed asphalt globules, or two interconnected continuous phases. FT-IR, {sup 1}H {sup 13}C NMR, and XRD data revealed that the AP-5 asphalt and SDA pitch experienced a number of distinct structural changes. TGA/DSC studies determined the occurrence of diverse events during thermal treatment. It is concluded that the degree of SBS modification depends strongly on SARA composition and polymer content. If the polymers are molded at higher concentrations along with aromatics-rich SDA pitches, then the mixtures

  10. Radiation crosslinked block copolymer blends with improved impact resistance

    International Nuclear Information System (INIS)

    Saunders, F.L.; Pelletier, R.R.

    1976-01-01

    Polymer blends having high impact resistance after mechanical working are produced by blending together a non-elastomeric monovinylidene aromatic polymer such as polystyrene with an elastomeric copolymer, such as a block copolymer of styrene and butadiene, in the form of crosslinked, colloidal size particles

  11. Unexpected differences between thermal and photoinitiated cationic curing of a diglycidyl ether of bisphenol A modified with a multiarm star poly(styrene-b-poly(ε-caprolactone polymer

    Directory of Open Access Journals (Sweden)

    J. M. Morancho

    2013-07-01

    Full Text Available The effect of adding a multiarm star poly(styrene-b-poly(ε-caprolactone polymer on the cationic thermal and photoinitiated curing of diglycidyl ether of bisphenol A was studied. This star-polymer decelerated the thermal curing of diglycidyl ether of bisphenol A and modified the final structure of the epoxy matrix. The photocuring was influenced significantly by the addition of the multiarm star. When the proportion of this modifier added was 5%, much more time was necessary for complete photocuring (160 min at 40ºC. In the presence of 10% of modifier, the degree of photocuring reached was very low (0.196 at 120°C. A subsequent thermal post-curing was necessary to cure completely the system. During photocuring in presence of poly(styrene-b-poly(ε-caprolactone, the formation of dormant species, which are reactivated when the temperature increases, takes places. The kinetics of the thermal curing and the photocuring was analyzed using an isoconversional method due to the complexity of the reactive process. Applying this method, it has been confirmed the dependence of activation energy on the degree of conversion. The fracture morphology analyzed by scanning electron microscopy exhibited a second phase originated during photocuring by the presence of the modifier.

  12. The Specific Refractive Index Increments for POSS Polymers in Solution

    National Research Council Canada - National Science Library

    Largo, Sheryl

    2004-01-01

    Partial contents: Hybrid Inorganic/Organic Polymers, Introduction to POSS, Anatomy of a POSS Nanostructure, POSS Polymer Incorporation, POSS Styrene Monomer Synthesis, POSS Styrene Copolymer Synthesis, 1HNMR...

  13. Towards quantification of butadiene content in styrene-butadiene block copolymers and their blends with general purpose polystyrene (GPPS) and the relation between mechanical properties and NMR relaxation times

    Energy Technology Data Exchange (ETDEWEB)

    Nestle, Nikolaus [BASF Aktiengesellschaft, GKP/P-G 201, D-67056 Ludwigshafen (Germany)], E-mail: nikolaus.nestle@basf.com; Heckmann, Walter; Steininger, Helmut; Knoll, Konrad [BASF Aktiengesellschaft, GKP/P-G 201, D-67056 Ludwigshafen (Germany)

    2007-11-26

    The properties of styrene-butadiene-styrene (SBS) block copolymers do not only depend on the butadiene content and the degree of polymerisation but also on their chain architecture. In this contribution we present the results of a low-field time domain (TD) NMR study in which the transverse relaxation behaviour of different SBS block copolymers was analysed and correlated with findings from mechanical testing on pure and blended materials and transmission electron microscopy data which provide information on the microphase separation. The results indicate that while a straightforward determination of the butadiene content as in blended materials like ABS is not possible for these materials, the TD-NMR results correlate quite well with the mechanical performance of blends from SBS block copolymers with general purpose polystyrene (GPPS), i.e. industrial grade homopolymer polystyrene. Temperature-dependent experiments on pure and blended materials revealed a slight reduction in the softening temperature of the GPPS fraction in the blends.

  14. Microtome Sliced Block Copolymers and Nanoporous Polymers as Masks for Nanolithography

    DEFF Research Database (Denmark)

    Shvets, Violetta; Schulte, Lars; Ndoni, Sokol

    2014-01-01

    Introduction. Block copolymers self-assembling properties are commonly used for creation of very fine nanostructures [1]. Goal of our project is to test new methods of the block-copolymer lithography mask preparation: macroscopic pieces of block-copolymers or nanoporous polymers with cross...... PDMS can be chemically etched from the PB matrix by tetrabutylammonium fluoride in tetrahydrofuran and macroscopic nanoporous PB piece is obtained. Both block-copolymer piece and nanoporous polymer piece were sliced with cryomicrotome perpendicular to the axis of cylinder alignment and flakes...... of etching patterns appear only under the certain parts of thick flakes and are not continuous. Although flakes from block copolymer are thinner and more uniform in thickness than flakes from nanoporous polymer, quality of patterns under nanoporous flakes appeared to be better than under block copolymer...

  15. Chain conformations of the component polymers and the microphase separation structures of homopolymer/block coplymer blends

    International Nuclear Information System (INIS)

    Torikai, Naoya; Mogi, Yasuhiro; Matsushita, Yushu; Noda, Ichiro; Han, C.C.

    1993-01-01

    Microdomain spacings of lamellar structures formed by styrene homopolymer/styrene-2-vinylpyridine diblock copolymer/2-vinylpyridine homopolymer blends were measured by small-angle X-ray scattering (SAXS) and single chain conformations of block copolymers in the same blend system were measured by small-angle neutron scattering (SANS). The molecular weight of diblock copolymers is 78K-72K, and three kinds of styrene homopolymer (S H ) and 2-vinylpyridine homopolymer (P H ) pairs were blended, their molecular weight ratios to that of host block chains were 0.17, 0.38, and 0.78, respectively. Two blend ratios of homopolymer (H)/block copolymer (B), i.e. 1/2 and 1/1 were examined. It was found that the domain spacings of all blends are larger than that of pure block copolymer and that they are increasing with increasing the molecular weight of homopolymers and/or with increasing the volume fraction of homopolymers. Further, block chains in the blends were confirmed to have almost the same chain dimension as that of block chain in pure block copolymer system in the direction parallel to the domain interface irrespective of molecular weight and volume fraction of homopolymers. (author)

  16. Amphiphilic block co-polymers: preparation and application in nanodrug and gene delivery.

    Science.gov (United States)

    Xiong, Xiao-Bing; Binkhathlan, Ziyad; Molavi, Ommoleila; Lavasanifar, Afsaneh

    2012-07-01

    Self-assembly of amphiphilic block co-polymers composed of poly(ethylene oxide) (PEO) as the hydrophilic block and poly(ether)s, poly(amino acid)s, poly(ester)s and polypropyleneoxide (PPO) as the hydrophobic block can lead to the formation of nanoscopic structures of different morphologies. These structures have been the subject of extensive research in the past decade as artificial mimics of lipoproteins and viral vectors for drug and gene delivery. The aim of this review is to provide an overview of the synthesis of commonly used amphiphilic block co-polymers. It will also briefly go over some pharmaceutical applications of amphiphilic block co-polymers as "nanodelivery systems" for small molecules and gene therapeutics. Copyright © 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  17. Polyhedral Oligomeric Silsesquioxane (POSS) Styrene Macromers

    National Research Council Canada - National Science Library

    Haddad, Timothy

    2001-01-01

    .... Cyclohexyl, cyclopentyl and isobutyl substituted POSS-stryenes (at 30 weight % loadings) undergo free radical bulk polymerizations with styrene to produce polymers with an enhanced modulus above the glass transition temperature...

  18. Effect of block composition on thermal properties and melt viscosity of poly[2-(dimethylaminoethyl methacrylate], poly(ethylene oxide and poly(propylene oxide block co-polymers

    Directory of Open Access Journals (Sweden)

    2011-09-01

    Full Text Available To modify the rheological properties of certain commercial polymers, a set of block copolymers were synthesized through oxyanionic polymerization of 2-(dimethylaminoethyl methacrylate to the chain ends of commercial prepolymers, namely poly(ethylene oxide (PEO, poly(ethylene oxide-block-poly(propylene oxide-block-poly(ethylene oxide (PEO-PPO-PEO, and poly(propylene oxide (PPO. The formed block copolymers were analysed with size exclusion chromatography and nuclear magnetic resonance spectroscopy in order to confirm block formation. Thermal characterization of the resulting polymers was done with differential scanning calorimetry. Thermal transition points were also confirmed with rotational rheometry, which was primarily used to measure melt strength properties of the resulting block co-polymers. It was observed that the synthesised poly[2-(dimethylaminoethyl methacrylate]-block (PDM affected slightly the thermal transition points of crystalline PEO-block but the influence was stronger on amorphous PPO-blocks. Frequency sweeps measured above the melting temperatures for the materials confirmed that the pre-polymers (PEO and PEO-PPO-PEO behave as Newtonian fluids whereas polymers with a PDM block structure exhibit clear shear thinning behaviour. In addition, the PDM block increased the melt viscosity when compared with that one of the pre-polymer. As a final result, it became obvious that pre-polymers modified with PDM were in entangled form, in the melted state as well in the solidified form.

  19. DMFC Performance of Polymer Electrolyte Membranes Prepared from a Graft-Copolymer Consisting of a Polysulfone Main Chain and Styrene Sulfonic Acid Side Chains

    Directory of Open Access Journals (Sweden)

    Nobutaka Endo

    2016-08-01

    Full Text Available Polymer electrolyte membranes (PEMs for direct methanol fuel cell (DMFC applications were prepared from a graft-copolymer (PSF-g-PSSA consisting of a polysulfone (PSF main chain and poly(styrene sulfonic acid (PSSA side chains with various average distances between side chains (Lav and side chain lengths (Lsc. The polymers were synthesized by grafting ethyl p-styrenesulfonate (EtSS on macro-initiators of chloromethylated polysulfone with different contents of chloromethyl (CM groups, and by changing EtSS content in the copolymers by using atom transfer radical polymerization (ATRP. The DMFC performance tests using membrane electrode assemblis (MEAs with the three types of the PEMs revealed that: a PSF-g-PSSA PEM (SF-6 prepared from a graft copolymer with short average distances between side chains (Lav and medium Lsc had higher DMFC performance than PEMs with long Lav and long Lsc or with short Lav and short Lsc. SF-6 had about two times higher PDmax (68.4 mW/cm2 than Nafion® 112 at 30 wt % of methanol concentration. Furthermore, it had 58.2 mW/cm2 of PDmax at 50 wt % of methanol concentration because of it has the highest proton selectivity during DMFC operation of all the PSF-g-PSSA PEMs and Nafion® 112.

  1. Effects of Grafting Density on Block Polymer Self-Assembly: From Linear to Bottlebrush.

    Science.gov (United States)

    Lin, Tzu-Pin; Chang, Alice B; Luo, Shao-Xiong; Chen, Hsiang-Yun; Lee, Byeongdu; Grubbs, Robert H

    2017-11-28

    Grafting density is an important structural parameter that exerts significant influences over the physical properties of architecturally complex polymers. In this report, the physical consequences of varying the grafting density (z) were studied in the context of block polymer self-assembly. Well-defined block polymers spanning the linear, comb, and bottlebrush regimes (0 ≤ z ≤ 1) were prepared via grafting-through ring-opening-metathesis polymerization. ω-Norbornenyl poly(d,l-lactide) and polystyrene macromonomers were copolymerized with discrete comonomers in different feed ratios, enabling precise control over both the grafting density and molecular weight. Small-angle X-ray scattering experiments demonstrate that these graft block polymers self-assemble into long-range-ordered lamellar structures. For 17 series of block polymers with variable z, the scaling of the lamellar period with the total backbone degree of polymerization (d* ∼ N bb α ) was studied. The scaling exponent α monotonically decreases with decreasing z and exhibits an apparent transition at z ≈ 0.2, suggesting significant changes in the chain conformations. Comparison of two block polymer systems, one that is strongly segregated for all z (System I) and one that experiences weak segregation at low z (System II), indicates that the observed trends are primarily caused by the polymer architectures, not segregation effects. A model is proposed in which the characteristic ratio (C ∞ ), a proxy for the backbone stiffness, scales with N bb as a function of the grafting density: C ∞ ∼ N bb f(z) . The scaling behavior disclosed herein provides valuable insights into conformational changes with grafting density, thus introducing opportunities for block polymer and material design.

  2. Synthesis of biodegradable styrene copolymers

    OpenAIRE

    Gevers, Dries; Kobben, Stephan; Junkers, Tanja; Copinet, Alain; Buntinx, Mieke; Peeters, Roos

    2017-01-01

    Polystyrene (PS), a versatile polymer with many applications (e.g. packaging) representing about 10% of the total annual polymer consumption, shows practically no biodegradability. In this study a styrene (ST) based copolymer is synthesized and examined regarding its ability to degrade in a composting test. As second monomer, to introduce biodegradable ester groups, 5,6-benzo-2-metylene-dioxepane (BMDO) has been used in radical copolymerization reactions performed in inert and stirred 10 m...

  3. Thinking Outside the 'Block': Alternative Polymer Compositions for Micellar Drug Delivery.

    Science.gov (United States)

    Jones, Marie-Christine

    2015-01-01

    With a number of formulations currently in clinical trials, the interest in polymer micelles as drug carriers in unlikely to subside. Historically, linear diblock copolymers have been used as the building blocks for micelle preparation. Yet, recent advances in polymer chemistry have meant that a wider variety of polymer architectures and compositions have become available and been trialed for pharmaceutical applications. This mini-review aims to provide an overview of recent, exciting developments in triblock, graft and hyperbranched polymer chemistries that may change the way polymeric micelles drug formulations are prepared.

  4. Processing of (in)tractable polymers using reactive solvents, 4: Structure development in the model system poly(ethylene)/styrene

    NARCIS (Netherlands)

    Goossens, J.G.P.; Rastogi, S.; Meijer, H.E.H.; Lemstra, P.J.

    1998-01-01

    The use of reactive solvents provides a unique opportunity to extend the processing characteristics of both intractable and standard (tractable) polymers beyond existing limits. The polymer to be processed is dissolved in the reactive solvent (monomer) and the solution is transferred into a mould.

  5. Photophysical processes study for poly (P-substituted styrenes) in solid films and in solutions

    International Nuclear Information System (INIS)

    Al-Hakeem, I.A.

    1985-01-01

    In this work, the absorption and emission spectra of poly (P-NN dimethyl amino styrene), poly (P-Fluoro Styrene), poly (P-CH2OCH3 styrene), poly (P-Methyl (styrene), poly(P-Tertiary butyl styrene) have been studied in solid films and solutions. The effect of added dimethylterph-thalate as a quencher to the fluorescence emission of the polymers used in this work were studied.(5 tabs., 39 figs., 60 refs.)

  6. Blocking effect and numerical study of polymer particles dispersion flooding in heterogeneous reservoir

    Science.gov (United States)

    Zhu, Weiyao; Li, Jianhui; Lou, Yu

    2018-02-01

    Polymer flooding has become an effective way to improve the sweep efficiency in many oil fields. Many scholars have carried out a lot of researches on the mechanism of polymer flooding. In this paper, the effect of polymer on seepage is analyzed. The blocking effect of polymer particles was studied experimentally, and the residual resistance coefficient (RRF) were used to represent the blocking effect. We also build a mathematical model for heterogeneous concentration distribution of polymer particles. Furthermore, the effects of polymer particles on reservoir permeability, fluid viscosity and relative permeability are considered, and a two-phase flow model of oil and polymer particles is established. In addition, the model was tested in the heterogeneous stratum model, and three influencing factors, such as particle concentration, injection volume and PPD (short for polymer particle dispersion) injection time, were analyzed. Simulation results show that PPD can effectively improve sweep efficiency and especially improve oil recovery of low permeability layer. Oil recovery increases with the increase of particle concentration, but oil recovery increase rate gradually decreases with that. The greater the injected amount of PPD, the greater oil recovery and the smaller oil recovery increase rate. And there is an optimal timing to inject PPD for specific reservoir.

  7. Self-Assembly of Block Copolymer Chains To Promote the Dispersion of Nanoparticles in Polymer Nanocomposites

    Science.gov (United States)

    2017-01-01

    In this paper we adopt molecular dynamics simulations to study the amphiphilic AB block copolymer (BCP) mediated nanoparticle (NP) dispersion in polymer nanocomposites (PNCs), with the A-block being compatible with the NPs and the B-block being miscible with the polymer matrix. The effects of the number and components of BCP, as well as the interaction strength between A-block and NPs on the spatial organization of NPs, are explored. We find that the increase of the fraction of the A-block brings different dispersion effect to NPs than that of B-block. We also find that the best dispersion state of the NPs occurs in the case of a moderate interaction strength between the A-block and the NPs. Meanwhile, the stress–strain behavior is probed. Our simulation results verify that adopting BCP is an effective way to adjust the dispersion of NPs in the polymer matrix, further to manipulate the mechanical properties. PMID:28892620

  8. Engineering cell factories for producing building block chemicals for bio-polymer synthesis

    OpenAIRE

    Tsuge, Yota; Kawaguchi, Hideo; Sasaki, Kengo; Kondo, Akihiko

    2016-01-01

    Synthetic polymers are widely used in daily life. Due to increasing environmental concerns related to global warming and the depletion of oil reserves, the development of microbial-based fermentation processes for the production of polymer building block chemicals from renewable resources is desirable to replace current petroleum-based methods. To this end, strains that efficiently produce the target chemicals at high yields and productivity are needed. Recent advances in metabolic engineerin...

  9. Crystallization analysis fractionation of poly(ethylene-co-styrene) produced by metallocene catalysts

    KAUST Repository

    Kamal, Muhammad Shahzad; Bahuleyan, Bijal Kottukkal; Sohail, Omer Bin; Emwas, Abdul-Hamid M.; Bercaw, John E.; Al-Harthi, Mamdouh Ahmed

    2013-01-01

    Ethylene homo polymer and ethylene-styrene copolymers were synthesized using Cp2ZrCl2 (1)/methyl aluminoxane (MAO) and rac-silylene-bis (indenyl) zirconium dichloride (2)/MAO catalyst systems by varying styrene concentration and reaction conditions

  10. Semiconducting Polymer Photodetectors with Electron and Hole Blocking Layers: High Detectivity in the Near-Infrared

    Directory of Open Access Journals (Sweden)

    Xiong Gong

    2010-07-01

    Full Text Available Sensing from the ultraviolet-visible to the infrared is critical for a variety of industrial and scientific applications. Photodetectors with broad spectral response, from 300 nm to 1,100 nm, were fabricated using a narrow-band gap semiconducting polymer blended with a fullerene derivative. By using both an electron-blocking layer and a hole-blocking layer, the polymer photodetectors, operating at room temperature, exhibited calculated detectivities greater than 1013 cm Hz1/2/W over entire spectral range with linear dynamic range approximately 130 dB. The performance is comparable to or even better than Si photodetectors.

  11. Immobilization of Styrene-acrylamide Co-polymer on Either Silica Particles or Inner Surface of Silica Capillary for the Separation of D-Glucose Anomers

    International Nuclear Information System (INIS)

    Ali, Faiz; Kim, Yune Sung; Cheong, Won Jo

    2014-01-01

    Styrene-acrylamide co-polymer was immobilized on porous partially sub-2 μm silica monolith particles and inner surface of fused silica capillary (50 μm ID and 28 cm length) to result in μLC and CEC stationary phases, respectively, for separation of anomeric D-glucose derivatives. Reversed addition-fragmentation transfer (RAFT) polymerization was incorporated to induce surface polymerization. Acrylamide was employed to incorporate amide-functionality in the stationary phase. The resultant μLC and CEC stationary phases were able to separate isomers of D-glucose derivatives with high selectivity and efficiency. The mobile phase of 75/ 25 (v/v) acetonitrile (ACN)/water with 0.1% TFA, was used for HPLC with a packed column (1 mm ID, 300 mm length). The effects of pH and ACN composition on anomeric separation of D-glucose in CEC have been examined. A mobile phase of 85/15 (v/v) ACN/30 mM sodium acetate pH 6.7 was found the optimized mobile phase for CEC. The CEC stationary phase also gave good separation of other saccharides such as maltotriose and Dextran 1500 (MW∼1500) with good separation efficiency (number of theoretical plates ∼300,000/m)

  12. Immobilization of Styrene-acrylamide Co-polymer on Either Silica Particles or Inner Surface of Silica Capillary for the Separation of D-Glucose Anomers

    Energy Technology Data Exchange (ETDEWEB)

    Ali, Faiz; Kim, Yune Sung; Cheong, Won Jo [Inha Univ., Incheon (Korea, Republic of)

    2014-02-15

    Styrene-acrylamide co-polymer was immobilized on porous partially sub-2 μm silica monolith particles and inner surface of fused silica capillary (50 μm ID and 28 cm length) to result in μLC and CEC stationary phases, respectively, for separation of anomeric D-glucose derivatives. Reversed addition-fragmentation transfer (RAFT) polymerization was incorporated to induce surface polymerization. Acrylamide was employed to incorporate amide-functionality in the stationary phase. The resultant μLC and CEC stationary phases were able to separate isomers of D-glucose derivatives with high selectivity and efficiency. The mobile phase of 75/ 25 (v/v) acetonitrile (ACN)/water with 0.1% TFA, was used for HPLC with a packed column (1 mm ID, 300 mm length). The effects of pH and ACN composition on anomeric separation of D-glucose in CEC have been examined. A mobile phase of 85/15 (v/v) ACN/30 mM sodium acetate pH 6.7 was found the optimized mobile phase for CEC. The CEC stationary phase also gave good separation of other saccharides such as maltotriose and Dextran 1500 (MW∼1500) with good separation efficiency (number of theoretical plates ∼300,000/m)

  13. Probing molecular interactions of poly(styrene-co-maleic acid) with lipid matrix models to interpret the therapeutic potential of the co-polymer.

    Science.gov (United States)

    Banerjee, Shubhadeep; Pal, Tapan K; Guha, Sujoy K

    2012-03-01

    To understand and maximize the therapeutic potential of poly(styrene-co-maleic acid) (SMA), a synthetic, pharmacologically-active co-polymer, its effect on conformation, phase behavior and stability of lipid matrix models of cell membranes were investigated. The modes of interaction between SMA and lipid molecules were also studied. While, attenuated total reflection-Fourier-transform infrared (ATR-FTIR) and static (31)P nuclear magnetic resonance (NMR) experiments detected SMA-induced conformational changes in the headgroup region, differential scanning calorimetry (DSC) studies revealed thermotropic phase behavior changes of the membranes. (1)H NMR results indicated weak immobilization of SMA within the bilayers. Molecular interpretation of the results indicated the role of hydrogen-bond formation and hydrophobic forces between SMA and zwitterionic phospholipid bilayers. The extent of membrane fluidization and generation of isotropic phases were affected by the surface charge of the liposomes, and hence suggested the role of electrostatic interactions between SMA and charged lipid headgroups. SMA was thus found to directly affect the structural integrity of model membranes. Copyright © 2011 Elsevier B.V. All rights reserved.

  14. Removal of Copper ions from aqueous solutions using polymer derivations of poly (styrene-alt-maleic anhydride

    Directory of Open Access Journals (Sweden)

    Naser Samadi

    2017-06-01

    Full Text Available In this study chelating resins have been considered to be suitable materials for the recovery of Copper (II ions in water treatments. Furthermore, these modified resins were reacted with 1,2-diaminoethane in the presence of ultrasonic irradiation for the preparation of a tridimensional chelating resin on the Nano scale for the recovery of Copper (II ions from aqueous solutions. This method which is used for removing and determining Copper (II ions using copolymers derived resins of poly (styrene-alternative-maleic anhydride (SMA and atomic absorption spectroscopy. The method is simple, sensitive, inexpensive and fast. The various parameters such as pH, contact time, concentrations of metal ions, mass of resin, and agitation speed were investigated on adsorption effect. The adsorption behavior of Copper (II ions were investigated by the synthesis of chelating resins at various pHs. The prepared resins showed a good tendency for removing the selected metal ions from aqueous solution, even at an acidic pH. Also, the prepared resins were examined for the removal of Copper (II ions from real samples such as industrial wastewater and were shown to be very efficient at adsorption in the cases of Copper (II ions. The pseudo-first-order, pseudo-second-order, and intra-particle diffusion kinetics equations were used for modeling of adsorption data and it was shown that pseudo-second-order kinetic equation could best describe the adsorption kinetics. The intra-particle diffusion study revealed that external diffusion might be involved in this case. The resins were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, and X-ray diffraction analysis.

  15. Environment-induced self-assembly in phase separated block copolymer systems: A SANS investigation

    International Nuclear Information System (INIS)

    Dutta, Naba K.; Thompson, Sandra; Roy Choudhury, Namita; Knott, Robert

    2006-01-01

    In this research, we examine the effect of non-selective solvent on the large-scale mesoscopic ordering in asymmetric block copolymers, poly(styrene-block-ethylene/butylene-block-styrene) (SEBS) using small angle neutron scattering technique (SANS). SANS measurements were carried out over a wide range of concentrations and temperatures. Evolution of the self-assembled phase morphology in such polymer with the thermodynamic selectivity of solvent, temperature and concentration has been discussed. Correlation between morphology and thermorheological behavior of the gels has also been established

  16. A chemical platform approach on cardanol oil: from the synthesis of building blocks to polymer synthesis

    Directory of Open Access Journals (Sweden)

    Jaillet Fanny

    2016-09-01

    Full Text Available This review proposes a platform approach for the synthesis of various building blocks from cardanol oil in one or two-steps synthesis. Cardanol is a natural phenol issued from Cashew nutshell liquid (CNSL. CNSL is a non-edible renewable resource, co-produced from cashew industry in large commercial volumes. Cardanol is non-toxic and particularly suitable as an aromatic renewable resource for polymers and materials. Various routes were used for the synthesis of di- and poly-functional building blocks used thereafter in polymer syntheses. Phenolation was used to dimerize/oligomerize cardanol to propose increase functionality of cardanol. Thio-ene was used to synthesize new reactive amines. Epoxidation and (methacrylation were also used to insert oxirane or (methacrylate groups in order to synthesize polymers and materials.

  17. Engineering cell factories for producing building block chemicals for bio-polymer synthesis.

    Science.gov (United States)

    Tsuge, Yota; Kawaguchi, Hideo; Sasaki, Kengo; Kondo, Akihiko

    2016-01-21

    Synthetic polymers are widely used in daily life. Due to increasing environmental concerns related to global warming and the depletion of oil reserves, the development of microbial-based fermentation processes for the production of polymer building block chemicals from renewable resources is desirable to replace current petroleum-based methods. To this end, strains that efficiently produce the target chemicals at high yields and productivity are needed. Recent advances in metabolic engineering have enabled the biosynthesis of polymer compounds at high yield and productivities by governing the carbon flux towards the target chemicals. Using these methods, microbial strains have been engineered to produce monomer chemicals for replacing traditional petroleum-derived aliphatic polymers. These developments also raise the possibility of microbial production of aromatic chemicals for synthesizing high-performance polymers with desirable properties, such as ultraviolet absorbance, high thermal resistance, and mechanical strength. In the present review, we summarize recent progress in metabolic engineering approaches to optimize microbial strains for producing building blocks to synthesize aliphatic and high-performance aromatic polymers.

  18. Polymer-Block-Polypeptides and Polymer-Conjugated Hybrid Materials as Stimuli-Responsive Nanocarriers for Biomedical Applications.

    Science.gov (United States)

    John, Johnson V; Johnson, Renjith P; Heo, Min Seon; Moon, Byeong Kyu; Byeon, Seong Jin; Kim, Il

    2015-01-01

    Stimuli-responsive nanocarriers are a class of soft materials that includes natural polymers, synthetic polymers, and polypeptides. Recently, modern synthesis tools such as atom transfer radical polymerization, reversible addition-fragmentation chain transfer polymerization, nitroxide-mediated radical polymerization, ring-opening polymerization of α-amino acid N-carboxyanhydrides, and various "click" chemistry strategies were simultaneously employed for the design and synthesis of nanosized drug delivery vehicles. Importantly, the research focused on the improvement of the nanocarrier targetability and the site-specific, triggered release of therapeutics with high drug loading efficiency and minimal drug leakage during the delivery to specific targets. In this context, nanocarriers responsive to common stimuli such as pH, temperature, redox potential, light, etc. have been widely used for the controlled delivery of therapeutics to pathological sites. Currently, different synthesis and self-assembly strategies improved the drug loading efficacy and targeted delivery of therapeutic agents to the desired site. In particular, polypeptide-containing hybrid materials have been developed for the controlled delivery of therapeutic agents. Therefore, stimuli-sensitive synthetic polypeptide-based materials have been extensively investigated in recent years. This review focuses on recent advances in the development of polymer-block-polypeptides and polymer-conjugated hybrid materials that have been designed and evaluated for various stimuli-responsive drug and gene delivery applications.

  19. Di-block co-polymer derived nanoporous polymer liquid core waveguides

    DEFF Research Database (Denmark)

    Christiansen, Mads Brøkner; Gopalakrishnan, Nimi; Sagar, Kaushal Shashikant

    2010-01-01

    pores. When the PDMS is etched, the hydrophobic PB is left with a porosity of 44%. The polymer is subsequently UV exposed through a shadow mask. This renders the exposed part hydrophilic, making it possible for water to infiltrate these areas. Water infiltration raises the refractive index, thus forming...

  20. Side chain alkylation of toluene with methanol over basic zeolites - novel production route towards styrene?

    NARCIS (Netherlands)

    Rep, M.; Rep, M.

    2002-01-01

    Styrene is an important monomer for the production of different types of (co-) polymers that are used in, e.g., toys, medical devices, food packaging, paper coatings etc. Styrene is produced with several different industrial processes. In 1998, the production of styrene monomer was approximately 21

  1. Natural polymers: an overview

    CSIR Research Space (South Africa)

    John, MJ

    2012-08-01

    Full Text Available The scarcity of natural polymers during the world war years led to the development of synthetic polymers like nylon, acrylic, neoprene, styrene-butadiene rubber (SBR) and polyethylene. The increasing popularity of synthetic polymers is partly due...

  2. Pinenes: Abundant and Renewable Building Blocks for a Variety of Sustainable Polymers.

    Science.gov (United States)

    Winnacker, Malte

    2018-05-14

    Pinenes - a group of monoterpenes containing a double bond - are very suitable renewable building blocks for a variety of sustainable polymers and materials. Their abundance from mainly non-edible parts of plants as well as the feasibility to isolate them render these compounds unique amongst the variety of biomass that is utilizable for novel materials. Accordingly, their use for the synthesis of biobased polymers has been investigated intensively, and strong progress has been made with this especially within the past 2-3 years. Direct cationic or radical polymerization via the double bonds as well as polymerization upon their further functionalization can afford a variety of sustainable polymers suitable for many applications, which is summarized in this article. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Dialkoxybithiazole: a new building block for head-to-head polymer semiconductors.

    Science.gov (United States)

    Guo, Xugang; Quinn, Jordan; Chen, Zhihua; Usta, Hakan; Zheng, Yan; Xia, Yu; Hennek, Jonathan W; Ortiz, Rocío Ponce; Marks, Tobin J; Facchetti, Antonio

    2013-02-06

    Polymer semiconductors have received great attention for organic electronics due to the low fabrication cost offered by solution-based printing techniques. To enable the desired solubility/processability and carrier mobility, polymers are functionalized with hydrocarbon chains by strategically manipulating the alkylation patterns. Note that head-to-head (HH) linkages have traditionally been avoided because the induced backbone torsion leads to poor π-π overlap and amorphous film microstructures, and hence to low carrier mobilities. We report here the synthesis of a new building block for HH linkages, 4,4'-dialkoxy-5,5'-bithiazole (BTzOR), and its incorporation into polymers for high performance organic thin-film transistors. The small oxygen van der Waals radius and intramolecular S(thiazolyl)···O(alkoxy) attraction promote HH macromolecular architectures with extensive π-conjugation, low bandgaps (1.40-1.63 eV), and high crystallinity. In comparison to previously reported 3,3'-dialkoxy-2,2'-bithiophene (BTOR), BTzOR is a promising building block in view of thiazole geometric and electronic properties: (a) replacing (thiophene)C-H with (thiazole)N reduces steric encumbrance in -BTzOR-Ar- dyads by eliminating repulsive C-H···H-C interactions with neighboring arene units, thereby enhancing π-π overlap and film crystallinity; and (b) thiazole electron-deficiency compensates alkoxy electron-donating characteristics, thereby lowering the BTzOR polymer HOMO versus that of the BTOR analogues. Thus, the new BTzOR polymers show substantial hole mobilities (0.06-0.25 cm(2)/(V s)) in organic thin-film transistors, as well as enhanced I(on):I(off) ratios and greater ambient stability than the BTOR analogues. These geometric and electronic properties make BTzOR a promising building block for new classes of polymer semiconductors, and the synthetic route to BTzOR reported here should be adaptable to many other bithiazole-based building blocks.

  4. Multiblock Copolymers of Styrene and Butyl Acrylate via Polytrithiocarbonate-Mediated RAFT Polymerization

    Directory of Open Access Journals (Sweden)

    Bastian Ebeling

    2011-03-01

    Full Text Available When linear polytrithiocarbonates as Reversible Addition-Fragmentation chain Transfer (RAFT agents are employed in a radical polymerization, the resulting macromolecules consist of several homogeneous polymer blocks, interconnected by the functional groups of the respective RAFT agent. Via a second polymerization with another monomer, multiblock copolymers—polymers with alternating segments of both monomers—can be prepared. This strategy was examined mechanistically in detail based on subsequent RAFT polymerizations of styrene and butyl acrylate. Size-exclusion chromatography (SEC of these polymers showed that the examined method yields low-disperse products. In some cases, resolved peaks for molecules with different numbers of blocks (polymer chains separated by the trithiocarbonate groups could be observed. Cleavage of the polymers at the trithiocarbonate groups and SEC analysis of the products showed that the blocks in the middle of the polymers are longer than those at the ends and that the number of blocks corresponds to the number of functional groups in the initial RAFT agent. Furthermore, the produced multiblock copolymers were analyzed via differential scanning calorimetry (DSC. This work underlines that the examined methodology is very well suited for the synthesis of well-defined multiblock copolymers.

  5. Anomalous Behaviors of Block Copolymers at the Interface of an Immiscible Polymer Blend

    Science.gov (United States)

    Ryu, Ji Ho; Lee, Won Bo

    We investigate the effects of structure and stiffness of block copolymers on the interface of an immiscible polymer blend using coarse-grained molecular dynamics (CGMD) simulation. The diblock and grafted copolymers, which are described by Kremer and Grest bead spring model, are used to compare the compatibilization efficiency, that is, reduction of the interfacial tension. It is found that, overall, the grafted copolymers are located more compactly at the interface and show better compatibilization efficiency than diblock copolymers. In addition, it is noted that an increase in the stiffness of one block of diblock copolymer causes inhomogeneous interfacial coverage due to bundle formation among the stiff blocks and orientational constraint on bundled structures near the interface, which makes copolymers poor compatibilizers. The dependence of anomalous orientational constraint on the chain length of homopolymers is also investigated. Theoretical and Computational Soft Matters Lab.

  6. Synthesis of ABA Tri-Block Co-Polymer Magnetopolymersomes via Electroporation for Potential Medical Application

    Directory of Open Access Journals (Sweden)

    Jennifer Bain

    2015-12-01

    Full Text Available The ABA tri-block copolymer poly(2-methyloxazoline–poly(dimethylsiloxane–poly(2-methyloxazoline (PMOXA–PDMS–PMOXA is known for its capacity to mimic a bilayer membrane in that it is able to form vesicular polymersome structures. For this reason, it is the subject of extensive research and enables the development of more robust, adaptable and biocompatible alternatives to natural liposomes for biomedical applications. However, the poor solubility of this polymer renders published methods for forming vesicles unreproducible, hindering research and development of these polymersomes. Here we present an adapted, simpler method for the production of PMOXA–PDMS–PMOXA polymersomes of a narrow polydispersity (45 ± 5.8 nm, via slow addition of aqueous solution to a new solvent/polymer mixture. We then magnetically functionalise these polymersomes to form magnetopolymersomes via in situ precipitation of iron-oxide magnetic nanoparticles (MNPs within the PMOXA–PDMS–PMOXA polymersome core and membrane. This is achieved using electroporation to open pores within the membrane and to activate the formation of MNPs. The thick PMOXA–PDMS–PMOXA membrane is well known to be relatively non-permeable when compared to more commonly used di-block polymer membranes due a distinct difference in both size and chemistry and therefore very difficult to penetrate using standard biological methods. This paper presents for the first time the application of electroporation to an ABA tri-block polymersome membrane (PMOXA–PDMS–PMOXA for intravesicular in situ precipitation of uniform MNPs (2.6 ± 0.5 nm. The electroporation process facilitates the transport of MNP reactants across the membrane yielding in situ precipitation of MNPs. Further to differences in length and chemistry, a tri-block polymersome membrane structure differs from a natural lipid or di-block polymer membrane and as such the application and effects of electroporation on this type of

  7. Radiation graft copolymerization of styrene with m/e and styrene with acrylic acid at highthyl methacryl dose rate

    International Nuclear Information System (INIS)

    Aliev, R.Eh.; Kabanov, B.Ya.

    1984-01-01

    Comparative investigation of radiation graft copolymerization of styrene with methyl methacrylate (MMA) and styrene with acrylic acid (AA) is carried out at considerably differing radiation dose rates. The monomer mixture was grafted to PE low density films at dose rates of 0.16, 0.25 Gy/s (1 MeV electron acceleration). The value of graft was 3-6 and 5-10%, respectively, for the styrene-MMA and styrene-AA systems. An essential difference in the dependences of the formed copolymer composition on initial monomer mixture composition is noticed. Difference in composition of graft polymers prepared at different dose rates is less for the systems with AA, than for systems with MMA. It is shown that at high dose rates in difference with low ones not only radical graft copolymerization of the styrene mixture with AA takes place, but a contribution of the graft styrene polymerization according to cation mechanism as well

  8. Efficiency of solution-processed multilayer polymer light-emitting diodes using charge blocking layers

    Science.gov (United States)

    Kasparek, Christian; Rörich, Irina; Blom, Paul W. M.; Wetzelaer, Gert-Jan A. H.

    2018-01-01

    By blending semiconducting polymers with the cross-linkable matrix ethoxylated-(4)-bisphenol-a-dimethacrylate (SR540), an insoluble layer is acquired after UV-illumination. Following this approach, a trilayer polymer light-emitting diode (PLED) consisting of a blend of poly[N,N'-bis(4-butylphenyl)-N,N'-bis(phenyl)-benzidine] (poly-TPD) and SR540 as an electron-blocking layer, Super Yellow-Poly(p-phenylene vinylene) (SY-PPV) blended with SR540 as an emissive layer, and poly(9,9-di-n-octylfluorenyl-2,7-diyl) as a hole-blocking layer is fabricated from solution. The trilayer PLED shows a 23% increase in efficiency at low voltage as compared to a single layer SY-PPV PLED. However, at higher voltage, the advantage in current efficiency gradually decreases. A combined experimental and modelling study shows that the increased efficiency is not only due to the elimination of exciton quenching at the electrodes but also due to suppressed nonradiative trap-assisted recombination due to carrier confinement. At high voltages, holes can overcome the hole-blocking barrier, which explains the efficiency roll-off.

  9. Effect of Nanoparticle Core Size on Polymer-Coated Gold Nanoparticle Location in Block Copolymers

    Science.gov (United States)

    Petrie, J. D.; Fredrickson, G. H.; Kramer, E. J.

    2009-03-01

    Gold nanoparticles modified by short chain polymer thiols [Au-PS] can be designed to strongly localize either in the PS domains of a polystyrene-b-poly(2-vinylpyridine) [PS-PVP] block copolymer or at the interface. The P2VP block has a stronger attractive interaction with bare gold than the PS block. Thus, when the areal chain density σ of end-attached PS chains falls below a critical areal chain density σc the Au-PS nanoparticles adsorb to the PS-b-P2VP interface. The effect of the polymer ligand molecular weight on the σc has been shown to scale as σc˜ ((R + Rg)/(R*Rg))̂2, where R is the curvature of the Au nanoparticle core radius. To test this scaling relation for σc further we are synthesizing gold nanoparticles with different core radii and will present preliminary results on σc as a function of R.

  10. Nanostructured Block Polymer Membranes as High Capacity Adsorbers for the Capture of Metal Ions from Water

    Science.gov (United States)

    Boudouris, Bryan; Weidman, Jacob; Mulvenna, Ryan; Phillip, William

    The efficient removal of metal ions from aqueous streams is of significant import in applications ranging from industrial waste treatment to the purification of drinking water. An emerging paradigm associated with this separation is one that utilizes membrane adsorbers as a means by which to bind metal salt contaminants. Here, we demonstrate that the casting of an A-B-C triblock polymer using the self-assembly and non-solvent induced phase separation (SNIPS) methodology results in a nanoporous membrane geometry. The nature of the triblock polymer affords an extremely high density of binding sites within the membrane. As such, we demonstrate that the membranes with binding capacities equal to that of state-of-the-art packed bed columns. Moreover, because the affinity of the C moiety can be tuned, highly selective binding events can occur based solely on the chemistry of the block polymer and the metal ions in solution (i.e., in a manner that is independent of the size of the metal ions). Due to these combined facts, these membranes efficiently remove heavy metal (e.g., lead- and cadmium-based) salts from contaminated water streams with greater than 95% efficiency. Finally, we show that the membranes can be regenerated through a simple treatment in order to provide long-lasting adsorber systems as well. Thus, it is anticipated that these nanostructured triblock polymer membranes are a platform by which to obtain next-generation water purification processes.

  11. Ultrasonic, Molecular and Mechanical Testing Diagnostics in Natural Fibre Reinforced, Polymer-Stabilized Earth Blocks

    Directory of Open Access Journals (Sweden)

    C. Galán-Marín

    2013-01-01

    Full Text Available The aim of this research study was to evaluate the influence of utilising natural polymers as a form of soil stabilization, in order to assess their potential for use in building applications. Mixtures were stabilized with a natural polymer (alginate and reinforced with wool fibres in order to improve the overall compressive and flexural strength of a series of composite materials. Ultrasonic pulse velocity (UPV and mechanical strength testing techniques were then used to measure the porous properties of the manufactured natural polymer-soil composites, which were formed into earth blocks. Mechanical tests were carried out for three different clays which showed that the polymer increased the mechanical resistance of the samples to varying degrees, depending on the plasticity index of each soil. Variation in soil grain size distributions and Atterberg limits were assessed and chemical compositions were studied and compared. X-ray diffraction (XRD, X-ray fluorescence spectroscopy (XRF, and energy dispersive X-ray fluorescence (EDXRF techniques were all used in conjunction with qualitative identification of the aggregates. Ultrasonic wave propagation was found to be a useful technique for assisting in the determination of soil shrinkage characteristics and fibre-soil adherence capacity and UPV results correlated well with the measured mechanical properties.

  12. Growing Embossed Nanostructures of Polymer Brushes on Wet-Etched Silicon Templated via Block Copolymers

    Science.gov (United States)

    Lu, Xiaobin; Yan, Qin; Ma, Yinzhou; Guo, Xin; Xiao, Shou-Jun

    2016-02-01

    Block copolymer nanolithography has attracted enormous interest in chip technologies, such as integrated silicon chips and biochips, due to its large-scale and mass production of uniform patterns. We further modified this technology to grow embossed nanodots, nanorods, and nanofingerprints of polymer brushes on silicon from their corresponding wet-etched nanostructures covered with pendent SiHx (X = 1-3) species. Atomic force microscopy (AFM) was used to image the topomorphologies, and multiple transmission-reflection infrared spectroscopy (MTR-IR) was used to monitor the surface molecular films in each step for the sequential stepwise reactions. In addition, two layers of polymethacrylic acid (PMAA) brush nanodots were observed, which were attributed to the circumferential convergence growth and the diffusion-limited growth of the polymer brushes. The pH response of PMAA nanodots in the same region was investigated by AFM from pH 3.0 to 9.0.

  13. SYNTHESIS OF STYRENE-BUTADIENE STATISTIC COPOLYMERS CONTAINING MAGNESIUM INITIATOR

    Directory of Open Access Journals (Sweden)

    A. V. Firsova

    2015-01-01

    Full Text Available The article discusses the use of organomagnesium initiators in the synthesis of styrene-butadiene random copolymer (SBR obtained solution polymerization and their influence on the properties of rubber. Selected organic magnesium dialkyl initiator is combined with a modifier, which is a mixed alkoxide of an alkali and alkaline earth metals, which allows to control the micr ostructure of the diene polymer and its molecular weight characteristics. Alcohol derivatives selected high-boiling alcohols tetra (hydroxypropyl ethylenediamine (lapromol 294 and tetrahydrofurfuryl alcohol (TGFS. Selection of high-boiling alcohols due to the fact that the destruction of alkoxide with aqueous polymer degassing they do not fall into the return solvent and almost fall into the exact water. The metal components of alkoxides are lithium, sodium, potassium, magnesium and calcium. The resulting solutions are stable when stored modifier t hroughout the year even at -40 °C. The scheme of obtaining the new catalyst systems based organomagnesium and alcoxide of alkali and alkaline earth metals, which yields as functionalized SBR with a statistical and a distribution block of butadiene and styrene was developed. The process of copolymerization with styrene to butadiene organomagnesium initiators as using an organolithium compound (n-butyllithium was carried out, and without it. Found that the addition of n-butyllithium in the reaction mixture leads to a sharp increase in the rate of reaction. The results of studies of the effect of composition of the initiator system on the structure of diene polymers. It was revealed that a mixed initiator system affords a high conversion of monomers (to 90 % in 1 hour 1,2-polybutadiene content increased to 60 %. The process of polymerization of only a mixture of organomagnesium initiators and alcoxide of alkali and alkaline earth metals are not actively proceeds, conversion of the monomers reaches to 90 % in 4 hours, the microstructure

  14. Hydrolysis of 4-Acetoxystyrene Polymers Prepared by Atom Transfer Radical Polymerization

    DEFF Research Database (Denmark)

    Chen, Xianyi; Jankova, Katja; Kops, Jørgen

    1999-01-01

    Hydrolysis of 4-acetoxystyrene polymers prepared by atom transfer radical polymerization was carried out under various reaction conditions. It was found that hydrazinolysis of 4-acetoxystyrene homopolymers, random and block copolymers with styrene in 1,4-dioxane, afforded the corresponding narrow...

  15. Amphiphilic block copolymers as efficiency boosters in microemulsions a SANS investigation of the role of polymers

    CERN Document Server

    Endo, H; Mihailescu, M; Monkenbusch, M; Gompper, G; Richter, D; Jakobs, B; Sottmann, T; Strey, R

    2002-01-01

    The effect of amphiphilic block copolymers on ternary microemulsions (water, oil and non-ionic surfactant) is investigated. Small amounts of PEP-PEO block copolymer lead to a dramatic expansion of the one-phase region where water and oil can be solubilized by the mediation of surfactant molecules. Small-angle neutron-scattering experiments employing a high-precision two-dimensional contrast-variation technique demonstrate that the polymer is distributed uniformly on the surfactant membrane, where it modifies the membrane curvature elasticity. Furthermore, a new approach to determine the bending rigidity of an amphiphilic membrane is proposed, which is precise enough to measure the logarithmic scale dependence of the bending rigidity and its universal prefactor in bicontinuous microemulsions. (orig.)

  16. Comparison of sodium naphthenate and air-ionization corona discharge as surface treatments for the ethylene-tetrafluoroethylene polymer (ETFE) to improve adhesion between ETFE and acrylonitrile-butadiene-styrene polymer (ABS) in the presence of a cyanoacrylate adhesive (CAA)

    International Nuclear Information System (INIS)

    Johanning-Solís, Ana Lucía; Stradi-Granados, Benito A

    2014-01-01

    This study compares two ethylene-tetrafluoroethylene (ETFE) surface activation treatments, namely chemical attack with a solution of sodium naphthenate and plasma erosion via air-ionization corona discharge in order to improve the adhesive properties of the ETFE. An experimental design was prepared for both treatments in order to assess the effect of the treatment characteristics on the tensile load needed to break the bond between the ETFE and the acrylonitrile-butadiene-styrene polymer (ABS) formed with a cyanoacrylate adhesive (CAA) applied between them. The reason for the selection of this problem is that both polymers are frequently used in the biomedical industry for their properties, and they need to be joined firmly in biomedical devices, and the cyanoacrylate adhesive is the adhesive traditionally used for fluoropolymers, in this case the ETFE, and the same CAA has also shown good adhesion with ABS. However, the strength of the bond for the triplet ETFE-CAA-ABS has not been reported and the improvement of the strength of the bond with surface treatments is not found in scholarly journals for modern medical devices such as stents and snares. Both treatments were compared based on the aforementioned design of experiments. The case where ETFE receives no surface treatment serves as the reference. The results indicated that the three factors evaluated (initial drying of the material, temperature of the chemical bath, and immersion time), and their interactions have no significant effect over the tensile load at failure (tensile strength) of the adhesive bond being evaluated. For the air-ionization corona discharge treatment, two factors were evaluated: discharge exposition time and air pressure. The results obtained from this experimental design indicate that there is no significant difference between the levels of the factors evaluated. These results were unexpected as the ranges used were representative of the maximum ranges permissible in manufacturing

  17. Comparison of sodium naphthenate and air-ionization corona discharge as surface treatments for the ethylene-tetrafluoroethylene polymer (ETFE) to improve adhesion between ETFE and acrylonitrile-butadiene-styrene polymer (ABS) in the presence of a cyanoacrylate adhesive (CAA)

    Science.gov (United States)

    Lucía Johanning-Solís, Ana; Stradi-Granados, Benito A.

    2014-09-01

    This study compares two ethylene-tetrafluoroethylene (ETFE) surface activation treatments, namely chemical attack with a solution of sodium naphthenate and plasma erosion via air-ionization corona discharge in order to improve the adhesive properties of the ETFE. An experimental design was prepared for both treatments in order to assess the effect of the treatment characteristics on the tensile load needed to break the bond between the ETFE and the acrylonitrile-butadiene-styrene polymer (ABS) formed with a cyanoacrylate adhesive (CAA) applied between them. The reason for the selection of this problem is that both polymers are frequently used in the biomedical industry for their properties, and they need to be joined firmly in biomedical devices, and the cyanoacrylate adhesive is the adhesive traditionally used for fluoropolymers, in this case the ETFE, and the same CAA has also shown good adhesion with ABS. However, the strength of the bond for the triplet ETFE-CAA-ABS has not been reported and the improvement of the strength of the bond with surface treatments is not found in scholarly journals for modern medical devices such as stents and snares. Both treatments were compared based on the aforementioned design of experiments. The case where ETFE receives no surface treatment serves as the reference. The results indicated that the three factors evaluated (initial drying of the material, temperature of the chemical bath, and immersion time), and their interactions have no significant effect over the tensile load at failure (tensile strength) of the adhesive bond being evaluated. For the air-ionization corona discharge treatment, two factors were evaluated: discharge exposition time and air pressure. The results obtained from this experimental design indicate that there is no significant difference between the levels of the factors evaluated. These results were unexpected as the ranges used were representative of the maximum ranges permissible in manufacturing

  18. Development of bio-based polymers for use in asphalt.

    Science.gov (United States)

    2014-02-01

    Asphalt binder is typically modified with poly type (styrene-butadiene-styrene or SBS) polymers to improve its rheological properties and performance grade. The elastic and principal component of SBS polymers is butadiene. For the last decade, butadi...

  19. Enhancing relative permittivity by incorporating PDMS-PEG multi block copolymers in binary polymer blends

    DEFF Research Database (Denmark)

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

    Polydimethylsiloxanes (PDMS) are well-known to actuate with relatively large strains due to low modulus, but they possess lowpermittivity. Contrary, polyethyleneglycols (PEG) are not stretchable but possess high permittivity. Combination of the two polymers in a block copolymer depicts a possibil......Polydimethylsiloxanes (PDMS) are well-known to actuate with relatively large strains due to low modulus, but they possess lowpermittivity. Contrary, polyethyleneglycols (PEG) are not stretchable but possess high permittivity. Combination of the two polymers in a block copolymer depicts...... a possibility for substantial improvement of properties such as high permittivity, stretchability and non-conductivity – if carefully designed. The objective is to synthesize PDMS-PEG multiblock copolymer assembling into discontinuous morphologies in PEG based on variation of volume fractions of PDMS....... The utilized synthesis of PDMS-PEG multiblock copolymer is based on hydrosilylation reaction, which is amended from Klasner et al.1 and Jukarainen etal.2 Variation in the ratio between the two constituents introduces distinctive properties in terms of dielectric permittivity and rheological behaviour. PDMS...

  20. Unlocking Chain Exchange in Highly Amphiphilic Block Polymer Micellar Systems: Influence of Agitation.

    Science.gov (United States)

    Murphy, Ryan P; Kelley, Elizabeth G; Rogers, Simon A; Sullivan, Millicent O; Epps, Thomas H

    2014-11-18

    Chain exchange between block polymer micelles in highly selective solvents, such as water, is well-known to be arrested under quiescent conditions, yet this work demonstrates that simple agitation methods can induce rapid chain exchange in these solvents. Aqueous solutions containing either pure poly(butadiene- b -ethylene oxide) or pure poly(butadiene- b -ethylene oxide- d 4 ) micelles were combined and then subjected to agitation by vortex mixing, concentric cylinder Couette flow, or nitrogen gas sparging. Subsequently, the extent of chain exchange between micelles was quantified using small angle neutron scattering. Rapid vortex mixing induced chain exchange within minutes, as evidenced by a monotonic decrease in scattered intensity, whereas Couette flow and sparging did not lead to measurable chain exchange over the examined time scale of hours. The linear kinetics with respect to agitation time suggested a surface-limited exchange process at the air-water interface. These findings demonstrate the strong influence of processing conditions on block polymer solution assemblies.

  1. Crystallization analysis fractionation of poly(ethylene-co-styrene) produced by metallocene catalysts

    KAUST Repository

    Kamal, Muhammad Shahzad

    2013-06-06

    Ethylene homo polymer and ethylene-styrene copolymers were synthesized using Cp2ZrCl2 (1)/methyl aluminoxane (MAO) and rac-silylene-bis (indenyl) zirconium dichloride (2)/MAO catalyst systems by varying styrene concentration and reaction conditions. Crystallization analysis fractionation (CRYSTAF), DSC, FTIR and 1H NMR spectroscopy were used for characterizing the synthesized polymers. Interestingly, styrene was able to increase the activity of 1/MAO and 2/MAO catalyst systems at low concentrations, but at higher concentrations the activity decreases. The 1/MAO system at low and high pressure was unable to incorporate styrene, and the final product was pure polyethylene. On the other hand, with 2/MAO polymerization of ethylene and styrene yielded copolymer containing both styrene and ethylene. Results obtained from CRYSTAF and DSC reveal that on using 1/MAO system at high pressure, the resulting polymer in the presence of styrene has similar crystallinity as the polymer produced without styrene. Using both 1/MAO at low pressure and 2/MAO leads to decrease in crystallinity with increase in styrene concentration, even though the former does not incorporate styrene. © 2013 Springer-Verlag Berlin Heidelberg.

  2. Polymer brush hexadecyltrimethylammonium bromide (CTAB) modified poly (propylene-g-styrene sulphonic acid) fiber (ZB-1): CTAB/ZB-1 as a promising strategy for improving the dissolution and physical stability of poorly water-soluble drugs.

    Science.gov (United States)

    Cao, Jinxu; Yang, Baixue; Wang, Yumei; Wei, Chen; Wang, Hongyu; Li, Sanming

    2017-11-01

    The feasibility of polymer brush as drug delivery vehicle was demonstrated with the goal of improving the dissolution and physical stability of poorly water-soluble drugs. Polymer brush CTAB/ZB-1 was synthesized by electrostatic interaction using a physical modification method with anionic poly (propylene-g-styrene sulphonic acid) fiber (ZB-1) as the substrate and cationic hexadecyltrimethylammonium bromide (CTAB) as the modifier. The polymer brush structure of CTAB/ZB-1 was validated by atomic force microscopy (AFM) and the channels of brush provided the drug loading sites. Flurbiprofen (FP), a BCS class II representative drug, was selected as the model poorly water-soluble drug to be loaded into this polymer brush. Then the drug loading and release were systematically investigated. Besides, the transformation from crystalline FP to amorphous state was observed by differential scanning calorimeter (DSC). In vitro dissolution in pure water and pH1.2 HCl media with/without 0.1% sodium dodecyl sulfate (SDS) was tested. Moreover, the optimal formulations (namely carrier/drug ratios) were determined. The results demonstrated prominent improvement of dissolution when FP was released from CTAB/ZB-1. After a long time storage, FP remained amorphous in CTAB/ZB-1 according to DSC determinations and performed an approximately equivalent dissolution compared with fresh samples, suggesting the advantage of CTAB/ZB-1 as carrier in enhancing the physical stability of drugs. The study introduced the versatile easily formulated polymer brush CTAB/ZB-1 and demonstrated the potential of polymer brush as an alternative approach for improving the dissolution and physical stability of poorly water-soluble drugs. Copyright © 2017 Elsevier B.V. All rights reserved.

  3. Preparation of pH-sensitive amphiphilic block star polymers, their self-assembling characteristics and release behavior on encapsulated molecules

    KAUST Repository

    Song, Xiaowan; Cao, Ming; Chen, Peng; Xia, Ru; Zheng, Zhengzhi; Miao, Jibin; Yang, Bin; Su, Lifen; Qian, Jiasheng; Feng, Xiaoshuang

    2016-01-01

    Poly(ethylene glycol) (PEG), a polymer with excellent biocompatibility, was widely used to form nanoparticles for drug delivery applications. In this paper, based on PEG, a series of pH-sensitive amphiphilic block star polymers of poly

  4. Gloss and Stain Resistance of Ceramic-Polymer CAD/CAM Restorative Blocks.

    Science.gov (United States)

    Lawson, Nathaniel C; Burgess, John O

    2016-03-01

    To evaluate the gloss and stain resistance of several new ceramic-polymer CAD/CAM blocks Specimens (4 mm) were sectioned from: Enamic (polymer-infused ceramic), LAVA Ultimate (nano-ceramic reinforced polymer), e.max (lithium disilicate), Paradigm C (porcelain), and Paradigm MZ100 (composite). Specimens were wet polished on a polishing wheel to either 320 grit silicon paper (un-polished, N = 8) or 2000 grit silicon carbide papers followed by a 0.05 μm alumina slurry (polished, N = 8). Initial gloss and color (L*a*b*) values were measured. Specimens were stored in a staining solution at 37°C in darkness for 12 days (simulating 1 year). After storage, L*a*b* values re-measured. Change in color was reported as ΔE00 based on the CIEDE2000 formula. Gloss and ΔE00 were analyzed by two-way analysis of variance (ANOVA) (alpha = .05). Separate one-way ANOVA and Tukey post-hoc analyses were performed for both polish conditions and all materials. Two-way ANOVA showed that factors material, polish and their interaction were significant for both gloss and ΔE00 (p gloss and less color change than all other materials. The composition and polish of CAD/CAM materials affects gloss and stain resistance. Ceramic-polymer hybrid materials can achieve the high gloss required for esthetic restorations. These materials should be polished in order to minimize staining. If polished, all of the tested materials exhibited clinically acceptable color changes at 1 year of simulated staining. (J Esthet Restor Dent 28:S40-S45, 2016). © 2015 Wiley Periodicals, Inc.

  5. Solubilization of Phenol Derivatives in Polymer Micelles Formed by Cationic Block Copolymer

    Directory of Open Access Journals (Sweden)

    Irma Fuentes

    2017-01-01

    Full Text Available The aggregation of cationic block copolymers formed by polystyrene (PS and poly(ethyl-4-vinylpyridine (PS-b-PE4VP was studied in aqueous solution. Diblock copolymers of PS and poly(4-vinylpyridine were synthesized by sequential anionic polymerization using BuLi as initiator. Subsequently, the 4-vinylpyridine units were quaternized with ethyl bromide to obtain cationic PS-b-PE4VP block copolymers with different quaternization degree. The self-aggregation of cationic block copolymers was studied by fluorescence probing, whereas the morphology and size of polymer micelles were determined by transmission electronic microscopy. Results indicate that spherical micelles with sizes lower than 100 nm were formed, whereas their micropolarity decreases with increasing quaternization degree. The partition of phenols between the micellar and aqueous phase was studied by using the pseudo-phase model, and the results show that the partition coefficients increase with increasing length of the side alkyl chain and are larger for star micelles. These results are discussed in terms of three-region model.

  6. Polymer brushes on nanoparticles: their positioning in and influence on block copolymer morphology.

    Science.gov (United States)

    Kim, Bumjoon

    2007-03-01

    Polymers brushes grafted to the nanoparticle surface enable the precise positioning of particles within a block copolymer matrix by determining the compatibility of nanoparticles within a polymeric matrix and modifying the interfacial properties between polymers and inorganic nanoparticle. Short thiol terminated polystyrene (PS-SH), poly(2-vinylpyridine) (P2VP-SH) and PS-r-P2VP with the molecular weight (Mn) of 3 kg/mol were used to control the location of Au nanoparticles over PS-b-P2VP diblock copolymer template. We will discuss further the approach of varying the areal chain density (σ) of PS-SH brushes on the PS coated particles, which utilizes the preferential wetting of one block of a copolymer (P2VP) on the Au substrate. Such favorable interaction provides the strong binding of Au particles to the PS/P2VP interface as σ of PS chains on the Au particle decreases. We find that at σ above a certain value, the nanoparticles are segregated to the center of the PS domains while below this value they are segregated to the interface. The transition σ for PS-SH chains (Mn = 3.4 kg/mol) is 1.3 chains/nm^2 but unexpectedly scales as Mn-0.55 as Mn is varied from 1.5 to 13 kg/mol. In addition, we will discuss changes in block copolymer morphology that occur as the nanoparticle volume fraction (φ) is increased for nanoparticles that segregate to the domain center as well as those that segregate to the interface, the latter behaving as nanoparticle surfactants. Small φ of such surfactants added to lamellar diblock copolymers lead initially to a decrease in lamellar thickness, a consequence of decreasing interfacial tension, up to a critical value of φ beyond which the block copolymer adopts a bicontinuous morphology. I thank my collaborators G. H. Fredrickson, J. Bang, C. J. Hawker, and E. J. Kramer as well as funding by the MRL as UCSB from the NSF-MRSEC-Program Award DMR05-20418.

  7. The effect of TiO2 nanocrystal shape on the electrical properties of poly(styrene-b-methyl methacrylate) block copolymer based nanocomposites for solar cell application

    International Nuclear Information System (INIS)

    Cano, Laida; Gutierrez, Junkal; Di Mauro, A. Evelyn; Curri, M. Lucia; Tercjak, Agnieszka

    2015-01-01

    Titanium dioxide (TiO 2 ) nanocrystals were synthesized into two shapes, namely spherical and rod-like and used for the fabrication of polystyrene-block-poly(methyl methacrylate) (PSMMA) block copolymer based nanocomposites, which were employed as the active top layer of electro-devices for solar cell application. Electro-devices were designed using nanocomposites with high TiO 2 nanocrystal contents (50-70 wt%) and for comparison as-synthesized TiO 2 nanospheres (TiO 2 NSs) and TiO 2 nanorods (TiO 2 NRs) were also used. The morphology of the electro-devices was studied by atomic force microscopy showing good nanocrystal dispersion. The electrical properties of the devices were investigated by PeakForce tunneling atomic force microscopy and Keithley semiconductor analyzer, which showed higher electrical current values for devices containing TiO 2 NRs in comparison to TiO 2 NSs. Remarkably, the influence of the PSMMA block copolymer on the improvement of the conductivity of the electro-devices was also assessed, demonstrating that the self-assembling ability of block copolymer can be beneficial to improve charge transfer in the fabricated electro-devices, thus representing relevant systems to be potentially developed for photovoltaic applications. Moreover, the absorbance of the prepared electro-devices in solar irradiation range was confirmed by UV–vis spectroscopy characterization.

  8. Synthesis of butyl acrylate-styrene block copolymers in emulsion by reversible addition-fragmentation chain transfer : effect of surfactant migration upon film formation

    NARCIS (Netherlands)

    Monteiro, M.J.; Sjöberg, M.; Göttgens, C.M.; Vlist, van der J.

    2000-01-01

    The synthesis of block copolymers in an environmentally friendly medium was carried out in emulsion polymerizations through the reversible addition-fragmentation chain transfer process, using a transfer active xanthate (MADIX) agent, under batch and starved-feed conditions. First, ab initio

  9. Synthesis and pH- and salinity-controlled self-assembly of novel amphiphilic block-gradient copolymers of styrene and acrylic acid

    Czech Academy of Sciences Publication Activity Database

    Borisova, O.; Billon, L.; Zaremski, M.; Grassl, B.; Bakaeva, Zulfiya; Lapp, A.; Štěpánek, Petr; Borisov, O.

    2012-01-01

    Roč. 8, č. 29 (2012), s. 7649-7659 ISSN 1744-683X R&D Projects: GA ČR GAP208/10/1600 Institutional research plan: CEZ:AV0Z40500505 Keywords : block-gradient copolymers * light scattering * small-angle neutron scattering Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.909, year: 2012

  10. 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. Copyright (c) 2010 Elsevier Ltd. All rights reserved.

  11. Elucidation of the Structure Formation of Polymer-Conjugated Proteins in Solution and Block Copolymer Templates

    Science.gov (United States)

    Ferebee, Rachel L.

    The broader technical objective of this work is to contribute to the development of enzyme-functionalized nanoporous membranes that can function as autonomous and target selective dynamic separators. The scientific objective of the research performed within this thesis is to elucidate the parameters that control the mixing of proteins in organic host materials and in block copolymers templates in particular. A "biomimetic" membrane system that uses enzymes to selectively neutralize targets and trigger a change in permeability of nanopores lined with a pH-responsive polymer has been fabricated and characterized. Mechanical and functional stability, as well as scalability, have been demonstrated for this system. Additional research has focused on the role of polymeric ligands on the solubility characteristics of the model protein, Bovine Serum Albumin (BSA). For this purpose BSA was conjugated with poly(ethylene glycol) (PEG) ligands of varied degree of polymerization and grafting density. Combined static and dynamic light scattering was used (in conjunction with MALDI-TOF) to determine the second virial coefficient in PBS solutions. At a given mass fraction PEG or average number of grafts, the solubility of BSA-PEG conjugates is found to increase with the degree of polymerization of conjugated PEG. This result informs the synthesis of protein-conjugate systems that are optimized for the fabrication of block copolymer blend materials with maximum protein loading. Blends of BSA-PEG conjugates and block copolymer (BCP) matrices were fabricated to evaluate the dispersion morphology and solubility limits in a model system. Electron microscopy was used to evaluate the changes in lamellar spacing with increased filling fraction of BSA-PEG conjugates.

  12. A ligand exchange strategy for one-pot sequential synthesis of (hyperbranched polyethylene)-b-(linear polyketone) block polymers.

    Science.gov (United States)

    Zhang, Zhichao; Ye, Zhibin

    2012-08-18

    Upon the addition of an equimolar amount of 2,2'-bipyridine, a cationic Pd-diimine complex capable of facilitating "living" ethylene polymerization is switched to catalyze "living" alternating copolymerization of 4-tertbutylstyrene and CO. This unique chemistry is thus employed to synthesize a range of well-defined treelike (hyperbranched polyethylene)-b-(linear polyketone) block polymers.

  13. Simultaneous determination of the styrene unit content and assessment of molecular weight of triblock copolymers in adhesives by a size exclusion chromatography method.

    Science.gov (United States)

    Wang, Mingfang; Wang, Yuerong; Luo, Pei; Zhang, Hongyang; Zhang, Min; Hu, Ping

    2017-10-01

    The content of styrene units in nonhydrogenated and hydrogenated styrene-butadiene-styrene and styrene-isoprene-styrene triblock copolymers significantly influences product performance. A size exclusion chromatography method was developed to determine the average styrene content of triblock copolymers blended with tackifier in adhesives. A complete separation of the triblock copolymer from the other additives was realized with size exclusion chromatography. The peak area ratio of the UV and refraction index signals of the copolymers at the same effective elution volume was correlated to the average styrene unit content using nuclear magnetic resonance spectroscopy with commercial copolymers as standards. The obtained calibration curves showed good linearity for both the hydrogenated and nonhydrogenated styrene-butadiene-styrene and styrene-isoprene-styrene triblock copolymers (r = 0.974 for styrene contents of 19.3-46.3% for nonhydrogenated ones and r = 0.970 for the styrene contents of 23-58.2% for hydrogenated ones). For copolymer blends, the developed method provided more accurate average styrene unit contents than nuclear magnetic resonance spectroscopy provided. These results were validated using two known copolymer blends consisting of either styrene-isoprene-styrene or hydrogenated styrene-butadiene-styrene and a hydrocarbon tackifying resin as well as an unknown adhesive with styrene-butadiene-styrene and an aromatic tackifying resin. The methodology can be readily applied to styrene-containing polymers in blends such as poly(acrylonitrile-butadiene styrene). © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. New highly fluorinated styrene-based materials with low surface energy prepared by ATRP

    DEFF Research Database (Denmark)

    Borkar, Sachin; Jankova Atanasova, Katja; Siesler, Heinz W

    2004-01-01

    2,3,5,6-Tetrafluoro-4-(2,2,3,3,3-pentafluoropropoxy)styrene (TF(F-5)S) and 2,3,5,6-tetrafluoro-4-(2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-pentadecafluorooctaoxy)styrene (TF(F,5)S) are prepared by nucleophilic substitution of 2,3,4,5,6-pentafluorostyrene. The neat monomers are subjected to atom transfer...... radical polymerization (ATRP) at 110 degreesC to high conversions in relatively short times, 10-120 min; TF(F-5)S is additionally polymerized at 70 and 90 degreesC. Block copolymers with styrene are prepared by the macroinitiator approach. All polymers, in the number-average molecular weight range from...... than 10 mol %. The fluorinated side chains of P(TF(F-5)S) and P(TF(F-15)S) enrich the surface of thin films, which results in an advancing water contact angle of 117degrees and 122degrees, respectively. Both XPS analyses and contact angle measurements strongly imply that the fluorinated parts...

  15. Homochiral Evolution in Self-Assembled Chiral Polymers and Block Copolymers.

    Science.gov (United States)

    Wen, Tao; Wang, Hsiao-Fang; Li, Ming-Chia; Ho, Rong-Ming

    2017-04-18

    The significance of chirality transfer is not only involved in biological systems, such as the origin of homochiral structures in life but also in man-made chemicals and materials. How the chiral bias transfers from molecular level (molecular chirality) to helical chain (conformational chirality) and then to helical superstructure or phase (hierarchical chirality) from self-assembly is vital for the chemical and biological processes in nature, such as communication, replication, and enzyme catalysis. In this Account, we summarize the methodologies for the examination of homochiral evolution at different length scales based on our recent studies with respect to the self-assembly of chiral polymers and chiral block copolymers (BCPs*). A helical (H*) phase to distinguish its P622 symmetry from that of normal hexagonally packed cylinder phase was discovered in the self-assembly of BCPs* due to the chirality effect on BCP self-assembly. Enantiomeric polylactide-containing BCPs*, polystyrene-b-poly(l-lactide) (PS-PLLA) and polystyrene-b-poly(d-lactide) (PS-PDLA), were synthesized for the examination of homochiral evolution. The optical activity (molecular chirality) of constituted chiral repeating unit in the chiral polylactide is detected by electronic circular dichroism (ECD) whereas the conformational chirality of helical polylactide chain can be explicitly determined by vibrational circular dichroism (VCD). The H* phases of the self-assembled polylactide-containing BCPs* can be directly visualized by 3D transmission electron microscopy (3D TEM) technique at which the handedness (hierarchical chirality) of the helical nanostructure is thus determined. The results from the ECD, VCD, and 3D TEM for the investigated chirality at different length scales suggest the homochiral evolution in the self-assembly of the BCPs*. For chiral polylactides, twisted lamellae in crystalline banded spherulite can be formed by dense packing scheme and effective interactions upon helical

  16. Ion solvation in polymer blends and block copolymer melts: effects of chain length and connectivity on the reorganization of dipoles.

    Science.gov (United States)

    Nakamura, Issei

    2014-05-29

    We studied the thermodynamic properties of ion solvation in polymer blends and block copolymer melts and developed a dipolar self-consistent field theory for polymer mixtures. Our theory accounts for the chain connectivity of polymerized monomers, the compressibility of the liquid mixtures under electrostriction, the permanent and induced dipole moments of monomers, and the resultant dielectric contrast among species. In our coarse-grained model, dipoles are attached to the monomers and allowed to rotate freely in response to electrostatic fields. We demonstrate that a strong electrostatic field near an ion reorganizes dipolar monomers, resulting in nonmonotonic changes in the volume fraction profile and the dielectric function of the polymers with respect to those of simple liquid mixtures. For the parameter sets used, the spatial variations near an ion can be in the range of 1 nm or larger, producing significant differences in the solvation energy among simple liquid mixtures, polymer blends, and block copolymers. The solvation energy of an ion depends substantially on the chain length in block copolymers; thus, our theory predicts the preferential solvation of ions arising from differences in chain length.

  17. Role of block copolymer adsorption versus bimodal grafting on nanoparticle self-assembly in polymer nanocomposites.

    Science.gov (United States)

    Zhao, Dan; Di Nicola, Matteo; Khani, Mohammad M; Jestin, Jacques; Benicewicz, Brian C; Kumar, Sanat K

    2016-09-14

    We compare the self-assembly of silica nanoparticles (NPs) with physically adsorbed polystyrene-block-poly(2-vinylpyridine) (PS-b-P2VP) copolymers (BCP) against NPs with grafted bimodal (BM) brushes comprised of long, sparsely grafted PS chains and a short dense carpet of P2VP chains. As with grafted NPs, the dispersion state of the BCP NPs can be facilely tuned in PS matrices by varying the PS coverage on the NP surface or by changes in the ratio of the PS graft to matrix chain lengths. Surprisingly, the BCP NPs are remarkably better dispersed than the NPs tethered with bimodal brushes at comparable PS grafting densities. We postulate that this difference arises because of two factors inherent in the synthesis of the NPs: In the case of the BCP NPs the adsorption process is analogous to the chains being "grafted to" the NP surface, while the BM case corresponds to "grafting from" the surface. We have shown that the "grafted from" protocol yields patchy NPs even if the graft points are uniformly placed on each particle. This phenomenon, which is caused by chain conformation fluctuations, is exacerbated by the distribution function associated with the (small) number of grafts per particle. In contrast, in the case of BCP adsorption, each NP is more uniformly coated by a P2VP monolayer driven by the strongly favorable P2VP-silica interactions. Since each P2VP block is connected to a PS chain we conjecture that these adsorbed systems are closer to the limit of spatially uniform sparse brush coverage than the chemically grafted case. We finally show that the better NP dispersion resulting from BCP adsorption leads to larger mechanical reinforcement than those achieved with BM particles. These results emphasize that physical adsorption of BCPs is a simple, effective and practically promising strategy to direct NP dispersion in a chemically unfavorable polymer matrix.

  18. Ultrasonic degradation of butadiene, styrene and their copolymers.

    Science.gov (United States)

    Sathiskumar, P S; Madras, Giridhar

    2012-05-01

    Ultrasonic degradation of commercially important polymers, styrene-butadiene (SBR) rubber, acrylonitrile-butadiene (NBR) rubber, styrene-acrylonitrile (SAN), polybutadiene rubber and polystyrene were investigated. The molecular weight distributions were measured using gel permeation chromatography (GPC). A model based on continuous distribution kinetics approach was used to study the time evolution of molecular weight distribution for these polymers during degradation. The effect of solvent properties and ultrasound intensity on the degradation of SBR rubber was investigated using different pure solvents and mixed solvents of varying volatility and different ultrasonic intensities. Copyright © 2011 Elsevier B.V. All rights reserved.

  19. UV shielding with visible transparency based properties of poly (styrene-co-acrylonitrile)/Ag doped ZnO nanocomposite

    Science.gov (United States)

    Singh, Rajender; Verma, Karan; Singh, Tejbir; Barman, P. B.; Sharma, Dheeraj

    2018-02-01

    Development of ultraviolet (UV) shielding with visible transparency based thermoplastic polymer nanocomposite (PNs) presents an important requisite in terms of their efficiency and cost. Present study contributed for the same approach by dispersion of Ag doped ZnO nanoparticles upto 10 wt% in poly (styrene-co-acrylonitrile) matrix by insitu emulsion polymerization method. The crystal and chemical structure of PNs has been analyzed by x-ray diffraction (XRD) and fourier infrared spectrometer (FTIR) techniques. The morphological and elemental information of synthesized nanomaterial has been studied by field emission scanning electron microscope (FESEM) and energy dispersive spectroscopy (EDS) technique. The optical properties of PNs has been studied by UV-visible spectroscopy technique. The incorporation of nanoparticles in polymer matrix absorb the complete UV light with visible transparency. The present reported polymer nanocomposite (PNs) have tuned refractive index with UV blocking and visible transparency based properties which can serve as a viable alternative as compared to related conventional materials.

  20. The effect of different component ratios in block polymers and processing conditions on electrodeposition efficiency onto titanium

    Energy Technology Data Exchange (ETDEWEB)

    Fukuhara, Yusuke; Kyuzo, Megumi [Department of Materials Engineering, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Tsutsumi, Yusuke [Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, 2-3-10 Kanda-surugadai, Chiyoda-ku, Tokyo 101-0062 (Japan); Nagai, Akiko [Department of Materials Engineering, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, 2-3-10 Kanda-surugadai, Chiyoda-ku, Tokyo 101-0062 (Japan); Chen, Peng [Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, 2-3-10 Kanda-surugadai, Chiyoda-ku, Tokyo 101-0062 (Japan); Hanawa, Takao, E-mail: hanawa.met@tmd.ac.jp [Department of Materials Engineering, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, 2-3-10 Kanda-surugadai, Chiyoda-ku, Tokyo 101-0062 (Japan)

    2015-11-15

    Graphical abstract: - Highlights: • MPC polymers with an ability of electrodeposition were synthesized. • MPC polymers were immobilized on titanium substrates by electrodeposition. • Immobilization by electrodeposition of MPC polymer decreased water contact angle and protein adsorption. • Length of MPC unit and electrodeposition time did not influence water contact angle and protein adsorption. - Abstract: 2-Methacryloyloxyethyl phosphorylcholine (MPC) polymers for electrodeposition to titanium surfaces were synthesized. The polymers were block-type copolymers composed of a poly(MPC) segment and a poly(2-aminoethylmethacrylate (AEMA)) segment, which could electronically adsorb to a titanium oxide film on the titanium surface. The polymer was synthesized as expected by nuclear magnetic resonance and gel permeation chromatography. In a 0.26 mmol L{sup −1} PMbA solution adjusted to pH 11, −3.0 V (vs. an Ag/AgCl electrode) was applied to a titanium substrate for 300 s. We evaluated the effects of the molecular structure of poly(MPC-block-AEMA) (PMbA) with a different polymerization degree of MPC unit, whereas the polymerization degree of the AEMA units was fixed. The 15-min electrodeposition of PMbA100 was the most efficient condition in this study. On the other hand, the results of the water contact angle and the amount of adsorbed protein did not change, even when altering the MPC unit number and electrodeposition time. This indicates that the immobilization by electrodeposition of PMbA is important for the inhibition of protein adsorption, while the polymerization degree of the MPC unit and the electrodeposition time do not influence them. This study will enhance the understanding of effective polymer structures for electrodeposition and electrodeposition conditions.

  1. Engineering responsive polymer building blocks with host-guest molecular recognition for functional applications.

    Science.gov (United States)

    Hu, Jinming; Liu, Shiyong

    2014-07-15

    CONSPECTUS: All living organisms and soft matter are intrinsically responsive and adaptive to external stimuli. Inspired by this fact, tremendous effort aiming to emulate subtle responsive features exhibited by nature has spurred the invention of a diverse range of responsive polymeric materials. Conventional stimuli-responsive polymers are constructed via covalent bonds and can undergo reversible or irreversible changes in chemical structures, physicochemical properties, or both in response to a variety of external stimuli. They have been imparted with a variety of emerging applications including drug and gene delivery, optical sensing and imaging, diagnostics and therapies, smart coatings and textiles, and tissue engineering. On the other hand, in comparison with molecular chemistry held by covalent bonds, supramolecular chemistry built on weak and reversible noncovalent interactions has emerged as a powerful and versatile strategy for materials fabrication due to its facile accessibility, extraordinary reversibility and adaptivity, and potent applications in diverse fields. Typically involving more than one type of noncovalent interactions (e.g., hydrogen bonding, metal coordination, hydrophobic association, electrostatic interactions, van der Waals forces, and π-π stacking), host-guest recognition refers to the formation of supramolecular inclusion complexes between two or more entities connected together in a highly controlled and cooperative manner. The inherently reversible and adaptive nature of host-guest molecular recognition chemistry, stemming from multiple noncovalent interactions, has opened up a new platform to construct novel types of stimuli-responsive materials. The introduction of host-guest chemistry not only enriches the realm of responsive materials but also confers them with promising new applications. Most intriguingly, the integration of responsive polymer building blocks with host-guest recognition motifs will endow the former with

  2. Effect of Areal Density of Polymer Chains on Gold Nanoparticles on Nanoparticle Location in a Block Copolymer Template

    Science.gov (United States)

    Kim, B. J.; Bang, J.; Hawker, C. J.; Kramer, E. J.

    2006-03-01

    It is well established that one block of a copolymer can interact preferentially with an inorganic substrate to produce wetting and domain orientation. We take advantage of this preferential interaction to control the location of 2.5 nm diameter Au nanoparticles coated with short thiol-terminated polystyrene (Mn=3.4 kg/mol) chains (PS-SH) in a symmetric poly(styrene-b-2 vinyl-pyridine) (PS-b-P2VP) diblock copolymer (Mn=196 kg/mol) by changing the areal density σ of the PS-SH on the Au. If σ >= 1.6 chains/nm^2, the preferential interaction between the P2VP of the PS-b-P2VP and the Au surface is screened and the Au localizes in the center of the PS domains. If σ <= 1.4 chains/nm^2 , the Au particles are localized at the PS-P2VP interface. Au nanoparticles coated with thiol terminated P2VP (Mn=3 kg/mol) localize in the center of the P2VP domain of the PS-P2VP over the entire range of σ, demonstrating the localization of the PS coated Au nanoparticles at the interface at low values of σ is due to the unscreened Au-P2VP interaction.

  3. Preparation of pinewood/polymer/composites using gamma irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Ajji, Zaki [Polymer Technology Division, Department of Radiation Technology, Atomic Energy Commission, P.O. Box 6091, Damascus (Syrian Arab Republic)]. E-mail: atomic@aec.org.sy

    2006-09-15

    Wood/polymer composites (WPC) have been prepared from pinewood with different compounds using gamma irradiation: butyl acrylate, butyl methacrylate, styrene, acrylamide, acrylonitrile, and unsaturated polyester styrene resin. The polymer loading was determined with respect to the compound concentration and the irradiation dose. The polymer loading increases generally with increase in the monomer or polymer concentration. Tensile and compression strength have been improved in the four cases, but no improvement was observed using unsaturated polyester styrene resin or acrylamide.

  4. Continuous emulsion copolymerisation of styrene and methyl acrylate

    NARCIS (Netherlands)

    Boomen, van den F.H.A.M.; Meuldijk, J.; Thoenes, D.

    1996-01-01

    For emulsion polymerisation the reactor type has a strong influence on the final product properties, for example the particle size (distribution) and the polymer composition. A batch copolymerisation of styrene and methyl acrylate shows strong composition drift. The course of the batch reaction has

  5. Synthesis of crosslinked poly (styrene-co-divinylbenzene-co ...

    Indian Academy of Sciences (India)

    Synthesis of crosslinked poly(styrene--divinylbenzene--sulfopropyl methacrylate) nanoparticles by emulsion polymerization: Tuning the particle size and surface charge density. Dhamodaran Arunbabu Mousumi Hazarika Somsankar Naik Tushar Jana. Polymers Volume 32 Issue 6 December 2009 pp 633-641 ...

  6. 21 CFR 177.1830 - Styrene-methyl methacrylate copolymers.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Styrene-methyl methacrylate copolymers. 177.1830 Section 177.1830 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) INDIRECT FOOD ADDITIVES: POLYMERS Substances for Use as Basic Components of Single and Repeated Us...

  7. 21 CFR 177.1820 - Styrene-maleic anhydride copolymers.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Styrene-maleic anhydride copolymers. 177.1820 Section 177.1820 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) INDIRECT FOOD ADDITIVES: POLYMERS Substances for Use as Basic Components of Single and Repeated Use...

  8. m-Carboranylphosphinate as Versatile Building Blocks To Design all Inorganic Coordination Polymers.

    Science.gov (United States)

    Oleshkevich, Elena; Viñas, Clara; Romero, Isabel; Choquesillo-Lazarte, Duane; Haukka, Matti; Teixidor, Francesc

    2017-05-15

    The first examples of coordination polymers of manganese(II) and a nickel(II) complex with a purely inorganic carboranylphosphinate ligand are reported, together with its exhaustive characterization. X-ray analysis revealed 1D polymeric chains with carboranylphosphinate ligands bridging two manganese(II) centers. The reactivity of polymer 1 with water and Lewis bases has also been studied.

  9. Mechanical Properties of Weakly Segregated Block Copolymers. 3. Influence of Strain Rate and Temperature on Tensile Properties of Poly(styrene-b-butyl methacrylate) Diblock Copolymers with Different Morphologies

    NARCIS (Netherlands)

    Weidisch, R.; Stamm, M.; Michler, G.H.; Fischer, H.R.; Jérôme, R.

    1999-01-01

    Poly(styrene-b-butyl methacrylate) diblock copolymers, PS-6-PBMA, with different morphologies are investigated with respect to the influence of strain rate and temperature on tensile properties. In the first part the mechanical properties of bicontinuous and perforated lamellar structure are

  10. Study on the Matching Relationship between Polymer Hydrodynamic Characteristic Size and Pore Throat Radius of Target Block S Based on the Microporous Membrane Filtration Method

    Directory of Open Access Journals (Sweden)

    Li Yiqiang

    2014-01-01

    Full Text Available The concept of the hydrodynamic characteristic size of polymer was proposed in this study, to characterize the size of aggregates of many polymer molecules in the polymer percolation process. The hydrodynamic characteristic sizes of polymers used in the target block S were examined by employing microporous membrane filtration method, and the factors were studied. Natural core flow experiments were conducted in order to set up the flow matching relationship plate. According to the flow matching plate, the relationship between the hydrodynamic characteristic size of polymer and pore throat radius obtained from core mercury injection data was found. And several suitable polymers for different reservoirs permeability were given. The experimental results of microporous membrane filtration indicated that the hydrodynamic characteristic size of polymer maintained a good nonlinear relationship with polymer viscosity; the value increased as the molecular weight and concentration of the polymer increased and increased as the salinity of dilution water decreased. Additionally, the hydrodynamic characteristic size decreased as the pressure increased, so the hydrodynamic characteristic size ought to be determined based on the pressure of the target block. In the core flow studies, good matching of polymer and formation was identified as polymer flow pressure gradient lower than the fracture pressure gradient of formation. In this case, good matching that was the pore throat radius should be larger than 10 times the hydrodynamic characteristic size of polymer in this study. Using relationship, more matching relationship between the hydrodynamic characteristic sizes of polymer solutions and the pore throat radius of target block was determined.

  11. Electron Transfer of Myoglobin Immobilized in Au Electrodes Modified with a RAFT PMMA-Block-PDMAEMA Polymer

    Directory of Open Access Journals (Sweden)

    Carla N. Toledo

    2014-01-01

    Full Text Available Myoglobin was immobilized with poly(methyl methacrylate-block-poly[(2-dimethylaminoethyl methacrylate]PMMA-block-PDMAEMA polymer synthesized by reversible addition-fragmentation chain transfer technique (RAFT. Cyclic voltammograms gave direct and slow quasireversible heterogeneous electron transfer kinetics between Mb-PMMA-block-PDMAEMA modified electrode and the redox center of the protein. The values for electron rate constant (Ks and transfer coefficient (α were 0.055±0.01·s−1 and 0.81±0.08, respectively. The reduction potential determined as a function of temperature (293–328 K revealed a value of reaction center entropy of ΔS0 of 351.3±0.0002 J·mol−1·K−1 and enthalpy change of -76.8±0.1 kJ·mol−1, suggesting solvent effects and charge ionization atmosphere involved in the reaction parallel to hydrophobic interactions with the copolymer. The immobilized protein also exhibits an electrocatalytical response to reduction of hydrogen peroxide, with an apparent Km of 114.7±58.7 μM. The overall results substantiate the design and use of RAFT polymers towards the development of third-generation biosensors.

  12. Effect of Ligand Molecular Weight and Nanoparticle Core Size on Polymer-Coated Gold Nanoparticle Location in Block Copolymers

    Science.gov (United States)

    Petrie, Joshua; Kim, Bumjoon; Fredrickson, Glenn; Kramer, Ed

    2008-03-01

    Gold nanoparticles modified by short chain polymer thiols [Au-PS] can be designed to strongly localize in either domain of a polystyrene-b-poly(2-vinylpyridine) [PS-PVP] block copolymer or at the interface. The P2VP block has a stronger attractive interaction with bare gold than the PS block. Thus, when the areal chain density σ of end-attached PS chains falls below a critical areal chain density σc the Au-PS nanoparticles adsorb to the PS-b-P2VP interface. The effect of the polymer ligand molecular weight on the σchas been shown to scale as σc˜ ((R+Rg)/(R*Rg))̂2, where R is the curvature of the Au nanoparticle core radius. To test this scaling relation for σc further we are synthesizing gold nanoparticles with different core radii and will present preliminary results on σcas a function of R.

  13. Olefin–Styrene Copolymers

    OpenAIRE

    Nunzia Galdi; Antonio Buonerba; Leone Oliva

    2016-01-01

    In this review are reported some of the most relevant achievements in the chemistry of the ethylene–styrene copolymerization and in the characterization of the copolymer materials. Focus is put on the relationship between the structure of the catalyst and that of the obtained copolymer. On the other hand, the wide variety of copolymer architecture is related to the properties of the material and to the potential utility.

  14. Design of nanocarriers for nanoscale drug delivery to enhance cancer treatment using hybrid polymer and lipid building blocks.

    Science.gov (United States)

    Zhang, Rui Xue; Ahmed, Taksim; Li, Lily Yi; Li, Jason; Abbasi, Azhar Z; Wu, Xiao Yu

    2017-01-26

    Polymer-lipid hybrid nanoparticles (PLN) are an emerging nanocarrier platform made from building blocks of polymers and lipids. PLN integrate the advantages of biomimetic lipid-based nanoparticles (i.e. solid lipid nanoparticles and liposomes) and biocompatible polymeric nanoparticles. PLN are constructed from diverse polymers and lipids and their numerous combinations, which imparts PLN with great versatility for delivering drugs of various properties to their nanoscale targets. PLN can be classified into two types based on their hybrid nanoscopic structure and assembly methods: Type-I monolithic matrix and Type-II core-shell systems. This article reviews the history of PLN development, types of PLN, lipid and polymer candidates, fabrication methods, and unique properties of PLN. The applications of PLN in delivery of therapeutic or imaging agents alone or in combination for cancer treatment are summarized and illustrated with examples. Important considerations for the rational design of PLN for advanced nanoscale drug delivery are discussed, including selection of excipients, synthesis processes governing formulation parameters, optimization of nanoparticle properties, improvement of particle surface functionality to overcome macroscopic, microscopic and cellular biological barriers. Future directions and potential clinical translation of PLN are also suggested.

  15. Naphthalene Bis(4,8-diamino-1,5-dicarboxyl)amide Building Block for Semiconducting Polymers.

    Science.gov (United States)

    Eckstein, Brian J; Melkonyan, Ferdinand S; Manley, Eric F; Fabiano, Simone; Mouat, Aidan R; Chen, Lin X; Facchetti, Antonio; Marks, Tobin J

    2017-10-18

    We report a new naphthalene bis(4,8-diamino-1,5-dicarboxyl)amide (NBA) building block for polymeric semiconductors. Computational modeling suggests that regio-connectivity at the 2,6- or 3,7-NBA positions strongly modulates polymer backbone torsion and, therefore, intramolecular π-conjugation and aggregation. Optical, electrochemical, and X-ray diffraction characterization of 3,7- and 2,6-dithienyl-substituted NBA molecules and corresponding isomeric NBA-bithiophene copolymers P1 and P2, respectively, reveals the key role of regio-connectivity. Charge transport measurements demonstrate that while the twisted 3,7-NDA-based P1 is a poor semiconductor, the planar 2,6-functionalized NBA polymers (P2-P4) exhibit ambipolarity, with μ e and μ h of up to 0.39 and 0.32 cm 2 /(V·s), respectively.

  16. Design, Synthesis, and Characterization of High Performance Polymer Electrolytes for Printed Electronics and Energy Storage

    Science.gov (United States)

    2016-03-31

    cross- linked , reversible ion gels exhibit among the highest ionic conductivities (>10 –2 S/cm) of known solvent-free, non-aqueous polymer...TFSA], the styrene domains were cross- linked by annealing at elevated temperature for ca. 20 min. The high ionic conductivity (ca. 10 mS/cm) of the...main innovations were the development of ion gels, materials that combine an ionic liquid with a gelating block copolymer to give mechanical strength

  17. Polymerization of styrene with cyclopentadienyl nickel complex/methylaluminoxane

    Science.gov (United States)

    Yu, Dongping; Zhang, Danfeng

    2017-09-01

    Polystyrene was synthesized by Cp(CH2CH2OCH3)NiCl(PPh3) in the presence of methylaluminoxane (MAO). This complex displayed a very high activity for styrene polymerization up to 107 g.mol-1Nih-1. 76.6% styrene was converted to polystyrene (PS) with an average molecular (Mn) of 1.13×105 at 50 °C in 30 min. The structure of the obtained polymer was characterized by 1H NMR and FT-IR.

  18. Conjugated Polymer Chains Confined in Vertical Nanocylinders of a Block-Copolymer Film: Preparation, Characterization, and Optoelectronic Function

    KAUST Repository

    Dong, Ban Xuan; Honmou, Yoshihiro; Komiyama, Hideaki; Furumaki, Shu; Iyoda, Tomokazu; Vacha, Martin

    2013-01-01

    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.

  19. Newton Output Blocking Force under Low-Voltage Stimulation for Carbon Nanotube-Electroactive Polymer Composite Artificial Muscles.

    Science.gov (United States)

    Chen, I-Wen Peter; Yang, Ming-Chia; Yang, Chia-Hui; Zhong, Dai-Xuan; Hsu, Ming-Chun; Chen, YiWen

    2017-02-15

    This is a study on the development of carbon nanotube-based composite actuators using a new ionic liquid-doped electroactive ionic polymer. For scalable production purposes, a simple hot-pressing method was used. Carbon nanotube/ionic liquid-Nafion/carbon nanotube composite films were fabricated that exhibited a large output blocking force and a stable cycling life with low alternating voltage stimuli in air. Of particular interest and importance, a blocking force of 1.5 N was achieved at an applied voltage of 6 V. Operational durability was confirmed by testing in air for over 30 000 cycles (or 43 h). The superior actuation performance of the carbon nanotube/ionic liquid-Nafion/carbon nanotube composite, coupled with easy manufacturability, low driving voltage, and reliable operation, promises great potential for artificial muscle and biomimetic applications.

  20. 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.

  1. Recovery of recycled acrylonitrile-butadiene-styrene, through mixing with styrene-ethylene/butylene-styrene

    OpenAIRE

    Peydro, M. A.; Parres, F.; Crespo Amorós, José Enrique; Navarro Vidal, Raúl

    2013-01-01

    Recovery of recycled acrylonitrile-butadiene-styrene (ABS) through mixing with styrene-ethylene/butylene-styrene (SEBS) has been studied in this paper. To simulate recycled ABS, virgin ABS was processed through 5 cycles, at extreme processing temperatures, 220 degrees C and 260 degrees C. The virgin ABS, the virgin SEBS, the recycled ABS and the mixtures were mechanically, thermally and rheologically characterized after the various cycles of reprocessing in order to evaluate their correspondi...

  2. π-Extended Isoindigo-Based Derivative: A Promising Electron-Deficient Building Block for Polymer Semiconductors.

    Science.gov (United States)

    Xu, Long; Zhao, Zhiyuan; Xiao, Mingchao; Yang, Jie; Xiao, Jian; Yi, Zhengran; Wang, Shuai; Liu, Yunqi

    2017-11-22

    The exploration of novel electron-deficient building blocks is a key task for developing high-performance polymer semiconductors in organic thin-film transistors. In view of the situation of the lack of strong electron-deficient building blocks, we designed two novel π-extended isoindigo-based electron-deficient building blocks, IVI and F 4 IVI. Owing to the strong electron-deficient nature and the extended π-conjugated system of the two acceptor units, their copolymers, PIVI2T and PF 4 IVI2T, containing 2,2'-bithiophene donor units, are endowed with deep-lying highest occupied molecular orbital (HOMO)/lowest unoccupied molecular orbital (LUMO) energy levels and strong intermolecular interactions. In comparison to PIVI2T, the fluorinated PF 4 IVI2T exhibits stronger intra- and intermolecular interactions, lower HOMO/LUMO energy levels up to -5.74/-4.17 eV, and more ordered molecular packing with a smaller π-π stacking distance of up to 3.53 Å, resulting in an excellent ambipolar transporting behavior and a promising application in logic circuits for PF 4 IVI2T in ambient with hole and electron mobilities of up to 1.03 and 1.82 cm 2 V -1 s -1 , respectively. The results reveal that F 4 IVI is a promising and strong electron-deficient building unit to construct high-performance semiconducting polymers, which provides an insight into the structure-property relationships for the exploration and molecular engineering of excellent electron-deficient building blocks in the field of organic electronics.

  3. Micro-shear bond strength of different resin cements to ceramic/glass-polymer CAD-CAM block materials.

    Science.gov (United States)

    Cekic-Nagas, Isil; Ergun, Gulfem; Egilmez, Ferhan; Vallittu, Pekka Kalevi; Lassila, Lippo Veli Juhana

    2016-10-01

    The aim of this study was to evaluate the effects of hydrofluoric acid treatment on bond strength of resin cements to three different types of ceramic/glass containing CAD-CAM block composite materials. CAD-CAM block materials of polymer infiltrated (Vita Enamic), resin nanoceramic (Lava Ultimate) and nanoceramic (Cerasmart) with a thickness of 1.5mm were randomly divided into two groups according to the surface treatment performed. In Group 1, specimens were wet-ground with silicon carbide abrasive papers up to no. 1000. In Group 2, 9.6% hydrofluoric acid gel was applied to ceramics. Three different resin cements (RelyX, Variolink Esthetic and G-CEM LinkAce) were applied to the tubes in 1.2-mm thick increments and light-cured for 40s using LED light curing unit. Half of the specimens (n=10) were submitted to thermal cycling (5000 cycles, 5-55°C). The strength measurements were accomplished with a universal testing machine (Lloyd Instruments) at a cross-head speed of 0.5mm/min until the failure occurs. Failure modes were examined using a stereomicroscope and scanning electron microscope. The data were analyzed with multivariate analysis of variance (MANOVA) and Tukey's post hoc tests (α=0.05). There were significant differences between ceramics and resin cements (pceramics (pceramic/glass-polymer materials might promote the bonding capacity of these systems. Copyright © 2016 Japan Prosthodontic Society. Published by Elsevier Ltd. All rights reserved.

  4. Block copolymer vesicles-using concepts from polymer chemistry to mimic biomembranes

    OpenAIRE

    Kita-Tokarczyk, Katarzyna; Grumelard, Julie; Haefele, Thomas; Meier, Wolfgang

    2005-01-01

    A review. Owing to the increasing interest in self-assembled structures from block copolymer materials, we present here a review of recent literature concerning amphiphilic block copolymer vesicles. A vesicular morphol. is applicable not only in such fields like delivery-release and biomineralization, but also has been utilized for prepn. of nanoreactors and incorporation of biol. macromols. The organization of this paper is the following: we first provide the readers with the overview of the...

  5. Block copolymer micelle coronas as quasi-two-dimensional dilute or semidilute polymer solutions

    DEFF Research Database (Denmark)

    Svaneborg, C.; Pedersen, J.S.

    2001-01-01

    Chain-chain interactions in a corona of polymers tethered to a spherical core under good solvent conditions are studied using Monte Carlo simulations. The total scattering function of the corona as well as different partial contributions are sampled. By combining the different contributions...

  6. Tuning of polymeric nanoparticles by coassembly of thermoresponsive polymers and a double hydrophilic thermoresponsive block copolymer

    Czech Academy of Sciences Publication Activity Database

    Zhang, Q.; Voorhaar, L.; Filippov, Sergey K.; Yesil, B. F.; Hoogenboom, R.

    2016-01-01

    Roč. 120, č. 20 (2016), s. 4635-4643 ISSN 1520-6106 R&D Projects: GA ČR(CZ) GC15-10527J Institutional support: RVO:61389013 Keywords : nanoparticles * thermoresponsive polymers * self-assembly Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.177, year: 2016

  7. Investigation of the use of recycled polymer-modified asphalt in asphaltic concrete pavements.

    Science.gov (United States)

    2004-06-30

    This report presents issues associated with recycling polymer modified asphalt cements (PMACs), particularly blending aged PMAC with new PMAC. A styrene-butadiene-styrene (SBS) PMAC was selected and graded using the Superpave Performance Grading (PG)...

  8. Inhomogeneity of block copolymers at the interface of an immiscible polymer blend

    Science.gov (United States)

    Ryu, Ji Ho; Kim, YongJoo; Lee, Won Bo

    2018-04-01

    We present the effects of structure and stiffness of block copolymers on the interfacial properties of an immiscible homopolymer blend. Diblock and two-arm grafted copolymers with variation in stiffness are modeled using coarse-grained molecular dynamics to compare the compatibilization efficiency, i.e., reduction of interfacial tension. Overall, grafted copolymers are located more compactly at the interface and show better compatibilization efficiency than diblock copolymers. In addition, an increase in the stiffness for one of the blocks of the diblock copolymers causes unusual inhomogeneous interfacial coverage due to bundle formation. However, an increase in the stiffness for one of blocks of the grafted copolymers prevents the bundle formation due to the branched chain. As a result, homogeneous interfacial coverage of homopolymer blends is realized with significant reduction of interfacial tension which makes grafted copolymer a better candidate for the compatibilizer of immiscible homopolymer blend.

  9. Thiazoloisoindigo: a Building Block that Merges the Merits of Thienoisoindigo and Diazaisoindigo for Conjugated Polymers.

    Science.gov (United States)

    Wan, Xiaobo; Li, Chenchen; Wang, Xiao; Hio-Ieng, Un; Peng, Jiawei; Lan, Zhenggang; Cai, Mian; Pei, Jian; Wang, Jieyu

    2018-04-24

    Thiazoloisoindigo, a novel structural variation of isoindigo, is for the first time utilized to synthesize conjugated polymers. Polymer based on thiazoloisoindigo merges the advantages of the one based on thienoisoindigo and diazaisoindigo: It not only exhibits a greatly red shifted UV-vis absorption to the near-infrared region due to its strong tendency to form quinoidal structures, similar to that based on thienoisoindigo, but also shows excellent ambipolar mobility (hole 3.93 and electron 1.07 cm2 V-1 s-1, respectively) in organic field-effect transistors (OFETs), superior than that based on diazaisoindigo, showing the strong electron-withdrawing capability of thiazoloisoindigo. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. A Thieno[3,2-b][1]benzothiophene Isoindigo Building Block for Additive- and Annealing-Free High-Performance Polymer Solar Cells

    KAUST Repository

    Yue, Wan; Ashraf, Raja Shahid; Nielsen, Christian B.; Collado-Fregoso, Elisa; Niazi, Muhammad Rizwan; Yousaf, Syeda Amber; Kirkus, Mindaugas; Chen, Hung-Yang; Amassian, Aram; Durrant, James R.; McCulloch, Iain

    2015-01-01

    A novel photoactive polymer with two different molecular weights is reported, based on a new building block: thieno[3,2-b][1]benzothiophene isoindigo. Due to the improved crystallinity, optimal blend morphology, and higher charge mobility, solar-cell devices of the high-molecular-weight polymer exhibit a superior performance, affording efficiencies of 9.1% without the need for additives, annealing, or additional extraction layers during device fabrication.

  11. A Thieno[3,2-b][1]benzothiophene Isoindigo Building Block for Additive- and Annealing-Free High-Performance Polymer Solar Cells

    KAUST Repository

    Yue, Wan

    2015-08-20

    A novel photoactive polymer with two different molecular weights is reported, based on a new building block: thieno[3,2-b][1]benzothiophene isoindigo. Due to the improved crystallinity, optimal blend morphology, and higher charge mobility, solar-cell devices of the high-molecular-weight polymer exhibit a superior performance, affording efficiencies of 9.1% without the need for additives, annealing, or additional extraction layers during device fabrication.

  12. Synthesis and photooxidation of styrene copolymer bearing camphorquinone pendant groups

    Science.gov (United States)

    Moszner, Norbert; Lukáč, Ivan

    2012-01-01

    Summary (±)-10-Methacryloyloxycamphorquinone (MCQ) was synthesized from (±)-10-camphorsulfonic acid either by a known seven-step synthetic route or by a novel, shorter five-step synthetic route. MCQ was copolymerized with styrene (S) and the photochemical behavior of the copolymer MCQ/S was compared with that of a formerly studied copolymer of styrene with monomers containing the benzil (BZ) moiety (another 1,2-dicarbonyl). Irradiation (λ > 380 nm) of aerated films of styrene copolymers with monomers containing the BZ moiety leads to the insertion of two oxygen atoms between the carbonyl groups of BZ and to the formation of benzoyl peroxide (BP) as pendant groups on the polymer backbone. An equivalent irradiation of MCQ/S led mainly to the insertion of only one oxygen atom between the carbonyl groups of camphorquinone (CQ) and to the formation of camphoric anhydride (11) covalently bound to the polymer backbone. While the decomposition of pendant BP groups formed in irradiated films of styrene copolymers with pendant BZ groups leads to crosslinking, only small molecular-weight changes in irradiated MCQ/S were observed. PMID:22509202

  13. Radiation induced vapour phase grafting of styrene onto fluorinated substrates

    International Nuclear Information System (INIS)

    Dargaville, T.; Hill, D.; George, G.; Cardona, F.

    2000-01-01

    Full text: Polytetrafluoroethylene (PTFE) is well known for being inert towards heat, solvents and harsh chemicals. However, in contrast, PTFE is extremely sensitive to radiation suffering from a dramatic decrease in mechanical strength even when exposed to low doses. In this study we have used a copolymer of PTFE, poly(tetrafluoroethylene-co-perfluoropropylvinyl ether) (PFA). The effect of the ether comonomer is to render the polymer melt processable, lower the crystallinity and increase the radical yield when compared with PTFE. When grafting styrene to PFA using a radiation initiated process, the resulting polymer has the desirable chemical and thermal resistance of the PFA substrate combined with the functionality of the styrene, however, due to the incidental degradative effect of radiation on the PFA substrate it is important to find conditions where the best graft is achieved without exposing the substrate to extraneous levels of radiation. We have successfully grafted styrene to PFA by simultaneously exposing PFA to styrene vapour and gamma radiation. This process was found to be independent of dose rate at low dose rates suggesting a diffusion controlled mechanism. The penetration of the graft into the PFA substrate was measured by mapping a cross-section using micro-probe Raman spectroscopy

  14. Polyoxyethylene/styrene - a model system for studying reaction-induced phase separation (RIPS)

    International Nuclear Information System (INIS)

    Sutton, D.; Stanford, J.L.; Ryan, A.J.

    2003-01-01

    Full text: Reaction-induced, phase-separation has been studied in polymer blends. A model crystalline-amorphous system consisted of semi-crystalline polyoxyethylene (POE) dissolved in the monomer styrene, which was employed as a reactive solvent to ease processing. When the styrene was polymerised to polystyrene (PS) in the mould, phase-separation and phase-inversion are induced, and a polymer blend was formed. POE was selected with a molar mass, Mn = 8578 g mol -1 and a polydispersity of 1.19 as determined using GPC. The polymerisation of styrene was initiated using 1 wt-% benzoin methyl ether (BME) and 0.2 wt-% 2,2'-azobisisobutyronitrile (AIBN) under ultra-violet (UV) light. The polymerisation kinetics were determined by monitoring the reduction in the intensity of the C=C stretching vibration band at 1631 cm -1 in the Raman spectrum of styrene. The onset times for the liquid-solid (L-S) phase-separation and crystallisation of POE from styrene/PS were observed using simultaneous small-angle X-ray scattering (SAXS) and wide-angle X-ray scattering (WAXS). Onset times for L-S phase-separation determined from the SAXS data were combined with the styrene polymerisation kinetics to plot the L-S phase-separation data onto a ternary phase diagram for the reactive system POE/styrene/PS at 45 and 50 deg C

  15. Fluorinated building blocks for next-generation polymer electrolyte membrane fuel cells

    NARCIS (Netherlands)

    Wadekar, M.N.

    2012-01-01

    The purpose of this thesis is to design, create and study basic building blocks for the construction of self-assembled nanostructured electrodes and membranes for PEMFC. The research described deals with the synthesis of polymerizable fluorosurfactant (1) and its non-polymerizable analogue (2) and

  16. Lithium Polymer Electrolytes Based On PMMA / PEG And Penetrant Diffusion In Kraton Penta-Block Ionomer

    Science.gov (United States)

    Meng, Yan

    The study of diffusion in polymeric material is critical to many research fields and applications, such as polymer morphology, protective coatings (paints and varnishes), separation membranes, transport phenomena, polymer electrolytes, polymer melt, and controlled release of drugs from polymer carriers [1-9]. However, it is still a challenge to understand, predict and control the diffusion of molecules and ions of different sizes in polymers [2]. This work studied the medium to long range diffusion of species (i.e., ions and molecules) in solid polymer electrolytes based on poly(ethylene glycol)/poly(methyl methacrylate) (PEG/PMMA) for Li-based batteries, and polymeric permselective membranes via pulsed-field gradient NMR and a.c. impedance. Over the past decades polymer electrolytes have attracted much attention because of their promising technological application as an ion-conducting medium in solid-state batteries, fuel cells, electrochromic displays, and chemical sensors [10, 11]. However, despite numerous studies related to ionic transport in these electrolytes the understanding of the migration mechanism is still far from being complete, and progress in the field remains largely empirical [10, 12-15]. Among various candidates for solid polymer electrolyte (SPE) material, the miscible polymer pair, poly(ethylene oxide)/poly(methyl methacrylate) (PEO/PMMA), is an attractive one, because there is a huge difference in mobility between PEO and PMMA in their blends, and PEO chains remain exceptionally mobile in the blend even at temperature below the glass transition temperature of the blend [ 16]. Thus the mechanical strength and dimensional stability is maintained by PMMA component, while the chain motions or rearrangements of the PEO component virtually contribute to the ion transport [17]. The current work prepared two types of SPE based on poly(ethylene glycol) (PEG) /PMMA (40/60 by weight) for Li-based batteries: lithium bis(trifluoromethylsulfonylimide) (Li

  17. Polymerization of styrene in DODAB vesicles : a small-angle neutron scattering study

    NARCIS (Netherlands)

    Jung, M.; Robinson, B.H.; Steytler, D.C.; German, A.L.; Heenan, R.K.

    2002-01-01

    The polymerization of styrene, located in the bilayer of dioctadecyldimethylammonium bromide (DODAB) vesicles, gives rise to phase separation between the growing polymer and the bilayer. The result is a small (20-30 nm) bead of polymer located in the bilayer of each vesicle giving them a

  18. RAFT technology for the production of advanced photoresist polymers

    Science.gov (United States)

    Sheehan, Michael T.; Farnham, William B.; Okazaki, Hiroshi; Sounik, James R.; Clark, George

    2008-03-01

    Reversible Addition Fragmentation Chain Transfer (RAFT) technology has been developed for use in producing high yield low polydispersity (PD) polymers for many applications. RAFT technology is being used to produce low PD polymers and to allow control of the polymer architecture. A variety of polymers are being synthesized for use in advanced photoresists using this technique. By varying the RAFT reagent used we can modulate the system reactivity of the RAFT reagent and optimize it for use in acrylate or methacrylate monomer systems (193 and 193i photoresist polymers) or for use in styrenic monomer systems (248 nm photoresist polymers) to achieve PD as low as 1.05. RAFT polymerization technology also allows us to produce block copolymers using a wide variety of monomers. These block copolymers have been shown to be useful in self assembly polymer applications to produce unique and very small feature sizes. The mutual compatibilities of all the components within a single layer 193 photoresist are very important in order to achieve low LWR and low defect count. The advent of immersion imaging demands an additional element of protection at the solid/liquid interface. We have used RAFT technology to produce block copolymers comprising a random "resist" block with composition and size based on conventional dry photoresist materials, and a "low surface energy" block for use in 193i lithography. The relative block lengths and compositions may be varied to tune solution behavior, surface energy, contact angles, and solubility in developer. The use of this technique will be explored to produce polymers used in hydrophobic single layer resists as well as additives compatible with the main photoresist polymer.

  19. Using graphene/styrene-isoprene-styrene copolymer composite thin film as a flexible microstrip antenna for the detection of heptane vapors

    Science.gov (United States)

    Olejnik, Robert; Matyas, Jiri; Slobodian, Petr; Riha, Pavel

    2018-03-01

    Most portable devices, such as mobile phones or tablets, use antennas made of copper. This paper demonstrates the possible use of antenna constructed from electrically conductive polymer composite materials for use in those applications. The method of preparation and the properties of the graphene/styrene-isoprene-styrene copolymer as flexible microstrip antenna are described in this contribution. Graphene/styrene-isoprene-styrene copolymer toluene solution was prepared by means of ultrasound and the PET substrate was dip coated to reach a fine thin film. The main advantages of using PET as a substrate are low weight and flexibility. The final size of the flexible microstrip antenna was 10 × 25 mm with thickness of 0.48 mm (PET substrate 0.25 mm) with a weight of 0.110 g. The resulting antenna operates at a frequency of 1.8 GHz and gain ‑40.02 dB.

  20. The effect of salt on the morphologies of compositionally asymmetric block copolymer electrolytes

    Science.gov (United States)

    Loo, Whitney; Maslyn, Jacqueline; Oh, Hee Jeung; Balsara, Nitash

    Block copolymer electrolytes are promising for applications in lithium metal solid-state batteries. Due to their ability to microphase separate into distinct morphologies, their ion transport and mechanical properties can be decoupled. The addition of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) salt to poly(styrene)-block-poly(ethylene oxide) (SEO) has been shown to increase microphase separation in symmetric block copolymer systems due to an increase in the effective interaction parameter (χeff) ; however the effect of block copolymer compositional asymmetry is not well-understood. The effect of compositional asymmetry on polymer morphology was investigated through small and wide angle X-ray scattering (SAXS/WAXS). The effective Flory-Huggins interaction parameter was extracted from the scattering profiles in order to construct a phase diagram to demonstrate the effect of salt and compositional asymmetry on block copolymer morphology.

  1. Design of block copolymer membranes using segregation strength trend lines

    KAUST Repository

    Sutisna, Burhannudin

    2016-05-18

    Block copolymer self-assembly and non-solvent induced phase separation are now being combined to fabricate membranes with narrow pore size distribution and high porosity. The method has the potential to be used with a broad range of tailor-made block copolymers to control functionality and selectivity for specific separations. However, the extension of this process to any new copolymer is challenging and time consuming, due to the complex interplay of influencing parameters, such as solvent composition, polymer molecular weights, casting solution concentration, and evaporation time. We propose here an effective method for designing new block copolymer membranes. The method consists of predetermining a trend line for the preparation of isoporous membranes, obtained by computing solvent properties, interactions and copolymer block sizes for a set of successful systems and using it as a guide to select the preparation conditions for new membranes. We applied the method to membranes based on poly(styrene-b-ethylene oxide) diblocks and extended it to newly synthesized poly(styrene-b-2-vinyl pyridine-b-ethylene oxide) (PS-b-P2VP-b-PEO) terpolymers. The trend line method can be generally applied to other new systems and is expected to dramatically shorten the path of isoporous membrane manufacture. The PS-b-P2VP-b-PEO membrane formation was investigated by in situ Grazing Incident Small Angle X-ray Scattering (GISAXS), which revealed a hexagonal micelle order with domain spacing clearly correlated to the membrane interpore distances.

  2. Fast assembly of ordered block copolymer nanostructures through microwave annealing.

    Science.gov (United States)

    Zhang, Xiaojiang; Harris, Kenneth D; Wu, Nathanael L Y; Murphy, Jeffrey N; Buriak, Jillian M

    2010-11-23

    Block copolymer self-assembly is an innovative technology capable of patterning technologically relevant substrates with nanoscale precision for a range of applications from integrated circuit fabrication to tissue interfacing, for example. In this article, we demonstrate a microwave-based method of rapidly inducing order in block copolymer structures. The technique involves the usage of a commercial microwave reactor to anneal block copolymer films in the presence of appropriate solvents, and we explore the effect of various parameters over the polymer assembly speed and defect density. The approach is applied to the commonly used poly(styrene)-b-poly(methyl methacrylate) (PS-b-PMMA) and poly(styrene)-b-poly(2-vinylpyridine) (PS-b-P2VP) families of block copolymers, and it is found that the substrate resistivity, solvent environment, and anneal temperature all critically influence the self-assembly process. For selected systems, highly ordered patterns were achieved in less than 3 min. In addition, we establish the compatibility of the technique with directed assembly by graphoepitaxy.

  3. Two-dimensional phase separated structures of block copolymers on solids

    Science.gov (United States)

    Sen, Mani; Jiang, Naisheng; Endoh, Maya; Koga, Tadanori; Ribbe, Alexander

    The fundamental, yet unsolved question in block copolymer (BCP) thin films is the self-organization process of BCPs at the solid-polymer melt interface. We here focus on the self-organization processes of cylinder-forming polystyrene-block-poly (4-vinylpyridine) diblock copolymer and lamellar-forming poly (styrene-block-butadiene-block-styrene) triblock copolymer on Si substrates as model systems. In order to reveal the buried interfacial structures, the following experimental protocols were utilized: the BCP monolayer films were annealed under vacuum at T>Tg of the blocks (to equilibrate the melts); vitrification of the annealed BCP films via rapid quench to room temperature; subsequent intensive solvent leaching (to remove unadsorbed chains) with chloroform, a non-selective good solvent for the blocks. The strongly bound BCP layers were then characterized by using atomic force microscopy, scanning electron microscopy, grazing incidence small angle X-ray scattering, and X-ray reflectivity. The results showed that both blocks lie flat on the substrate, forming the two-dimensional, randomly phase-separated structure irrespective of their microdomain structures and interfacial energetics. Acknowledgement of financial support from NSF Grant (CMMI -1332499).

  4. The role of ultra-fast solvent evaporation on the directed self-assembly of block polymer thin films

    Science.gov (United States)

    Drapes, Chloe; Nelson, G.; Grant, M.; Wong, J.; Baruth, A.

    The directed self-assembly of nano-structures in block polymer thin films viasolvent vapor annealing is complicated by several factors, including evaporation rate. Solvent vapor annealing exposes a disordered film to solvent(s) in the vapor phase, increasing mobility and tuning surface energy, with the intention of producing an ordered structure. Recent theoretical predictions reveal the solvent evaporation affects the resultant nano-structuring. In a competition between phase separation and kinetic trapping during drying, faster solvent removal can enhance the propagation of a given morphology into the bulk of the thin film down to the substrate. Recent construction of a purpose-built, computer controlled solvent vapor annealing chamber provides control over forced solvent evaporation down to 15 ms. This is accomplished using pneumatically actuated nitrogen flow into and out of the chamber. Furthermore, in situ spectral reflectance, with 10 ms temporal resolution, monitors the swelling and evaporation. Presently, cylinder-forming polystyrene-block-polylactide thin films were swollen with 40% (by volume) tetrahydrofuran, followed by immediate evaporation under a variety of designed conditions. This includes various evaporation times, ranging from 15 ms to several seconds, and four unique rate trajectories, including linear, exponential, and combinations. Atomic force microscopy reveals specific surface, free and substrate, morphologies of the resultant films, dependent on specific evaporation conditions. Funded by the Clare Boothe Luce Foundation and Nebraska EPSCoR.

  5. Water-soluble building blocks for terpyridine-containing supramolecular polymers : synthesis, complexation, and pH stability studies of poly(ethylene oxide) moieties

    NARCIS (Netherlands)

    Lohmeijer, B.G.G.; Schubert, U.S.

    2003-01-01

    Poly(ethylene oxide) of various molecular weights ([bar M ]n = 3 000, 5 200, 10 000, 16 500 g · mol-1) has been modified with terpyridine end groups as building blocks for water-soluble metallo-supramolecular polymers. Metallo-supramolecular A-A homopolymers have been prepared and characterized by

  6. Polymer Based Molecular Composites. Volume 171. Materials Research Society Symposium Proceedings Held in Boston, Massachusetts on 27-30 November 1989

    Science.gov (United States)

    1990-09-01

    reactivity features promoted by the polymeric sulfonic acid moiety in contrast to HCI. Further work is being undertaken utilizing para toluene 21 sulfonic...styrene and isoprene block and homo- polymers were synthesized by anionic polymerization. Cyclohexane (Burdick and Jackson HPLC Grade) was degassed and...terephthalic acid and 21 mole-% 4 aminophenol , was purchased from Hoechst Celanese. Blends containing 70 weight-% PPE and 30 weight-% PS were kindly

  7. Development of molecularly imprinted polymers to block quorum sensing and inhibit bacterial biofilm formation.

    Science.gov (United States)

    Ma, Luyao; Feng, Shaolong; de la Fuente-Nunez, Cesar; Hancock, Robert E W; Lu, Xiaonan

    2018-05-16

    Bacterial biofilms are responsible for most clinical infections and show increased antimicrobial resistance. In this study, molecularly imprinted polymers (MIPs) were developed to specifically capture prototypical quorum sensing autoinducers [i.e., N-(3-oxododecanoyl)-L-homoserine lactone (3-oxo-C12AHL)], interrupt quorum sensing, and subsequently inhibit biofilm formation of Pseudomonas aeruginosa, an important human nosocomial pathogen. The synthesis of MIPs was optimized by considering the amount and type of the functional monomers itaconic acid (IA) and 2-hydroxyethyl methacrylate (HEMA). IA-based MIPs showed high adsorption affinity towards 3-oxo-C12AHL with an imprinting factor of 1.68. Compared to IA-based MIPs, the adsorption capacity of HEMA-based MIPs was improved 5-fold. HEMA-based MIPs significantly reduced biofilm formation (by ~65%), while biofilm suppression by IA-based MIPs was neutralized due to increased bacterial attachment. The developed MIPs represent promising alternative biofilm intervention agents that can be applied to surfaces relevant to clinical settings and food processing equipment.

  8. Designing block copolymer architectures for targeted membrane performance

    KAUST Repository

    Dorin, Rachel Mika; Phillip, William A.; Sai, Hiroaki; Werner, Jö rg; Elimelech, Menachem; Wiesner, Ulrich

    2014-01-01

    Using a combination of block copolymer self-assembly and non-solvent induced phase separation, isoporous ultrafiltration membranes were fabricated from four poly(isoprene-b-styrene-b-4-vinylpyridine) triblock terpolymers with similar block volume

  9. 78 FR 6213 - Styrene-2-Ethylhexyl Acrylate Copolymer; Tolerance Exemption

    Science.gov (United States)

    2013-01-30

    ...This regulation establishes an exemption from the requirement of a tolerance for residues of 2-propenoic acid, 2-ethylhexyl ester, polymer with ethenylbenzene; also known as styrene-2-ethylhexyl acrylate copolymer when used as an inert ingredient in a pesticide chemical formulation. H. B. Fuller Company submitted a petition to EPA under the Federal Food, Drug, and Cosmetic Act (FFDCA), requesting an exemption from the requirement of a tolerance. This regulation eliminates the need to establish a maximum permissible level for residues of 2-propenoic acid, 2-Ethylhexyl Ester, Polymer with Ethenylbenzene on food or feed commodities.

  10. Poly[(3-hexylthiophene-block-(3-semifluoroalkylthiophene] for Polymer Solar Cells

    Directory of Open Access Journals (Sweden)

    Takeshi Toru

    2010-12-01

    Full Text Available We report the synthesis of poly[(3-hexylthiophene-block-(3-(4,4,5,5,6,6,7,7,7-nonafluoroheptylthiophene], P(3HT-b-3SFT, carried out by the Grignard Metathesis Method (GRIM. The copolymers composition was determined by 1H and 19F NMR spectroscopies, and gel permeation chromatography (GPC. The thin films of P(3HT‑b‑3SFT were investigated by ultraviolet-visible absorption spectroscopy and atomic force microscopy (AFM. We also fabricated bulk-hetero junction (BHJ solar cells based on blends of P(3HT-b-3SFT and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM. Although the composition ratio of P3SFT in P(3HT-b-3SFT was low, the influence of P3SFT on the morphology and properties of solar cells was significant. The annealing process for the BHJ solar cells induced the formation of large domains and led to poor solar cell performance. The BHJ solar cells, based on PCBM and P(3HT-b-3SFT, prepared by the non-annealing process, had a maximum power conversion efficiency of 0.84% under 100 mW/cm2 (AM 1.5 solar illumination in air.

  11. Styrene exposure and risk of cancer

    Science.gov (United States)

    Huff, James; Infante, Peter F.

    2011-01-01

    Styrene is widely used in the manufacture of synthetic rubber, resins, polyesters and plastics. Styrene and the primary metabolite styrene-7,8-oxide are genotoxic and carcinogenic. Long-term chemical carcinogenesis bioassays showed that styrene caused lung cancers in several strains of mice and mammary cancers in rats and styrene-7,8-oxide caused tumours of the forestomach in rats and mice and of the liver in mice. Subsequent epidemiologic studies found styrene workers had increased mortality or incidences of lymphohematopoietic cancers (leukaemia or lymphoma or all), with suggestive evidence for pancreatic and esophageal tumours. No adequate human studies are available for styrene-7,8-oxide although this is the primary and active epoxide metabolite of styrene. Both are genotoxic and form DNA adducts in humans. PMID:21724974

  12. Solution small-angle x-ray scattering as a screening and predictive tool in the fabrication of asymmetric block copolymer membranes

    KAUST Repository

    Dorin, Rachel Mika; Marques, Debora S.; Sai, Hiroaki; Vainio, Ulla; Phillip, William A.; Peinemann, Klaus; Nunes, Suzana Pereira; Wiesner, Ulrich B.

    2012-01-01

    Small-angle X-ray scattering (SAXS) analysis of the diblock copolymer poly(styrene-b-(4-vinyl)pyridine) in a ternary solvent system of 1,4-dioxane, tetrahydrofuran, and N,N-dimethylformamide, and the triblock terpolymer poly(isoprene-b-styrene-b-(4-vinyl)-pyridine) in a binary solvent system of 1,4-dioxane and tetrahydrofuran, reveals a concentration-dependent onset of ordered structure formation. Asymmetric membranes fabricated from casting solutions with polymer concentrations at or slightly below this ordering concentration possess selective layers with the desired nanostructure. In addition to rapidly screening possible polymer solution concentrations, solution SAXS analysis also predicts hexagonal and square pore lattices of the final membrane surface structure. These results suggest solution SAXS as a powerful tool for screening casting solution concentrations and predicting surface structure in the fabrication of asymmetric ultrafiltration membranes from self-assembled block copolymers. (Figure presented) © 2012 American Chemical Society.

  13. Solution small-angle x-ray scattering as a screening and predictive tool in the fabrication of asymmetric block copolymer membranes

    KAUST Repository

    Dorin, Rachel Mika

    2012-05-15

    Small-angle X-ray scattering (SAXS) analysis of the diblock copolymer poly(styrene-b-(4-vinyl)pyridine) in a ternary solvent system of 1,4-dioxane, tetrahydrofuran, and N,N-dimethylformamide, and the triblock terpolymer poly(isoprene-b-styrene-b-(4-vinyl)-pyridine) in a binary solvent system of 1,4-dioxane and tetrahydrofuran, reveals a concentration-dependent onset of ordered structure formation. Asymmetric membranes fabricated from casting solutions with polymer concentrations at or slightly below this ordering concentration possess selective layers with the desired nanostructure. In addition to rapidly screening possible polymer solution concentrations, solution SAXS analysis also predicts hexagonal and square pore lattices of the final membrane surface structure. These results suggest solution SAXS as a powerful tool for screening casting solution concentrations and predicting surface structure in the fabrication of asymmetric ultrafiltration membranes from self-assembled block copolymers. (Figure presented) © 2012 American Chemical Society.

  14. Molecular changes in copolymers of styrene and methyl methacrylate caused by radiation

    International Nuclear Information System (INIS)

    Busfield, W.K.; O'Donnell, J.H.; Smith, C.A.

    1976-01-01

    Homopolymers of styrene and methyl methacrylate and copolymers of these monomers were irradiated in vacuo at room temperature using 60 Co γ-radiation to various doses. The gaseous radiolysis products of the polymers were analysed by gas chromatography. The radiation chemical yield, G values, of the gaseous and liquid products were calculated for the homopolymers and copolymers. The G values obtained for the homopolymers were compared with those obtained by previous workers. The graphs of G value versus composition (% Styrene) showed a marked deviation from linearity which indicated that the styrene in the copolymer had a greater effect on the behaviour than did the methyl methacrylate units. It has been postulated that the benzene ring on the styrene unit acts in some way as an energy sink, and hence protects the copolymer from radiation damage in an analogous way to that suggested for hydrocarbon mixtures. Mechanisms for the process are discussed. (author)

  15. Environmentally benign electroless nickel plating using supercritical carbon-dioxide on hydrophilically modified acrylonitrile-butadiene-styrene

    Science.gov (United States)

    Tengsuwan, Siwach; Ohshima, Masahiro

    2014-08-01

    Electroless Ni-P plating using supercritical carbon dioxide (scCO2) in conjunction with copolymer-based hydrophilic modification was applied to an acrylonitrile-butadiene-styrene (ABS) substrate. The surface of ABS substrate was hydrophilically modified by blending with a multi-block copolymer, poly(ether-ester-amide)s (PEEA), in injection molding process. The substrate was then impregnated with Pd(II)-hexafluoroacetylacetonate, Pd(hfa)2, using scCO2, followed by the electroless plating reaction. ABS/PEEA substrates with different PEEA to ABS blend ratios and different volume ratios of butadiene to the styrene-acrylonitrile copolymer (SAN) matrix were prepared to investigate how the dispersed PEEA and butadiene domains affected the blend morphology and the adhesive strength of the plating metal-to-polymer contact. Increasing the PEEA copolymer to ABS blend ratio increased the mass transfer rate of the plating solution in the ABS substrate. Consequently, the metal-polymer composite layer became thicker, which increased the adhesive strength of the metal-to-polymer contact because of the anchoring effect. The butadiene domains appeared to attract the Pd catalyst precursor, and thus, the proportion of butadiene in the ABS matrix also affected the adhesive strength of the contact between the metal layer and the substrate. The ABS substrate was successfully plated with a Ni-P metal layer with an average adhesive strength of 9.1 ± 0.5 N cm-1 by choosing appropriate ABS/PEEA blend ratios and a Pd(hfa)2 concentration.

  16. Cell Penetrating Polymers Containing Guanidinium Trigger Apoptosis in Human Hepatocellular Carcinoma Cells unless Conjugated to a Targeting N-Acetyl-Galactosamine Block.

    Science.gov (United States)

    Tan, Zhe; Dhande, Yogesh K; Reineke, Theresa M

    2017-12-20

    A series of 3-guanidinopropyl methacrylamide (GPMA)-based polymeric gene delivery vehicles were developed via aqueous reversible addition-fragmentation chain transfer (RAFT) polymerization. The polymers have been evaluated for their cellular internalization ability, transfection efficiency, and cytotoxicity. Two homopolymers: P(GPMA 20 ), P(GPMA 34 ), were synthesized to study the effect of guanidium polymer length on delivery efficiency and toxicity. In addition, an N-acetyl-d-galactosamine (GalNAc)-based hydrophilic block was incorporated to produce diblock polymers, which provides a neutral hydrophilic block that sterically protects plasmid-polymer complexes (polyplexes) from colloidal aggregation and aids polyplex targeting to hepatocytes via binding to asialoglycoprotein receptors (ASGPRs). Polyplexes formed with P(GPMA x ) (x = 20, 34) homopolymers were shown to be internalized via both energy-dependent and independent pathways, whereas polyplexes formed with block polymers were internalized through endocytosis. Notably, P(GPMA x ) polyplexes enter cells very efficiently but are also very toxic to human hepatocellular carcinoma (HepG2) cells and triggered cell apoptosis. In comparison, the presence of a carbohydrate block in the polymer structures reduced the cytotoxicity of the polyplex formulations and increased gene delivery efficiency with HepG2 cells. Transfection efficiency and toxicity studies were also carried out with HEK 293T (human embryonic kidney) cells for comparison. Results showed that polyplexes formed with the P(GPMA x ) homopolymers exhibit much higher transfection efficiency and lower toxicity with HEK 293T cells. The presence of the carbohydrate block did not further increase transfection efficiency in comparison to the homopolymers with HEK 293T cells, likely due to the lack of ASGPRs on the HEK 293T cell line. This study revealed that although guanidinium-based polymers have high membrane permeability, their application as plasmid

  17. Effect of swelling behavior of organoclays in styrene on flammability of polystyrene nanocomposites obtained through in situ incorporation

    International Nuclear Information System (INIS)

    Timochenco, Licinia; Sayer, Claudia; Machado, Ricardo A.F.; Araujo, Pedro H.H.

    2009-01-01

    In this work the effect of the interaction between organoclays and styrene on the flammability of polystyrene/clay nanocomposites obtained through in-situ incorporation was investigated. The reactions were carried out in bulk polymerization. The interaction between organoclays and styrene was inferred by swelling of the organoclay in styrene. The nanocomposites were characterized by X-ray diffraction and Transmission Electron Microscopy. The heat release rate was obtained by Cone Calorimeter and the nanocomposites were tested through UL94 horizontal burn test. Thermogravimetric analysis were also performed. Results showed that intercalated and partially exfoliated nanocomposites were obtained depending on the swelling behavior of the organoclay in styrene. It was also observed an increase of the higher decomposition temperature and an accentuated decrease on the peak of heat release of the nanocomposites when comparing to the virgin polymer. No remarkable effect between the swelling behavior of the organoclay in styrene and the flammability properties was observed. (author)

  18. Reversible pH Stimulus-Response Material Based on Amphiphilic Block Polymer Self-Assembly and Its Electrochemical Application

    Directory of Open Access Journals (Sweden)

    Tianyi Wang

    2016-06-01

    Full Text Available Stimulus-responsive microporous solid thin films were successfully fabricated by simple molecular self-assembly via an amphiphilic block polymer, polystryene–b–polyacrylic acid (PS–b–PAA. The solid thin films exhibit different surface morphologies in response to external stimuli, such as environments with different pH values in aqueous solutions. The experiments have successfully applied atomic force microscope (AFM technology to observe in-situ surface morphological changes. There is a reversible evolution of the microstructures in buffer solutions over a pH range of 2.4–9.2. These observations have been explained by positing that there is no conventional PAA swelling but that the PAA chains in the micropores stretch and contract with changes in the pH of the solution environment. The hydrophobicity of the solid thin film surface was transformed into super-hydrophilicity, as captured by optical contact angle measurements. The stimulus-responsive dynamics of pore sizes was described by a two-stage mechanism. A promising electrochemical application of this film is suggested via combination with an electrochemical impedance technique. This study is aimed at strategies for the functionalization of stimulus-responsive microporous solid thin films with reversible tunable surface morphologies, and exploring new smart materials with switch-on/switch-off behavior.

  19. Development of Styrene-Grafted Polyurethane by Radiation-Based Techniques

    Directory of Open Access Journals (Sweden)

    Jin-Oh Jeong

    2016-06-01

    Full Text Available Polyurethane (PU is the fifth most common polymer in the general consumer market, following Polypropylene (PP, Polyethylene (PE, Polyvinyl chloride (PVC, and Polystyrene (PS, and the most common polymer for thermosetting resins. In particular, polyurethane has excellent hardness and heat resistance, is a widely used material for electronic products and automotive parts, and can be used to create products of various physical properties, including rigid and flexible foams, films, and fibers. However, the use of polar polymer polyurethane as an impact modifier of non-polar polymers is limited due to poor combustion resistance and impact resistance. In this study, we used gamma irradiation at 25 and 50 kGy to introduce the styrene of hydrophobic monomer on the polyurethane as an impact modifier of the non-polar polymer. To verify grafted styrene, we confirmed the phenyl group of styrene at 690 cm−1 by Attenuated Total Reflection Fourier Transform Infrared Spectroscopy (ATR-FTIR and at 6.4–6.8 ppm by 1H-Nuclear Magnetic Resonance (1H-NMR. Scanning Electron Microscope (SEM, X-ray Photoelectron Spectroscopy (XPS, Thermogravimetric Analysis (TGA and contact angle analysis were also used to confirm styrene introduction. This study has confirmed the possibility of applying high-functional composite through radiation-based techniques.

  20. Functionalized Vegetable Oils for Utilization as Polymer Building Blocks: Office of Industrial Technologies (OIT) Agriculture Project Fact Sheet

    International Nuclear Information System (INIS)

    Carde, T.

    2001-01-01

    Vegetable oils such as soybean oil will be converted to novel polymers using hydroformylation and other catalytic processes. These polymers can be used in the construction, automotive, packaging, and electronic sectors

  1. Production and characterization of poly(styrene-co-methylmethacrylate)

    International Nuclear Information System (INIS)

    Augustinho, Tiago R.; Coan, Thais; Abarca, Silvia A.C.; Testoni, Alex A.S.; Baumgarten, Bruno P.; Machado, Ricardo A.F.

    2009-01-01

    Polystyrene (PS) is a polymer used in diverse industrial segments. It is easy to process and has a low cost when compared to other materials. However, PS has low mechanical resistance, which limits its application in some areas. Thus, a methodology that is sufficiently used is the synthesis of a copolymer, formed of two or more monomers to get products that have characteristics that are not possible to obtain with only one monomer. In this work, the styrene and methyl methacrylate monomers had been carried through reactions of copolymerization by means of polymerization in suspension using (MMA) with styrene in a bigger percentage. MMA was selected for being a monomer that results in a polymeric configuration more resistant than the PS. The copolymerization was proven to occur by infra-red spectroscopy (IR) and Nuclear Magnetic Resonance (NMR). Different analyses were performed using different initiators, weight molar and conversion studies. (author)

  2. Polymers with alternating anthracene and phenylene building blocks linked by ethynylene and/or vinylene units: Studying structure-properties-relationships

    Czech Academy of Sciences Publication Activity Database

    Boudiba, S.; Růžička, Aleš; Ulbricht, C.; Enengl, S.; Enengl, C.; Gasiorowski, J.; Yumusak, C.; Pokorná, Veronika; Výprachtický, Drahomír; Hingerl, K.; Zahn, D. R. T.; Tinti, F.; Camaioni, N.; Bouguessa, S.; Gouasmia, A.; Cimrová, Věra; Egbe, D. A. M.

    2017-01-01

    Roč. 55, č. 1 (2017), s. 129-143 ISSN 0887-624X R&D Projects: GA ČR(CZ) GA13-26542S Institutional support: RVO:61389013 Keywords : anthracene building block * charge transport * conjugated polymers Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 2.952, year: 2016

  3. Preparation of pH-sensitive amphiphilic block star polymers, their self-assembling characteristics and release behavior on encapsulated molecules

    KAUST Repository

    Song, Xiaowan

    2016-05-28

    Poly(ethylene glycol) (PEG), a polymer with excellent biocompatibility, was widely used to form nanoparticles for drug delivery applications. In this paper, based on PEG, a series of pH-sensitive amphiphilic block star polymers of poly(ethylene glycol)-block-poly(ethoxy ethyl glycidyl ether) (PEG-b-PEEGE) with different hydrophobic length were synthesized by living anionic ring-opening polymerization method. The products were characterized using 1H NMR and gel permeation chromatography. These copolymers could self-assemble in aqueous solution to form micellar structure with controlled morphologies. Transmission electron microscopy showed that the nanoparticles are spherical or rodlike with different hydrophilic mass fractions. The pH response of polymeric aggregates from PEG-b-PEEGE was detected by fluorescence probe technique at different pH. A pH-dependent release behavior was observed and pH-responsiveness of PEG-b-PEEGE was affected by the hydrophobic block length. These results demonstrated that star-shaped polymers (PEG-b-PEEGE) are attractive candidates as anticancer drug delivery carriers. © 2016 Springer-Verlag Berlin Heidelberg

  4. LET and dose rate effect on radiation-induced copolymerization of maleimide with styrene in 2-propanol solution

    Energy Technology Data Exchange (ETDEWEB)

    Nakagawa, Seiko, E-mail: Nakagawa.Seiko@iri-tokyo.jp [Tokyo Metropolitan Industrial Technology Research Institute, 2-4-10 Aoumi, Koto-ku, Tokyo 135-0064 (Japan); Taguchi, Mitsumasa; Kimura, Atsushi [Environmental Radiation Processing Group, Environment and Industrial Materials Research Division, Quantum Beam Science Directorate, Japan Atomic Energy Agency, 1233 Watanuki, Takasaki, Gunma 370-1292 (Japan)

    2011-11-15

    N{sub 2}-saturated 2-propanol solutions containing styrene and maleimide were irradiated by electron, proton, He and C-ion beams. The styrene-maleimide copolymer was produced by radical polymerization induced during irradiation. The effects of the radical distribution, which depends on the LET or dose rate, on the molecular weight and the polymer yield were discussed. - Highlights: > Maleimide with styrene in N{sub 2}-saturated 2-propanol was irradiated by electron and heavy ions. > LET and dose rate effects of radical polymerization induced by irradiation were studied. > Results have shown the relation between radical distribution and efficiency of polymerization.

  5. Selective nickel-catalyzed conversion of model and lignin-derived phenolic compounds to cyclohexanone-based polymer building blocks.

    Science.gov (United States)

    Schutyser, Wouter; Van den Bosch, Sander; Dijkmans, Jan; Turner, Stuart; Meledina, Maria; Van Tendeloo, Gustaaf; Debecker, Damien P; Sels, Bert F

    2015-05-22

    Valorization of lignin is essential for the economics of future lignocellulosic biorefineries. Lignin is converted into novel polymer building blocks through four steps: catalytic hydroprocessing of softwood to form 4-alkylguaiacols, their conversion into 4-alkylcyclohexanols, followed by dehydrogenation to form cyclohexanones, and Baeyer-Villiger oxidation to give caprolactones. The formation of alkylated cyclohexanols is one of the most difficult steps in the series. A liquid-phase process in the presence of nickel on CeO2 or ZrO2 catalysts is demonstrated herein to give the highest cyclohexanol yields. The catalytic reaction with 4-alkylguaiacols follows two parallel pathways with comparable rates: 1) ring hydrogenation with the formation of the corresponding alkylated 2-methoxycyclohexanol, and 2) demethoxylation to form 4-alkylphenol. Although subsequent phenol to cyclohexanol conversion is fast, the rate is limited for the removal of the methoxy group from 2-methoxycyclohexanol. Overall, this last reaction is the rate-limiting step and requires a sufficient temperature (>250 °C) to overcome the energy barrier. Substrate reactivity (with respect to the type of alkyl chain) and details of the catalyst properties (nickel loading and nickel particle size) on the reaction rates are reported in detail for the Ni/CeO2 catalyst. The best Ni/CeO2 catalyst reaches 4-alkylcyclohexanol yields over 80 %, is even able to convert real softwood-derived guaiacol mixtures and can be reused in subsequent experiments. A proof of principle of the projected cascade conversion of lignocellulose feedstock entirely into caprolactone is demonstrated by using Cu/ZrO2 for the dehydrogenation step to produce the resultant cyclohexanones (≈80 %) and tin-containing beta zeolite to form 4-alkyl-ε-caprolactones in high yields, according to a Baeyer-Villiger-type oxidation with H2 O2 . © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Examining the Self-Assembly of Rod-Coil Block Copolymers via Physics Based Polymer Models and Polarized X-Ray Scattering

    Science.gov (United States)

    Hannon, Adam; Sunday, Daniel; Windover, Donald; Liman, Christopher; Bowen, Alec; Khaira, Gurdaman; de Pablo, Juan; Delongchamp, Dean; Kline, R. Joseph

    Photovoltaics, flexible electronics, and stimuli-responsive materials all require enhanced methodology to examine their nanoscale molecular orientation. The mechanical, electronic, optical, and transport properties of devices made from these materials are all a function of this orientation. The polymer chains in these materials are best modeled as semi-flexible to rigid rods. Characterizing the rigidity and molecular orientation of these polymers non-invasively is currently being pursued by using polarized resonant soft X-ray scattering (P-RSoXS). In this presentation, we show recent work on implementing such a characterization process using a rod-coil block copolymer system in the rigid-rod limit. We first demonstrate how we have used physics based models such as self-consistent field theory (SCFT) in non-polarized RSoXS work to fit scattering profiles for thin film coil-coil PS- b-PMMA block copolymer systems. We then show by using a wormlike chain partition function in the SCFT formulism to model the rigid-rod block, the methodology can be used there as well to extract the molecular orientation of the rod block from a simulated P-RSoXS experiment. The results from the work show the potential of the technique to extract thermodynamic and morphological sample information.

  7. Graft polymerization of styrene onto starch by simultaneous cobalt-60 irradiation

    International Nuclear Information System (INIS)

    Fanta, G.F.; Burr, R.C.; Doane, W.M.; Russell, C.R.

    1977-01-01

    Starch-g-polystyrene copolymers have been prepared by the simultaneous 60 Co irradiation of starch--styrene mixtures, and copolymers have been characterized with respect to weight per cent polystyrene (% add-on) and also the molecular weight and molecular weight distribution of polystyrene grafts. In a typical polymerization, 4g each of starch and styrene were blended with 1 ml water and 1.5 ml of an organic solvent; the resulting semisolid paste was irradiated to a total dose of 1 Mrad. With ethylene glycol, acetonitrile, ethanol, methanol, acetone, and dimethylformamide as the organic solvent, values for % add-on ranged from 24% to 29%. The highest % add-on (43%) and the highest conversion of styrene to grafted polymer (76%) were obtained when the organic solvent was omitted, and water alone was used. When water was also omitted, polymerization of styrene was negligible; however, graft copolymer was formed in the absence of water when either ethylene glycol or ethanol was added. Attempts were unsuccessful to achieve a % add-on greater than 43% by doubling the amount of styrene in the polymerization recipe. Mixtures of equal weights of starch and styrene are relatively nonviscous, but these mixtures thicken when either water or ethylene glycol is blended in. Reasons for this thickening action and the possible influence of thickening on the graft polymerization reaction were explored

  8. Ionomeric membranes based on partially sulfonated poly(styrene) : synthesis, proton conduction and methanol permeation

    NARCIS (Netherlands)

    Picchioni, F.; Tricoli, V.; Carretta, N.

    2000-01-01

    Homogeneuosly sulfonated poly(styrene) (SPS) was prepared with various concentration of sulfonic acid groups in the base polymer. Membranes cast from these materials were investigated in relation to proton conductivity and methanol permeability in the temperature range from 20°C to 60°C. It was

  9. Ionomeric membranes based on partially sulfonated poly(styrene): synthesis, proton conduction and methanol permeation

    NARCIS (Netherlands)

    Carretta, N.; Tricoli, V.; Picchioni, F.

    2000-01-01

    Homogeneuosly sulfonated poly(styrene) (SPS) was prepared with various concentration of sulfonic acid groups in the base polymer. Membranes cast from these materials were investigated in relation to proton conductivity and methanol permeability in the temperature range from 20°C to 60°C. It was

  10. 21 CFR 177.2710 - Styrene-divinylbenzene resins, cross-linked.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Styrene-divinylbenzene resins, cross-linked. 177.2710 Section 177.2710 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) INDIRECT FOOD ADDITIVES: POLYMERS Substances for Use Only as Components of Articles Intended...

  11. 21 CFR 177.1040 - Acrylonitrile/styrene copoly-mer.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Acrylonitrile/styrene copoly-mer. 177.1040 Section 177.1040 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) INDIRECT FOOD ADDITIVES: POLYMERS Substances for Use as Basic Components of Single and Repeated Use Food...

  12. 21 CFR 173.70 - Chloromethylated aminated styrene-divinylbenzene resin.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Chloromethylated aminated styrene-divinylbenzene resin. 173.70 Section 173.70 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) SECONDARY DIRECT FOOD ADDITIVES PERMITTED IN FOOD FOR HUMAN CONSUMPTION Polymer...

  13. Polymer flooding effect of seepage characteristics of the second tertiary combined model of L oilfield block B

    Directory of Open Access Journals (Sweden)

    Huan ZHAO

    2015-06-01

    Full Text Available The second tertiary combined model is applied to develop the second and third type reservoirs which have more oil layer quantity and strong anisotropism, compared to the regular main reservoir with polymer injection, whose seepage characteristics of polymer-injection-after-water-drive shows a remarkable difference, in addition. This development appears to have a larger effect on the remaining oil development and production. Simulating the second tertiary combined model by reservoir numerical simulation under different polymer molecular weight, polymer concentration, polymer injection rate on the polymer injection period, conclusions of the influenced seepage characteristics of original and added perforated interval pressure and water saturation are drawn. The conclusion shows that the polymer molecular weight could influence water saturation of added perforated interval; polymer concentration makes a significant impact on reservoir pressure; polymer injection rate has a great influence on the separate rate of original and added perforated interval. This research provides firm science evidence to the theory of the second tertiary combined model to develop and enhance oil injection-production rate.

  14. Adsorption of copolymers at polymer/air and polymer/solid interfaces

    Science.gov (United States)

    Oslanec, Robert

    Using mainly low-energy forward recoil spectrometry (LE-FRES) and neutron reflectivity (NR), copolymer behavior at polymer/air and polymer/solid interfaces is investigated. For a miscible blend of poly(styrene-ran-acrylonitrile) copolymers, the volume fraction profile of the copolymer with lower acrylonitrile content is flat near the surface in contrast to mean field predictions. Including copolymer polydispersity into a self consistent mean field (SCMF) model does not account for this profile shape. LE-FRES and NR is also used to study poly(deuterated styrene-block-methyl-methacrylate) (dPS-b-PMMA) adsorption from a polymer matrix to a silicon oxide substrate. The interfacial excess, zsp*, layer thickness, L, and layer-matrix width, w, depend strongly on the number of matrix segments, P, for P 2N, the matrix chains are repelled from the adsorbed layer and the layer characteristics become independent of P. An SCMF model of block copolymer adsorption is developed. SCMF predictions are in qualitative agreement with the experimental behavior of zsp*, L, and w as a function of P. Using this model, the interaction energy of the MMA block with the oxide substrate is found to be -8ksb{B}T. In a subsequent experiment, the matrix/dPS interaction is made increasingly unfavorable by increasing the 4-bromostyrene mole fraction, x, in a poly(styrene-ran-4-bromostyrene) (PBrsbxS) matrix. Whereas experiments show that zsp* slightly decreases as x increases, the SCMF model predicts that zsp* should increase as the matrix becomes more unfavorable. Upon including a small matrix attraction for the substrate, the SCMF model shows that zsp* decreases with x because of competition between PBrsbxS and dPS-b-PMMA for adsorbing sites. In thin film dewetting experiments on silicon oxide, the addition of dPS-b-PMMA to PS coatings acts to slow hole growth and prevent holes from impinging. Dewetting studies show that longer dPS-b-PMMA chains are more effective stabilizing agents than shorter

  15. Novel lift-off technique for Transmission Electron Microscopy imaging of block copolymer films

    International Nuclear Information System (INIS)

    Roache, Fergus J.M.; Radjainia, Mazdak; Williams, David E.; Gerrard, Juliet A.; Travas-Sejdic, Jadranka; Malmström, Jenny

    2015-01-01

    We have developed a simple technique to allow for the lift-off and subsequent transfer of poly(styrene-block-ethylene glycol) films to Transmission Electron Microscopy (TEM) grids. The block copolymer is spin coated onto carbon coated mica and annealed. After the thin film is produced it can easily be floated onto water and picked up by a TEM grid. This method offers better control over film processing than dip coating the TEM grid and is also a significant improvement over methods using etchants such as hydrofluoric acid. - Highlights: • We have developed a simple method to lift block copolymer films to TEM grids. • Polymer films prepared on carbon coated mica are easily floated on water. • The new method circumvents the use of harsh chemicals

  16. Radiation-induced polymerization of water-saturated styrene in a wide range of dose rate

    International Nuclear Information System (INIS)

    Takezaki, J.; Okada, T.; Sakurada, I.

    1978-01-01

    Radiation-induced polymerization of water-saturated styrene (water content 3.5 x 10 -2 mole/liter) was carried out in a wide range of dose rate between 1.2 x 10 3 and 1.8 x 10 7 rad/sec, and compared with the polymerization of the moderately dried styrene (water content 3.2 x 10 -3 mole/liter). Molecular weight distribution curves of the polymerization products showed that they were generally consisted of four parts, namely, oligomers, radical, cationic, and super polymers. Contributions of the four constituents to the polymerization and the number average degrees of polymerization (DP) of the four kinds of polymers were calculated by the graphical analysis of the curves. The rate of radical polymerization and DP of radical polymers are independent of the water content; the dose rate dependences of the polymerization rate and DP agree with the well known square root and inverse square root laws, respectively, of the radical polymerization of styrene. The rate of ionic polymerization is directly proportional to the dose rate, but it decreases, at a given dose rate, inversely proportional to the water content of styrene. DP of ionic polymer is independent of the dose rate but decreases with increasing water content. The super polymer of DP about 10 4 is not formed in the case of the moderately dried styrene. G values for the initiating radical and ion formation are calculated to be independently of the dose rate and water content, 0.66 and 0.027, respectively. It was suggested that oligomer was formed in the early stage by the interaction of cation with anion and only those cations which had survived underwent polymerization. 10 figures, 4 tables

  17. Cationic polymerization of styrene by means of pulse radiolysis

    International Nuclear Information System (INIS)

    Egusa, S.; Arai, S.; Kira, A.; Imamura, M.; Tabata, Y.

    1977-01-01

    The radiation-induced cationic polymerization of styrene has been studied by microsecond pulse radiolysis. It was possible to observe absorption bands of a monomer cation radical (St. + ) at 630 nm and at 350 nm in a mixture of isopentane and n-butyl chloride at - 165 0 C. Three absorption bands, around 1600 nm, at 600 nm and at 450 nm, grew in parallel with the decay of St. + after pulse. The 1600-nm and 600-nm bands were assigned to an associated dimer cation radical (St 2 . + ), and the 450-nm band to a bonded dimer cation radical (St-St. + ) by comparison of absorption spectra of α-methylstyrene, 1,2-dihydronaphthalene and trans-β-methylstyrene. The kinetic behaviour of these species suggests that St-St. + and a part of St 2 . + are formed by the reaction of St. + with a styrene monomer, and the rest of St 2 . + may be formed by positive charge transfer from a solvent cation radical to an auto-associated neutral dimer of styrene. A long-lived absorption band at 340 nm grew with the decay of St-St. + . This band is considered due to a growing polymer carbonium ion. (author)

  18. Muonium radicals in benzene-styrene mixtures

    International Nuclear Information System (INIS)

    Ng, B.W.; Stadlbauer, J.W.; Walker, D.C.

    1984-01-01

    Muonium radicals were observed through their μ + SR precession frequencies in high transverse magnetic fields in pure benzene, pure styrene and their mixtures, all as liquids at room temperature. In benzene-styrene mixtures, the radicals obtained in each pure liquid are both present, so no slow (10 -9 -10 -5 s) intermolecular exchange occurs; but strong selectivity was found with the formation of the radical from styrene being about eight-times more probable than the radical from benzene. (Auth.)

  19. Block Copolymers: Synthesis and Applications in Nanotechnology

    Science.gov (United States)

    Lou, Qin

    This study is focused on the synthesis and study of (block) copolymers using reversible deactivation radical polymerizations (RDRPs), including atom transfer radical polymerization (ATRP) and reversible addition-fragmentation chain transfer (RAFT) polymerization. In particular, two primary areas of study are undertaken: (1) a proof-of-concept application of lithographic block copolymers, and (2) the mechanistic study of the deposition of titania into block copolymer templates for the production of well-ordered titania nanostructures. Block copolymers have the ability to undergo microphase separation, with an average size of each microphase ranging from tens to hundreds of nanometers. As such, block copolymers have been widely considered for nanotechnological applications over the past two decades. The development of materials for various nanotechnologies has become an increasingly studied area as improvements in many applications, such as those found in the semiconductor and photovoltaic industries are constantly being sought. Significant growth in developments of new synthetic methods ( i.e. RDRPs) has allowed the production of block copolymers with molecular (and sometimes atomic) definition. In turn, this has greatly expanded the use of block copolymers in nanotechnology. Herein, we describe the synthesis of statistical and block copolymers of 193 nm photolithography methacrylate and acrylate resist monomers with norbornyl and adamantyl moieties using RAFT polymerization.. For these resist (block) copolymers, the phase separation behaviors were examined by atomic force microscopy (AFM). End groups were removed from the polymers to avoid complications during the photolithography since RAFT end groups absorb visible light. Poly(glycidyl methacrylate-block-polystyrene) (PGMA-b-PS) was synthesize by ATRP and demonstrated that this block copolymer acts as both a lithographic UV (365 nm) photoresist and a self-assembly material. The PGMA segments can undergo cationic

  20. Nanoporous capsules of block co-polymers of [(MeO-PEG-NH)-b-(L-GluA)]-PCL for the controlled release of anticancer drugs for therapeutic applications

    Science.gov (United States)

    Amgoth, Chander; Dharmapuri, Gangappa; Kalle, Arunasree M.; Paik, Pradip

    2016-03-01

    Herein, new nanoporous capsules of the block co-polymers of MeO-PEG-NH-(L-GluA)10 and polycaprolactone (PCL) have been synthesized through a surfactant-free cost-effective self-assembled soft-templating approach for the controlled release of drugs and for therapeutic applications. The nanoporous polymer capsules are designed to be biocompatible and are capable of encapsulating anticancer drugs (e.g., doxorubicin hydrochloride (DOX) and imatinib mesylate (ITM)) with a high extent (˜279 and ˜480 ng μg-1, respectively). We have developed a nanoformulation of porous MeO-PEG-NH-(L-GluA)10-PCL capsules with DOX and ITM. The porous polymer nanoformulations have been programmed in terms of the release of anticancer drugs with a desired dose to treat the leukemia (K562) and human carcinoma cells (HepG2) in vitro and show promising IC50 values with a very high mortality of cancer cells (up to ˜96.6%). Our nanoformulation arrests the cell divisions due to ‘cellular scenescence’ and kills the cancer cells specifically. The present findings could enrich the effectiveness of idiosyncratic nanoporous polymer capsules for use in various other nanomedicinal and biomedical applications, such as for killing cancer cells, immune therapy, and gene delivery.

  1. Nanoporous capsules of block co-polymers of [(MeO-PEG-NH)-b-(L-GluA)]-PCL for the controlled release of anticancer drugs for therapeutic applications

    International Nuclear Information System (INIS)

    Amgoth, Chander; Paik, Pradip; Dharmapuri, Gangappa; Kalle, Arunasree M

    2016-01-01

    Herein, new nanoporous capsules of the block co-polymers of MeO-PEG-NH-(L-GluA) 10 and polycaprolactone (PCL) have been synthesized through a surfactant-free cost-effective self-assembled soft-templating approach for the controlled release of drugs and for therapeutic applications. The nanoporous polymer capsules are designed to be biocompatible and are capable of encapsulating anticancer drugs (e.g., doxorubicin hydrochloride (DOX) and imatinib mesylate (ITM)) with a high extent (∼279 and ∼480 ng μg −1 , respectively). We have developed a nanoformulation of porous MeO-PEG-NH-(L-GluA) 10 -PCL capsules with DOX and ITM. The porous polymer nanoformulations have been programmed in terms of the release of anticancer drugs with a desired dose to treat the leukemia (K562) and human carcinoma cells (HepG2) in vitro and show promising IC 50 values with a very high mortality of cancer cells (up to ∼96.6%). Our nanoformulation arrests the cell divisions due to ‘cellular scenescence’ and kills the cancer cells specifically. The present findings could enrich the effectiveness of idiosyncratic nanoporous polymer capsules for use in various other nanomedicinal and biomedical applications, such as for killing cancer cells, immune therapy, and gene delivery. (paper)

  2. Variation of long periodicity in blends of styrene butadiene, styrene ...

    Indian Academy of Sciences (India)

    relationship between long periodicity and concentration of blends. These parameters are ... tential customers for conducting polymers [10]. 2. ... Theory. The linear paracrystalline model of polymer morphology of blends comprises stacks.

  3. Well-defined single-chain polymer nanoparticles via thiol-Michael addition

    NARCIS (Netherlands)

    Kröger, A. Pia P.; Boonen, Roy J.E.A.; Paulusse, Jos M.J.

    2017-01-01

    A synthetic strategy has been developed giving facile access to well-defined single-chain polymer nanoparticles (SCNPs) from styrene-, acrylate- and methacrylate-based polymers. Random copolymers (polydispersity indices 1.10–1.15) of methyl (meth)acrylate, benzyl methacrylate or styrene containing

  4. Designing dual phase sensing materials from polyaniline filled styrene–isoprene–styrene composites

    International Nuclear Information System (INIS)

    Sadasivuni, Kishor Kumar; Ponnamma, Deepalekshmi; Kasak, Peter; Krupa, Igor; Ali S A Al-Maadeed, Mariam

    2014-01-01

    The demand for developing oil detectors is ever increasing since the cleanup and recovery from oil spill usually take long time. Here we propose oil sensors made of polyaniline (PANI) filled poly(styrene–isoprene–styrene) (SIS) block copolymer composite films with good uniformity and dispersion. The changes in resistivity of the samples in presence of both oil and water media reveal the good sensing ability of SIS–PANI films towards oil in water (dual phase). The morphology and chemical composition of the developed products are characterized by scanning electron microscopy and Fourier transformation infrared spectroscopy. Swelling studies are performed to correlate the sensing response to the structural variations and based on it a mechanism is derived for the dual phase sensing. Contact angle measurements confirm the behavior further. The thermal properties and crystallinity of the composites are also addressed by the thermogravimetric and differential scanning calorimetric studies. The developed oil sensor material is able to withstand extreme temperature condition as well. - Highlights: • We model a dual phase sensor capable of detecting oil in water. • A mechanism is proposed to correlate sensing with diffusion. • In situ polymerization helps in the uniform distribution of filler. • Polymer composite sensor could be used as stickers on oil pipelines

  5. Designing dual phase sensing materials from polyaniline filled styrene–isoprene–styrene composites

    Energy Technology Data Exchange (ETDEWEB)

    Sadasivuni, Kishor Kumar, E-mail: kishor_kumars@yahoo.com [Centre for Advanced Materials, Qatar University, Doha (Qatar); Ponnamma, Deepalekshmi [School of Chemical Sciences, Mahatma Gandhi University, Kottayam 686560, Kerala (India); Kasak, Peter; Krupa, Igor; Ali S A Al-Maadeed, Mariam [Centre for Advanced Materials, Qatar University, Doha (Qatar)

    2014-10-15

    The demand for developing oil detectors is ever increasing since the cleanup and recovery from oil spill usually take long time. Here we propose oil sensors made of polyaniline (PANI) filled poly(styrene–isoprene–styrene) (SIS) block copolymer composite films with good uniformity and dispersion. The changes in resistivity of the samples in presence of both oil and water media reveal the good sensing ability of SIS–PANI films towards oil in water (dual phase). The morphology and chemical composition of the developed products are characterized by scanning electron microscopy and Fourier transformation infrared spectroscopy. Swelling studies are performed to correlate the sensing response to the structural variations and based on it a mechanism is derived for the dual phase sensing. Contact angle measurements confirm the behavior further. The thermal properties and crystallinity of the composites are also addressed by the thermogravimetric and differential scanning calorimetric studies. The developed oil sensor material is able to withstand extreme temperature condition as well. - Highlights: • We model a dual phase sensor capable of detecting oil in water. • A mechanism is proposed to correlate sensing with diffusion. • In situ polymerization helps in the uniform distribution of filler. • Polymer composite sensor could be used as stickers on oil pipelines.

  6. Polyfunctional monomers as additives for enhancing the radiation copolymerization of styrene with polyethylene, polypropylene, and PVC

    International Nuclear Information System (INIS)

    Ang, C.H.; Garnett, J.L.; Levot, R.; Long, M.A.

    1982-01-01

    Additives which can increase the yield in the radiation grafting of monomers to polymers are useful. The use of polyfunctional monomers as additives (approx. = 1% v/v) are shown to enhance significantly the copolymerization yields of styrene in methanol to films of polyethylene and polypropylene under certain radiation conditions. The results obtained when the polyolefins are replaced by PVC as backbone polymer in these accelerated grafting reactions are reported. Divinylbenzene (DVB) and trimethylolpropane triacrylate (TMPTA) were used as representative polyfunctional monomers for the enhancement effect. When polypropylene was used as backbone polymer, the inclusion of DVB significantly enhanced the radiation grafting of styrene in methanol at all monomer concentrations studied above 35%. At certain monomer concentrations (50% , 60%), the yield of graft copolymer was almost doubled by the addition of DVB. 3 tables. (DP)

  7. Ionic polymerization of p-methoxystyrene and other styrene derivatives by radiation. [Gamma radiation

    Energy Technology Data Exchange (ETDEWEB)

    Hayashi, K; Pepper, D C [Trinity Coll., Dublin (Ireland)

    1976-01-01

    Polymerization of p-methoxystyrene by radiation was studied in bulk. Upon drying the monomer, the rate of polymerization, Rsub(p), became greater, changing its dose rate dependence from 0.5 to 1. The molecular weight distribution of the obtained polymers failed to give a bimodal curve; however, the peak molecular weight increased with higher Rsub(p). These kinetic features can be explained by a coexistence of radical and cationic mechanisms, as has been established in styrene, though there remain ambiguities about the effects of additives. Copolymerizations with styrene and 2-chloroethyl vinyl ether also showed a cationic nature for the reaction. A survey of possibilities of ionic polymerization by radiation was also carried out in ten ring-substituted styrene derivatives.

  8. Energy efficiency analysis of styrene production by adiabatic ethylbenzene dehydrogenation using exergy analysis and heat integration

    Directory of Open Access Journals (Sweden)

    Ali Emad

    2018-03-01

    Full Text Available Styrene is a valuable commodity for polymer industries. The main route for producing styrene by dehydrogenation of ethylbenzene consumes a substantial amount of energy because of the use of high-temperature steam. In this work, the process energy requirements and recovery are studied using Exergy analysis and Heat Integration (HI based on Pinch design method. The amount of steam plays a key role in the trade-off between Styrene yield and energy savings. Therefore, optimizing the operating conditions for energy reduction is infeasible. Heat integration indicated an insignificant reduction in the net energy demand and exergy losses, but 24% and 34% saving in external heating and cooling duties, respectively. When the required steam is generated by recovering the heat of the hot reactor effluent, a considerable saving in the net energy demand, as well as the heating and cooling utilities, can be achieved. Moreover, around 68% reduction in the exergy destruction is observed.

  9. Final Technical Report - Autothermal Styrene Manufacturing Process with Net Export of Energy

    Energy Technology Data Exchange (ETDEWEB)

    Trubac, Robert , E.; Lin, Feng; Ghosh, Ruma: Greene, Marvin

    2011-11-29

    The overall objectives of the project were to: (a) develop an economically competitive processing technology for styrene monomer (SM) that would reduce process energy requirements by a minimum 25% relative to those of conventional technology while achieving a minimum 10% ROI; and (b) advance the technology towards commercial readiness. This technology is referred to as OMT (Oxymethylation of Toluene). The unique energy savings feature of the OMT technology would be replacement of the conventional benzene and ethylene feedstocks with toluene, methane in natural gas and air or oxygen, the latter of which have much lower specific energy of production values. As an oxidative technology, OMT is a net energy exporter rather than a net energy consumer like the conventional ethylbenzene/styrene (EB/SM) process. OMT plants would ultimately reduce the cost of styrene monomer which in turn will decrease the costs of polystyrene making it perhaps more cost competitive with competing polymers such as polypropylene.

  10. X-ray structure determination of new monomers to establish their polymerizability: copolymerization of two tetrasubstituted electrophilic olefins with electron-rich styrenes giving polymers with an average 1.25 functional groups per chain carbon atom

    International Nuclear Information System (INIS)

    Hall, H.K. Jr.; Reineke, K.E.; Ried, J.H.; Sentman, R.C.; Miller, D.

    1982-01-01

    X-ray crystal structure determination for two tetrasubstituted electrophilic olefins, tetramethyl ethylenetetracarboxylate TMET and dimethyl dicyanofumarate DDCF, revealed two fundamentally different molecular structures. TMET is a nonplanar molecule that possesses two opposite ester groups planar and the others above and below the molecular plane. In contrast, DDCF is a molecule for which both ester groups lie in the plane of the double bond and nitrile groups. DDCF underwent thermal spontaneous copolymerization with electron-rich styrenes to give 1:1 alternating copolymers in moderate yields and molecular weights. These copolymers, which result from the first copolymerization of a tetrasubstituted olefin, possess an average functionality of 1.25 per chain carbon atom. Polymerization is made possible by low steric hindrance and the high delocalization in the propagating radical. The yields were limited by competing cycloaddition reaction. The corresponding diethyl ester also copolymerized, but not so well. Neither electrophilic olefin homopolymerized under γ-irradiation. TMET did not copolymerize at all when treated under identical conditions

  11. Helbredsrisici ved eksponering for styren i glasfiberplastindustrien

    DEFF Research Database (Denmark)

    Kolstad, Henrik Albert; Ebbehøj, Nielse; Bonde, Jens Peter

    2012-01-01

    or relevant exposure levels. We recommend reconsideration of the current Danish threshold limit value of 25 ppm, biological monitoring of styrene exposed workers, and epidemiological analyses of styrene exposure levels and long-term health effects among employees of the Danish reinforced plastics industry....

  12. Exposure to styrene and chronic health effects

    DEFF Research Database (Denmark)

    Kolstad, Henrik; Juel, K; Olsen, J H

    1995-01-01

    To study the occurrence of non-malignant diseases and solid cancers in workers exposed to styrene in the Danish reinforced plastics industry.......To study the occurrence of non-malignant diseases and solid cancers in workers exposed to styrene in the Danish reinforced plastics industry....

  13. Electrically and chemically tunable soft-solid block copolymer structural color (Conference Presentation)

    Science.gov (United States)

    Park, Cheolmin

    2016-09-01

    1D photonic crystals based on the periodic stacking of two different dielectric layers have been widely studied due to their potential use in low-power reflective mode displays, e-books and sensors, but the fabrication of mechanically flexible polymer structural color (SC) films, with electro-active color switching, remains challenging. Here, we demonstrate free-standing electric field tunable ionic liquid swollen block copolymer films. Placement of a polymer/ionic liquid (IL) film-reservoir adjacent to a self-assembled poly(styrene-block-quaternized 2vinyl pyridine) (PS-b-QP2VP) copolymer SC film allowed the development of R, G and B full-color SC block copolymer films by swelling of the QP2VP domains by the ionic liquid associated with water molecules. The IL-polymer/BCP SC film is mechanically flexible with excellent color stability over several days at ambient conditions. The selective swelling of the QP2VP domains could be controlled by both the ratio of the IL to a polymer in the gel-like IL reservoir layer and by an applied voltage in the range of -3V to +6V using a metal/IL reservoir/SC film/IL reservoir/metal capacitor type device.

  14. Dielectric study of Poly(styrene- co -butadiene) Composites with Carbon Black, Silica, and Nanoclay

    KAUST Repository

    Vo, Loan T.

    2011-08-09

    Dielectric spectroscopy is used to measure polymer relaxation in styrene-butadiene rubber (SBR) composites. In addition to the bulk polymer relaxation, the SBR nanocomposites also exhibit a slower relaxation attributed to polymer relaxation at the polymer-nanoparticle interface. The glass transition temperature associated with the slower relaxation is used as a way to quantify the interaction strength between the polymer and the surface. Comparisons were made among composites containing nanoclay, silica, and carbon black. The interfacial relaxation glass transition temperature of SBR-clay nanocomposites is more than 80 °C higher than the SBR bulk glass transition temperature. An interfacial mode was also observed for SBR-silica nanocomposites, but the interfacial glass transition temperature of SBR-silica nanocomposite is somewhat lower than that of clay nanocomposites. An interfacial mode is also seen in the carbon black filled system, but the signal is too weak to analyze quantitatively. The interfacial polymer relaxation in SBR-clay nanocomposites is stronger compared to both SBR-carbon black and SBR-silica composites indicating a stronger interfacial interaction in the nanocomposites containing clay. These results are consistent with dynamic shear rheology and dynamic mechanical analysis measurements showing a more pronounced reinforcement for the clay nanocomposites. Comparisons were also made among clay nanocomposites using different SBRs of varying styrene concentration and architecture. The interfacial glass transition temperature of SBR-clay nanocomposites increases as the amount of styrene in SBR increases indicating that styrene interacts more strongly than butadiene with clay. © 2011 American Chemical Society.

  15. Highly conductive side chain block copolymer anion exchange membranes.

    Science.gov (United States)

    Wang, Lizhu; Hickner, Michael A

    2016-06-28

    Block copolymers based on poly(styrene) having pendent trimethyl styrenylbutyl ammonium (with four carbon ring-ionic group alkyl linkers) or benzyltrimethyl ammonium groups with a methylene bridge between the ring and ionic group were synthesized by reversible addition-fragmentation radical (RAFT) polymerization as anion exchange membranes (AEMs). The C4 side chain polymer showed a 17% increase in Cl(-) conductivity of 33.7 mS cm(-1) compared to the benzyltrimethyl ammonium sample (28.9 mS cm(-1)) under the same conditions (IEC = 3.20 meq. g(-1), hydration number, λ = ∼7.0, cast from DMF/1-propanol (v/v = 3 : 1), relative humidity = 95%). As confirmed by small angle X-ray scattering (SAXS), the side chain block copolymers with tethered ammonium cations showed well-defined lamellar morphologies and a significant reduction in interdomain spacing compared to benzyltrimethyl ammonium containing block copolymers. The chemical stabilities of the block copolymers were evaluated under severe, accelerated conditions, and degradation was observed by (1)H NMR. The block copolymer with C4 side chain trimethyl styrenylbutyl ammonium motifs displayed slightly improved stability compared to that of a benzyltrimethyl ammonium-based AEM at 80 °C in 1 M NaOD aqueous solution for 30 days.

  16. Helbredsrisici ved eksponering for styren i glasfiberplastindustrien

    DEFF Research Database (Denmark)

    Kolstad, Henrik Albert; Ebbehøj, Nielse; Bonde, Jens Peter

    2012-01-01

    or relevant exposure levels. We recommend reconsideration of the current Danish threshold limit value of 25 ppm, biological monitoring of styrene exposed workers, and epidemiological analyses of styrene exposure levels and long-term health effects among employees of the Danish reinforced plastics industry.......This is a summary of the health risks of occupational styrene exposure based on recent reviews. We conclude about the exposure levels that there is strong evidence that styrene causes acute irritation of eyes and respiratory tract above 25 ppm, genotoxic effects above 10 ppm, and persistent nervous...... system effects with for instance reduced psychological performance, colour discrimination and hearing level following long-term styrene exposure above 10 ppm. There is moderate evidence of a causal association with cancer, but data are not sufficient to allow us to pinpoint specific cancers at risk...

  17. Designing block copolymer architectures for targeted membrane performance

    KAUST Repository

    Dorin, Rachel Mika

    2014-01-01

    Using a combination of block copolymer self-assembly and non-solvent induced phase separation, isoporous ultrafiltration membranes were fabricated from four poly(isoprene-b-styrene-b-4-vinylpyridine) triblock terpolymers with similar block volume fractions but varying in total molar mass from 43 kg/mol to 115 kg/mol to systematically study the effect of polymer size on membrane structure. Small-angle X-ray scattering was used to probe terpolymer solution structure in the dope. All four triblocks displayed solution scattering patterns consistent with a body-centered cubic morphology. After membrane formation, structures were characterized using a combination of scanning electron microscopy and filtration performance tests. Membrane pore densities that ranged from 4.53 × 1014 to 1.48 × 1015 pores/m 2 were observed, which are the highest pore densities yet reported for membranes using self-assembly and non-solvent induced phase separation. Hydraulic permeabilities ranging from 24 to 850 L m-2 h-1 bar-1 and pore diameters ranging from 7 to 36 nm were determined from permeation and rejection experiments. Both the hydraulic permeability and pore size increased with increasing molar mass of the parent terpolymer. The combination of polymer characterization and membrane transport tests described here demonstrates the ability to rationally design macromolecular structures to target specific performance characteristics in block copolymer derived ultrafiltration membranes. © 2013 Elsevier Ltd. All rights reserved.

  18. Synthesis and controlled self-assembly of UV-responsive gold nanoparticles in block copolymer templates.

    Science.gov (United States)

    Song, Dong-Po; Wang, Xinyu; Lin, Ying; Watkins, James J

    2014-11-06

    We demonstrate the facile synthesis of gold nanoparticles (GNPs) functionalized by UV-responsive block copolymer ligands, poly(styrene)-b-poly(o-nitrobenzene acrylate)-SH (PS-b-PNBA-SH), followed by their targeted distribution within a lamellae-forming poly(styrene)-b-poly(2-vinylpyridine) (PS-b-P2VP) block copolymer. The multilayer, micelle-like structure of the GNPs consists of a gold core, an inner PNBA layer, and an outer PS layer. The UV-sensitive PNBA segment can be deprotected into a layer containing poly(acrylic acid) (PAA) when exposed to UV light at 365 nm, which enables the simple and precise tuning of GNP surface properties from hydrophobic to amphiphilic. The GNPs bearing ligands of different chemical compositions were successfully and selectively incorporated into the PS-b-P2VP block copolymer, and UV light showed a profound influence on the spatial distributions of GNPs. Prior to UV exposure, GNPs partition along the interfaces of PS and P2VP domains, while the UV-treated GNPs are incorporated into P2VP domains as a result of hydrogen bond interactions between PAA on the gold surface and P2VP domains. This provides an easy way of controlling the arrangement of nanoparticles in polymer matrices by tailoring the nanoparticle surface using UV light.

  19. Styrene-butadiene-styrene copolymer compatibilized carbon black/polypropylene/polystyrene composites with tunable morphology, electrical conduction and rheological stabilities.

    Science.gov (United States)

    Song, Yihu; Xu, Chunfeng; Zheng, Qiang

    2014-04-21

    We report a facile kinetic strategy in combination with styrene-butadiene-styrene (SBS) copolymer compatibilizers for preparing carbon black (CB) filled immiscible polypropylene (PP)/polystyrene (PS) (1/1) blends with finely tuned morphologies and show the important role of location and migration of CB nanoparticles in determining the electrical conductivity and rheological behaviour of the composites. A novel method of mixing a SBS/CB (5/3) masterbatch with the polymers allowed producing composites with CB aggregates dispersed partially in the unfavorable PP phase and partially in the PP side of the interface to exhibit diverse phase connectivity and electrical conductivity depending on the compounding sequences. A cocontinuous morphology with CB enrichment along the interface was formed in the composite prepared by mixing the SBS/CB masterbatch with the premixed PP/PS blend, giving rise to a highest electrical conductivity and dynamic moduli at low frequencies. On the other hand, mixing the masterbatch with one and then with another polymer yielded droplet (PS)-in-matrix (filled PP) composites. The composites underwent phase coalescence and CB redistribution accompanied by marked dynamic electrical conduction and modulus percolations as a function of time during thermal annealing at 180 °C. The composites with the initial droplet-in-matrix morphology progressed anomalously into the cocontinuous morphology, reflecting a common mechanism being fairly nonspecific for understanding the processing of filled multicomponent composites with tailored performances of general concern.

  20. Polymer Thin Film Stabilization.

    Science.gov (United States)

    Costa, A. C.; Oslanec, R.; Composto, R. J.; Vlcek, P.

    1998-03-01

    We study the dewetting dynamics of thin polystyrene (PS) films deposited on silicon oxide surfaces using optical (OM) and atomic force (AFM) microscopes. Quantitative analysis of the hole diameter as a function of annealing time at 175^oC shows that blending poly(styrene-block-methyl-methacrylate) (PS-b-PMMA) with PS acts to dramatically slow down the dewetting rate and even stops holes growth before they impinge. AFM studies show that the hole floor is smooth for a pure PS film but contains residual polymer for the blend. At 5% vol., a PS-b-PMMA with high molar mass and low PMMA is a more effective stabilizing agent than a low molar mass/high PMMA additive. The optimum copolymer concentration is 3% vol. beyond which film stability doesn't improve. Although dewetting is slowed down relative to pure PS, PS/PS-b-PMMA bilayers dewet at a faster rate than blends having the same overall additive concentration.

  1. Structural studies of three-arm star block copolymers exposed to extreme stretch suggests persistent polymer tube

    DEFF Research Database (Denmark)

    Garvey, Christopher J.; Almdal, Kristoffer; Dorokhin, Andriy

    2018-01-01

    We present structural SANS-studies of a three-armed polystyrene star polymer with short deuterated segments at the end of each arm. We show that the form factor of the three-armed star molecules in the relaxed state agrees with that of the random phase approximation of Gaussian chains. Upon...

  2. Controlling Styrene Maleic Acid Lipid Particles through RAFT.

    Science.gov (United States)

    Smith, Anton A A; Autzen, Henriette E; Laursen, Tomas; Wu, Vincent; Yen, Max; Hall, Aaron; Hansen, Scott D; Cheng, Yifan; Xu, Ting

    2017-11-13

    The ability of styrene maleic acid copolymers to dissolve lipid membranes into nanosized lipid particles is a facile method of obtaining membrane proteins in solubilized lipid discs while conserving part of their native lipid environment. While the currently used copolymers can readily extract membrane proteins in native nanodiscs, their highly disperse composition is likely to influence the dispersity of the discs as well as the extraction efficiency. In this study, reversible addition-fragmentation chain transfer was used to control the polymer architecture and dispersity of molecular weights with a high-precision. Based on Monte Carlo simulations of the polymerizations, the monomer composition was predicted and allowed a structure-function analysis of the polymer architecture, in relation to their ability to assemble into lipid nanoparticles. We show that a higher degree of control of the polymer architecture generates more homogeneous samples. We hypothesize that low dispersity copolymers, with control of polymer architecture are an ideal framework for the rational design of polymers for customized isolation and characterization of integral membrane proteins in native lipid bilayer systems.

  3. Study of the Influence of adding styrene-ethylene/butadiene-styrene in acrylonitrile-butadiene-styrene and polyethylene blends

    OpenAIRE

    Peydro, M. A.; Parres, F.; Navarro Vidal, Raúl; Sanchez-Caballero, Samuel

    2014-01-01

    This work studies the recovery of two grades of acrylonitrile butadiene styrene (ABS) contaminated with low-density polyethylene (LDPE), by adding styrene ethylene/butadiene styrene (SEBS). To simulate contaminated ABS, virgin ABS was mixed with 1, 2, 4, and 8% of LDPE and then extruded at 220°C. After this, the ABS with the highest percentage of LDPE (8%) was mixed with 1, 2, 4, and 8% of SEBS and then extruded. Different blends were mechanically, rheologically, optically, and dimensionally ...

  4. Effect of plasticiser on properties of styrene-butadiene-styrene thermoplastic elastomers

    International Nuclear Information System (INIS)

    Norzalia, S.; Farid, A.S.; O'Brien, M.G.

    1999-01-01

    This study investigates the properties of plasticised styrene-butadiene-styrene thermoplastic elastomers for possible applications in pharmaceutical, medical and food industries. Unplasticised styrene-butadiene-styrene (USBS) materials: vector 8550-D and vector 4461-D, which are developmental materials introduced by Exxon, and blends of vector 8550-D with vector 4461-D were plasticised paraffinic type plasticisers plastol 172 and plastol 352. Shore A hardness, tensile stress at break, modulus at 100% strain, elongation at break and density values showed a decrease whereas flow properties such as melt flow index (MFI) increased considerably with increasing plasticiser concentration. The properties of the plasticised styrene-butadiene-styrene thermoplastic elastomers were compared to the USBS materials. (author)

  5. Structural Studies of Three-Arm Star Block Copolymers Exposed to Extreme Stretch Suggests a Persistent Polymer Tube

    Science.gov (United States)

    Mortensen, Kell; Borger, Anine L.; Kirkensgaard, Jacob J. K.; Garvey, Christopher J.; Almdal, Kristoffer; Dorokhin, Andriy; Huang, Qian; Hassager, Ole

    2018-05-01

    We present structural small-angle neutron scattering studies of a three-armed polystyrene star polymer with short deuterated segments at the end of each arm. We show that the form factor of the three-armed star molecules in the relaxed state agrees with that of the random phase approximation of Gaussian chains. Upon exposure to large extensional flow conditions, the star polymers change conformation resulting in a highly stretched structure that mimics a fully extended three-armed tube model. All three arms are parallel to the flow, one arm being either in positive or negative stretching direction, while the two other arms are oriented parallel, right next to each other in the direction opposite to the first arm.

  6. Design and Synthesis of Network-Forming Triblock Copolymers Using Tapered Block Interfaces

    OpenAIRE

    Kuan, Wei-Fan; Roy, Raghunath; Rong, Lixia; Hsiao, Benjamin S.; Epps, Thomas H.

    2012-01-01

    We report a strategy for generating novel dual-tapered poly(isoprene-b-isoprene/styrene-b-styrene-b-styrene/methyl methacrylate-b-methyl methacrylate) [P(I-IS-S-SM-M)] triblock copolymers that combines anionic polymerization, atom transfer radical polymerization (ATRP), and Huisgen 1,3-dipolar cycloaddition click chemistry. The tapered interfaces between blocks were synthesized via a semi-batch feed using programmable syringe pumps. This strategy allows us to manipulate the transition region ...

  7. A controlled release system for proteins based on poly(ether ester) block-copolymers: polymer network characterization

    NARCIS (Netherlands)

    Bezemer, J.M.; Grijpma, Dirk W.; Dijkstra, Pieter J.; van Blitterswijk, Clemens; Feijen, Jan

    1999-01-01

    The properties of a series of multiblock copolymers, based on hydrophilic poly(ethylene glycol) (PEG) and hydrophobic poly(butylene terephthalate) (PBT) blocks were investigated with respect to their application as a matrix for controlled release of proteins. The degree of swelling, Q, of the

  8. Asymmetric PS-block-(PS-co-PB)-block-PS block copolymers: morphology formation and deformation behaviour

    International Nuclear Information System (INIS)

    Adhikari, Rameshwar; Huy, Trinh An; Buschnakowski, Matthias; Michler, Goerg H; Knoll, Konrad

    2004-01-01

    Morphology formation and deformation behaviour of asymmetric styrene/butadiene triblock copolymers (total polystyrene (PS) content ∼70%) consisting of PS outer blocks held apart by a styrene-co-butadiene random copolymer block (PS-co-PB) each were investigated. The techniques used were differential scanning calorimetry, transmission electron microscopy, uniaxial tensile testing and Fourier-transform infrared spectroscopy. A significant shift of the phase behaviour relative to that of a neat symmetric triblock copolymer was observed, which can be attributed to the asymmetric architecture and the presence of PS-co-PB as a soft block. The mechanical properties and the microdeformation phenomena were mainly controlled by the nature of their solid-state morphology. Independent of morphology type, the soft phase was found to deform to a significantly higher degree of orientation when compared with the hard phase

  9. Nanostructured poly(styrene-b-butadiene-b-styrene) (SBS) membranes for the separation of nitrogen from natural gas

    Energy Technology Data Exchange (ETDEWEB)

    Buonomenna, Maria Giovanna; Golemme, Giovanni [Department of Chemical Engineering and Materials, University of Calabria, and Consorzio INSTM, Rende (Italy); Tone, Caterina Maria; De Santo, Maria Penelope; Ciuchi, Federica [IPCF-CNR UOS Cosenza, c/o Physics Department, University of Calabria, Rende (Italy); Perrotta, Enrico [Department of Ecology, University of Calabria, Rende (Italy)

    2012-04-24

    The preparation and characterization of new, tailor-made polymeric membranes using poly(styrene-b-butadiene-b-styrene) (SBS) triblock copolymers for gas separation are reported. Structural differences in the copolymer membranes, obtained by manipulation of the self-assembly of the block copolymers in solution, are characterized using atomic force microscopy, transmission electron microscopy, and the transport properties of three gases (CO{sub 2}, N{sub 2}, and CH{sub 4}). The CH{sub 4}/N{sub 2} ideal selectivity of 7.2, the highest value ever reported for block copolymers, with CH{sub 4} permeability of 41 Barrer, is obtained with a membrane containing the higher amount of polybutadiene (79 wt%) and characterized by a hexagonal array of columnar polystyrene cylinders normal to the membrane surface. Membranes with such a high separation factor are able to ease the exploitation of natural gas with high N{sub 2} content. The CO{sub 2}/N{sub 2} ideal selectivity of 50, coupled with a CO{sub 2} permeability of 289 Barrer, makes SBS a good candidate for the preparation of membranes for the post-combustion capture of carbon dioxide. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  10. In situ NMR and modeling studies of nitroxide mediated copolymerization of styrene and n-butyl acrylate

    NARCIS (Netherlands)

    Hlalele, L.; Klumperman, L.

    2011-01-01

    The combination of in situ1H NMR and in situ31P NMR was used to study the nitroxide mediated copolymerization of styrene and n-butyl acrylate. The alkoxyamine MAMA-DEPN was employed to initiate and mediate the copolymerization. The nature of the ultimate/terminal monomer units of dormant polymer

  11. 21 CFR 177.1635 - Poly(p-methylstyrene) and rubber-modified poly(p-methyl-styrene).

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Poly(p-methylstyrene) and rubber-modified poly(p-methyl-styrene). 177.1635 Section 177.1635 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) INDIRECT FOOD ADDITIVES: POLYMERS Substances for Use as Basic Components...

  12. Compatibilization of low-density polyethylene/polystyrene blends by segmented EB(PS-block-EB)(n) block copolymers

    NARCIS (Netherlands)

    Kroeze, E; ten Brinke, G.; Hadziioannou, G

    Hydrogenated segmented poly[butadiene-block-(styrene-block-butadiene)(n)] block copolymers, which were developed by use of a polymeric iniferter technique, were tested on their compatibilizing effectiveness for (10/90) LDPE/PS blends. They were found to be effective compatibilizers for this mixture,

  13. Polymer Coatings of Cochlear Implant Electrode Surface - An Option for Improving Electrode-Nerve-Interface by Blocking Fibroblast Overgrowth.

    Directory of Open Access Journals (Sweden)

    C Hadler

    Full Text Available Overgrowth of connective tissue and scar formation induced by the electrode array insertion increase the impedance and, thus, diminish the interactions between neural probes as like cochlear implants (CI and the target tissue. Therefore, it is of great clinical interest to modify the carrier material of the electrodes to improve the electrode nerve interface for selective cell adhesion. On one side connective tissue growth needs to be reduced to avoid electrode array encapsulation, on the other side the carrier material should not compromise the interaction with neuronal cells. The present in vitro-study qualitatively and quantitatively characterises the interaction of fibroblasts, glial cells and spiral ganglion neurons (SGN with ultrathin poly(N,N-dimethylacrylamide (PDMAA, poly(2-ethyloxazoline (PEtOx and poly([2-methacryloyloxyethyl]trimethylammoniumchlorid (PMTA films immobilised onto glass surfaces using a photoreactive anchor layer. The layer thickness and hydrophilicity of the polymer films were characterised by ellipsometric and water contact angle measurement. Moreover the topography of the surfaces was investigated using atomic force microscopy (AFM. The neuronal and non-neuronal cells were dissociated from spiral ganglions of postnatal rats and cultivated for 48 h on top of the polymer coatings. Immunocytochemical staining of neuronal and intermediary filaments revealed that glial cells predominantly attached on PMTA films, but not on PDMAA and PEtOx monolayers. Hereby, strong survival rates and neurite outgrowth were only found on PMTA, whereas PDMAA and PEtOx coatings significantly reduced the SG neuron survival and neuritogenesis. As also shown by scanning electron microscopy (SEM SGN strongly survived and retained their differentiated phenotype only on PMTA. In conclusion, survival and neuritogenesis of SGN may be associated with the extent of the glial cell growth. Since PMTA was the only of the polar polymers used in this study

  14. Solvent and irradiation doses effects on the ion exchange capacity of sulfonated styrene grafted PVDF

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira, Henrique P.; Parra, Duclerc F.; Lugao, Ademar B. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2011-07-01

    Polymers exhibiting ion exchange capacity are studied for many years due to their application in several fields, such as membranes for proton exchange fuel cells, filtration membranes, heavy ions recovery and artificial muscles and sensors. Radiation induced grafting followed by sulfonation is a well-known way to obtain ion exchange polymers. Fluorinated polymers are frequently used as polymeric matrix for grafting due to their excellent physicochemical properties. Radiation induced grafting of styrene into poly (vinylidene fluoride) (PVDF) by simultaneous method in 1:1 styrene/toluene or styrene/N,N-dimethylformamide solutions was studied. Irradiations were performed under nitrogen atmosphere, room temperature and at doses of 5, 10 and 20 kGy with dose rate of 5 kGy.h{sup -1} from a {sup 60}Co gamma source. After washing, grafted materials were sulfonated in 10% chlorosulfonic acid/1,2-dichloroethane solutions for 4 h at room temperature. Characterization shows that increasing irradiation dose corresponds to increases in the grafting yield (GY %) gravimetrically calculated and these different solvents shows different grafting behaviors. Toluene allows no more than 3 % of grafting while DMF allows up to 55 % of grafting in the same condition. Grafting in toluene solution occurs on the surface and in DMF solution it occurs in the bulk, as confirmed by SEM. Both irradiation doses and solvent used have direct effects in the ion exchange capacities (calculated after titrations). FT-IR spectra exhibit new peaks after grafting and after sulfonation, attributed to grafted monomer and sulfonic groups attached to the styrene. DSC shows differences in thermal behavior of the polymer before and after each step. (author)

  15. Solvent and irradiation doses effects on the ion exchange capacity of sulfonated styrene grafted PVDF

    International Nuclear Information System (INIS)

    Ferreira, Henrique P.; Parra, Duclerc F.; Lugao, Ademar B.

    2011-01-01

    Polymers exhibiting ion exchange capacity are studied for many years due to their application in several fields, such as membranes for proton exchange fuel cells, filtration membranes, heavy ions recovery and artificial muscles and sensors. Radiation induced grafting followed by sulfonation is a well-known way to obtain ion exchange polymers. Fluorinated polymers are frequently used as polymeric matrix for grafting due to their excellent physicochemical properties. Radiation induced grafting of styrene into poly (vinylidene fluoride) (PVDF) by simultaneous method in 1:1 styrene/toluene or styrene/N,N-dimethylformamide solutions was studied. Irradiations were performed under nitrogen atmosphere, room temperature and at doses of 5, 10 and 20 kGy with dose rate of 5 kGy.h -1 from a 60 Co gamma source. After washing, grafted materials were sulfonated in 10% chlorosulfonic acid/1,2-dichloroethane solutions for 4 h at room temperature. Characterization shows that increasing irradiation dose corresponds to increases in the grafting yield (GY %) gravimetrically calculated and these different solvents shows different grafting behaviors. Toluene allows no more than 3 % of grafting while DMF allows up to 55 % of grafting in the same condition. Grafting in toluene solution occurs on the surface and in DMF solution it occurs in the bulk, as confirmed by SEM. Both irradiation doses and solvent used have direct effects in the ion exchange capacities (calculated after titrations). FT-IR spectra exhibit new peaks after grafting and after sulfonation, attributed to grafted monomer and sulfonic groups attached to the styrene. DSC shows differences in thermal behavior of the polymer before and after each step. (author)

  16. Poly(ferrocenylsilane)-block-Polylactide Block Copolymers

    NARCIS (Netherlands)

    Roerdink, M.; van Zanten, Thomas S.; Hempenius, Mark A.; Zhong, Zhiyuan; Feijen, Jan; Vancso, Gyula J.

    2007-01-01

    A PFS/PLA block copolymer was studied to probe the effect of strong surface interactions on pattern formation in PFS block copolymer thin films. Successful synthesis of PFS-b-PLA was demonstrated. Thin films of these polymers show phase separation to form PFS microdomains in a PLA matrix, and

  17. Transport of Water in Semicrystalline Block Copolymer Membranes

    Science.gov (United States)

    Hallinan, Daniel; Oparaji, Onyekachi

    Poly(styrene)-block-poly(ethylene oxide) (PS- b-PEO) is a semicrystalline block copolymer (BCP) with interesting properties. It is mechanically tough, amphiphilic, and has a polar phase. The mechanical toughness is due to the crystallinity of PEO and the high glass transition temperature of PS, as well as the morphological structure of the BCP. The polymer has high CO2, water, and salt solubility that derive from the polar PEO component. Potential applications include CO2 separation, water purification, and lithium air batteries. In all of the aforementioned applications, water transport is an important parameter. The presence of water can also affect thermal and mechanical properties. Water transport and thermal and mechanical properties of a lamellar PS- b-PEO copolymer have been measured as a function of water activity. Water transport can be affected by the heterogeneous nature of a semicrystalline BCP. Therefore, Fourier transform infrared - attenuated total reflectance (FTIR-ATR) spectroscopy has been employed, because water transport and polymer swelling can be measured simultaneously. The effect of BCP structure on transport has been investigated by comparing water transport in PS- b-PEO to a PEO homopolymer. The crystalline content of the PEO and the presence of glassy PS lamellae will be used to explain the transport results.

  18. Dynamic mechanical and molecular weight measurements on polymer bonded explosives from thermally accelerated aging tests. III. Kraton block copolymer binder and plasticizers

    International Nuclear Information System (INIS)

    Caley, L.E.; Hoffman, D.M.

    1981-01-01

    The dynamic mechanical properties and molecular weight distribution of two experimental polymer bonded explosives, X-0287 and X-0298, maintained at 23, 60, and 74 0 C for 3 years were examined. X-0287 is 97% 1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane explosive, 1.8% Kraton G-1650, and 1.2% B 2 was 170. X-0298 is 97.4% explosive, 1.4% Kraton G-1650, and 1.2% Cenco Hi-vac oil. The relaxation associated with the Kraton rubber block glass transition is observed in both X-0287 and X-0298. In the unaged X-0298 it occurs at -59 0 C and in the aged explosive at 50 0 C. This is caused by migration of the oil plasticizer out of the explosive. In X-0287 the Kraton rubber block T/sub g/ is weak and broad due to the presence of the wax plasticizer. X-0287 has a second broad relaxation associated with the melting of the wax from 10 to 65 0 C. The molecular weight of the Kraton binder decreased with increasing accelerated aging temperature. The oil plasticizer had no stabilizing effect, but below its melting point the wax reduced Kraton chain scission considerably. The simple random chain scission model predicted a 20.5 year use-life for X-0298, but X-0287 was stabilized against degradation below the wax melting point

  19. Radical polymerization of styrene and styrene-butylmethacrylate in a counterrotating twin screw extruder

    NARCIS (Netherlands)

    vanderGoot, AJ; Janssen, LPB

    1997-01-01

    This article describes the copolymerization of styrene-butylmethacrylate (St-BMA) and the homopolymerization of styrene (St) in a counterrotating twin screw extruder. The effect of prepolymerization on both the product properties and process was studied. It turned out that the process of reactive

  20. Fabrication of Completely Polymer-Based Solar Cells with p- and n-Type Semiconducting Block Copolymers with Electrically Inert Polystyrene

    Directory of Open Access Journals (Sweden)

    Eri Tomita

    2018-02-01

    Full Text Available It is widely recognized that fullerene derivatives show several advantages as n-type materials in photovoltaic applications. However, conventional [6,6]-phenyl-C61-butyric acid methyl ester (PCBM exhibits weak absorption in the visible region, and poor morphological stability, due to the facile aggregation. For further improvement of the device performance and durability, utilization of n-type polymeric materials instead of PCBM is considered to be a good way to solve the problems. In this study, we fabricated completely polymer-based solar cells utilizing p- and n-type block copolymers consisting of poly(3-hexylthiophene (P3HT and poly{[N,N′-bis(2-octyldodecylnaphthalene-1,4,5,8-bis(dicarboximide-2,6-diyl]-alt-5,5′-(2,2′-bithiophene} [P(NDI2OD-T2], respectively, containing common polystyrene (PSt inert blocks, which decreased the size of phase separated structures. Electron mobility in synthesized P(NDI2OD-T2-b-PSt film enhanced by a factor of 8 compared with homopolymer. The root mean square roughness of the blend film of two block copolymers (12.2 nm was decreased, compared with that of the simple homopolymers blend (18.8 nm. From the current density-voltage characteristics, it was confirmed that the introduction of PSt into both P3HT and P(NDI2OD-T2 improves short-circuit current density (1.16 to 1.73 mA cm−2 and power-conversion efficiency (0.24% to 0.32%. Better performance is probably due to the uniformity of the phase separation, and the enhancement of charge mobility.

  1. Effect of polymer degradation on prolonged release of paclitaxel from filomicelles of polylactide/poly(ethylene glycol) block copolymers.

    Science.gov (United States)

    Jelonek, Katarzyna; Li, Suming; Kasperczyk, Janusz; Wu, Xiaohan; Orchel, Arkadiusz

    2017-06-01

    Paclitaxel is one of the most efficient anticancer agents, but the conventional dosage formulations cause many side effects. PLA-PEG filomicelles are promising carriers of paclitaxel because high loading capacity and long term release can be achieved. Slow release of cytostatic drugs is very advantageous due to prolonged exposure of tumor cells to cytostatic over multiple cell cycles. The aim of this study was to evaluate the potential of bioresorbable PLA-PEG filomicelles for prolonged delivery of paclitaxel. Paclitaxel is encapsulated in PLLA-PEG filomicelles and PDLLA-PEG spherical micelles. Drug release was studied in PBS at 37°C at various pH values to elucidate the influence of polymer degradation on drug release. NMR, GPC and HPLC were used to follow polymer degradation and drug release. The release of paclitaxel is strongly dependent on the degradation of micelles. A biphasic drug release profile is observed for both PLLA-PEG and PDLLA-PEG micelles: slow release in the first phase and faster release in the second phase. Degradation is faster at acidic pH than at pH7.4, and PLLA-PEG filomicelles degrade less rapidly than PDLLA-PEG spherical micelles, leading to various rates of drug release. The correlation between degradation and drug release is very helpful for the development of novel drug carriers with tailored properties. Importantly, the cytotoxic activity of PLLA-PEG filomicelles was evidenced, thus showing their potential as carrier of antitumor drugs. Copyright © 2017 Elsevier B.V. All rights reserved.

  2. Exploiting Molecular Weight Distribution Shape to Tune Domain Spacing in Block Copolymer Thin Films.

    Science.gov (United States)

    Gentekos, Dillon T; Jia, Junteng; Tirado, Erika S; Barteau, Katherine P; Smilgies, Detlef-M; DiStasio, Robert A; Fors, Brett P

    2018-04-04

    We report a method for tuning the domain spacing ( D sp ) of self-assembled block copolymer thin films of poly(styrene- block-methyl methacrylate) (PS- b-PMMA) over a large range of lamellar periods. By modifying the molecular weight distribution (MWD) shape (including both the breadth and skew) of the PS block via temporal control of polymer chain initiation in anionic polymerization, we observe increases of up to 41% in D sp for polymers with the same overall molecular weight ( M n ≈ 125 kg mol -1 ) without significantly changing the overall morphology or chemical composition of the final material. In conjunction with our experimental efforts, we have utilized concepts from population statistics and least-squares analysis to develop a model for predicting D sp based on the first three moments of the MWDs. This statistical model reproduces experimental D sp values with high fidelity (with mean absolute errors of 1.2 nm or 1.8%) and provides novel physical insight into the individual and collective roles played by the MWD moments in determining this property of interest. This work demonstrates that both MWD breadth and skew have a profound influence over D sp , thereby providing an experimental and conceptual platform for exploiting MWD shape as a simple and modular handle for fine-tuning D sp in block copolymer thin films.

  3. Selective Metallization of Well Aligned PS-b-P2VP Block Copolymers in Thin Films and in Confined Geometries

    Science.gov (United States)

    Sievert, James D.; Watkins, James J.; Russell, Thomas P.

    2006-03-01

    Well aligned, microphase-separated structures of styrene-2-vinylpyridine block copolymers are being used as templates for macromolecule-metal nanocomposites. These composites are either prepared as thin films or confined in nanoporous aluminum oxide membranes. Under optimal conditions, templates are prepared as thin films or confined nanorods and metallized without disturbing the ordered structure. We have developed a procedure that deposits metal within the polymer using supercritical carbon dioxide-soluble metal precursors. The use of supercritical carbon dioxide allows for selective metallization of the polymer at or below the glass transition, without disrupting the morphology. In addition, similar procedures have been investigated using metal salts and acids. Using these techniques, metals and metal-sulfides including silver, gold, platinum and zinc sulfide have been selectively deposited.

  4. Simulation of styrene polymerization reactors: kinetic and thermodynamic modeling

    Directory of Open Access Journals (Sweden)

    A. S. Almeida

    2008-06-01

    Full Text Available A mathematical model for the free radical polymerization of styrene is developed to predict the steady-state and dynamic behavior of a continuous process. Special emphasis is given for the kinetic and thermodynamic models, where the most sensitive parameters were estimated using data from an industrial plant. The thermodynamic model is based on a cubic equation of state and a mixing rule applied to the low-pressure vapor-liquid equilibrium of polymeric solutions, suitable for modeling the auto-refrigerated polymerization reactors, which use the vaporization rate to remove the reaction heat from the exothermic reactions. The simulation results show the high predictive capability of the proposed model when compared with plant data for conversion, average molecular weights, polydispersity, melt flow index, and thermal properties for different polymer grades.

  5. Highly efficient and selective pressure-assisted photon-induced polymerization of styrene

    Energy Technology Data Exchange (ETDEWEB)

    Guan, Jiwen [Department of Physics and Astronomy, University of Western Ontario, London, Ontario N6A 3K7 (Canada); Song, Yang, E-mail: yang.song@uwo.ca [Department of Physics and Astronomy, University of Western Ontario, London, Ontario N6A 3K7 (Canada); Department of Chemistry, University of Western Ontario, London, Ontario N6A 5B7 (Canada)

    2016-06-07

    The polymerization process of condensed styrene to produce polystyrene as an industrially important polymeric material was investigated using a novel approach by combining external compression with ultraviolet radiation. The reaction evolution was monitored as a function of time and the reaction products were characterized by in situ Fourier transform infrared spectroscopy. By optimizing the loading pressures, we observed highly efficient and selective production of polystyrene of different tacticities. Specifically, at relatively low loading pressures, infrared spectra suggest that styrene monomers transform to amorphous atactic polystyrene (APS) with minor crystalline isotactic polystyrene. In contrast, APS was found to be the sole product when polymerization occurs at relatively higher loading pressures. The time-dependent reaction profiles allow the examination of the polymerization kinetics by analyzing the rate constant and activation volume as a function of pressure. As a result, an optimized pressure condition, which allows a barrierless reaction to proceed, was identified and attributed to the very desirable reaction yield and kinetics. Finally, the photoinitiated reaction mechanism and the growth geometry of the polymer chains were investigated from the energy diagram of styrene and by the topology analysis of the crystal styrene. This study shows strong promise to produce functional polymeric materials in a highly efficient and controlled manner.

  6. Isolation and characterization of styrene metabolism genes from styrene-assimilating soil bacteria Rhodococcus sp. ST-5 and ST-10.

    Science.gov (United States)

    Toda, Hiroshi; Itoh, Nobuya

    2012-01-01

    Styrene metabolism genes were isolated from styrene-assimilating bacteria Rhodococcus sp. ST-5 and ST-10. Strain ST-5 had a gene cluster containing four open reading frames which encoded styrene degradation enzymes. The genes showed high similarity to styABCD of Pseudomonas sp. Y2. On the other hand, strain ST-10 had only two genes which encoded styrene monooxygenase and flavin oxidoreductase (styAB). Escherichia coli transformants possessing the sty genes of strains ST-5 and ST-10 produced (S)-styrene oxide from styrene, indicating that these genes function as styrene degradation enzymes. Metabolite analysis by resting-cell reaction with gas chromatography-mass spectrometry revealed that strain ST-5 converts styrene to phenylacetaldehyde via styrene oxide by styrene oxide isomerase (styC) reaction. On the other hand, strain ST-10 lacked this enzyme, and thus accumulated styrene oxide as an intermediate. HPLC analysis showed that styrene oxide was spontaneously isomerized to phenylacetaldehyde by chemical reaction. The produced phenylacetaldehyde was converted to phenylacetic acid (PAA) in strain ST-10 as well as in strain ST-5. Furthermore, phenylacetic acid was converted to phenylacetyl-CoA by the catalysis of phenylacetate-CoA ligase in strains ST-5 and ST-10. This study proposes possible styrene metabolism pathways in Rhodococcus sp. strains ST-5 and ST-10. Copyright © 2011 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

  7. Improved synthesis of polystyrene-poly(ethylene oxide)-heparin block copolymers

    NARCIS (Netherlands)

    Vulic, I.; Loman, A.J.B.; Feijen, Jan; Okano, T.; Kim, S.W.

    1990-01-01

    A novel procedure for the synthesis of block copolymers composed of a hydrophobic block of polystyrene, a hydrophilic block of poly(ethylene oxide) and a bioactive block of nitrous acid-degraded heparin was developed. Amino-semitelechelic polystyrene was prepared by anionic polymerization of styrene

  8. Small Angle Neutron Scattering Studies on Blends of Poly (Styrene-ran-Vinyl Phenol) with Liquid Crystalline Polyurethane

    Science.gov (United States)

    Mehta, Rujul

    2005-03-01

    Molecular composites, composed of uniformly dispersed rigid-rod liquid crystalline polymer (LCP) molecules in a flexible amorphous polymer matrix, have remained hitherto elusive due to a scarcity of miscible systems containing a LCP and an amorphous polymer. The production of such a blend, with an experimentally accessible miscibility window, has become possible by modifying the architecture of the flexible polymer, so as to induce favorable intermolecular hydrogen bonding. Specifically, liquid crystalline polyurethanes (LCPU) are found to be miscible with a copolymer of styrene and vinyl phenol; with optimum hydrogen bonding between the carbonyl groups of the urethane linkages and the hydroxyl groups present in the styrenic matrix. Availability of a truly miscible molecular composite presents a unique opportunity of studying the confirmation of polymer chains containing rigid-rods that are uniformly dispersed in a flexible coil matrix. A system consisting of the LCPU and the deuterated styrenic copolymer containing 20% vinyl phenol is examined by Small Angle Neutron Scattering at the National Center for Neutron Research at Gaithersburg and Technology, and the Institute of Solid State Research (IFF) at Jülich. Scattering curves for neat dPS-VPh did not fit the Debye-Bueche model; indicating complex structure. A two correlation length Debye-Bueche model was considered to accommodate for this nonlinear behavior. This model utilizes four fitting parameters, including two correlation lengths a1 and a2, corresponding to a Debye-Bueche model and Guinier model.

  9. Thermotropic properties of phosphatidylcholine nanodiscs bounded by styrene-maleic acid copolymers.

    Science.gov (United States)

    Dominguez Pardo, J J; Dörr, J M; Renne, M F; Ould-Braham, T; Koorengevel, M C; van Steenbergen, M J; Killian, J A

    2017-11-01

    Styrene-maleic acid copolymers (SMA) have been gaining interest in the field of membrane research due to their ability to solubilize membranes into nanodics. The SMA molecules act as an amphipathic belt that surrounds the nanodiscs, whereby the hydrophobic styrene moieties can insert in between the lipid acyl chains. Here we used SMA variants with different styrene-to-maleic acid ratio (i.e. 2:1, 3:1 and 4:1) to investigate how lipid packing in the nanodiscs is affected by the presence of the polymers and how it depends on polymer composition. This was done by analyzing the thermotropic properties of a series of saturated phosphatidylcholines in nanodiscs using laurdan fluorescence and differential scanning calorimetry. In all cases it was found that the temperature of the main phase transition (T m ) of the lipids in the nanodiscs is downshifted and that its cooperativity is strongly reduced as compared to the situation in vesicles. These effects were least pronounced for lipids in nanodiscs bounded by SMA 2:1. Unexpected trends were observed for the calorimetric enthalpy of the transition, suggesting that the polymer itself contributes, possibly by rearranging around the nanodiscs when the lipids adopt the fluid phase. Finally, distinct differences in morphology were observed for nanodiscs at relatively high polymer concentrations, depending on the SMA variant used. Overall, the results suggest that the extent of preservation of native thermodynamic properties of the lipids as well as the stability of the nanodiscs at high polymer concentrations is better for SMA 2:1 than for the other SMA variants. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

  10. Ab initio study of styrene isotopomers

    International Nuclear Information System (INIS)

    Zhang Jicheng; Tang Yongjian; Wu Weidong; Wang Hongyan; Zhu Zhenghe

    2002-01-01

    Using Gaussian98W program, the equilibrium geometry molecule structure of styrene has been optimized with HF/6-31G, MP2/6-31G and BLYP/6-31G methods. At same time, using BLYP/6-31G method, the harmonic frequency of styrene and its isotopomers, the bond energy of C-D bond (with ZPE correction), the intensity of IR spectrum are studied, and the modes of harmonic vibrational frequencies are simply discussed. At the same time, the effect of temperature and pressure on the thermodynamics parameter-entropy are studied. The results show that the calculated results are in good agreement with the experimental results

  11. Co-polymerization of methyl methacrylate and styrene via surfactant-free emulsion polymerization, as a potential material for photonic crystal application

    Science.gov (United States)

    Kassim, Syara; Zahari, Siti Balqis; Tahrin, Rabiatul Addawiyah Azwa; Harun, Noor Aniza

    2017-09-01

    Photonic crystals are being the great interest of researcher to studies due to a variety of potential application for the interaction of light including the solar cells, optical sensors and paints. In order to evaluate the fabrication of photonic crystals thin film, a free-emulsifier emulsion copolymerization of styrene and methyl methacrylate was carried out. By using the self -assembly approach, this method offers the opportunity to produce crystalline polymer sphere in more ease operation, low cost and environmental friendly. The influences of the mixing ratio of monomer and amount of initiators were studied. In advance, the presence of styrene as co-monomer had improved the thermal degradation of polymer methyl methacrylate. While in changing the mixing ratio of styrene and methyl methacrylate resulted in particle size of the sphere. The size of polymer particles slightly increased on increasing volume of styrene monomer ratio. This occurred because the properties of styrene in water where it sparingly soluble and lead to coagulation of particles. This simple, yet effective method for preparing functional complex 3D structures has the potential to be used generically to fabricate a variety of functional porous 3D structures that could find application not only in new or improved photonic crystal (PC) devices but also in areas such as catalysis, solar cell, separation, fuel cells technology, microelectronics and optoelectronics.

  12. Effect of annealing and UV-radiation time over micropore architecture of self-assembled block copolymer thin film

    Directory of Open Access Journals (Sweden)

    G. del C. Pizarro

    2015-06-01

    Full Text Available Block copolymers have been recognized as versatile materials to prepare nanoporous polymer films or membranes, but their potential has not been completely explored. This study focuses on the formation and characterization of nanoporous polymer films based on poly(styrene-block-(methylmethacrylate/methacrylic acid; (PS-b-MMA/MAA were obtained through atom transfer radical polymerization (ATRP, by using two different protocols: annealing and annealingirradiation; for improving the formation of microporous surface. The composition, crystallinity and structural order of the films were studied by Raman spectroscopy. The film polymer thickness was obtained through very high resolution ellipsometry (VHRE. Finally, atomic force microcopy (AFM and scanning electron microscopy (SEM techniques were used to detect changes in the porous-structure. These results show that the morphological properties of the block copolymer were affected via the modification of two variables, UV-radiation time and annealing. SEM and AFM micrographs showed that the morphology exhibit a porous ordered structure. Contact angle measurement suggests additional interactions between hydrophilic functional groups that influence the film wettability.

  13. Application of polyhydroxybutyrate-b-polyethyleneglycol (a block co-polymer) for solid phase extraction of lead and copper in different food samples

    International Nuclear Information System (INIS)

    Kazi, T.G.; Afridi, H.I.; Tuzen, M.; Naeemullah, A.

    2014-01-01

    In present work, a new adsorbent, polyhydroxybutyrate-b-polyethyleneglycol (block copolymer) was used for the preconcentration and separation of copper (Cu) and lead (Pb) ions without consuming expensive complexing reagent. The influence of various parameters like pH, adsorbent amount, and rates of flow of eluent, sample and sample volumes has been investigated. The polymer does not interact with alkaline earth metals, transition metals, alkaline, and few anions. The enrichment factor 50 was achieved in this method. The detection limit of method was found to be 0.36 micro g L/sup 1/ and 1.93 micro g L/sup 1/ for copper and lead, respectively. The recovery values of both analytes were found >96% and relative standard deviations (RSD) for all experiments were found less than 5%. The present method was validated by the analysis of Cu and Pb contents in various related certified reference materials (CRM) like; NIST SRM 1515 Apple leaves, IAEA -336 Lichen and GBW-07605 Tea. Found results and CRM values were precise and accurate. This developed method was then successfully applied for analysis of Cu and Pb in tap and bottled mineral water and real food samples. (author)

  14. Controlled specific placement of nanoparticles into microdomains of block copolymer thin films

    Energy Technology Data Exchange (ETDEWEB)

    Bae, Joonwon, E-mail: joonwonbae@gmail.com [Department of Applied Chemistry, Dongduk Women' s University, Seoul 136-714 (Korea, Republic of); Kim, Jungwook [Department of Chemical and Biomolecular Engineering, Sogang University, Seoul 121-742 (Korea, Republic of); Park, Jongnam, E-mail: jnpark@unist.ac.kr [Interdisciplinary School of Green Energy, Ulsan National Institute of Science and Technology (UNIST), Ulsan 689-798 (Korea, Republic of)

    2014-07-01

    Conceptually attractive hybrid materials composed of nanoparticles and elegant block copolymers have become important for diverse applications. In this work, controlled specific placement of nanoparticles such as gold (Au) and titania (TiO{sub 2}) into microphase separated domains in poly(styrene)-b-poly(2-vinylpyridine) (PS-b-P2VP) block copolymer thin films was demonstrated. The effect of nanoparticle surface functionality on the spatial location of particles inside polymer film was observed by transmission electron microscopy. It was revealed that the location of nanoparticles was highly dependent on the surface ligand property of nanoparticle. In addition, the microphase separation behavior of thin block copolymer film was also affected by the nanoparticle surface functional groups. This study might provide a way to understand the properties and behaviors of numerous block copolymer/nanoparticle hybrid systems. - Highlights: • Controlled location of nanoparticles in the block copolymer matrix • Tailoring surface functionality of metal nanocrystals • Fabrication of homogeneous nanocomposites using organic inorganic components • Possibility for the preparation of nanohybrids.

  15. Controlled specific placement of nanoparticles into microdomains of block copolymer thin films

    International Nuclear Information System (INIS)

    Bae, Joonwon; Kim, Jungwook; Park, Jongnam

    2014-01-01

    Conceptually attractive hybrid materials composed of nanoparticles and elegant block copolymers have become important for diverse applications. In this work, controlled specific placement of nanoparticles such as gold (Au) and titania (TiO 2 ) into microphase separated domains in poly(styrene)-b-poly(2-vinylpyridine) (PS-b-P2VP) block copolymer thin films was demonstrated. The effect of nanoparticle surface functionality on the spatial location of particles inside polymer film was observed by transmission electron microscopy. It was revealed that the location of nanoparticles was highly dependent on the surface ligand property of nanoparticle. In addition, the microphase separation behavior of thin block copolymer film was also affected by the nanoparticle surface functional groups. This study might provide a way to understand the properties and behaviors of numerous block copolymer/nanoparticle hybrid systems. - Highlights: • Controlled location of nanoparticles in the block copolymer matrix • Tailoring surface functionality of metal nanocrystals • Fabrication of homogeneous nanocomposites using organic inorganic components • Possibility for the preparation of nanohybrids

  16. Synthesis of Hydrophilic and Amphiphilic Acryl Sucrose Monomers and Their Copolymerisation with Styrene, Methylmethacrylate and α- and β-Pinenes

    Directory of Open Access Journals (Sweden)

    Maria Teresa Barros

    2010-04-01

    Full Text Available Herein, we report the synthesis of monomethacryloyl sucrose esters, and their successful free radical homo- and co-polymerisation with styrene, methylmethacrylate, α- and β-pinene. The chemical, physical, structural and surface chemical properties of these polymers, containing a hydrophobic olefin backbone and hydrophilic sugar moieties as side chains, have been investigated. Biodegradation tests of the copolymer samples by a microbial fungal culture (Aspergillus niger method showed good biodegradability. The chemical structure and surface chemistry of the synthesized homo- and co-polymers demonstrate their potential technological relevance as amphiphilic and biodegradable polymers.

  17. Hydrothermal Synthesis of Fe3O4 Nanoparticles and Flame Resistance Magnetic Poly styrene Nanocomposite

    Directory of Open Access Journals (Sweden)

    Kambiz Hedayati

    2017-01-01

    Full Text Available Fe3O4 nanostructures were synthesized via a facile hydrothermal reaction. The effect of various surfactants such as cationic and anionic on the morphology of the product was investigated. Magnetic nanoparticles were added to poly styrene for preparation of magnetic nanocomposite. Nanostructures were then characterized using X-ray diffraction, scanning electron microscopy and Fourier transform infrared spectroscopy. The magnetic properties of the samples were also investigated using vibrating sample magnetometer. The magnesium ferrite nanoparticles exhibit super paramagnetic behaviour at room temperature, with a saturation magnetization of 66 emu/g and a coercivity less than 5 Oe. Distribution of the magnetic nanoparticles into poly styrene matrix increases the coercivity. Nanoparticles appropriately enhanced flame retardant property of the PS matrix. Nanoparticles act as barriers which decrease thermal transport and volatilization during decomposition of the polymer.

  18. Creating surfactant nanoparticles for block copolymer composites through surface chemistry.

    Science.gov (United States)

    Kim, Bumjoon J; Bang, Joona; Hawker, Craig J; Chiu, Julia J; Pine, David J; Jang, Se Gyu; Yang, Seung-Man; Kramer, Edward J

    2007-12-04

    A simple strategy to tailor the surface of nanoparticles for their specific adsorption to and localization at block copolymer interfaces was explored. Gold nanoparticles coated by a mixture of low molecular weight thiol end-functional polystyrene (PS-SH) (Mn = 1.5 and 3.4 kg/mol) and poly(2-vinylpyridine) homopolymers (P2VP-SH) (Mn = 1.5 and 3.0 kg/mol) were incorporated into a lamellar poly(styrene-b-2-vinylpyridine) diblock copolymer (PS-b-P2VP) (Mn = 196 kg/mol). A library of nanoparticles with varying PS and P2VP surface compositions (FPS) and high polymer ligand areal chain densities was synthesized. The location of the nanoparticles in the PS-b-P2VP block copolymer was determined by transmission electron microscopy. Sharp transitions in particle location from the PS domain to the PS/P2VP interface, and subsequently to the P2VP domain, were observed at FPS = 0.9 and 0.1, respectively. This extremely wide window of FPS values where the polymer-coated gold nanoparticles adsorb to the interface suggests a redistribution of PS and P2VP polymers on the Au surface, inducing the formation of amphiphilic nanoparticles at the PS/P2VP interface. In a second and synthetically more challenging approach, gold nanoparticles were covered with a thiol terminated random copolymer of styrene and 2-vinylpyridine synthesized by RAFT polymerization. Two different random copolymers were considered, where the molecular weight was fixed at 3.5 kg/mol and the relative incorporation of styrene and 2-vinylpyridine repeat units varied (FPS = 0.52 and 0.40). The areal chain density of these random copolymers on Au is unfortunately not high enough to preclude any contact between the P2VP block of the block copolymer and the Au surface. Interestingly, gold nanoparticles coated by the random copolymer with FPS = 0.4 were dispersed in the P2VP domain, while those with FPS = 0.52 were located at the interface. A simple calculation for the adsorption energy to the interface of the nanoparticles

  19. Surface Morphology Diagram for Cylinder-Forming Block Copolymer Thin Films

    International Nuclear Information System (INIS)

    Zhang, Xiaohua; Berry, Brian C.; Yager, Kevin G.; Kim, Sangcheol; Jones, Ronald L.; Satija, Sushil; Pickel, Deanna L.; Douglas, Jack F.; Karim, Alamgir

    2008-01-01

    We investigate the effect of annealing temperature (T), film thickness (hf) on the surface morphology of flow coated films of a cylinder forming block copolymer, poly (styrene-block-methyl methacrylate) (PS-b-PMMA). Surface morphology transitions from a perpendicular to a parallel cylinder orientation with respect to the substrate with increasing hf are observed in these model 'frustrated-interaction' films where the substrate interaction is preferential for one of the blocks (PMMA) and nearly neutral for the other interface (polymer-air). In these films a transition occurs from cylinders oriented parallel to the substrate to a mixed or 'hybrid' state where the two orientations coexist followed by a transition to cylinders oriented perpendicularly to the polymer-air interface for larger hf. The characteristic values of hf defining these surface morphological transitions depend on T and we construct a surface morphology diagram as a function of hf and T. The surface morphology diagram is found to depend on the method of film formation (flow coated versus spun cast films) so non-equilibrium effects evidently have a large effect on the surface pattern morphology. In particular, the residual solvent within the film (quantified by neutron reflectivity measurements) in the context of physics of glass-formation can have a large effect on the surface morphology diagram

  20. Homogeneous graft copolymerization of styrene onto cellulose in a sulfur dioxide-diethylamine-dimethyl sulfoxide cellulose solvent

    International Nuclear Information System (INIS)

    Tsuzuki, M.; Hagiwara, I.; Shiraishi, N.; Yokota, T.

    1980-01-01

    Graft copolymerization of styrene onto cellulose was studied in a homogeneous system [SO 2 (liquid)- diethylamine (DEA)-dimethyl sulfoxide (DMSO) medium)] by γ-ray mutual irradiation technique. At the same time, homopolymerization of styrene was also examined separately in DMSO, SO 2 -DMSO, DEA-DMSO, and SO 2 -DEA-DMSO media by the same technique. Polymerization of styrene hardly occurs on concentrations above 10 mole SO 2 -DEA complex per mole glucose unit. Maximum percent grafting was obtained in concentrations of 4 mole, after which it decreased rapidly. Total conversion and percent grafting increased with the irradiation time. The value (=0.55) of the slope of the total conversion rate plotted against the dose was only a little higher than the 1/2 which was expected from normal kinetics. No retardation in homopolymerization of styrene in DMSO, SO 2 -DMSO, and DEA-DMSO was evident, while the retardation of homopolymerization in the SO 2 -DEA-DMSO medium was measurable. Sulfur atoms were detected in the polymers obtained in both of SO 2 -DMSO and SO 2 -DEA-DMSO solutions. All of the molecular weights of polymers obtained in the present experiment were very low

  1. Helbredsrisici ved eksponering for styren i glasfiberplastindustrien

    DEFF Research Database (Denmark)

    Kolstad, Henrik Albert; Ebbehøj, Nielse; Bonde, Jens Peter

    2012-01-01

    system effects with for instance reduced psychological performance, colour discrimination and hearing level following long-term styrene exposure above 10 ppm. There is moderate evidence of a causal association with cancer, but data are not sufficient to allow us to pinpoint specific cancers at risk...

  2. Styrene metabolism, genotoxicity, an potential carcinogenicity

    Czech Academy of Sciences Publication Activity Database

    Vodička, Pavel; Koskinen, M.; Naccarati, Alessio; Oesch-Bartlomowicz, B.; Vodičková, Ludmila; Hemminki, K.; Oesch, F.

    2006-01-01

    Roč. 38, č. 4 (2006), s. 805-853 ISSN 0360-2532 R&D Projects: GA ČR GA310/03/0437 Institutional research plan: CEZ:AV0Z50390512 Keywords : Styrene * Biotransformation * DNA and chromosomal damage Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 5.754, year: 2006

  3. Radiation resistance of ethylene-styrene copolymers

    International Nuclear Information System (INIS)

    Matsumoto, Kaoru; Ikeda, Masaaki; Ohki, Yoshimichi; Kusama, Yasuo; Harashige, Masahiro; Yazaki, Fumihiko.

    1988-01-01

    In this paper, the radiation resistance of ethylene-styrene copolymer, a polymeric resin developed newly by the authors, is reported. Resin examined were five kinds of ethylene-styrene copolymers: three random and two graft copolymers with different styrene contents. Low-density polyethylene was used as a reference. The samples were irradiated by 60 Co γ-rays to total absorbed doses up to 10 MGy. The mechanical properties of the smaples were examined. Infrared spectroscopy, differential scanning calorimetry and X-ray scattering techniques were used to examine the morphology of the samples. The random copolymers are soft and easy to extend, because benzene rings which exisist highly at random hinder the crystallization. As for the radiation resistance, they are highly resistant to γ-rays in the aspects of carbonyl group formation, gel formation, and elongation. Further, they show even better radiation resistance when proper additives were compounded in. The graft copolymers are hard to extend, because they consist of segregated polystyrene and polyethylene regions which are connected with each other. The tensile strength of irradiated graft copolymers does not decrease below that of unirradiated copolymers, up to a total dose of 10 MGy. As a consequence, it can be said that ethylene-styrene copolymers have good radiation resistance owing to the so-called 'sponge' effect of benzene rings. (author)

  4. Lewis acid controlled regioselectivity in styrene hydrocyanation

    NARCIS (Netherlands)

    Bini, L.; Pidko, E.A.; Müller, C.; Santen, van R.A.; Vogt, D.

    2009-01-01

    According to present knowledge, the Ni-catalyzed hydrocyanation of styrene leads predominantly to the branched product 2-phenylpropionitrile (98%). We observed a dramatic inversion of the regioselectivity upon addition of a Lewis acid. Up to 83 % of the linear product 3-phenylpropionitrile was

  5. Rh-catalyzed linear hydroformylation of styrene

    NARCIS (Netherlands)

    Boymans, E.H.; Janssen, M.C.C.; Mueller, C.; Lutz, M.; Vogt, D.

    2012-01-01

    Usually the Rh-catalyzed hydroformylation of styrene predominantly yields the branched, chiral aldehyde. An inversion of regioselectivity can be achieved using strong p-acceptor ligands. Binaphthol-based diphosphite and bis(dipyrrolyl-phosphorodiamidite) ligands were applied in the Rh-catalyzed

  6. Polymer encapsulated upconversion nanoparticle/iron oxide nanocomposites for multimodal imaging and magnetic targeted drug delivery.

    Science.gov (United States)

    Xu, Huan; Cheng, Liang; Wang, Chao; Ma, Xinxing; Li, Yonggang; Liu, Zhuang

    2011-12-01

    Multimodal imaging and imaging-guided therapies have become a new trend in the current development of cancer theranostics. In this work, we encapsulate hydrophobic upconversion nanoparticles (UCNPs) together with iron oxide nanoparticles (IONPs) by using an amphiphilic block copolymer, poly (styrene-block-allyl alcohol) (PS(16)-b-PAA(10)), via a microemulsion method, obtaining an UC-IO@Polymer multi-functional nanocomposite system. Fluorescent dye and anti-cancer drug molecules can be further loaded inside the UC-IO@Polymer nanocomposite for additional functionalities. Utilizing the Squaraine (SQ) dye loaded nanocomposite (UC-IO@Polymer-SQ), triple-modal upconversion luminescence (UCL)/down-conversion fluorescence (FL)/magnetic resonance (MR) imaging is demonstrated in vitro and in vivo, and also applied for in vivo cancer cell tracking in mice. On the other hand, a chemotherapy drug, doxorubicin, is also loaded into the nanocomposite, forming an UC-IO@Polymer-DOX complex, which enables novel imaging-guided and magnetic targeted drug delivery. Our work provides a method to fabricate a nanocomposite system with highly integrated functionalities for multimodal biomedical imaging and cancer therapy. Copyright © 2011 Elsevier Ltd. All rights reserved.

  7. Phase boundary in compatible and incompatible polymer blends studied by micro indentation test and microscopic observations

    International Nuclear Information System (INIS)

    Mina, M. F.; Akhtar, F.; Haque, M.E.

    2003-10-01

    The phase boundary of incompatible polymer blends such as poly (methyl methacrylate) (PMMA)/natural rubber (NR) and polyestyrene (PS)/NR as well as compatible blends such as PMMA/NR/epoxidizer NR (compatibilizer) and PS/NR/styrene-butadiene-styrene (SBS) block copolymer (compatibilizer) was studied by means of microhardness (H) technique and microscopy. Solution grown films of neat PMMA, PS and blended films of PMMA/NR, PS/NR, PMMA/NR/ENR and PS/NR/SBS were cast using a common solvent (toluene). While the neat PMMA and PS provide constant hardness values of 178 and 173 MPa, respectively, the binary (incompatible) and the ternary (compatible) blends show a conspicuous H-decrease (PMMA/NR=140 MPa, PS/NR=167 MPa, PMMA/NR/ENR=109 MPa and PS/NR/SBS=127 MPa). Scanning electron microscopy and optical microscopy reveal clear difference of the phase boundary of compatible (smooth boundary) and incompatible (sharp boundary) blends. Besides, the compatibilizer blends are characterised by the thinnest phase boundary (30 μm), which is found about 60 μm in the incompatible blends, showing a final hardness value that demonstrates the compatibilizer to be smoothly distributed in the interface between the two blend components. Results highlight that microindentation technique, in combination with microscopic observations, is a sensitive tool for studying the breadth and quality of the interphase boundary in non- or compatibilized polymer blends and other inhomogeneous materials. (author)

  8. Radiation Induced Grafting of Styrene onto ETFE: Influence of Crosslinker

    International Nuclear Information System (INIS)

    Gursel, S. A.

    2006-01-01

    Polymer electrolyte fuel cells are promising types of electrochemical devices for future power production with low operation temperature. In order to make this technology attractive, further cost reduction and improved reliability are required. These can be achieved in part by means of radiation induced grafting for the preparation of low cost proton-conducting polymer membranes. Indeed, the method can be performed with low-cost starting materials (fluorinated and partially fluorinated polymers). In our laboratory at Paul Scherrer Institut, most of the work has been performed using styrene and DVB as the monomers and poly (tetrafluoroethylene-co-hexafluoropropylene) as the base material. Performance comparable to Nafion 112 membranes and durability of several thousands hours at steady-state conditions have been achieved for this type of membranes under fuel cell operation conditions. Previously, poly(ethylene-alt-tetrafluoroethylene) (ETFE) based membranes have been prepared in the presence of divinylbenzene (DVB) as the crosslinking agent and found to exhibit encouraging fuel cell performance. However, the synthesis parameters were not optimized in detail to further improve the membrane properties. Recently, we have investigated the parameters of ETFE based grafting without crosslinking agent. In this study, proton-exchange membranes were prepared by pre-irradiation grafting of styrene onto ETFE and subsequent sulfonation in the presence of DVB containing different isomers (m- and p-isomer of DVB and m- and p-ethylvinylbenzene) as the crosslinker. The grafted films and membranes with varying DVB concentrations and similar degree of grafting (25%) were characterized by Fourier transform infrared spectroscopy (FTIR-ATR) and differential scanning calorimetry (DSC). In addition, dimensional changes and fuel cell relevant properties were examined. FTIR-ATR measurements revealed that the p- isomers are more reactive than m-isomers, and the grafted films are more highly

  9. Radiation-induced grafting of styrene on polypropylene pellets

    International Nuclear Information System (INIS)

    Souza, Camila P.; Ferreira, Henrique P.; Parra, Duclerc F.; Lugao, Ademar B.

    2009-01-01

    The changes of radiation-induced in polypropylene (PP) pellets exposed to gamma irradiation in inert atmosphere were investigated in correlation with the applied doses (10 and 50 kGy). Also, results from the grafting of styrene onto PP pellets using simultaneous irradiation at the same doses are presented. The grafting reaction was carried out using toluene as solvent, under nitrogen atmosphere and at room temperature. The properties of the irradiated and grafted PP pellets were studied using Melt Flow Index, thermal analysis (TG and DSC), and ATR-IR. The degree of grafting (DOG) for the grafted pellets was gravimetrically determined. The results showed that radiation-induced graft polymerization on pellets were successfully obtained and the influence of dose irradiated did not change the thermal properties in spite of the increase in the MFI and consequently this increase in the viscosity results an decrease the molecular mass. The MFI for grafted pellets was not achievable because the high degree of viscosity of polymer, even arising the test temperature, the polymer was not flow enough. (author)

  10. Powder wastes confinement block and manufacturing process of this block

    International Nuclear Information System (INIS)

    Dagot, L.; Brunel, G.

    1996-01-01

    This invention concerns a powder wastes containment block and a manufacturing process of this block. In this block, the waste powder is encapsulated in a thermo hardening polymer as for example an epoxy resin, the encapsulated resin being spread into cement. This block can contain between 45 and 55% in mass of wastes, between 18 and 36% in mass of polymer and between 14 and 32% in mass of cement. Such a containment block can be used for the radioactive wastes storage. (O.M.). 4 refs

  11. Thermodynamics of poly(7-methoxy-2-acetylbenzofurane methyl methacrylate-co-styrene) and poly(2-acetylbenzofurane methyl methacrylate-co-styrene)-probe interactions at different temperatures by inverse gas chromatography

    International Nuclear Information System (INIS)

    İlter, Zülfiye; Demir, Abdullah; Kaya, İsmet

    2016-01-01

    Highlights: • Thermodynamic of methacrylate-co-styrene polymers were studied by the inverse gas chromatography. • The sorption parameters of polymer-solute systems were determined under glass transition temperature of polymers. • The solubility parameter (δ 2 ) of the polymer was obtained from the slope and intercepts. • Flory-Huggins interaction parameter (χ 12 ∞ ) were determined for polymer-solute systems. - Abstract: In this study, some thermodynamic properties of poly(7-methoxy-2-acetylbenzofurane methyl methacrylate-co-styrene) Poly(MABMM-co-St) and poly(2-acetylbenzofurane methyl methacrylate-co-styrene) Poly(ABMM-co-St) were studied by the inverse gas chromatography (IGC) technique. The retention times (t r ) of selected organic probes were determined from the interactions with Poly(MABMM-co-St) and Poly(ABMM-co-St) of four groups of solvents with different chemical natures and polarities. Then, specific volume (V g 0 ) values of probes were calculated at different column temperatures. The glass transition temperatures (T g ) of Poly(MABMM-co-St) and Poly(ABMM-co-St) were found as 393, 413 K from inverse gas chromatography measurements, respectively. Under the glass transition temperatures adsorption heat (ΔH a ) and above the glass transition molar heat (ΔH 1 S ), free energies (ΔG 1 S ) and entropies (ΔS 1 S ) belonging to sorption for every probe were calculated from inverse gas chromatography measurements. The partial molar heat (ΔH 1 ∞ ), partial molar free energy (ΔG 1 ∞ ), Flory-Huggins interaction parameter (χ 12 ∞ ) and weight fraction activity coefficient (a 1 /w 1 ) ∞ , values for infinite dilute solutions were calculated for polymer-probe systems. The solubility parameter (δ 2 ) of the polymer was obtained from the slope and intercepts of Flory-Huggins interaction parameter (χ 12 ∞ ) graphs with solubility parameters (δ 1 ) of probes.

  12. Effect of modified graphene and microwave irradiation on the mechanical and thermal properties of poly(styrene-co-methyl methacrylate)/graphene nanocomposites

    KAUST Repository

    Zubair, Mukarram; Jose, Jobin Vinodh; Emwas, Abdul-Hamid M.; Al-Harthi, Mamdouh Ahmed

    2014-01-01

    The effect of modified graphene (MG) and microwave irradiation on the interaction between graphene (G) and poly(styrene-co-methyl meth acrylate) [P(S-co-MMA)] polymer matrix has been studied in this article. Modification of graphene was performed

  13. Advanced analytical methods for the structure elucidation of polystyrene-b-poly(n-butyl acrylate) block copolymers prepared by reverse iodine transfer polymerisation

    Energy Technology Data Exchange (ETDEWEB)

    Wright, Trevor Gavin; Pfukwa, Helen; Pasch, Harald, E-mail: hpasch@sun.ac.za

    2015-09-10

    Reverse iodine transfer polymerisation (RITP) is a living radical polymerisation technique that has shown to be feasible in synthesising segmented styrene-acrylate copolymers. Polymers synthesised via RITP are typically only described regarding their bulk properties using nuclear magnetic resonance spectroscopy and size exclusion chromatography. To fully understand the complex composition of the polymerisation products and the RITP reaction mechanism, however, it is necessary to use a combination of advanced analytical methods. In the present RITP procedure, polystyrene was synthesised first and then used as a macroinitiator to synthesise polystyrene-block-poly(n-butyl acrylate) (PS-b-PBA) block copolymers. For the first time, these PS-b-PBA block copolymers were analysed by a combination of SEC, in situ{sup 1}H NMR and HPLC. {sup 1}H NMR was used to determine the copolymer composition and the end group functionality of the samples, while SEC and HPLC were used to confirm the formation of block copolymers. Detailed information on the living character of the RITP process was obtained. - Highlights: • Comprehensive analysis of novel block copolymers. • Polymers were prepared for the first time by reverse iodine transfer polymerisation. • Combination of SEC, NMR, kinetic NMR, HPLC and comprehensive 2D-HPLC was used. • Detailed information about complex molecular composition and polymerisation kinetics was obtained.

  14. Segregation of chain ends to polymer melt surfaces and interfaces

    International Nuclear Information System (INIS)

    Zhao, W.; Zhao, X.; Rafailovich, M.H.; Sokolov, J.; Composto, R.J.; Smith, S.D.; Satkowski, M.; Russell, T.P.; Dozier, W.D.; Mansfield, T.

    1993-01-01

    The conformation of polymer chains in the melt near an impenetrable boundary has recently been studied by molecular dynamics and off-lattice Monte Carlo simulations. Both types of calculations show an enhancement of the chain end density within a distance of approximately two polymer segment lengths of the interface relative to the bulk. In the absence of preferential interactions between monomers and the interface, the segregation arises from minimizing the loss of conformational entropy near an impenetrable boundary; i.e., by positioning an end near the surface, only one unit rather than two is reflected. In order to obtain an experimental measure of this effect, monodisperse polystyrene (PS) chains of molecular weight 63 000 with short blocks of deuterated polystyrene (dPS) at each end were prepared. The block length was kept as short as possible, while yet producing sufficient neutron scattering contrast in order to minimize any preferential surface segregation due to isotopic effects. The synthesis was carried out via living anionic polymerization of a purified styrene monomer in cyclohexane at 60 C, utilizing sec-butyllithium as the initiator. The process was terminated using degassed methanol

  15. Kinethical Aspects of High Solid Contents Copoly(Styrene/Butylacrylate-Cloisite 30B Nanocomposites

    Directory of Open Access Journals (Sweden)

    M. Mirzataheri

    2014-01-01

    Full Text Available High solid content poly (styrene-co-butyl acrylate latex ( with 20% and 40% solid content including high amounts of Cloisite 30B (7 wt% and 10 wt% were kinetically investigated. Gravimetric method via measuring the rate of polymerization, number of particles and average number of radicals per particle was used. Results showed that by increasing the solid content; the average diameter of polymer particles decreased. Studies on the polymerization rate depict that the increase in polymer particle size provides more average reactive radicals per polymer particle, which increased from 0.48 to 0.88 for the sample containing 7 wt% clay and 20 wt% solid content. Observed armored particles with honeycomb morphology is the most novelty of this research work, which is suitable for making barrier packaging films.

  16. 21 CFR 177.1020 - Acrylonitrile/butadiene/sty-rene co-polymer.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Acrylonitrile/butadiene/sty-rene co-polymer. 177... SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) INDIRECT FOOD ADDITIVES: POLYMERS Substances.../butadiene/sty-rene co-polymer. Acrylonitrile/butadiene/styrene copolymer identified in this section may be...

  17. Nerve Blocks

    Science.gov (United States)

    ... News Physician Resources Professions Site Index A-Z Nerve Blocks A nerve block is an injection to ... the limitations of Nerve Block? What is a Nerve Block? A nerve block is an anesthetic and/ ...

  18. In situ preparation of magnetic nanocomposites of goethite in a styrene-maleimide copolymer template

    International Nuclear Information System (INIS)

    Sepulveda-Guzman, S.; Perez-Camacho, O.; Rodriguez-Fernandez, O.; Garcia-Zamora, M.

    2005-01-01

    Magnetic composites were prepared by in situ precipitation of α-FeOOH (goethite) using a new styrene-co-N-4 carboxybutylmaleimide cross-linked copolymer as template. Thermogravimetric analysis showed iron oxide content in the composites up to 45%. The iron oxide phase was identified as goethite by X-ray diffraction analysis. Transmission electron microscopy revealed that the crosslinking extent of polymeric templates affected both the shape and dimension of the goethite particles, and consequently, the magnetic behavior of the polymer/iron oxide composites

  19. Modified hydrogenated PBLH copolymer synthesis with styrene for proton exchange membranes fuel cell application

    International Nuclear Information System (INIS)

    Ferraz, Fernando A.; Oliveira, Angelo R.S.; Rodrigues, Maraiza F.; Groetzner, Mariana B.; Cesar-Oliveira, Maria Aparecida F.; Cantao, Mauricio P.

    2005-01-01

    Polymers used as electrolyte in fuel cells are expected to have functional groups in their structure which are responsible for proton conductivity. Since the use of hydroxylated liquid polybutadiene (PBLH) has not been mentioned in the literature as an ion exchange membrane for fuel cell application (PEMFC), and its structure can be modified for a later sulfonation, it has been studied. In this work, PBLH was modified through a hydrogenation reaction. Furthermore, hydrogenated polymeric esters were obtained by esterification and transesterification reactions (PBLH- estearate and PBLH- methacrylate). Reacting the PBLH methacrylate with styrene, it was generated a copolymer with appropriated structure for sulfonation, justifying researches for fuel cell. (author)

  20. High Solid Contents Copoly (Styrene/Butyl Acrylate-Cloisite 30B Nanocomposites

    Directory of Open Access Journals (Sweden)

    M. Mirzataheri

    2013-03-01

    Full Text Available Higher solid contents (20 % and 40 % nanocomposites of poly (styrene-co-butyl acrylate including higher content of Cloisite 30B (7 wt% and 10 wt % were prepared via miniemulsion polymerization. Stability of the final latexes proved outstanding combination of polymerization procedure and surfactants. Morphological studies revealed by TEM, SAX and XRD showed three structures of core-shell, armored and individual dispersion of clay layers within the polymer particles. The effect of Cloisite 30B content on the barrier properties presents excellent and wide use of these films for packaging and nanocoatings industries.

  1. Copper-catalyzed radical carbooxygenation: alkylation and alkoxylation of styrenes.

    Science.gov (United States)

    Liao, Zhixiong; Yi, Hong; Li, Zheng; Fan, Chao; Zhang, Xu; Liu, Jie; Deng, Zixin; Lei, Aiwen

    2015-01-01

    A simple copper-catalyzed direct radical carbooxygenation of styrenes is developed utilizing alkyl bromides as radical resources. This catalytic radical difunctionalization accomplishes both alkylation and alkoxylation of styrenes in one pot. A broad range of styrenes and alcohols are well tolerated in this transformation. The EPR experiment shows that alkyl halides could oxidize Cu(I) to Cu(II) in this transformation. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Biofiltration of Air/Styrene and Air/Styrene/Acetone mixtures in a bubble column reactor

    OpenAIRE

    Vieira, Ana

    2009-01-01

    The goal of this work was the treatment of polluted waste gases in a bubble column reactor (BCR), in order to determinate the maximum value of reactor’s efficiency (RE), varying the inlet concentration (C in) of the pollutants. The gaseous mixtures studied were: (i) air with styrene and (ii) air with styrene and acetone. The liquid phase used to contain the biomass in the reactor was a basal salt medium (BSM), fundamental for the microorganisms’ development. The reactor used in this pro...

  3. Styrene and Azo-Styrene Based Colorimetric Sensors for Highly Selective Detection of Cyanide

    OpenAIRE

    Prestiani, Agustina Eka; Purwono, Bambang

    2017-01-01

    A novel styrene (1) and azo-styrene (2) based chemosensor from vanillin has been successfully synthesized. Sensor 1 was obtained by one step Knoevenagel condensation of Ultrasound method and sensor 2 by coupling diazo and Knoevenagel condensation reaction. Both of sensors showed high sensitivity and selectivity to detect CN- in aqueous media, even the presence of other anions, such as F-, Cl-, Br-, I-, CO32-, SO42-, H2PO4-, and AcO-. Colorimetric sensing of sensor 1 is inclined to be deproton...

  4. Matrix-assisted laser desorption/ionization sample preparation optimization for structural characterization of poly(styrene-co-pentafluorostyrene) copolymers

    International Nuclear Information System (INIS)

    Tisdale, Evgenia; Kennedy, Devin; Wilkins, Charles

    2014-01-01

    Graphical abstract: -- Highlights: •We optimized sample preparation for MALDI TOF poly(styrene-copentafluorostyrene) co-polymers. •Influence of matrix choice was investigated. •Influence of matrix/analyte ratio was examined. •Influence of analyte/salt ratio (for Ag+ salt) was studied. -- Abstract: The influence of the sample preparation parameters (the choice of the matrix, matrix:analyte ratio, salt:analyte ratio) was investigated and optimal conditions were established for the MALDI time-of-flight mass spectrometry analysis of the poly(styrene-co-pentafluorostyrene) copolymers. These were synthesized by atom transfer radical polymerization. Use of 2,5-dihydroxybenzoic acid as matrix resulted in spectra with consistently high ion yields for all matrix:analyte:salt ratios tested. The optimized MALDI procedure was successfully applied to the characterization of three copolymers obtained by varying the conditions of polymerization reaction. It was possible to establish the nature of the end groups, calculate molecular weight distributions, and determine the individual length distributions for styrene and pentafluorostyrene monomers, contained in the resulting copolymers. Based on the data obtained, it was concluded that individual styrene chain length distributions are more sensitive to the change in the composition of the catalyst (the addition of small amount of CuBr 2 ) than is the pentafluorostyrene component distribution

  5. Matrix-assisted laser desorption/ionization sample preparation optimization for structural characterization of poly(styrene-co-pentafluorostyrene) copolymers

    Energy Technology Data Exchange (ETDEWEB)

    Tisdale, Evgenia; Kennedy, Devin; Wilkins, Charles, E-mail: cwilkins@uark.edu

    2014-01-15

    Graphical abstract: -- Highlights: •We optimized sample preparation for MALDI TOF poly(styrene-copentafluorostyrene) co-polymers. •Influence of matrix choice was investigated. •Influence of matrix/analyte ratio was examined. •Influence of analyte/salt ratio (for Ag+ salt) was studied. -- Abstract: The influence of the sample preparation parameters (the choice of the matrix, matrix:analyte ratio, salt:analyte ratio) was investigated and optimal conditions were established for the MALDI time-of-flight mass spectrometry analysis of the poly(styrene-co-pentafluorostyrene) copolymers. These were synthesized by atom transfer radical polymerization. Use of 2,5-dihydroxybenzoic acid as matrix resulted in spectra with consistently high ion yields for all matrix:analyte:salt ratios tested. The optimized MALDI procedure was successfully applied to the characterization of three copolymers obtained by varying the conditions of polymerization reaction. It was possible to establish the nature of the end groups, calculate molecular weight distributions, and determine the individual length distributions for styrene and pentafluorostyrene monomers, contained in the resulting copolymers. Based on the data obtained, it was concluded that individual styrene chain length distributions are more sensitive to the change in the composition of the catalyst (the addition of small amount of CuBr{sub 2}) than is the pentafluorostyrene component distribution.

  6. Morphology and Phase Transitions in Styrene-Butadiene-Styrene Triblock Copolymer Grafted with Isobutyl Substituted Polyhedral Oligomeric Silsesquioxanes (Postprint)

    National Research Council Canada - National Science Library

    Drazowski, Daniel B; Lee, Andre; Haddad, Timothy S

    2007-01-01

    Two symmetric triblock polystyrene-butadiene-polystyrene (SBS) copolymers with different styrene content were grafted with varying amounts of isobutyl-substituted polyhedral oligomeric silsesquioxane (POSS) molecules...

  7. Morphology and Phase Transitions in Styrene-Butadiene-Styrene Triblock Copolymer Grafted with Isobutyl Substituted Polyhedral Oligomeric Silsesquioxanes (preprint)

    National Research Council Canada - National Science Library

    Drazkowski, Daniel B; Lee, Andre; Haddad, Timothy S

    2006-01-01

    Two symmetric triblock polystyrene-butadiene-polystyrene (SBS) copolymers with different styrene content were grafted with varying amounts of isobutyl-substituted polyhedral oligomeric silsesquioxane (POSS) molecules...

  8. Preparation of poly (styrene)-b-poly (acrylic acid)/{gamma}-Fe{sub 2}O{sub 3} composites

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, L.D. [School of Materials Science and Engineering, Shandong Polytechnic University, Key Laboratory of Processing and Testing Technology of Glass Functional Ceramics of Shandong Province, Daxue Road, Western University Science Park, Jinan 250353 (China); Liu, W.L., E-mail: wlliu@sdu.edu.cn [School of Materials Science and Engineering, Shandong Polytechnic University, Key Laboratory of Processing and Testing Technology of Glass Functional Ceramics of Shandong Province, Daxue Road, Western University Science Park, Jinan 250353 (China); Xiao, C.L.; Yao, J.S.; Fan, Z.P.; Sun, X.L.; Zhang, X.; Wang, L. [School of Materials Science and Engineering, Shandong Polytechnic University, Key Laboratory of Processing and Testing Technology of Glass Functional Ceramics of Shandong Province, Daxue Road, Western University Science Park, Jinan 250353 (China); Wang, X.Q. [State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100 (China)

    2011-12-15

    The use of a block copolymer, poly (styrene)-b-poly (acrylic acid) (PS-b-PAA) to prepare a magnetic nanocomposite was investigated. Poly (styrene)-poly (t-butyl acrylate) block copolymer, being synthesized by atom transfer radical polymerization, was hydrolyzed with hydrochloric acid for obtaining PS-b-PAA. The obtained PS-b-PAA was then compounded with the modified {gamma}-Fe{sub 2}O{sub 3}, and subsequently the magnetic nanocomposite was achieved. The products were characterized by {sup 1}H NMR, FTIR, gel permeation chromatography, thermogravimetric analysis, transmission electron microscopy and vibrating sample magnetometer. The results showed that the nanocomposites exhibited soft magnetism, with the mean diameter of 100 nm approximately. - Highlights: > Magnetic composites were prepared using {gamma}-Fe{sub 2}O{sub 3} and PS-b-PAA. > PS-b-PAA was synthesized by atom transfer radical polymerization. > The obtained composite exhibited soft magnetism.

  9. Cotton fibers encapsulated with homo- and block copolymers: synthesis by the atom transfer radical polymerization grafting-from technique and solid-state NMR dynamic investigations.

    Science.gov (United States)

    Castelvetro, Valter; Geppi, Marco; Giaiacopi, Simone; Mollica, Giulia

    2007-02-01

    Cotton fibers were modified by surface-initiated atom transfer radical polymerization of ethyl acrylate (EA) followed by copolymerization with styrene. Either ethyl 2-bromopropionate as a sacrificial free initiator or Cu(II) as a deactivator was used to optimize the EA grafting yield and to preserve the livingness of the chain ends for the subsequent growth of a poly(styrene) (PSty) block from the poly(ethyl acrylate) (PEA) grafts. The polymer-encapsulated cotton fibers were analyzed by Fourier transform infrared spectroscopy, scanning electron microscopy, differential scanning calorimetry (DSC), thermogravimetric analysis, and solid-state NMR (high-resolution 13C cross-polarization magic angle spinning, 1H spin-lattice relaxation times, and 1H free induction decay analysis NMR). The latter allowed the detection of the dynamic modifications associated with the presence of homo- and block copolymer grafts. In particular, the results of the DSC and NMR investigations suggest a heterogeneous morphology of the g-PEA-b-PSty grafted skin, which could be described as an inner layer of g-PEA sandwiched between the semicrystalline cellulose of the core fiber and the high glass transition temperature PSty of the covalently linked outer layer. Such morphology results in a reduced molecular mobility of the PEA chains.

  10. Synthesis of poly(2-ethyl-2-oxazoline)-b-poly(styrene) copolymers via a dual initiator route combining cationic ring-opening polymerization and atom transfer radical polymerization

    NARCIS (Netherlands)

    Becer, C.R.; Paulus, R.M.; ppener, S.; Hoogenboom, R.; Fustin, C.A.; Gohy, J.M.W.; Schubert, U.S.

    2008-01-01

    Block copolymers of 2-ethyl-2-oxazoline (EtOx) and styrene were synthesized by a combination of cationic ring-opening polymerization (CROP) and atom transfer radical polymerization (ATRP). Initially, a detailed kinetic investigation for the ?-bromoisobutyrylbromide (BrEBBr) initiated CROP of EtOx

  11. PENGARUH TEMPERATUR TERHADAP TINGKAT SERAPAN AIR DALAM BAHAN POLY (2-VINYL PYRIDINE -CO-STYRENE

    Directory of Open Access Journals (Sweden)

    Mr Wiendartun

    2015-01-01

    Full Text Available Hydrophilic properties of organic polymer such as Poly (2-Vinylpyridine- Co-Styrene have been found to have a correlation with other physical properties especially the electric resistivity. In this work, we have studied one of the physical properties of a polymer material, Poly (2-Vinylpyridine- Co-Styrene, that is the electric resistivity. It was studied on the basis of its relation with the concentration, temperature, humidity and the distance between their electrodes. The sample fabricated consists of two types of consentration: 0.03 gr/ml and 0.05 gr/ml with the distance between the two electrodes are 0.40 mm and 0.80 mm respectively. Towards these samples, we investigated the resistance coefficient for every 2% change in humidity for both drying and watering processes. From the experiment we obtain the following results: 1 There is hysteresis during the watering and drying processes indicating the continuity of resistance of this material, 2 Sample with smaller distance of electrodes performs better than that of the longer ones, 3 Sample fabricated from solution with higher concentration performs better than that of the lower ones, 4 Room temperature plays a significant role on the performance of the polymer material between the associated electrodes. These results could be used as a stepping-stone toward the more advance research leading the determination of film stability, resistancy upon temperature variation etc, so that this polymer material could be further developed into the humidity sensor device material. Key words: Hydrophilic, electric resistance, humidity sensor and polymer.

  12. Gamma radiation-initiated polymerization of styrene at high pressure. II. Chain termination

    International Nuclear Information System (INIS)

    Moore, P.W.; Clouston, J.G.; Chaplin, R.P.

    1981-01-01

    The pressure dependence of the termination rate constant k/sub t/ for the free radical polymerization of monomers such as styrene is a function of polymer chain length, chain stiffness, and monomer viscosity, all of which influence the rate of segmental diffusion of an active radical chain end out of the coiled polymer chain to a position in which it can react with a proximate radical. Although k/sub t/ is not sensitive to changes in chain length, the large increase in molecular weight is responsible for a significant reduction in k/sub t/ at high pressures. For most of the common vinyl polymers, which exhibit some degree of chain stiffness, k/sub t/is inversely proportional to a fractional power of the monomer viscosity because it depends in part on the resistance of chain segments to movement and in part on the influence of viscosity in controlling diffusion of the chain ends. The fractional exponent appears to increase with pressure and this is interpreted as evidence that the polymer chains become more flexible in a more viscous solvent. Because the fractional exponent is higher for more flexible chains, the value of the activation volume for chain termination is an indication of the degree of flexibility of the polymer chains, provided that the monomer is a good solvent for the polymer and that chain transfer is negligible

  13. Indolo-naphthyridine-6,13-dione Thiophene Building Block for Conjugated Polymer Electronics: Molecular Origin of Ultrahigh n-Type Mobility

    KAUST Repository

    Fallon, Kealan J.

    2016-10-18

    Herein, we present the synthesis and characterization of four conjugated polymers containing a novel chromophore for organic electronics based on an indigoid structure. These polymers exhibit extremely small band gaps of ∼1.2 eV, impressive crystallinity, and extremely high n-type mobility exceeding 3 cm V s. The n-type charge carrier mobility can be correlated with the remarkably high crystallinity along the polymer backbone having a correlation length in excess of 20 nm. Theoretical analysis reveals that the novel polymers have highly rigid nonplanar geometries demonstrating that backbone planarity is not a prerequisite for either narrow band gap materials or ultrahigh mobilities. Furthermore, the variation in backbone crystallinity is dependent on the choice of comonomer. OPV device efficiencies up to 4.1% and charge photogeneration up to 1000 nm are demonstrated, highlighting the potential of this novel chromophore class in high-performance organic electronics.

  14. Indolo-naphthyridine-6,13-dione Thiophene Building Block for Conjugated Polymer Electronics: Molecular Origin of Ultrahigh n-Type Mobility

    KAUST Repository

    Fallon, Kealan J.; Wijeyasinghe, Nilushi; Manley, Eric F.; Dimitrov, Stoichko D.; Yousaf, Syeda A.; Ashraf, Raja S.; Duffy, Warren; Guilbert, Anne A. Y.; Freeman, David M. E.; Al-Hashimi, Mohammed; Nelson, Jenny; Durrant, James R.; Chen, Lin X.; McCulloch, Iain; Marks, Tobin J.; Clarke, Tracey M.; Anthopoulos, Thomas D.; Bronstein, Hugo

    2016-01-01

    Herein, we present the synthesis and characterization of four conjugated polymers containing a novel chromophore for organic electronics based on an indigoid structure. These polymers exhibit extremely small band gaps of ∼1.2 eV, impressive crystallinity, and extremely high n-type mobility exceeding 3 cm V s. The n-type charge carrier mobility can be correlated with the remarkably high crystallinity along the polymer backbone having a correlation length in excess of 20 nm. Theoretical analysis reveals that the novel polymers have highly rigid nonplanar geometries demonstrating that backbone planarity is not a prerequisite for either narrow band gap materials or ultrahigh mobilities. Furthermore, the variation in backbone crystallinity is dependent on the choice of comonomer. OPV device efficiencies up to 4.1% and charge photogeneration up to 1000 nm are demonstrated, highlighting the potential of this novel chromophore class in high-performance organic electronics.

  15. Grafting of styrene onto poly(vinylidene fluoride) films by gamma irradiation; Enxertia de estireno em filmes de poli(fluoreto de vinilideno) induzida por irradiacao gama

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira, H.P.; Souza, C.P. de; Parra, D.F.; Lugao, A.B., E-mail: hp.ferreira@yahoo.com.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil). Centro de Quimica e Meio Ambiente

    2010-07-01

    Radiation induced grafting of styrene onto poly(vinylidene fluoride) (PVDF) was studied owing to the crescent interest in use of grafted films to produce membranes with ion exchange capability. A Cobalt-60 source was used, with doses of 5 and 10 kGy, at dose rate of 5 kGy.h{sup -1}, at room temperature, inert atmosphere and according to the simultaneous method. Solutions of styrene/toluene (1:1, v/v) and styrene/N,N-dimethylformamide (DMF) (1:1, v/v) were used. The films were characterized by FT-IR spectroscopy (Infrared Spectroscopy), Differential Scanning Calorimetry (DSC), Thermogravimetric Measurement (TG) and the degree of grafting (DOG) were calculated gravimetrically. Results shown that in studied conditions, DMF allow greatest DOG than toluene and that increasing the irradiation dose correspond an increase in DOG. Infrared and thermal analyses confirmed the presence in the grafted polymers. (author)

  16. Atom transfer radical copolymerization of styrene and butyl acrylate

    NARCIS (Netherlands)

    Chambard, G.; Klumperman, B.; Matyjaszewski, K.

    2000-01-01

    Atom transfer radical polymerization of styrene and butyl acrylate has been investigated from a kinetic point of view. Attention is focused on the activation of the dormant species as well as on the termination that plays a role in these reactions. It has been shown that the activation of a styrene

  17. COPOLYMER BLENDS OF STYRENE AND ORTHO-FLUOROSTYRENE

    NARCIS (Netherlands)

    TENBRINKE, G; KARASZ, FE

    1991-01-01

    The traditional method, using differential scanning calorimetry, to study phase behaviour in blends containing styrene and fluorinated styrene is hampered by the fact that the glass transition temperatures of fluorinated polystyrenes are almost independent of the degree of fluorination. To deal with

  18. Uranium isotope separation using styrene cation exchangers

    International Nuclear Information System (INIS)

    Kahovec, J.

    1980-01-01

    The separation of 235 U and 238 U isotopes is carried out either by simple isotope exchange in the system uranium-cation exchanger (sulphonated styrene divinylbenzene resin), or by combination of isotope exchange in a uranium-cation exchanger (Dowex 50, Amberlite IR-120) system and a chemical reaction. A review is presented of elution agents used, the degree of cation exchanger cross-linking, columns length, and 235 U enrichment. The results are described of the isotope effect study in a U(IV)-U(VI)-cation exchanger system conducted by Japanese and Romanian authors (isotope exchange kinetics, frontal analysis, reverse (indirect) frontal analysis). (H.S.)

  19. Thermo-Physical Properties of Kenaf-Filled Acrylonitrile Butadiene Styrene Composites

    Directory of Open Access Journals (Sweden)

    Nikmatin Siti

    2017-01-01

    Full Text Available Studies on advantageous of natural fillers incorporated into polymer composites on thermo-physical and mechanical properties are still intensively investigated. Several evidences suggest that the natural fillers with small contents combined with polymer increase their composite properties. We thus investigate thermo-physical properties of kenaf-filled acrylonitrile butadiene styrene (ABS composites. ABS with 5% kenaf microparticle size (ABS/K5, ABS with 5% kenaf short fiber (ABS/KSF5, and recycled ABS with 5% kenaf microparticle size (RABS/K5 were manufactured. Granular composites were manufactured by the twin screw extruder. Composite properties in terms of X-ray diffractions, surface morphologies, and thermal behaviors were investigated. The present work found that ABS/KSF5 has the highest degree of crystallinity compared to others. No significant difference was found in terms of thermal properties of the composites.

  20. Radiation-induced grafting of styrene onto poly-vinylidene fluoride) film by simultaneous method with two different solvents

    International Nuclear Information System (INIS)

    Ferreira, H.P.; Parra, D.F.; Lugao, A.B.

    2011-01-01

    Complete text of publication follows. Radiation-induced grafting to create membranes with ion exchange capacity in fluorinated polymers has been studied for applications such as fuel cells, filtration and waste treatment and polymeric actuators due to their good physical and chemical properties. In this work, radiation-induced grafting of styrene into poly(vinylidene fluoride) (PVDF) films with 0.125 mm thickness at doses of 1 and 2.5 kGy in the presence of a styrene/N,N- dimethylformamide (DMF) solution (1:1, v/v) and at doses of 20, 40 and 80 kGy in presence of a styrene/toluene solution (1:1, v/v) at dose rate of 5 kGy h-1 was carried out by simultaneous method under nitrogen atmosphere and at room temperature, using gamma-rays form a Co-60. The films were characterized before and after modification by the grafting yield (GY), infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and thermogravimetry (TG/DTG). GY results shows that grafting increases with dose, and it was possible to confirm the grafting of styrene by FT-IR due to the new characteristics peaks and by the TG and DSC due to changes in thermal behavior of the grafted material. Results showed that the system allows the homogeneous grafting of styrene into PVDF using gamma irradiation at doses as low as 1 kGy when DMF is used and heterogeneous grafting when toluene is used, showing the importance of the solvent nature during the simultaneous method.

  1. Biofiltration of a styrene/acetone vapor mixture in two reactor types under conditions of styrene overloading

    Directory of Open Access Journals (Sweden)

    Lubos Zapotocky

    2014-10-01

    Full Text Available This aim of study was to compare the performance of a biofilter (BF and trickle bed reactor (TBR under increased styrene loading with a constant acetone load, 2 gc/m3/h. At styrene loading rates up to 30 gc/m3/h, the BF showed higher styrene removal than TBR. However, the BF efficiency started to drop beyond this threshold loading and could never reach steady state, whereas the TBR continued to yield a 50% styrene removal. The acetone removal remained constant (93-98% in both the reactors at any styrene loading. Once the overloading was lifted, the BF recovered within 26 min, whereas the TBR efficiency bounced back only to 95%, gradually returning to complete removal only in 10 h.

  2. Production and characterization of poly(styrene-co-methylmethacrylate);Producao e caracterizacao de poliestireno-co-metacrilato de metila

    Energy Technology Data Exchange (ETDEWEB)

    Augustinho, Tiago R.; Coan, Thais; Abarca, Silvia A.C.; Testoni, Alex A.S.; Baumgarten, Bruno P.; Machado, Ricardo A.F., E-mail: tiagoqmc@gmail.co [Universidade Federal de Santa Catarina (UFSC), Florianopolis (Brazil). Dept. de Engenharia Quimica e Alimentos

    2009-07-01

    Polystyrene (PS) is a polymer used in diverse industrial segments. It is easy to process and has a low cost when compared to other materials. However, PS has low mechanical resistance, which limits its application in some areas. Thus, a methodology that is sufficiently used is the synthesis of a copolymer, formed of two or more monomers to get products that have characteristics that are not possible to obtain with only one monomer. In this work, the styrene and methyl methacrylate monomers had been carried through reactions of copolymerization by means of polymerization in suspension using (MMA) with styrene in a bigger percentage. MMA was selected for being a monomer that results in a polymeric configuration more resistant than the PS. The copolymerization was proven to occur by infra-red spectroscopy (IR) and Nuclear Magnetic Resonance (NMR). Different analyses were performed using different initiators, weight molar and conversion studies. (author)

  3. Synthesis of Poly(3,4-Ethylenedioxy thiophene)-Poly(Styrene-4-Sulfonate) Composites for Support Fuel Cell Catalyst Layer

    International Nuclear Information System (INIS)

    Eko Sulistiyono; Murni Handayani

    2009-01-01

    Synthesis of poly(3,4-ethylenedioxy thiophene)-poly(styrene-4-sulfonate) composites for support fuel cell catalyst layer are synthesis composites which become fuel cell catalyst support so that catalyst has optimal performance. Main function of composites is support platinum particle for application in fuel cell. This article explains the result of composites production process from ( 3,4 Ethylenedioxy thiophene) and Sodium poly( styrene - 4-sulfonate) using two methods Jingning Shan method (method 1) and Zhigang Qi and Peter G.Pickup method (method 2). Analysis of the synthesis results used Scanning Electron Microscopic –Electron Dispersive X – Ray Spectrophotometer (SEM-EDS ). The analysis result show that both methods produce polymer agglomerate into a sponge-like morphology. Composite from method 1 has morphology, pores and proton transport better than composite produced by method 2. (author)

  4. Influence of Emulsion Polymerization Techniques to Particle Size of Copoly(styrene/butyl acrylate/methyl methacrylate

    Directory of Open Access Journals (Sweden)

    Tresye Utari

    2008-04-01

    Full Text Available In the majority of applications, particle size and particle size distribution are highly significant factors that determine the properties of a polymer dispersion, such as its flow behavior or its stability. For example, a coating material with small particle size will give smooth coating result, good adhesive strength, good water resistance and latex stability. This article describes influence of various emulsion polymerization techniques to particle size of copoly(styrene/butyl acrylate/methyl methacrylate with mix surfactant SDBS linear chain and nonyl fenol (EO10 and initiator ammonium persulphate. DSC data, solid content and IR spectrum showed that copoly(styrene/butyl acrylate/methyl methacrylate was produced. Batch emulsion polymerization technique gave the highest particle size i.e. 615 nm and also the highest % conversion of monomer i.e. 97%. The more concentration of monomer was seeded to initial charge gave greater particle size and greater poly dispersity index.

  5. Copper mediated controlled radical copolymerization of styrene and2-ethylhexyl acrylate and determination of their reactivity ratios.

    Directory of Open Access Journals (Sweden)

    Bishnu Prasad Koiry

    2014-10-01

    Full Text Available Copolymerization is an important synthetic tool to prepare polymers with desirable combination of properties which are difficult to achieve from the different homopolymers concerned. This investigation reports the copolymerization of 2-ethylhexyl acrylate (EHA and styrene using copper bromide (CuBr as catalyst in combination with N,N,N’,N,N- pentamethyldiethylenetriamine (PMDETA as ligand and 1-phenylethyl bromide (PEBr as initiator. Linear kinetic plot and linear increase in molecular weights versus conversion indicate that copolymerization reactions were controlled. The copolymer composition was calculated using 1H NMR studies. The reactivity ratio of styrene and EHA (r1 and r2 were determined using the Finemann-Ross (FR, inverted Finemann-Ross (FR and Kelen-Tudos (KT methods. Thermal properties of the copolymers were also studied by using TGA and DSC analysis.

  6. (Electro)Mechanical Properties of Olefinic Block Copolymers

    Science.gov (United States)

    Spontak, Richard

    2014-03-01

    Conventional styrenic triblock copolymers (SBCs) swollen with a midblock-selective oil have been previously shown to exhibit excellent electromechanical properties as dielectric elastomers. In this class of electroactive polymers, compliant electrodes applied as active areas to opposing surfaces of an elastomer attract each other, and thus compress the elastomer due to the onset of a Maxwell stress, upon application of an external electric field. This isochoric process is accompanied by an increase in lateral area, which yields the electroactuation strain (measuring beyond 300% in SBC systems). Performance parameters such as the Maxwell stress, transverse strain, dielectric breakdown, energy density and electromechanical efficiency are determined directly from the applied electric field and resulting electroactuation strain. In this study, the same principle used to evaluate SBC systems is extended to olefinic block copolymers (OBCs), which can be described as randomly-coupled multiblock copolymers that consist of crystallizable polyethylene hard segments and rubbery poly(ethylene-co-octene) soft segments. Considerations governing the development of a methodology to fabricate electroresponsive OBC systems are first discussed for several OBCs differing in composition and bulk properties. Evidence of electroactuation in selectively-solvated OBC systems is presented and performance metrics measured therefrom are quantitatively compared with dielectric elastomers derived from SBC and related materials.

  7. Block copolymer lithography of rhodium nanoparticles for high temperature electrocatalysis.

    Science.gov (United States)

    Boyd, David A; Hao, Yong; Li, Changyi; Goodwin, David G; Haile, Sossina M

    2013-06-25

    We present a method for forming ordered rhodium nanostructures on a solid support. The approach makes use of a block copolymer to create and assemble rhodium chloride nanoparticles from solution onto a surface; subsequent plasma and thermal processing are employed to remove the polymer and fully convert the nanostructures to metallic rhodium. Films cast from a solution of the triblock copolymer poly(styrene-b-2-vinyl pyridine-b-ethylene oxide) dissolved in toluene with rhodium(III) chloride hydrate were capable of producing a monolayer of rhodium nanoparticles of uniform size and interparticle spacing. The nanostructures were characterized by scanning electron microscopy, X-ray photoelectron spectroscopy, and atomic force microscopy. The electrocatalytic performance of the nanoparticles was investigated with AC impedance spectroscopy. We observed that the addition of the particles to a model solid oxide fuel cell anode provided up to a 14-fold improvement in the anode activity as evidenced by a decrease in the AC impedance resistance. Examination of the anode after electrochemical measurement revealed that the basic morphology and distribution of the particles were preserved.

  8. Immobilization of Acidithiobacillus ferrooxidans on sulfonated microporous poly(styrene-divinylbenzene) copolymer with granulated activated carbon and its use in bio-oxidation of ferrous iron.

    Science.gov (United States)

    Koseoglu-Imer, Derya Yuksel; Keskinler, Bulent

    2013-01-01

    The immobilization efficiencies of Acidithiobacillus ferrooxidans cells on different immobilization matrices were investigated for biooxidation of ferrous iron (Fe(2+)) to ferric iron (Fe(3+)). Six different matrices were used such as the polyurethane foam (PUF), granular activated carbon (GAC), raw poly(styrene-divinylbenzene) copolymer (rawSDVB), raw poly(styrene-divinylbenzene) copolymer with granular activated carbon (rawSDVB-GAC), sulfonated poly(styrene-divinylbenzene) copolymer (sulfSDVB) and sulfonated poly(styrene-divinylbenzene) copolymer with granular activated carbon (sulfSDVB-GAC). The sulfSDVB-GAC polymer showed the best performance for Fe(2+) biooxidation. It was used at packed-bed bioreactor and the kinetic parameters were obtained. The highest Fe(2+) biooxidation rate (R) was found to be 4.02 g/L h at the true dilution rate (Dt) of 2.47 1/h and hydraulic retention time (τ) of 0.4 h. The sulfSDVB-GAC polymer was used for the first time as immobilization material for A. ferrooxidans for Fe(2+) biooxidation. Copyright © 2012 Elsevier B.V. All rights reserved.

  9. Designing N-halamine based antibacterial surface on polymers: Fabrication, characterization, and biocidal functions

    Energy Technology Data Exchange (ETDEWEB)

    Chen Yong, E-mail: ychen168@126.com [Department of Applied Chemistry, College of Chemical and Environmental Engineering, Shandong University of Science and Technology, 579 Qianwangang Rd., Huangdao Zone, Qingdao 266510 (China); Han Qiuxia [Department of Biological Engineering, College of Chemical and Environmental Engineering, Shandong University of Science and Technology, Qingdao 266510 (China)

    2011-05-01

    We demonstrate a valuable method to generate reactive groups on inert polymer surfaces and bond antibacterial agents for biocidal ability. Polystyrene (PS) surfaces were functionalized by spin coating of sub-monolayer and monolayer films of poly(styrene-b-tert-butyl acrylate) (PS-PtBA) block copolymer from solutions in toluene. PS-PtBA self-assembled to a bilayer structure on PS that contains a surface layer of the PtBA blocks ordering at the air-polymer interface and a bottom layer of the PS blocks entangling with the PS substrate. The thickness of PtBA layer could be linearly controlled by the concentration of the spin coating solution and a 2.5 nm saturated monolayer coverage of PtBA was achieved at 0.35% (w/w). Carboxyl groups were generated by exposing the tert-butyl ester groups of PtBA on saturated surface to trifluoroacetic acid (TFA) to bond tert-butylamine via amide bonds that were further chlorinated to N-halamine with NaOCl solution. The density of N-halamine on the chlorinated surface was calculated to be 1.05 x 10{sup -5} mol/m{sup 2} by iodimetric/thiosulfate titration. Presented data showed the N-halamine surface provided powerful antibacterial activities against Staphylococcus aureus and Escherichia coli. Over 50% of the chlorine lost after UVA irradiation could be regained upon rechlorination. This design concept can be virtually applied to any inert polymer by choosing appropriate block copolymers and antibacterial agents to attain desirable biocidal activity.

  10. CYP2E1 Metabolism of Styrene Involves Allostery

    Science.gov (United States)

    Hartman, Jessica H.; Boysen, Gunnar

    2012-01-01

    We are the first to report allosterism during styrene oxidation by recombinant CYP2E1 and human liver microsomes. At low styrene concentrations, oxidation is inefficient because of weak binding to CYP2E1 (Ks = 830 μM). A second styrene molecule then binds CYP2E1 with higher affinity (Kss = 110 μM) and significantly improves oxidation to achieve a kcat of 6.3 nmol · min−1 · nmol CYP2E1−1. The transition between these metabolic cycles coincides with reported styrene concentrations in blood from exposed workers; thus, this CYP2E1 mechanism may be relevant in vivo. Scaled modeling of the in vitro-positive allosteric mechanism for styrene metabolism to its in vivo clearance led to significant deviations from the traditional model based on Michaelis-Menten kinetics. Low styrene levels were notably much less toxic than generally assumed. We interrogated the allosteric mechanism using the CYP2E1-specific inhibitor and drug 4-methylpyrazole, which we have shown binds two CYP2E1 sites. From the current studies, styrene was a positive allosteric effector on 4-methylpyrazole binding, based on a 10-fold increase in 4-methylpyrazole binding affinity from Ki 0.51 to Ksi 0.043 μM. The inhibitor was a negative allosteric effector on styrene oxidation, because kcat decreased 6-fold to 0.98 nmol · min−1 · nmol CYP2E1−1. Consequently, mixtures of styrene and other molecules can induce allosteric effects on binding and metabolism by CYP2E1 and thus mitigate the efficiency of their metabolism and corresponding effects on human health. Taken together, our elucidation of mechanisms for these allosteric reactions provides a powerful tool for further investigating the complexities of CYP2E1 metabolism of drugs and pollutants. PMID:22807108

  11. Artificially Engineered Protein Polymers.

    Science.gov (United States)

    Yang, Yun Jung; Holmberg, Angela L; Olsen, Bradley D

    2017-06-07

    Modern polymer science increasingly requires precise control over macromolecular structure and properties for engineering advanced materials and biomedical systems. The application of biological processes to design and synthesize artificial protein polymers offers a means for furthering macromolecular tunability, enabling polymers with dispersities of ∼1.0 and monomer-level sequence control. Taking inspiration from materials evolved in nature, scientists have created modular building blocks with simplified monomer sequences that replicate the function of natural systems. The corresponding protein engineering toolbox has enabled the systematic development of complex functional polymeric materials across areas as diverse as adhesives, responsive polymers, and medical materials. This review discusses the natural proteins that have inspired the development of key building blocks for protein polymer engineering and the function of these elements in material design. The prospects and progress for scalable commercialization of protein polymers are reviewed, discussing both technology needs and opportunities.

  12. The effect of long-term oxidation on the rheological properties of polymer modified asphalts

    Energy Technology Data Exchange (ETDEWEB)

    Yonghong Ruan; Richard R. Davison; Charles J. Glover [Texas A & M University, College Station, TX (United States). Department of Chemical Engineering

    2003-10-01

    The effect of long-term aging on rheological properties of polymer modified asphalt binders was studied. Modifiers included diblock poly(styrene-b-butadiene) rubber, triblock poly(styrene-b-butadiene-b-styrene), and tire rubber. Asphalt aging was carried out either at 60{sup o}C in a controlled environmental room or at 100{sup o}C in a pressure aging vessel (AASHTO Provisional Standards, 1993). Both dynamic shear properties and extensional properties were investigated. Polymer modification resulted in increased asphalt complex modulus at high temperatures, decreased asphalt complex modulus at low temperatures, broadened relaxation spectra, and improved ductility. Oxidative aging decreased asphalt temperature susceptibility, damaged the polymer network in binders, further broadened the relaxation spectrum, and diminished polymer effectiveness in improving asphalt ductility. 27 refs., 8 figs., 3 tabs.

  13. Growth of polymer nanoparticles in microemulsion polymerization initiated with γ ray

    International Nuclear Information System (INIS)

    Xu Xiangling; Ge Xuewu; Ye Qiang; Zhang Zhicheng; Zuo Ju; Niu Aizhen; Zhang Manwei

    1999-01-01

    In microemulsion polymerization of styrene, butyl acrylate and methyl methacrylate initiated with gamma ray, growth of polymer nanoparticles was observed with photon correlation spectroscopy, and the conversion curve was recorded with a dilatometer. There is some similarity in the growth of polymer particles. The size of polymer particles rapidly increases up to their maximum at the early stage. With the increase of conversion, the large particles supply their monomer to newly formed particles and become smaller. In all these three microemulsion polymerizations, the evidence of continuous nucleation was observed. When monomer is styrene or butyl acrylate, a plateau of polymerization rate emerges. When monomer is methyl methacrylate, no plateau of polymerization is observed

  14. [Studies on the industrial styrene poisoning (Part X). Determination of styrene in biological materials by gas chromatography (author's transl)].

    Science.gov (United States)

    Teramoto, K; Horiguchi, S

    1980-09-01

    For monitoring solvents exposure, it is useful to determine not only metabolites of the solvents in urine but also the solvents themselves in blood and tissues. In a series of studies on the industrial styrene poisoning, we have been determining styrene in blood and other tissues as occasion calls. Our examination of the method is presented in this report. The outline on the method is as follows: Aliquots of 0.5g of tissues being added 5 ml of n-hexane are homogenized by a high-speed homogenizer (Polytoron) for 10 to 30 seconds and the filtrates containing extracts are analyzed for styrene by gas chromatography. The linearity was ascertained from the calibration curve obtained by adding the known quantities of styrene (4, 10, 20, 40, 100 ppm) to the blood, liver and adipose tissues of rats. Rates of recoveries of styrene from the above tissues were 92 to 101 per cent. Reproducibility of this method was examined by repeating determinations of styrene in the blood, liver and adipose tissues of rats exposed to 500 ppm styrene for 4 hours, the coefficients of variation being 2.8 to 14.0 per cent. There was an approximately linear relationship between the styrene concentration (0 to 1,000 ppm) of the exposed air and those in the blood of exposed rats. We conclude that our simple and rapid method is applicable to determination of solvents other than styrene in organs and tissues by combining suitable solvents for extraction and packings of gas chromatography.

  15. Progress in development of low density polymer foams for the ICF Program

    International Nuclear Information System (INIS)

    Letts, S.A.; Lucht, L.M.; Morgan, R.J.; Cook, R.C.; Tillotson, T.M.; Mercer, M.B.; Miller, D.E.

    1985-01-01

    This report describes the status of CH foam development with densities of 50 mg/ccs and cell sizes of 1 μm for the ICF Program. Two approaches that both involve polymer phase separation are being investigated. The first involves a gelation-crystallization of high molecular weight polyethylene from solution, whereas the second approach involves the modification of the phase separation morphology of water-styrene emulsions by molecularly-tailored surfactants followed by polymerization of the continuous styrene phase

  16. Proton conducting sulphonated fluorinated poly(styrene) crosslinked electrolyte membranes

    Energy Technology Data Exchange (ETDEWEB)

    Soules, A.; Ameduri, B.; Boutevin, B.; David, G. [Institut Charles Gerhardt UMR CNRS 5253 Equipe, Ingenierie et Architectures Macromoleculaires,' ' Ecole Nationale Superieure de Chimie de Montpellier, 8 rue de l' Ecole Normale, 34296 Montpellier, Cedex 05 (France); Perrin, R. [CEA Le Ripault Departement des Materiaux, DMAT/SCMF/LSTP, BP16 - 37260 Monts (France); Gebel, G. [Structure et Proprietes des Architectures Moleculaires UMR 5819 (CEA-CNRS-UJF), INAC, SPrAM, CEA Grenoble, 17 Rue des Martyrs, 38054 Grenoble, Cedex 9 (France)

    2011-10-15

    Potential membranes for polymer electrolyte membrane fuel cell based on crosslinked sulphonated fluorinated polystyrenes (PS) were synthesised in two steps. First, azide-telechelic polystyrene was obtained by iodine transfer polymerisation of styrene in the presence of 1,6-diiodoperfluorohexane followed by azido chain-end functionalisation. Then azide-telechelic polystyrene was efficiently crosslinked with 1,10-diazido-1H,1H,2H,2H,9H,9H,10H,10H-perfluorodecane under UV irradiation. After 45 min only, almost completion of azide crosslinking could be achieved, resulting in crosslinked membranes with insoluble fractions higher than 95%. The sulphonation of the crosslinked membranes afforded ionic exchange capacities (IECs) ranging from 2.2 to 3.2 meq g{sup -1}. The hydration number was shown to be very high (from 30 to 75), depending on both the content of perfluorodecane and of sulphonic acid groups. The morphology of the membranes, assessed by small-angle X-ray scattering, was found to be a lamellar-type structure with two types of ionic domains. For the membrane that exhibited an IEC value of 2.2 meq.g{sup -1}, proton conductivity was in the same range as that of Nafion {sup registered} (120-135 mS.cm{sup -1}), whereas the membrane IEC value of 3.2 meq.g{sup -1} showed a proton conductivity higher than that of Nafion {sup registered} in liquid water from 25 to 80 C, though a high water uptake. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  17. Proton conductive membranes based on poly (styrene-co-allyl alcohol semi-IPN

    Directory of Open Access Journals (Sweden)

    Felipe Augusto Moro Loureiro

    2014-01-01

    Full Text Available The optimization of fuel cell materials, particularly polymer membranes, for PEMFC has driven the development of methods and alternatives to achieve systems with more adequate properties to this application. The sulfonation of poly (styrene-co-allyl alcohol (PSAA, using sulfonating agent:styrene ratios of 2:1, 1:1, 1:2, 1:4, 1:6, 1:8 and 1:10, was previously performed to obtain proton conductive polymer membranes. Most of those membranes exhibited solubility in water with increasing temperature and showed conductivity of approximately 10-5 S cm-1. In order to optimize the PSAA properties, especially decreasing its solubility, semi-IPN (SIPN membranes are proposed in the present study. These membranes were obtained from the diglycidyl ether of bisphenol A (DGEBA, curing reactions in presence of DDS (4,4-diaminodiphenyl sulfone and PSAA. Different DGEBA/PSAA weight ratios were employed, varying the PSAA concentration between 9 and 50% and keeping the mass ratio of DGEBA:DDS as 1:1. The samples were characterized by FTIR and by electrochemical impedance spectroscopy. Unperturbed bands of PSAA were observed in the FTIR spectra of membranes, suggesting that chemical integrity of the polymer is maintained during the synthesis. In particular, bands involving C-C stretching (1450 cm-1, C=C (aromatic, ~ 3030 cm-1 and C-H (2818 and 2928 cm-1 were observed, unchanged after the synthesis. The disappearance or reduction of the intensity of the band at 916 cm-1, attributed to the DGEBA epoxy ring, is evidenced for all samples, indicating the epoxy ring opening and the DGEBA crosslinking. Conductivity of H3PO4 doped membranes increases with temperature, reaching 10-4 S cm-1.

  18. Core–Shell Structure and Aggregation Number of Micelles Composed of Amphiphilic Block Copolymers and Amphiphilic Heterografted Polymer Brushes Determined by Small-Angle X-ray Scattering

    Energy Technology Data Exchange (ETDEWEB)

    Szymusiak, Magdalena; Kalkowski, Joseph; Luo, Hanying; Donovan, Alexander J.; Zhang, Pin; Liu, Chang; Shang, Weifeng; Irving, Thomas; Herrera-Alonso, Margarita; Liu, Ying (JHU); (IIT); (UIC)

    2017-08-31

    A large group of functional nanomaterials employed in biomedical applications, including targeted drug delivery, relies on amphiphilic polymers to encapsulate therapeutic payloads via self-assembly processes. Knowledge of the micelle structures will provide critical insights into design of polymeric drug delivery systems. Core–shell micelles composed of linear diblock copolymers poly(ethylene glycol)-b-poly(caprolactone) (PEG-b-PCL), poly(ethylene oxide)-b-poly(lactic acid) (PEG-b-PLA), as well as a heterografted brush consisting of a poly(glycidyl methacrylate) backbone with PEG and PLA branches (PGMA-g-PEG/PLA) were characterized by dynamic light scattering (DLS) and small-angle X-ray scattering (SAXS) measurements to gain structural information regarding the particle morphology, core–shell size, and aggregation number. The structural information at this quasi-equilibrium state can also be used as a reference when studying the kinetics of polymer micellization.

  19. Core–Shell Structure and Aggregation Number of Micelles Composed of Amphiphilic Block Copolymers and Amphiphilic Heterografted Polymer Brushes Determined by Small-Angle X-ray Scattering

    Energy Technology Data Exchange (ETDEWEB)

    Szymusiak, Magdalena [Department; Kalkowski, Joseph [Department; Luo, Hanying [Department; Donovan, Alexander J. [Department; Zhang, Pin [Department; Liu, Chang [Department; Shang, Weifeng [Department; Irving, Thomas [Department; Herrera-Alonso, Margarita [Department; Liu, Ying [Department; Department

    2017-08-16

    A large group of functional nanomaterials employed in biomedical applications, including targeted drug delivery, relies on amphiphilic polymers to encapsulate therapeutic payloads via self-assembly processes. Knowledge of the micelle structures will provide critical insights into design of polymeric drug delivery systems. Core–shell micelles composed of linear diblock copolymers poly(ethylene glycol)-b-poly(caprolactone) (PEG-b-PCL), poly(ethylene oxide)-b-poly(lactic acid) (PEG-b-PLA), as well as a heterografted brush consisting of a poly(glycidyl methacrylate) backbone with PEG and PLA branches (PGMA-g-PEG/PLA) were characterized by dynamic light scattering (DLS) and small-angle X-ray scattering (SAXS) measurements to gain structural information regarding the particle morphology, core–shell size, and aggregation number. The structural information at this quasi-equilibrium state can also be used as a reference when studying the kinetics of polymer micellization.

  20. Binary Polymer Brushes of Strongly Immiscible Polymers.

    Science.gov (United States)

    Chu, Elza; Babar, Tashnia; Bruist, Michael F; Sidorenko, Alexander

    2015-06-17

    The phenomenon of microphase separation is an example of self-assembly in soft matter and has been observed in block copolymers (BCPs) and similar materials (i.e., supramolecular assemblies (SMAs) and homo/block copolymer blends (HBCs)). In this study, we use microphase separation to construct responsive polymer brushes that collapse to generate periodic surfaces. This is achieved by a chemical reaction between the minor block (10%, poly(4-vinylpyridine)) of the block copolymer and a substrate. The major block of polystyrene (PS) forms mosaic-like arrays of grafted patches that are 10-20 nm in size. Depending on the nature of the assembly (SMA, HBC, or neat BCP) and annealing method (exposure to vapors of different solvents or heating above the glass transition temperature), a range of "mosaic" brushes with different parameters can be obtained. Successive grafting of a secondary polymer (polyacrylamide, PAAm) results in the fabrication of binary polymer brushes (BPBs). Upon being exposed to specific selective solvents, BPBs may adopt different conformations. The surface tension and adhesion of the binary brush are governed by the polymer occupying the top stratum. The "mosaic" brush approach allows for a combination of strongly immiscible polymers in one brush. This facilitates substantial contrast in the surface properties upon switching, previously only possible for substrates composed of predetermined nanostructures. We also demonstrate a possible application of such PS/PAAm brushes in a tunable bioadhesion-bioadhesive (PS on top) or nonbioadhesive (PAAm on top) surface as revealed by Escherichia coli bacterial seeding.

  1. RAFT Synthesis and Self-Assembly of Free-Base Porphyrin Cored Star Polymers

    Directory of Open Access Journals (Sweden)

    Lin Wu

    2011-01-01

    Full Text Available Reversible addition fragmentation chain transfer (RAFT synthesis and self-assembly of free-base porphyrin cored star polymers are reported. The polymerization, in the presence of a free-base porphyrin cored chain transfer agent (CTA-FBP, produced porphyrin star polymers with controlled molecular weights and narrow polydispersities for a number of monomers including N, N-dimethylacrylamide (DMA and styrene (St. Well-defined amphiphilic star block copolymers, P-(PS-PDMA4 and P-(PDMA-PS4 (P: porphyrin, were also prepared and used for self-assembly studies. In methanol, a selective solvent for PDMA, spherical micelles were observed for both block copolymers as characterized by TEM. UV-vis studies suggested star-like micelles were formed from P-(PS-PDMA4, while P-(PDMA-PS4 aggregated into flower-like micelles. Spectrophotometric titrations indicated that the optical response of these two micelles to external ions was a function of micellar structures. These structure-related properties will be used for micelle studies and functional material development in the future.

  2. Core Cross-Linked Multiarm Star Polymers with Aggregation-Induced Emission and Temperature Responsive Fluorescence Characteristics

    KAUST Repository

    Zhang, Zhen

    2017-05-19

    Aggregation-induced emission (AIE) active core cross-linked multiarm star polymers, carrying polystyrene (PS), polyethylene (PE), or polyethylene-b-polycaprolactone (PE-b-PCL) arms, have been synthesized through an “arm-first” strategy, by atom transfer radical copolymerization (ATRP) of a double styrene-functionalized tetraphenylethene (TPE-2St) used as a cross-linker with linear arm precursors possessing terminal ATRP initiating moieties. Polyethylene macroinitiator (PE–Br) was prepared via the polyhomologation of dimethylsulfoxonium methylide with triethylborane followed by oxidation/hydrolysis and esterification of the produced PE–OH with 2-bromoisobutyryl bromide; polyethylene-block-poly(ε-caprolactone) diblock macroinitiator was derived by combining polyhomologation with ring-opening polymerization (ROP). All synthesized star polymers showed AIE-behavior either in solution or in bulk. At high concentration in good solvents (e.g., THF, or toluene) they exhibited low photoluminescence (PL) intensity due to the inner filter effect. In sharp contrast to the small molecule TPE-2St, the star polymers were highly emissive in dilute THF solutions. This can be attributed to the cross-linked structure of poly(TPE-2St) core which restricts the intramolecular rotation and thus induces emission. In addition, the PL intensity of PE star polymers in THF(solvent)/n-hexane(nonsolvent) mixtures, due to their nearly spherical shape, increased when the temperature decreased from 55 to 5 °C with a linear response in the range 40–5 °C.

  3. Synthesis and characterization of poly(styrene-co-methyl methacrylate)

    International Nuclear Information System (INIS)

    Augustinho, Tiago R.; Abarca, Silvia A.C.; Machado, Ricardo A.F.

    2011-01-01

    Polystyrene (PS) is nowadays commonly used due its advantages over competitors. PS presents a lower cost when compared with Acrylonitrile Butadiene Styrene (ABS) and with Polyethylene Tere-phthalate (PET), and can be easier processed than polypropylene (PP). At expandable form (EPS), can be used as projective equipment, thermal insulation, floating boards, refrigerators, isothermal, and low cost applications such as packaging and disposable material. Searching for more resistant materials and with a low cost, researches with copolymers materials are being developed. In this study, copolymerization reactions were carried out by suspension polymerization using monomers styrene and methyl methacrylate (MMA) with styrene. Styrene was in the highest percentage in relation to the MMA. The MMA was selected because is a monomer that presents a higher resistance than PS. The copolymerization was confirmed by performing infrared spectroscopy (IR), nuclear magnetic resonance of hydrogen (RMN 1 H), differential scanning calorimetry (DSC) and thermogravimetry (TGA). (author)

  4. Automated batch emulsion copolymerization of styrene and butyl acrylate

    NARCIS (Netherlands)

    Mballa Mballa, M.A.; Schubert, U.S.; Heuts, J.P.A.; Herk, van A.M.

    2011-01-01

    This article describes a method for carrying out emulsion copolymerization using an automated synthesizer. For this purpose, batch emulsion copolymerizations of styrene and butyl acrylate were investigated. The optimization of the polymerization system required tuning the liquid transfer method,

  5. Subcellular distribution of styrene oxide in rat liver

    International Nuclear Information System (INIS)

    Pacifici, G.M.; Cuoci, L.; Rane, A.

    1984-01-01

    The subcellular distribution of ( 3 H)-styrene-7,8-oxide was studied in the rat liver. The compound was added to liver homogenate to give a final concentration of 2 X 10(-5); 2 X 10(-4) and 2 X 10(-3) M. Subcellular fractions were obtained by differential centrifugation. Most of styrene oxide (59-88%) was associated with the cytosolic fraction. Less than 15 percent of the compound was retrieved in each of the nuclear, mitochondrial and microsomal fractions. A considerable percentage of radioactivity was found unextractable with the organic solvents, suggesting that styrene oxide reacted with the endogenous compounds. The intracellular distribution of this epoxide was also studied in the perfused rat liver. Comparable results with those previously described were obtained. The binding of styrene oxide to the cytosolic protein was investigated by equilibrium dialysis and ultrafiltration. Only a small percentage of the compound was bound to protein

  6. Gel polymer electrolytes for batteries

    Science.gov (United States)

    Balsara, Nitash Pervez; Eitouni, Hany Basam; Gur, Ilan; Singh, Mohit; Hudson, William

    2014-11-18

    Nanostructured gel polymer electrolytes that have both high ionic conductivity and high mechanical strength are disclosed. The electrolytes have at least two domains--one domain contains an ionically-conductive gel polymer and the other domain contains a rigid polymer that provides structure for the electrolyte. The domains are formed by block copolymers. The first block provides a polymer matrix that may or may not be conductive on by itself, but that can soak up a liquid electrolyte, thereby making a gel. An exemplary nanostructured gel polymer electrolyte has an ionic conductivity of at least 1.times.10.sup.-4 S cm.sup.-1 at 25.degree. C.

  7. Nanoparticle packing within block copolymer micelles prepared by the interfacial instability method.

    Science.gov (United States)

    Nabar, Gauri M; Winter, Jessica O; Wyslouzil, Barbara E

    2018-05-02

    The interfacial instability method has emerged as a viable approach for encapsulating high concentrations of nanoparticles (NPs) within morphologically diverse micelles. In this method, transient interfacial instabilities at the surface of an emulsion droplet guide self-assembly of block co-polymers and NP encapsulants. Although used by many groups, there are no systematic investigations exploring the relationship between NP properties and micelle morphology. Here, the effect of quantum dot (QD) and superparamagnetic iron oxide NP (SPION) concentration on the shape, size, and surface deformation of initially spherical poly(styrene-b-ethylene oxide) (PS-b-PEO) micelles was examined. Multi-NP encapsulation and uniform dispersion within micelles was obtained even at low NP concentrations. Increasing NP concentration initially resulted in larger numbers of elongated micelles and cylinders with tightly-controlled diameters smaller than those of spherical micelles. Beyond a critical NP concentration, micelle formation was suppressed; the dominant morphology became densely-loaded NP structures that were coated with polymer and exhibited increased polydispersity. Transmission electron microscopy (TEM) and small angle X-ray scattering (SAXS) revealed that NPs in densely-loaded structures can be well-ordered, with packing volume fractions of up to 24%. These effects were enhanced in magnetic composites, possibly by dipole interactions. Mechanisms governing phase transitions triggered by NP loading in the interfacial instability process were proposed. The current study helps establish and elucidate the active role played by NPs in directing block copolymer assembly in the interfacial instability process, and provides important guiding principles for the use of this approach in generating NP-loaded block copolymer composites.

  8. Experimental Investigations on Tribological Behaviour of Alumina Added Acrylonitrile Butadiene Styrene (ABS Composites

    Directory of Open Access Journals (Sweden)

    T. Panneerselvam

    2016-09-01

    Full Text Available Composite materials are multifunctional in nature, which can be custom-made based on the nature of the applications. The challenge of composite materials lie on complementing the properties of one another i.e. materials which go in the making of composites strengthen each other by inhibiting their weaknesses. Polymers are one of the widely used materials which serve a wide spectrum of engineering needs. In the present work, the tribological behaviour of a composite containing Acrylonitrile Butadiene Styrene (ABS and traces of Alumina is experimentally investigated. Alumina is added to ABS in various percentages such as 1%, and 3% by weight in order to improve the wear resistance of the polymer. Central Composite Design was used to design the experiments and a standard Pin-On-Disk apparatus was used to conduct the experiments. It is observed from the test results that the addition of alumina significantly enhances the wear behavior of the polymer. However, adding more percentage of alumina has led to adverse effect on wear resistance of polymer materials. Abrasive wear mechanism is found to be predominant in the case of alumina added composite materials. It is also found that 1% alumina added composite exhibits excellent wear properties compared to other materials.

  9. Superhydrophilic poly (styrene co acrylonitrile)-ZnO nanocomposite surfaces for UV shielding and self-cleaning applications

    Science.gov (United States)

    Singh, Rajender; Sharma, Ramesh; Barman, P. B.; Sharma, Dheeraj

    2017-11-01

    UV shielding based super hydrophilic material is developed in the present formulation by in situ emulsion polymerization of poly (styrene-acrylonitrile) with ZnO nanoparticles. The ESI-MS technique confirms the structure of polymer nanocomposite by their mass fragments. The XRD study confirms the presence of ZnO phase in polymer matrix. PSAN/ZnO nanocomposite leads to give effective UV shielding (upto 375 nm) and visible luminescence with ZnO content in polymer matrix. The FESEM and TEM studies confirm the symmetrical, controlled growth of PNs. The incorporation of ZnO nanofillers into PSAN matrix lead to restructuring the PNs surfaces into superhydrophilic surfaces in water contact angle (WCA) from 70° to 10°. We believe our synthesized PSAN/ZnO nanocomposite could be potential as UV shielding, luminescent and super hydrophilic nature based materials in related commercial applications.

  10. Liquid-liquid phase separation in dilute solutions of poly(styrene sulfonate) with multivalent cations: Phase diagrams, chain morphology, and impact of temperature

    Science.gov (United States)

    Hansch, Markus; Hämisch, Benjamin; Schweins, Ralf; Prévost, Sylvain; Huber, Klaus

    2018-01-01

    The dilute solution behavior of sodium poly(styrene sulfonate) is studied in the presence of trivalent Al3+ and bivalent Ba2+ cations at various levels of excess NaCl. The study evaluates the phase behavior and the morphology of the polyelectrolyte chains with increasing extent of decoration with the Al3+ and Ba2+ cations and analyses the effect of temperature on these decorated chains. The phase behavior is presented in the form of the cation concentration versus the respective poly(styrene sulfonate) concentration, recorded at the onset of precipitation. Whereas poly(styrene sulfonate) with Al3+ exhibits a linear phase boundary, denoted as the "threshold line," which increases with increasing poly(styrene sulfonate) concentration, Ba2+ cations show a threshold line which is independent of the poly(styrene sulfonate) concentration. An additional re-entrant phase, at considerably higher cation content than those of the threshold lines, is observed with Al3+ cations but not with Ba2+ cations. The threshold line and the re-entrant phase boundary form parts of the liquid-liquid phase boundary observed at the limit of low polymer concentration. The dimensions of the polyelectrolyte chains shrink considerably while approaching the respective threshold lines on increase of the Al3+ and Ba2+ cation content. However, subtle differences occur between the morphological transformation induced by Al3+ and Ba2+. Most strikingly, coils decorated with Al3+ respond very differently to temperature variations than coils decorated with Ba2+ do. As the temperature increases, the poly(styrene sulfonate) chains decrease their size in the presence of Al3+ cations but increase in size in the presence of Ba2+ cations.

  11. Design and Synthesis of Network-Forming Triblock Copolymers Using Tapered Block Interfaces

    Science.gov (United States)

    Kuan, Wei-Fan; Roy, Raghunath; Rong, Lixia; Hsiao, Benjamin S.; Epps, Thomas H.

    2012-01-01

    We report a strategy for generating novel dual-tapered poly(isoprene-b-isoprene/styrene-b-styrene-b-styrene/methyl methacrylate-b-methyl methacrylate) [P(I-IS-S-SM-M)] triblock copolymers that combines anionic polymerization, atom transfer radical polymerization (ATRP), and Huisgen 1,3-dipolar cycloaddition click chemistry. The tapered interfaces between blocks were synthesized via a semi-batch feed using programmable syringe pumps. This strategy allows us to manipulate the transition region between copolymer blocks in triblock copolymers providing control over the interfacial interactions in our nanoscale phase-separated materials independent of molecular weight and block constituents. Additionally, we show the ability to retain a desirous and complex multiply-continuous network structure (alternating gyroid) in our dual-tapered triblock material. PMID:23066522

  12. Emprego de catalisadores à base de níquel para homo- e copolimerização de estireno The use of nickel-based catalysts for homo-and copolymerization of styrene

    Directory of Open Access Journals (Sweden)

    Luis Carlos Ferreira Jr.

    2004-12-01

    Full Text Available This review deals with the homo- and copolymerization of styrene with nickel catalysts. The catalytic activity, polymer stereoregularity, polymer molecular weight and polydispersity are dependent upon nickel ligands and reaction parameters. Catalysts supported on silica, treated with methylaluminoxane (MAO, have shown higher stereospecificity and activity compared to homogeneous ones. The influence of these parameters is discussed focusing on the elucidation of some aspects of the polymerization mechanism.

  13. Synaptic contacts impaired by styrene-7,8-oxide toxicity

    International Nuclear Information System (INIS)

    Corsi, P.; D'Aprile, A.; Nico, B.; Costa, G.L.; Assennato, G.

    2007-01-01

    Styrene-7,8-oxide (SO), a chemical compound widely used in industrial applications, is a potential hazard for humans, particularly in occupational settings. Neurobehavioral changes are consistently observed in occupationally exposed individuals and alterations of neurotransmitters associated with neuronal loss have been reported in animal models. Although the toxic effects of styrene have been extensively documented, the molecular mechanisms responsible for SO-induced neurotoxicity are still unclear. A possible dopamine-mediated effect of styrene neurotoxicity has been previously demonstrated, since styrene oxide alters dopamine neurotransmission in the brain. Thus, the present study hypothesizes that styrene neurotoxicity may involve synaptic contacts. Primary striatal neurons were exposed to styrene oxide at different concentrations (0.1-1 mM) for different time periods (8, 16, and 24 h) to evaluate the dose able to induce synaptic impairments. The expression of proteins crucial for synaptic transmission such as Synapsin, Synaptophysin, and RAC-1 were considered. The levels of Synaptophysin and RAC-1 decreased in a dose-dependent manner. Accordingly, morphological alterations, observed at the ultrastructural level, primarily involved the pre-synaptic compartment. In SO-exposed cultures, the biochemical cascade of caspases was activated affecting the cytoskeleton components as their target. Thus the impairments in synaptic contacts observed in SO-exposed cultures might reflect a primarily morphological alteration of neuronal cytoskeleton. In addition, our data support the hypothesis developed by previous authors of reactive oxygen species (ROS) initiating events of SO cytotoxicity

  14. 21 CFR 177.1050 - Acrylonitrile/styrene copoly-mer modified with butadiene/styrene elastomer.

    Science.gov (United States)

    2010-04-01

    ... parts by weight of a grafted rubber consisting of (i) 8-12 parts of butadiene/styrene elastomer... limitations are determined by an infrared spectro-photo-metric method titled “Infrared Spectro-photo-metric...

  15. Polymer supported sulphanilic acid: A highly efficient and recyclable ...

    Indian Academy of Sciences (India)

    The resulting chloromethylated styrene- divinylbenzene copolymer beads were designated as. P2 and analysed for chlorine content by Stepnow method.37. 2.3 Procedure for polymer supported sulphanilic acid (P3). P2 (5 gm) were dispersed in methanol (15 ml) and allowed to swell for 2 h. To the swollen bead, aque-.

  16. Band gap control using electric field of photonic gel cells fabricated with block copolymer and hydrogel.

    Science.gov (United States)

    Lee, Sung Nam; Baek, Young Bin; Shin, Dong Myung

    2014-08-01

    Optical and electrical characteristics of the devices using photonic gel film and hydrogel electrolyte were studied. Poly(styrene-b-2-vinylpyridine) (PS-b-P2VP) lamellar film with alternating hydrophobic block and hydrophilic polyelectrolyte block polymers (52 kg/mol-b-57 kg/mol) were prepared for the photonic gel. Poly(isobutylene-co-maleic acid) sodium salts were prepared for the hydrogel. This hydrogel fiber is common water swelling material and it owned ions for a device has conductivity. Photonic gel and hydrogel was spin coating onto Indium-tin-oxide (ITO) glass for make electric fields. The reflectance maximum wavelength of photonic crystal device shifted from 538 nm and reached to 557 nm, 585 nm and 604 nm during 30 min voltage applying time. The bandwidth variation was very limited. Loss of electrolyte was much less with hydrogel compared to the pure water. We can control color of hydrogel used photonic device by electric field with reasonable time range under moderate electric field by applying 2 V between two facing electrodes.

  17. A molecular dynamics study on Young's modulus and tribology of carbon nanotube reinforced styrene-butadiene rubber.

    Science.gov (United States)

    Chawla, Raj; Sharma, Sumit

    2018-03-18

    Styrene-butadiene rubber is a copolymer widely used in making car tires and has excellent abrasion resistance. The Young's modulus and tribology of pure styrene butadiene rubber (SBR) polymer and carbon nanotube reinforced polymer composites have been investigated using molecular dynamics simulations. The mechanism of enhanced tribology properties using carbon nanotube has been studied and discussed. The obtained Young's modulus shows the enhancement in mechanical properties of SBR polymer when carbon nanotubes are used as reinforcement. The concentration, temperature and velocity profiles, radial distribution function, frictional stresses, and cohesive energy density are calculated and analyzed in detail. The Young's modulus of SBR matrix increases about 29.16% in the presence of the 5% CNT. The atom movement velocity and average cohesive energy density in the friction area of pure SBR matrix was found to be more than that of the CNT/SBR composite. Graphical abstract Initial and final conditions of (a) pure SBR matrix and (b) CNT/SBR matrix subjected toshear loading and frictional stresses of top Fe layers of both pure SBR and CNT/SBR composite.

  18. Fabrication of Acrylonitrile-Butadiene-Styrene Nanostructures with Anodic Alumina Oxide Templates, Characterization and Biofilm Development Test for Staphylococcus epidermidis.

    Directory of Open Access Journals (Sweden)

    Camille Desrousseaux

    Full Text Available Medical devices can be contaminated by microbial biofilm which causes nosocomial infections. One of the strategies for the prevention of such microbial adhesion is to modify the biomaterials by creating micro or nanofeatures on their surface. This study aimed (1 to nanostructure acrylonitrile-butadiene-styrene (ABS, a polymer composing connectors in perfusion devices, using Anodic Alumina Oxide templates, and to control the reproducibility of this process; (2 to characterize the physico-chemical properties of the nanostructured surfaces such as wettability using captive-bubble contact angle measurement technique; (3 to test the impact of nanostructures on Staphylococcus epidermidis biofilm development. Fabrication of Anodic Alumina Oxide molds was realized by double anodization in oxalic acid. This process was reproducible. The obtained molds present hexagonally arranged 50 nm diameter pores, with a 100 nm interpore distance and a length of 100 nm. Acrylonitrile-butadiene-styrene nanostructures were successfully prepared using a polymer solution and two melt wetting methods. For all methods, the nanopicots were obtained but inside each sample their length was different. One method was selected essentially for industrial purposes and for better reproducibility results. The flat ABS surface presents a slightly hydrophilic character, which remains roughly unchanged after nanostructuration, the increasing apparent wettability observed in that case being explained by roughness effects. Also, the nanostructuration of the polymer surface does not induce any significant effect on Staphylococcus epidermidis adhesion.

  19. Grafting of Styrene onto Commercial Polytetrafluorethylene (PTFE) Membrane and Sulfonation for Possible use in Fuel Cell

    International Nuclear Information System (INIS)

    Abdel-Hady, E.E.; Abdel-Hamed, M.O.; Hammam, A.M.; El-toony, M.M.

    2010-01-01

    The purpose of this work is to initiate the fundamental research necessary for the development of a novel proton-exchange membranes (PEM) to overcome the material and performance limitations of the s tate of the art N afion that is used in both hydrogen and methanol fuel cells. Silica was inserted in commercial PTFE membrane in ratio 8%. Gamma irradiation was used for grafting of different ratios of styrene onto the membrane in one and two steps. Methacrylic acid and styrene were used as binary monomers for grafting of such membranes to raise the grafting percentage. Thermal characterization of the grafted membrane was discussed using thermal gravimetric analysis (TGA). The mechanical properties were tested by measuring ultimate tensile value, and Young modulus. The positron annihilation lifetime spectroscopy has been used to investigate the free volume hole size, while the surface morphology of the membrane was studied by scanning electron microscope (SEM). It was found that the maximum water uptake of the sulfonated membrane reached 20% by weight. The proton conductivity of the prepared polymer electrolyte was measured by ac impedance spectroscopic analysis. And it was found to be 0.9 x 10 -4 ohm -1 cm -1 .

  20. Metabolism of styrene to styrene oxide and vinylphenols in cytochrome P450 2F2- and P450 2E1-knockout mouse liver and lung microsomes.

    Science.gov (United States)

    Shen, Shuijie; Li, Lei; Ding, Xinxin; Zheng, Jiang

    2014-01-21

    Pulmonary toxicity of styrene is initiated by cytochromes P450-dependent metabolic activation. P450 2E1 and P450 2F2 are considered to be two main cytochrome P450 enzymes responsible for styrene metabolism in mice. The objective of the current study was to determine the correlation between the formation of styrene metabolites (i.e., styrene oxide and 4-vinylphenol) and pulmonary toxicity of styrene, using Cyp2e1- and Cyp2f2-null mouse models. A dramatic decrease in the formation of styrene glycol and 4-vinylphenol was found in Cyp2f2-null mouse lung microsomes relative to that in the wild-type mouse lung microsomes; however, no significant difference in the production of the styrene metabolites was observed between lung microsomes obtained from Cyp2e1-null and the wild-type mice. The knockout and wild-type mice were treated with styrene (6.0 mmol/kg, ip), and cell counts and LDH activity in bronchoalveolar lavage fluids were monitored to evaluate the pulmonary toxicity induced by styrene. Cyp2e1-null mice displayed a susceptibility to lung toxicity of styrene similar to that of the wild-type animals; however, Cyp2f2-null mice were resistant to styrene-induced pulmonary toxicity. In conclusion, both P450 2E1 and P450 2F2 are responsible for the metabolic activation of styrene. The latter enzyme plays an important role in styrene-induced pulmonary toxicity. Both styrene oxide and 4-vinylphenol are suggested to participate in the development of lung injury induced by styrene.

  1. 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

  2. Moessbauer spectroscopic study of Fe{sup II}-doped sulphonated poly(ether-urethane)-styrene-acrylate copolymer

    Energy Technology Data Exchange (ETDEWEB)

    Kamnev, A. A. [Russian Academy of Sciences, Institute of Biochemistry and Physiology of Plants and Microorganisms (Russian Federation); Grigoryeva, O. P.; Fainleib, A. M. [National Academy of Sciences of Ukraine, Institute of Macromolecular Chemistry (Ukraine); Kuzmann, E., E-mail: kuzmann@ludens.elte.hu [Eoetvoes Lorand University, Institute of Chemistry (Hungary)

    2013-04-15

    Thermoplastic linear ionomer based on sulphonated poly(ether-urethane)-styrene-acrylate copolymer, doped with natural Fe{sup 2 + }, was studied by Moessbauer spectroscopy at T = 78 and 290 K to monitor the chemical state of Fe species. The Fe{sup 2 + } added to aqueous suspension of the system was only partly oxidised in the course of polymer film preparation and drying in air. The oxidised part comprised a magnetic phase ({approx}19 % of total Fe both at T = 78 and 298 K) and a quadrupole doublet ({approx}40 %), while Fe{sup II} (over 40 %) stabilised in two types of microenvironments.

  3. Carbon nanotubes and carbon onions for modification of styrene-acrylate copolymer based nanocomposites

    International Nuclear Information System (INIS)

    Merijs-Meri, Remo; Zicans, Janis; Ivanova, Tatjana; Bitenieks, Juris; Kuzhir, Polina; Maksimenko, Sergey; Kuznetsov, Vladimir; Moseenkov, Sergey

    2014-01-01

    Styrene acrylate polymer (SAC) nanocomposites with various carbon nanofillers (multiwalled carbon nanotubes MWCNTs and onion like carbon OLC) are manufactured by means of latex based routes. Concentration of the carbon nanofillers is changed in a broad interval starting from 0.01 up to 10 wt. %. Elastic, dielectric and electromagnetic properties of SAC nanocomposites are investigated. Elastic modulus, electrical conductivity and electromagnetic radiation absorption of the investigated SAC nanocomposites increase along with rising nanofiller content. The effect of the addition of anisometric MWCNTs on the elastic properties of the composite is higher than in the case of the addition of OLC. Higher electrical conductivity of the OLC containing nanocomposites is explained with the fact that reasonable agglomeration of the nanofiller can promote the development of electrically conductive network. Efficiency of the absorption of electromagnetic radiation depends on the development of conductive network within the SAC matrix

  4. Comparison between some determination methods of residual styrene in plastic scintillators

    International Nuclear Information System (INIS)

    Bezuglyi, V.D.; Ponomarev, Yu.P.; Gunder, O.A.; Biteman, V.B.; Senchishin, V.G.

    1988-01-01

    Scintillators made of plastic materials based on polystyrene with addition of p-terphenyl and 1,4-di-[(2,5-phenyl)oxazolyl] benzene have found wide application principally in the detection of radioactivity. The stability of the scintillating characteristics of these materials depends to great degree on the concentration of the residual monomer and for this reason it is important to have a sufficiently convenient method for the determination of this latter. We investigated the bromometric and acid-base titration methods with visual and potentiometric titration end point detection. We also examined the polarographic methods, direct and indirect, using the electroreduction of the mercury acetate complex of the monomer. We checked the methods on a scintillator sample and on synthetic mixtures, i.e., mixtures of monomer, polymer, and p-terphenyl. We compared the determination results for styrene and showed that the most accurate procedure is the bromometric determination with potentiometric indication of the end-point

  5. Carbon nanotubes and carbon onions for modification of styrene-acrylate copolymer based nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Merijs-Meri, Remo; Zicans, Janis; Ivanova, Tatjana; Bitenieks, Juris [Institute of Polymer Materials, Riga Technical University, Azenes street 14/24, LV-1048, Riga (Latvia); Kuzhir, Polina; Maksimenko, Sergey [Institute of Nuclear Problems, Belarus State University, Bobruiskaya str. 11, 220030, Minsk (Belarus); Kuznetsov, Vladimir; Moseenkov, Sergey [Boreskov Institute of Catalyst Siberian branch of RAS, pr. Lavrentieva 5, 630090, Novosibirsk (Russian Federation)

    2014-05-15

    Styrene acrylate polymer (SAC) nanocomposites with various carbon nanofillers (multiwalled carbon nanotubes MWCNTs and onion like carbon OLC) are manufactured by means of latex based routes. Concentration of the carbon nanofillers is changed in a broad interval starting from 0.01 up to 10 wt. %. Elastic, dielectric and electromagnetic properties of SAC nanocomposites are investigated. Elastic modulus, electrical conductivity and electromagnetic radiation absorption of the investigated SAC nanocomposites increase along with rising nanofiller content. The effect of the addition of anisometric MWCNTs on the elastic properties of the composite is higher than in the case of the addition of OLC. Higher electrical conductivity of the OLC containing nanocomposites is explained with the fact that reasonable agglomeration of the nanofiller can promote the development of electrically conductive network. Efficiency of the absorption of electromagnetic radiation depends on the development of conductive network within the SAC matrix.

  6. Styrene and methyl methacrylate copolymer synthesized by RF inductively coupled plasma

    Energy Technology Data Exchange (ETDEWEB)

    Li, Z; Gillon, X; Diallo, M; Houssiau, L; Pireaux, J-J, E-mail: zhiling.li@fundp.ac.be [University of Namur (FUNDP) Research Centre in Physics of Matter and Radiation (PMR), 61, Rue de Bruxelles, 5000 Namur (Belgium)

    2011-01-01

    A series of random copolymers of styrene and methyl methacrylate was prepared on a silicon substrate by RF pulsed inductively coupled plasma. The plasma gas phase was investigated by optical emission spectroscopy (OES). The physico-chemical characteristics of the deposited copolymer films were analyzed by several surface techniques: X-ray photoelectron spectroscopy (XPS), Fourier-Transform infrared absorption (FT-IR), Time-of-flight secondary ion mass spectrometry (ToF-SIMS), etc. OES of the plasma and FT-IR spectra of the films are predictive: plasma emitting a higher relative benzyl radical signal results in the deposition of a more aromatic plasma polymer. The functional thin films can be deposited by selection of the co-monomers.

  7. Performance of asphaltic concrete incorporating styrene butadiene rubber subjected to varying aging condition

    Science.gov (United States)

    Salah, Faisal Mohammed; Jaya, Ramadhansyah Putra; Mohamed, Azman; Hassan, Norhidayah Abdul; Rosni, Nurul Najihah Mad; Mohamed, Abdullahi Ali; Agussabti

    2017-12-01

    The influence of styrene butadiene rubber (SBR) on asphaltic concrete properties at different aging conditions was presented in this study. These aging conditions were named as un-aged, short-term, and long-term aging. The conventional asphalt binder of penetration grade 60/70 was used in this work. Four different levels of SBR addition were employed (i.e., 0 %, 1 %, 3 %, and 5 % by binder weight). Asphalt concrete mixes were prepared at selected optimum asphalt content (5 %). The performance was evaluated based on Marshall Stability, resilient modulus, and dynamic creep tests. Results indicated the improving stability and permanent deformation characteristics that the mixes modified with SBR polymer have under aging conditions. The result also showed that the stability, resilient modulus, and dynamic creep tests have the highest rates compared to the short-term aging and un-aged samples. Thus, the use of 5 % SBR can produce more durable asphalt concrete mixtures with better serviceability.

  8. Characteristic features of heterophase polymerisation of styrene with simultaneous formation of surfactants at the interface

    International Nuclear Information System (INIS)

    Prokopov, Nikolai I; Gritskova, Inessa A

    2001-01-01

    Data on the heterophase polymerisation of styrene under conditions of surfactant formation at the monomer-water interface are generalised. A new, in principle, approach is proposed the essence of which is to obtain a monomer emulsion simultaneously with the synthesis of an emulsifier at the monomer-water interface and with initiation of the polymerisation in the interfacial layer. The preparation of surfactants at the interface allows one to control efficiently the degree of dispersion and the stability of the emulsions formed. By varying the nature of the acid and the metal counter-ion used in the surfactant synthesis at the interface, it is possible to change the interfacial tension, to influence the microemulsification, disintegration of the monomer, and the formation of structure of interfacial adsorption layers. The mechanism of formation of polymer-monomeric particles as well as their diameter and size distribution depend substantially on the solubility of the resulting surfactants in water. The bibliography includes 47 references.

  9. Characteristic features of heterophase polymerisation of styrene with simultaneous formation of surfactants at the interface

    Energy Technology Data Exchange (ETDEWEB)

    Prokopov, Nikolai I; Gritskova, Inessa A [M.V. Lomonosov Moscow State Academy of Fine Chemical Technology, Moscow (Russian Federation)

    2001-09-30

    Data on the heterophase polymerisation of styrene under conditions of surfactant formation at the monomer-water interface are generalised. A new, in principle, approach is proposed the essence of which is to obtain a monomer emulsion simultaneously with the synthesis of an emulsifier at the monomer-water interface and with initiation of the polymerisation in the interfacial layer. The preparation of surfactants at the interface allows one to control efficiently the degree of dispersion and the stability of the emulsions formed. By varying the nature of the acid and the metal counter-ion used in the surfactant synthesis at the interface, it is possible to change the interfacial tension, to influence the microemulsification, disintegration of the monomer, and the formation of structure of interfacial adsorption layers. The mechanism of formation of polymer-monomeric particles as well as their diameter and size distribution depend substantially on the solubility of the resulting surfactants in water. The bibliography includes 47 references.

  10. MODELING STYRENE HYDROGENATION KINETICS USING PALLADIUM CATALYSTS

    Directory of Open Access Journals (Sweden)

    G. T. Justino

    Full Text Available Abstract The high octane number of pyrolysis gasoline (PYGAS explains its insertion in the gasoline pool. However, its use is troublesome due to the presence of gum-forming chemicals which, in turn, can be removed via hydrogenation. The use of Langmuir-Hinshelwood kinetic models was evaluated for hydrogenation of styrene, a typical gum monomer, using Pd/9%Nb2O5-Al2O3 as catalyst. Kinetic models accounting for hydrogen dissociative and non-dissociative adsorption were considered. The availability of one or two kinds of catalytic sites was analyzed. Experiments were carried out in a semi-batch reactor at constant temperature and pressure in the absence of transport limitations. The conditions used in each experiment varied between 16 - 56 bar and 60 - 100 ºC for pressure and temperature, respectively. The kinetic models were evaluated using MATLAB and EMSO software. Models using adsorption of hydrogen and organic molecules on the same type of site fitted the data best.

  11. STUDY OF SURFACE MODIFIED POLYMERS IN THE MODIFICATION OF NANOMATERIALS

    Directory of Open Access Journals (Sweden)

    G. V. Popov

    2014-01-01

    Full Text Available The comparative study of change of surface tension of solutions of some commercial rubbers before and after thermal ageing technique du-Nui, analyzed the features of change of surface tension of solutions of various rubbers in the presence of a mixture of fullerenes. Calculations of the Gibbs energy and the analysis of the obtained data to predict the behavior of polymer systems when changes are made to mix of fullerenes in a wide concentration range. When comparing the results of changes in Gibbs energy and the surface tension in fluids rubbers shown that mentioned above in solutions of elastomers aged, than the control. This fact confirms the initial chapeau of physic-chemical interactions of molecules fullerenes by segments of the Kuna and end groups of the polymer chains, as it is known that when thermal-oxidative degradation of rubbers, respectively the number of segments of the Kuna and branched loose ends of macromolecules that are free to react with fullerenes in solution, free from spatial constraints. A comparative analysis of the interaction of rubbers with different chemical composition with double branches has shown that it is easier to just react and has minimum energy polibutadien interaction that has to do with lack of branching and no radicals in its structure and in the backbone chain. The maximum energy of interaction with Fullerenes have SBS rubber because it has large styrene blocks in the main polymer chain that causes the spatial constraints to direct contact with fullerene molecules, you can assume that the interaction is only low-molecular fraction of Fullerenes mixture, possessing the necessary dimensions. As a result of the study shows that the application of the method of separation ring (Du-Nui allows you to predict the properties of rubber with modified nanomaterial’s with minimal labor costs.

  12. Analysis of Mechanical and Thermogravimetric Properties of Composite Materials Based on PVA/MWCNT and Styrene-Acrylic Copolymer/MWCNT

    Science.gov (United States)

    Volynets, N. I.; Poddubskaya, O. G.; Demidenko, M. I.; Lyubimov, A. G.; Kuzhir, P. P.; Suslyaev, V. I.; Pletnev, M. A.; Zicans, Janis

    2017-08-01

    Mechanical and thermogravimetric properties of polymer composite materials with various concentrations of multiwalled carbon nanotubes effectively shielding radiation in the radio frequency (20 Hz - 1 MHz) and microwave (26-36 GHz) frequency ranges are studied. As a matrix, widely available polymeric materials, such as polyvinyl acetate and styrene-acrylate, were used in the form of dispersions. From the analysis of the obtained experimental data, it was shown that the introduction of carbon nanotubes into the polymer matrix makes it possible to increase mechanical properties and thermal stability of composite materials.

  13. Epidural block

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/patientinstructions/000484.htm Epidural block - pregnancy To use the sharing features on this page, please enable JavaScript. An epidural block is a numbing medicine given by injection (shot) ...

  14. Microstructure Development and Its Influence on the Properties of Styrene-Ethylene-Butylene-Styrene/Polystyrene Blends

    Directory of Open Access Journals (Sweden)

    Ritima Banerjee

    2018-04-01

    Full Text Available The present work is a novel attempt to understand the microstructure of styrene-ethylene-butylene-styrene (SEBS/polystyrene (PS blends not only through morphological studies, but also thermal, mechanical and rheological characterizations. SEBS/PS blends containing 10, 30 and 50 wt % PS were processed in a micro-compounder and characterized. Scanning electron microscopy (SEM studies, with selective staining of the PS phase, revealed the presence of PS as nanometer-sized domains, as well as phase-separated micrometer-sized aggregates. Blends with 30 and 50 wt % PS exhibited a fibrillar microstructure, obeying Hirsch’s model of short fiber composites. A remarkable increase in glass transition temperature indicated a strong interaction of the fibrils with SEBS. All blends showed two modes of relaxation corresponding to the two phases. A single mode of relaxation of the PS phase has been attributed to combined effects of the partial miscibility of the added PS, along with the interaction of the fibrils with SEBS. The long relaxation time of the elastomeric phase indicated the tendency of these materials to undergo time-dependent shrinkage in secondary processing operations. An increase in PS content resulted in the lowering of the shear viscosity and energy requirement for mixing, indicating the ease of processing.

  15. Preparation and Characterization of Styrene Bearing Diethanolamine Side Group, Styrene Copolymer Systems, and Their Metal Complexes

    Directory of Open Access Journals (Sweden)

    Aslışah Açıkses

    2018-01-01

    Full Text Available The two copolymer systems of styrene bearing diethanol amine side group and styrene were prepared by free radical polymerization method at 60°C in presence of 1,4-dioxane as solvent and AIBN as initiator. Their metal complexes were prepared by reaction of the copolymer used as ligand P(DEAMSt-co-StL′′ and Ni(II and Co(II metal ions, which was carried out in presence of ethanol and NaOH at 65°C for 48 h in pH = 7.5. The structures of the copolymers used as ligand and metal complexes were identified by FT-IR, 1H-NMR spectra, and elemental analysis. The properties of the copolymers used as ligand and metal complexes were characterized by SEM-EDX, AAS, DSC, TGA, and DTA techniques. Then, the electrical properties of the copolymers and metal complexes were examined as a function of the temperature and frequency, and the activation energies (Ea were estimated with conductivity measurements.

  16. Population Blocks.

    Science.gov (United States)

    Smith, Martin H.

    1992-01-01

    Describes an educational game called "Population Blocks" that is designed to illustrate the concept of exponential growth of the human population and some potential effects of overpopulation. The game material consists of wooden blocks; 18 blocks are painted green (representing land), 7 are painted blue (representing water); and the remaining…

  17. Styrene removal from wate gas by the fungus Exophiala Jeanselmei in a biofilter

    NARCIS (Netherlands)

    Cox, Hubertus Henricus Jacobus

    1995-01-01

    Styrene is an environmental pollutant, emitted in large quantities to the atmosphere by various industrial sectors. Legislation requires industry to reduce the emission of styrene. One option to purify industrial waste gases is biological treatment in biofilters. ... Zie: Summary

  18. High temperature polymer concrete compositions

    Science.gov (United States)

    Fontana, Jack J.; Reams, Walter

    1985-01-01

    This invention is concerned with a polymer concrete composition, which is a two-component composition useful with many bases including metal. Component A, the aggregate composition, is broadly composed of silica, silica flour, portland cement, and acrylamide, whereas Component B, which is primarily vinyl and acrylyl reactive monomers, is a liquid system. A preferred formulation emphasizing the major necessary components is as follows: ______________________________________ Component A: Silica sand 60-77 wt. % Silica flour 5-10 wt. % Portland cement 15-25 wt. % Acrylamide 1-5 wt. % Component B: Styrene 50-60 wt. % Trimethylolpropane 35-40 wt. % trimethacrylate ______________________________________ and necessary initiators, accelerators, and surfactants.

  19. Solvent influence during radiation induced grafting of styrene in PVDF

    International Nuclear Information System (INIS)

    Ferreira, Henrique P.; Parra, Duclerc F.; Lugao, Ademar B.

    2013-01-01

    Radiation-induced grafting was studied to produce styrene grafted poly(vinylidene fluoride) (PVDF) membranes. PVDF films with 0.125 mm thickness were irradiated at doses between 5 and 20 kGy in the presence of styrene/N,N-dimethylformamide (DMF), styrene/acetone or styrene/toluene solutions (1:1, v/v) at dose rate of 5 kGy h -1 by simultaneous method, using gamma rays from a Co-60, under nitrogen atmosphere and at room temperature. The films were characterized before and after modification by grafting yield (GY %), infrared spectroscopy (FT-IR), scanning electron microscopy (SEM and EDS), differential scanning calorimetry (DSC) and thermogravimetry (TG/DTG). GY results shows that grafting increases with dose and toluene hinders the grafting, leading to a small GY comparing to DMF and acetone. It was possible to confirm the grafting of styrene by FT-IR due to the new characteristics peaks and by the TG and DSC due to changes in thermal behavior of the grafted material. SEM and EDS show surface and cross-section distribution of the grafting, which takes place on the surface and heterogeneously with toluene as solvent and homogeneously and penetrating into the inner layers of the matrix using DMF and acetone as solvent. (author)

  20. Features of radiation chemical processes in ethylene-styrene copolymers

    International Nuclear Information System (INIS)

    Leshchenko, S.S.; Mal'tseva, A.P.; Iskakov, L.I.; Karpov, V.L.

    1976-01-01

    A study was made of statistical copolymers of ethylene with styrene to determine their structure and properties and radio-chemical transformations. The styrene content of the copolymers ranged from 1 to 85 mole%. The investigation covered non-irradiated copolymers and those irradiated with doses of 1-1000Mrad at room temperature and at liquid nitrogen temperature. It is shown that styrene units present in the CES inhibited all radio-chemical processes compared with PE irradiated under similar conditions. It is suggested that the radiation resistance of CES with styrene contents up to 10 mole % increases in the course of irradiation as a result of the formation of structures with a high degree of conjugation which are more capable of scattering absorbed energy than in the case of phenyl rings by themselves. The most promising of the CES examined is the one with a styrene content of 5 mole %. The mechanical properties of this copolymer are similar to those of PE, and its radiation resistance rises under service conditions in the presence of ionizing radiation

  1. Solvent influence during radiation induced grafting of styrene in PVDF

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira, Henrique P.; Parra, Duclerc F.; Lugao, Ademar B., E-mail: hp.ferreira@usp.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2013-07-01

    Radiation-induced grafting was studied to produce styrene grafted poly(vinylidene fluoride) (PVDF) membranes. PVDF films with 0.125 mm thickness were irradiated at doses between 5 and 20 kGy in the presence of styrene/N,N-dimethylformamide (DMF), styrene/acetone or styrene/toluene solutions (1:1, v/v) at dose rate of 5 kGy h{sup -1} by simultaneous method, using gamma rays from a Co-60, under nitrogen atmosphere and at room temperature. The films were characterized before and after modification by grafting yield (GY %), infrared spectroscopy (FT-IR), scanning electron microscopy (SEM and EDS), differential scanning calorimetry (DSC) and thermogravimetry (TG/DTG). GY results shows that grafting increases with dose and toluene hinders the grafting, leading to a small GY comparing to DMF and acetone. It was possible to confirm the grafting of styrene by FT-IR due to the new characteristics peaks and by the TG and DSC due to changes in thermal behavior of the grafted material. SEM and EDS show surface and cross-section distribution of the grafting, which takes place on the surface and heterogeneously with toluene as solvent and homogeneously and penetrating into the inner layers of the matrix using DMF and acetone as solvent. (author)

  2. Melt dispersion of thermoplastic polystyrene in polymer polyols

    OpenAIRE

    2009-01-01

    Polystyrene is dispersed into a polyol via a mechanical dispersion process. A stabilizer is present to stabilize the dispersed polymer particles. The stabilizer includes a copolymer of (1) from 10 to 70% by weight of a branched polyol which has a molecular weight of from 4000 to 20,000, from 0.2 to about 1.2 polymerizable ethylenically unsaturated groups per molecule and from about 3 to about 8 hydroxyl groups per molecule with (2) from 30 to 90% by weight of styrene or a mixture of styrene a...

  3. Radiation Grafted Polymer Membranes for Fuel Cell Applications

    International Nuclear Information System (INIS)

    Scherer, G.G.; Wallasch, F.; Ben Youcef, H.; Gubler, L.

    2012-01-01

    Partially fluorinated proton exchange membranes prepared via radiation induced graft copolymerization ('radiation grafting') offer the prospect of cost-effective and tailor made membrane electrolytes for the polymer electrolyte fuel cell (PEFC). The composition and structure of radiation grafted membranes can be adjusted in a broad range to balance the different requirements of proton transport and mechanical robustness. Based on the earlier work on Styrene grafting, the novel monomer combination α-methyl-styrene/methacrylonitrile (AMS/MAN) is introduced for improved stability in the prevailing fuel cell environment. Successful fuel cell experiments proved the concept. (author)

  4. Radiation Grafted Polymer Membranes for Fuel Cell Applications

    Energy Technology Data Exchange (ETDEWEB)

    Scherer, G G; Wallasch, F; Ben Youcef, H; Gubler, L [Electrochemistry Laboratory, Paul Scherrer Institut, CH-5232 Villigen (Switzerland)

    2012-09-15

    Partially fluorinated proton exchange membranes prepared via radiation induced graft copolymerization ('radiation grafting') offer the prospect of cost-effective and tailor made membrane electrolytes for the polymer electrolyte fuel cell (PEFC). The composition and structure of radiation grafted membranes can be adjusted in a broad range to balance the different requirements of proton transport and mechanical robustness. Based on the earlier work on Styrene grafting, the novel monomer combination {alpha}-methyl-styrene/methacrylonitrile (AMS/MAN) is introduced for improved stability in the prevailing fuel cell environment. Successful fuel cell experiments proved the concept. (author)

  5. Wood-Polymer composites obtained by gamma irradiation

    International Nuclear Information System (INIS)

    Gago, J.; Lopez, A.; Rodriguez, J.; Santiago, J.; Acevedo, M.

    2007-01-01

    In this work we impregnate three Peruvian woods (Calycophy spruceanum Be, Aniba amazonica Meiz and Hura crepitans L) with styrene-polyester resin and methyl methacrylate. The polymerization of the system was promoted by gamma radiation and the experimental optimal condition was obtained with styrene-polyester 1:1 and 15 kGy. The obtained composites show reduced water absorption and better mechanical properties compared to the original wood. The structure of the wood-polymer composites was studied by light microscopy. Water absorption and hardness were also obtained

  6. Wood-Polymer composites obtained by gamma irradiation

    Science.gov (United States)

    Gago, J.; López, A.; Santiago, J.; Acevedo, M.; Rodríguez, J.

    2007-10-01

    In this work we impregnate three Peruvian woods (Calycophy spruceanum Be, Aniba amazonica Meiz and Hura crepitans L) with styrene-polyester resin and methyl methacrylate. The polymerization of the system was promoted by gamma radiation and the experimental optimal condition was obtained with styrene-polyester 1:1 and 15 kGy. The obtained composites show reduced water absorption and better mechanical properties compared to the original wood. The structure of the wood-polymer composites was studied by light microscopy. Water absorption and hardness were also obtained.

  7. Preparation of Fe3O4/poly(styrene-butyl acrylate-[2-(methacryloxy)ethyl]trimethylammonium chloride) by emulsifier-free emulsion polymerization and its interaction with DNA

    International Nuclear Information System (INIS)

    Li Xiaolong; Liu Guoqiang; Yan Wei; Chu, Paul K.; Yeung, Kelvin W.K.; Wu Shuilin; Yi Changfeng; Xu Zushun

    2012-01-01

    Cationic magnetic polymer particles Fe 3 O 4 /poly(styrene-butyl acrylate-[2-(methacryloxy)ethyl]trimethylammonium chloride), a type of potential gene carrier, were prepared by emulsifier-free emulsion polymerization with oleic acid modified magnetite Fe 3 O 4 , styrene, butyl acrylate and [2-(methacryloxy)ethyl]trimethylammonium chloride) (METAC). The morphology of the particles was characterized by transmission electron microscopy and the composites of particles were characterized by FT-IR spectroscopy, X-ray diffraction. These results showed that magnetic particles were well dispersed in polymers with the content of about 15%(wt/wt). The composites exhibited superparamagnetism and possessed a certain level of magnetic response. The interactions between the particles with calf-thymus DNA (ct DNA) were confirmed by zeta potential measurement, UV–vis spectroscopy and fluorescence spectroscopy. The DNA-binding capacity determined by the agarose gel electrophoresis showed good binding capacity of the emulsion to DNA. These results suggested the potential of the cationic magnetic polymer emulsion as gene target delivery carrier. - Highlights: ► A new type of cationic magnetic polymer particles was synthesized by emulsifier-free emulsion polymerization. ► Structural, morphological, and magnetic properties of the composite were evaluated. ► The interaction between cationic magnetic polymer particles with DNA was confirmed by zeta potential measurements. ► UV–vis spectrophotometry, fluorescent spectroscopy and agarose gel electrophoresis. ► This process may have potential applications to gene carrier and DNA separation.

  8. Poly(styrene-co-butadiene) random copolymer thin films and nanostructures on a mica surface: morphology and contact angles of nanodroplets.

    Science.gov (United States)

    McClements, Jake; Buffone, Cosimo; Shaver, Michael P; Sefiane, Khellil; Koutsos, Vasileios

    2017-09-20

    The self-assembly of poly(styrene-co-butadiene) random copolymers on mica surfaces was studied by varying solution concentrations and polymer molecular weights. Toluene solutions of the poly(styrene-co-butadiene) samples were spin coated onto a mica surface and the resulting polymer morphology was investigated by atomic force microscopy. At higher concentrations, thin films formed with varying thicknesses; some dewetting was observed which depended on the molecular weight. Total dewetting did not occur despite the polymer's low glass transition temperature. Instead, partial dewetting was observed suggesting that the polymer was in a metastable equilibrium state. At lower concentrations, spherical cap shaped nanodroplets formed with varying sizes from single polymer chains to aggregates containing millions of chains. As the molecular weight was increased, fewer aggregates were observed on the surface, albeit with larger sizes resulting from increased solution viscosities and more chain entanglements at higher molecular weights. The contact angles of the nanodroplets were shown to be size dependent. A minimum contact angle occurs for droplets with radii of 100-250 nm at each molecular weight. Droplets smaller than 100 nm showed a sharp increase in contact angle; attributed to an increase in the elastic modulus of the droplets, in addition, to a positive line tension value. Droplets larger than 250 nm also showed an increased contact angle due to surface heterogeneities which cannot be avoided for larger droplets. This increase in contact angle plateaus as the droplet size reaches the macroscopic scale.

  9. An enantioselective approach toward 3,4-dihydroisocoumarin through the bromocyclization of styrene-type carboxylic acids.

    Science.gov (United States)

    Chen, Jie; Zhou, Ling; Tan, Chong Kiat; Yeung, Ying-Yeung

    2012-01-20

    A facile and enantioselective approach toward 3,4-dihydroisocoumarin was developed. The method involved an amino-thiocarbamate catalyzed enantioselective bromocyclization of styrene-type carboxylic acids, yielding 3-bromo-3,4-dihydroisocoumarins with good yields and ee's. 3-Bromo-3,4-dihydroisocoumarins are versatile building blocks for various dihydroisocoumarin derivatives in which the Br group can readily be modified to achieve biologically important 4-O-type and 4-N-type 3,4-dihydroisocoumarin systems. In addition, studies indicated that, by refining some parameters, the synthetically useful 5-exo phthalide products could be achieved with good yields and ee's.

  10. Effects of Molecular Iodine and 4-tert-Butylcatechol Radical Inhibitor on the Radical Polymerization of Styrene

    Directory of Open Access Journals (Sweden)

    Mojtaba Bozorg

    2017-05-01

    Full Text Available The presence of molecular iodine was studied in relation the molecular weight and molecular weight distribution of polystyrene, produced by radical poly merization. Radical polymerization of styrene initiated by 2,2׳-azobisisobutyronitrile (AIBN was performed at 70°C in the presence of molecular iodine. The synthesized polymers were characterized by gel permeation chromatography (GPC and proton- nuclear magnetic resonance (1H NMR techniques. The results of these reactions including conversion data, number-average molecular weight and molecular weight distribution were compared with those obtained for styrene radical polymerization initiated by AIBN at the same temperature in the absence of molecular iodine. It was found that the presence of iodine had a profound effect on the molecular weight and its distribution in the produced polystyrene. This was attributed to the ability of iodine to control the polymerization of styrene initiated by AIBN via reverse iodine transfer polymerization (RITP mechanism. The polymer produced by this method had a molecular weight of 10600 g/mol with a molecular weight polydispersity index of 1.3. Due to the importance of induction period in reverse iodine transfer radical polymerization, increasing the temperature to 120°C during the induction period resulted in shorter induction periods and the produced species led to better control of the molecular weight. Also, due to the role of iodine molecules as a radical inhibitor, the presence of a secondary radical inhibitor, i.e. 4-tert-butylcatechol, along with the iodine was investigated in radical polymerization of polystyrene initiated by AIBN. It was observed that the secondary radical inhibitor prevented the consumption of the iodine molecules by the radicals produced from decomposition of the AIBN initiator; therefore, alkyl halides were not produced during the induction period.

  11. The role of water on the structure and mechanical properties of a thermoplastic natural block co-polymer from squid sucker ring teeth.

    Science.gov (United States)

    Rieu, Clément; Bertinetti, Luca; Schuetz, Roman; Salinas-Zavala, Cesar Ca; Weaver, James C; Fratzl, Peter; Miserez, Ali; Masic, Admir

    2016-09-02

    Hard biological polymers exhibiting a truly thermoplastic behavior that can maintain their structural properties after processing are extremely rare and highly desirable for use in advanced technological applications such as 3D-printing, biodegradable plastics and robust composites. One exception are the thermoplastic proteins that comprise the sucker ring teeth (SRT) of the Humboldt jumbo squid (Dosidicus gigas). In this work, we explore the mechanical properties of reconstituted SRT proteins and demonstrate that the material can be re-shaped by simple processing in water and at relatively low temperature (below 100 °C). The post-processed material maintains a high modulus in the GPa range, both in the dry and the wet states. When transitioning from low to high humidity, the material properties change from brittle to ductile with an increase in plastic deformation, where water acts as a plasticizer. Using synchrotron x-ray scattering tools, we found that water mostly influences nano scale structure, whereas at the molecular level, the protein structure remains largely unaffected. Furthermore, through simultaneous in situ x-ray scattering and mechanical tests, we show that the supramolecular network of the reconstituted SRT material exhibits a progressive alignment along the strain direction, which is attributed to chain alignment of the amorphous domains of SRT proteins. The high modulus in both dry and wet states, combined with their efficient thermal processing characteristics, make the SRT proteins promising substitutes for applications traditionally reserved for petroleum-based thermoplastics.

  12. CYP2F2-generated metabolites, not styrene oxide, are a key event mediating the mode of action of styrene-induced mouse lung tumors.

    Science.gov (United States)

    Cruzan, G; Bus, J; Hotchkiss, J; Harkema, J; Banton, M; Sarang, S

    2012-02-01

    Styrene induces lung tumors in mice but not in rats. Although metabolism of styrene to 7,8-styrene oxide (SO) by CYP2E1 has been suggested as a mediator of styrene toxicity, lung toxicity is not attenuated in CYP2E1 knockout mice. However, styrene and/or SO metabolism by mouse lung Clara cell-localized CYP2F2 to ring-oxidized cytotoxic metabolite(s) has been postulated as a key metabolic gateway responsible for both lung toxicity and possible tumorigenicity. To test this hypothesis, the lung toxicity of styrene and SO was evaluated in C57BL/6 (WT) and CYP2F2⁻/⁻ knockout mice treated with styrene (400 mg/kg/day, gavage, or 200 or 400 mg/kg/day, ip) or S- or R-SO (200 mg/kg/day, ip) for 5 days. Styrene treated WT mice displayed significant necrosis and exfoliation of Clara cells, and cumulative BrdU-labeling index of S-phase cells was markedly increased in terminal bronchioles of WT mice exposed to styrene or S- or RSO. In contrast, Clara and terminal bronchiole cell toxicity was not observed in CYP2F2⁻/⁻ mice exposed to either styrene or SO. This study clearly demonstrates that the mouse lung toxicity of both styrene and SO is critically dependent on metabolism by CYP2F2. Importantly, the human isoform of CYP2F, CYP2F1, is expressed at much lower levels and likely does not catalyze significant styrene metabolism, supporting the hypothesis that styrene-induced mouse lung tumors may not quantitatively, or possibly qualitatively, predict lung tumor potential in humans. Copyright © 2011 Elsevier Inc. All rights reserved.

  13. 40 CFR 721.3800 - Formaldehyde, condensated polyoxyethylene fatty acid, ester with styrenated phenol, ethylene...

    Science.gov (United States)

    2010-07-01

    ... polyoxyethylene fatty acid, ester with styrenated phenol, ethylene oxide adduct. 721.3800 Section 721.3800... Formaldehyde, condensated polyoxyethylene fatty acid, ester with styrenated phenol, ethylene oxide adduct. (a... generically as formaldehyde, condensated polyoxyethylene fatty acid, ester with styrenated phenol, ethylene...

  14. Conceptual process design of extractive distillation processes for ethylbenzene/styrene separation

    NARCIS (Netherlands)

    Jongmans, Mark; Hermens, E.; Raijmakers, M.; Maassen, J.I.W.; Schuur, Boelo; de Haan, A.B.

    2012-01-01

    In the current styrene production process the distillation of the close-boiling ethylbenzene/styrene mixture to obtain an ethylbenzene impurity level of 100 ppm in styrene accounts for 75–80% of the energy requirements. The future target is to reach a level of 1–10 ppm, which will increase the

  15. Radiation chemical grafting of vinyl acetate and styrene on nitrocellulose

    International Nuclear Information System (INIS)

    Chapiro, A.; Foex, M.; Jendrychowska-Bonamour, A.M.

    1977-01-01

    Vinyl acetate and styrene were grafted onto nitrocellulose using the direct radiation grafting technique with 500 and 3000 Ci 60 Co γ sources. For vinyl acetate, the reaction proceeds homogeneously. The kinetics are dominated by degradative chain transfer to the nitrocellulose. The polymerization of vinyl acetate was examined in the presence of isoamyl nitrate, a model for nitrocellulose; the transfer constant was determined and the results are treated semi-quantitatively. For styrene, grafting occurs in a swollen film irradiated in the presence of excess monomer. The diffusion of styrene into nitrocellulose is extremely slow; methanol was added to the reaction mixture to favour diffusion which was found to obey Fick's law. The diffusion constant and activation energy of diffusion are evaluated. The grafting kinetics are controlled by monomer diffusion, accounting for the increase of dose-rate exponent with temperature. A spontaneous grafting process occurs in the absence of irradiation. It is initiated by macroradicals arising from thermal decomposition of nitrocellulose. (author)

  16. Photorefractivity of triphenylamine polymers

    Science.gov (United States)

    Tsujimura, S.; Kinashi, K.; Sakai, W.; Tsutsumi, N.

    2012-10-01

    We present here the enhanced photorefractive performance and dynamic holographic image of poly(4-diphenylamino)styrene (PDAS)-based photorefractive polymeric composites (PPCs). PDAS and FDCST were synthesized as a photoconductive polymer and a nonlinear optical (NLO) dye, respectively. PPC films including PDAS, TPA (or ECZ), FDCST, and PCBM were investigated. The photorefractive quantities of the PDAS-based PPCs were measured by a degenerate four-wave mixing (DFWM) technique. Additionally, the dynamic holographic images were recorded through an appropriate PDAS-based PPC. Those dynamic holographic images clearly duplicate the original motion with high-speed quality. The present approach provides a promising candidate for the future application of dynamic holographic displays.

  17. Characterization of polyethyleneterephthalate (PET) based proton exchange membranes prepared by UV-radiation-induced graft copolymerization of styrene

    Energy Technology Data Exchange (ETDEWEB)

    Ahmed, Mostak; Khan, Mohammad B.; Alam, S. Shamsul; Khan, M. Anwar H. [Department of Chemistry, Shahjalal University of Science and Technology, Sylhet 3114 (Bangladesh); Khan, Mubarak A. [Radiation and Polymer Chemistry Laboratory, Institute of Nuclear Science and Technology, Bangladesh Atomic Energy Commission, P.O. Box 3787, Dhaka (Bangladesh); Halim, Md. Abdul [Department of Chemistry, Jahangirnagar University, savar, Dhaka (Bangladesh)

    2011-01-15

    Polymer electrolyte membranes (PEMs) were successfully prepared by simultaneous ultraviolet (UV) radiation-induced graft copolymerization of styrene (35 vol.% concentration) onto poly(ethyleneterephthalate) (PET) film, followed by sulfonation on the styrene monomer units in the grafting chain using 0.05 M chlorosulfonic acid (ClSO{sub 3}H). The radiation grafting and the sulfonation have been confirmed by titrimetric and gravimetric analyses as well as Fourier Transform Infrared (FTIR) spectroscopy. The maximum ion-exchange capacity (IEC) of the PEM was measured to be 0.04385 mmol g{sup -1} at its highest level of grafting and sulfonation. They exhibited high thermal and mechanical properties as well as oxidative stability. They are highly stable in H{sub 2}SO{sub 4} solutions and can be used in the acidic fuel cells. The membranes showed low water uptake as well as low proton conductivity than Nafion. In this study, the preparation of PEMs from commodity-type polymers is found to be very inexpensive and is a suitable candidate for applications in fuel cells. (author)

  18. Magnetic Field Alignment of PS-P4VP: a Non-Liquid Crystalline Coil-Coil Block Copolymer

    Science.gov (United States)

    Rokhlenko, Yekaterina; Zhang, Kai; Larson, Steven; Gopalan, Padma; O'Hern, Corey; Osuji, Chinedum

    2015-03-01

    Magnetic fields provide the ability to control alignment of self-assembled soft materials such as block copolymers. Most prior work in this area has relied on the presence of ordered assemblies of anisotropic liquid crystalline species to ensure sufficient magnetic anisotropy to drive alignment. Recent experiments with poly(styrene-b-4-vinylpyridine), a non-liquid crystalline BCP, however, show field-induced alignment of a lamellar microstructure during cooling across the order-disorder transition. Using in situ x-ray scattering, we examine the roles of field strength and cooling rate on the alignment response of this low MW coil-coil BCP. Alignment is first observed at field strengths as low as 1 Tesla and improves markedly with both increasing field strength and slower cooling. We present a geometric argument to illustrate the origin of a finite, non-trivial magnetic susceptibility anisotropy for highly stretched surface-tethered polymer chains and corroborate this using coarse-grained molecular dynamics simulations. We rationalize the magnetic field response of the system in terms of the mobility afforded by the absence of entanglements, the intrinsic anisotropy resulting from the stretched polymer chains and sterically constrained conjugated rings, and the large grain size in these low molecular weight materials.

  19. AFM study of excimer laser patterning of block-copolymer: Creation of ordered hierarchical, hybrid, or recessed structures

    International Nuclear Information System (INIS)

    Švanda, Jan; Siegel, Jakub; Švorčík, Vaclav; Lyutakov, Oleksiy

    2016-01-01

    Highlights: • Combination of bottom-up (BCP separation) and top-down (laser patterning) technologies allows obtaining hierarchical structures. • Surface morphologies were determined by the order of patterning steps (laser modification, annealing, surface reconstruction). • Tuning the order of steps enables the reorientation of BCP domain at large scale, fabrication of hierarchical, hybrid or recessed structures. • The obtained structures can find potential applications in nanotechnology, plasmonics, information storage, sensors and smart surfaces. - Abstract: We report fabrication of the varied range of hierarchical structures by combining bottom-up self-assembly of block copolymer poly(styrene-block-vinylpyridine) (PS-b-P4VP) with top-down excimer laser patterning method. Different procedures were tested, where laser treatment was applied before phase separation and after phase separation or phase separation and surface reconstruction. Laser treatment was performed using either polarized laser light with the aim to create periodical pattern on polymer surface or non-polarized light for preferential removing of polystyrene (PS) part from PS-b-P4VP. Additionally, dye was introduced into one part of block copolymer (P4VP) with the aim to modify its response to laser light. Resulting structures were analyzed by XPS, UV–vis and AFM techniques. Application of polarized laser light leads to creation of structures with hierarchical, recessed or hybrid geometries. Non-polarized laser beam allows pronouncing the block copolymer phase separated structure. Tuning the order of steps or individual step conditions enables the efficient reorientation of block-copolymer domain at large scale, fabrication of hierarchical, hybrid or recessed structures. The obtained structures can find potential applications in nanotechnology, photonics, plasmonics, information storage, optical devices, sensors and smart surfaces.

  20. Effect of time and temperature exposition in the crystallinity degree of sulfonated poly-(styrene acrylic acid) (PSAA-S)

    Energy Technology Data Exchange (ETDEWEB)

    Duarte, G.W.; Becker, E.B.; Silva, L.; Naspolini, A.M.; Consenso, E.C.; Paula, M.M.S.; Fiori, M.A., E-mail: glau_bn@hotmail.co [University of Extreme South of Santa Catarina Criciuma, SC (Brazil). Dept. of Materials Engineering; Silveira, F.Z. [Federal University of Santa Catarina (UFSC), Florianopolis, SC (Brazil). Dept. of Chemical Engineering

    2010-07-01

    Polymers with special properties have been increasingly applied in the development of technological devices. For example, polymeric materials with special electric properties, such as sulfonated poly-(styrene-acrylic acid) - PSAA-S, are of great interest for showing different conductivities depending on the environment where they are applied. The special properties of PSAA are obtained only after sulfonation step in acidic media. The present work aimed to evaluate the effect of time and temperature exposition in the crystallinity degree of PSAA-S, through a statistical experimental factorial planning. The samples of PSAA-S were submitted to FT-IR and DRX tests. The results showed that the temperature and the time of exposition are significant factors in the crystallinity degree of PSAA-S, considering that the crystal lattices created during the polymerization are damaged by the action of time and temperature at which the polymer is exposed. (author)

  1. Effect of time and temperature exposition in the crystallinity degree of sulfonated poly-(styrene acrylic acid) (PSAA-S)

    International Nuclear Information System (INIS)

    Duarte, G.W.; Becker, E.B.; Silva, L.; Naspolini, A.M.; Consenso, E.C.; Paula, M.M.S.; Fiori, M.A.; Silveira, F.Z.

    2010-01-01

    Polymers with special properties have been increasingly applied in the development of technological devices. For example, polymeric materials with special electric properties, such as sulfonated poly-(styrene-acrylic acid) - PSAA-S, are of great interest for showing different conductivities depending on the environment where they are applied. The special properties of PSAA are obtained only after sulfonation step in acidic media. The present work aimed to evaluate the effect of time and temperature exposition in the crystallinity degree of PSAA-S, through a statistical experimental factorial planning. The samples of PSAA-S were submitted to FT-IR and DRX tests. The results showed that the temperature and the time of exposition are significant factors in the crystallinity degree of PSAA-S, considering that the crystal lattices created during the polymerization are damaged by the action of time and temperature at which the polymer is exposed. (author)

  2. Fast & scalable pattern transfer via block copolymer nanolithography

    DEFF Research Database (Denmark)

    Li, Tao; Wang, Zhongli; Schulte, Lars

    2015-01-01

    A fully scalable and efficient pattern transfer process based on block copolymer (BCP) self-assembling directly on various substrates is demonstrated. PS-rich and PDMS-rich poly(styrene-b-dimethylsiloxane) (PS-b-PDMS) copolymers are used to give monolayer sphere morphology after spin-casting of s......A fully scalable and efficient pattern transfer process based on block copolymer (BCP) self-assembling directly on various substrates is demonstrated. PS-rich and PDMS-rich poly(styrene-b-dimethylsiloxane) (PS-b-PDMS) copolymers are used to give monolayer sphere morphology after spin...... on long range lateral order, including fabrication of substrates for catalysis, solar cells, sensors, ultrafiltration membranes and templating of semiconductors or metals....

  3. Self-assembled Block Copolymer Membranes with Bioinspired Artificial Channels

    KAUST Repository

    Sutisna, Burhannudin

    2018-04-01

    Nature is an excellent design that inspires scientists to develop smart systems. In the realm of separation technology, biological membranes have been an ideal model for synthetic membranes due to their ultrahigh permeability, sharp selectivity, and stimuliresponse. In this research, fabrications of bioinspired membranes from block copolymers were studied. Membranes with isoporous morphology were mainly prepared using selfassembly and non-solvent induced phase separation (SNIPS). An effective method that can dramatically shorten the path for designing new isoporous membranes from block copolymers via SNIPS was first proposed by predetermining a trend line computed from the solvent properties, interactions and copolymer block sizes of previously-obtained successful systems. Application of the method to new copolymer systems and fundamental studies on the block copolymer self-assembly were performed. Furthermore, the manufacture of bioinspired membranes was explored using (1) poly(styrene-b-4-hydroxystyrene-b-styrene) (PS-b-PHS-b-PS), (2) poly(styrene-bbutadiene- b-styrene) (PS-b-PB-b-PS) and (3) poly(styrene-b-γ-benzyl-L-glutamate) (PSb- PBLG) copolymers via SNIPS. The structure formation was investigated using smallangle X-ray scattering (SAXS) and time-resolved grazing-Incidence SAXS. The PS-b- PHS-b-PS membranes showed preferential transport for proteins, presumably due to the hydrogen bond interactions within the channels, electrostatic attraction, and suitable pore dimension. Well-defined nanochannels with pore sizes of around 4 nm based on PS-b- PB-b-PS copolymers could serve as an excellent platform to fabricate bioinspired channels due to the modifiable butadiene blocks. Photolytic addition of thioglycolic acid was demonstrated without sacrificing the self-assembled morphology, which led to a five-fold increase in water permeance compared to that of the unmodified. Membranes with a unique feather-like structure and a lamellar morphology for dialysis and

  4. Water Soluble Polymers for Pharmaceutical Applications

    OpenAIRE

    Veeran Gowda Kadajji; Guru V. Betageri

    2011-01-01

    Advances in polymer science have led to the development of novel drug delivery systems. Some polymers are obtained from natural resources and then chemically modified for various applications, while others are chemically synthesized and used. A large number of natural and synthetic polymers are available. In the present paper, only water soluble polymers are described. They have been explained in two categories (1) synthetic and (2) natural. Drug polymer conjugates, block copolymers, hydrogel...

  5. Copolymerization of propene and styrene using a zirconocene - methylaluminoxane initiator system

    International Nuclear Information System (INIS)

    Rabagliati, F.M.; Rodriguez, F.J.; Quijada, R.; Galland, G.B.

    2009-01-01

    The copolymerization of propene with styrene has been tested using the rac-Et(Ind) 2 ZrCl 2 -methylaluminoxane initiator system. The various proportion of styrene in initial feed showed an important effect on the polymerization activity. Low contents of styrene in the reaction produced a considerable fall in the activity. Respect to thermal behavior, it is noted that obtained propene/styrene copolymers showed Tm values slightly lower than the corresponding polypropene one. NMR spectroscopy allowed to confirm that the copolymer composition includes a very low incorporation of styrene in polypropylene chains. (author)

  6. Microwave-assisted synthesis of SiO2 nanoparticles and its application on the flame retardancy of poly styrene and poly carbonate nanocomposites

    Directory of Open Access Journals (Sweden)

    A. Esmaeili-Bafghi-Karimabad

    2015-07-01

    Full Text Available Various morphologies of silica nanoparticles were synthesized by a microwave-assisted Pechini method. Silica nanostructures were synthesized via a fast reaction between tetra ethyl ortho silicate and ammonia at presence citric acid and other effective agents in Pechini procedure. Then for preparation of polymer-matrix nanocomposites, SiO2 nanoparticles were added to poly carbonate (PC and poly styrene (PS matrices. Nanostructures were characterized by X-ray diffraction (XRD, scanning electron microscopy (SEM and Fourier transform infrared (FT-IR. The influence of SiO2 nanostructures on the flame retardancy of the polymeric matrix was studied using UL- 94 analysis. Our results show that the SiO2 nanostructure can enhance the flame retardant property of the poly carbonate matrix. PC shows better flame retardancy compare to poly styrene.

  7. Reaction of CO2 with propylene oxide and styrene oxide catalyzed by a chromium(III) amine-bis(phenolate) complex.

    Science.gov (United States)

    Dean, Rebecca K; Devaine-Pressing, Katalin; Dawe, Louise N; Kozak, Christopher M

    2013-07-07

    A diamine-bis(phenolate) chromium(III) complex, {CrCl[O2NN'](BuBu)}2 catalyzes the copolymerization of propylene oxide with carbon dioxide. The synthesis of this metal complex is straightforward and it can be obtained in high yields. This catalyst incorporates a tripodal amine-bis(phenolate) ligand, which differs from the salen or salan ligands typically used with Cr and Co complexes that have been employed as catalysts for the synthesis of such polycarbonates. The catalyst reported herein yields low molecular weight polymers with narrow polydispersities when the reaction is performed at room temperature. Performing the reaction at elevated temperatures causes the selective synthesis of propylene carbonate. The copolymerization activity for propylene oxide and carbon dioxide, as well as the coupling of carbon dioxide and styrene oxide to give styrene carbonate are presented.

  8. Enhanced performance of organic light-emitting devices by using electropolymerized poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) film as the anode modification layer

    Energy Technology Data Exchange (ETDEWEB)

    Liu Xiaona [Graduate University of Chinese Academy of Sciences, Beijing 100049 (China); Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Yan Jun [Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Meng Lingchuan [Key Laboratory of Luminescence and Optical Information, Ministry of Education, Institute of Optoelectronic Technology, Beijing Jiaotong University, Beijing 100044 (China); Sun Chenghua; Hu Xiujie; Chen Ping [Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Zhou Shuyun, E-mail: zhou_shuyun@mail.ipc.ac.cn [Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Teng Feng [Key Laboratory of Luminescence and Optical Information, Ministry of Education, Institute of Optoelectronic Technology, Beijing Jiaotong University, Beijing 100044 (China)

    2012-01-31

    Poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) films were prepared by electropolymerization on patterned indium tin oxide substrates in isopropanol solution. The thickness and doping level of the PEDOT:PSS films were controlled by adjusting the electropolymerization time and the concentration of poly(styrene sulfonate) acid, respectively. Organic light-emitting diodes were fabricated using the electropolymerized PEDOT:PSS film as the anode modification layer. The dependence of the performance on thickness of PEDOT:PSS films was investigated. It is shown that the performance of the device can be further enhanced when the thickness of PEDOT:PSS films reached an optimum condition. This method facilitates manufacturing procedures of conducting polymers films and may offer an economical route for producing organic electroluminescent devices.

  9. Fabrication and actuation of electro-active polymer actuator based on PSMI-incorporated PVDF

    Science.gov (United States)

    Lu, Jun; Kim, Sang-Gyun; Lee, Sunwoo; Oh, Il-Kwon

    2008-08-01

    In this study, an ionic networking membrane (INM) of poly(styrene-alt-maleimide) (PSMI)-incorporated poly(vinylidene fluoride) (PVDF) was applied to fabricate electro-active polymer. Based on the same original membrane of PSMI-incorporated PVDF, various samples of INM actuator were prepared for different reduction times with the electroless-plating technique. The as-prepared INM actuators were tested in terms of surface resistance, platinum morphology, resonance frequency, tip displacement, current and blocked force, and their performances were compared to those of the widely used traditional Nafion actuator. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) revealed that much smaller and more uniform platinum particles were formed on the surfaces of the INM actuators as well as within their polymer matrix. Although excellent harmonic responses were observed for the newly developed INM actuators, they were found to be sensitive to the applied reduction times during the fabrication. The mechanical displacement of the INM actuator fabricated after the optimum reduction times was much larger than that of its Nafion counterpart of comparable thickness under the stimulus of constant and alternating current voltage. The PSMI-incorporated PVDF actuator can become a promising smart material to be used in the fields of biomimetic robots, biomedical devices, sensors and actuator, haptic interfaces, energy harvesting and so on.

  10. Fabrication and actuation of electro-active polymer actuator based on PSMI-incorporated PVDF

    International Nuclear Information System (INIS)

    Lu, Jun; Oh, Il-Kwon; Kim, Sang-Gyun; Lee, Sunwoo

    2008-01-01

    In this study, an ionic networking membrane (INM) of poly(styrene-alt-maleimide) (PSMI)-incorporated poly(vinylidene fluoride) (PVDF) was applied to fabricate electro-active polymer. Based on the same original membrane of PSMI-incorporated PVDF, various samples of INM actuator were prepared for different reduction times with the electroless-plating technique. The as-prepared INM actuators were tested in terms of surface resistance, platinum morphology, resonance frequency, tip displacement, current and blocked force, and their performances were compared to those of the widely used traditional Nafion actuator. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) revealed that much smaller and more uniform platinum particles were formed on the surfaces of the INM actuators as well as within their polymer matrix. Although excellent harmonic responses were observed for the newly developed INM actuators, they were found to be sensitive to the applied reduction times during the fabrication. The mechanical displacement of the INM actuator fabricated after the optimum reduction times was much larger than that of its Nafion counterpart of comparable thickness under the stimulus of constant and alternating current voltage. The PSMI-incorporated PVDF actuator can become a promising smart material to be used in the fields of biomimetic robots, biomedical devices, sensors and actuator, haptic interfaces, energy harvesting and so on

  11. Thermal degradation of biocidal organic N-halamines and N-halamine polymers

    Energy Technology Data Exchange (ETDEWEB)

    Chylińska, Marta; Kaczmarek, Halina, E-mail: halina@chem.umk.pl

    2014-05-01

    Highlights: • Novel biocidal N-halamines have been substituted to poly(p-methyl styrene). • Thermal stability of all obtained compounds has been studied by thermogravimetry. • Stabilization of selected polymer has been achieved using octyl tin mercaptide. • The mechanism of thermal degradation of N-halamine polymers has been proposed. - Abstract: Novel biocidal organic N-halamines (based on imidazoline dione rings) were used as a substituents for poly(p-methyl styrene). The biocidal polymers and substituents have been investigated using thermogravimetric analysis. The thermal resistance of investigated compounds was compared to those of non-halogenated precursors. The introduction of chlorine atoms to polymers decreases their thermal resistance comparing to precursors but efficient stabilization is possible by using octyl tin mercaptide. The complex mechanism of thermal decomposition of polymers has been discussed.

  12. Boundary layers of aqueous surfactant and block copolymer solutions against hydrophobic and hydrophilic solid surfaces

    International Nuclear Information System (INIS)

    Steitz, Roland; Schemmel, Sebastian; Shi Hongwei; Findenegg, Gerhard H

    2005-01-01

    The boundary layer of aqueous surfactants and amphiphilic triblock copolymers against flat solid surfaces of different degrees of hydrophobicity was investigated by neutron reflectometry (NR), grazing incidence small angle neutron scattering (GISANS) and atomic force microscopy (AFM). Solid substrates of different hydrophobicities were prepared by appropriate surface treatment or by coating silicon wafers with polymer films of different chemical natures. For substrates coated with thin films (20-30 nm) of deuterated poly(styrene) (water contact angle θ w ∼ 90), neutron reflectivity measurements on the polymer/water interface revealed a water depleted liquid boundary layer of 2-3 nm thickness and a density about 90% of the bulk water density. No pronounced depletion layer was found at the interface of water against a less hydrophobic polyelectrolyte coating (θ w ∼ 63). It is believed that the observed depletion layer at the hydrophobic polymer/water interface is a precursor of the nanobubbles which have been observed by AFM at this interface. Decoration of the polymer coatings by adsorbed layers of nonionic C m E n surfactants improves their wettability by the aqueous phase at surfactant concentrations well below the critical micellar concentration (CMC) of the surfactant. Here, GISANS experiments conducted on the system SiO 2 /C 8 E 4 /D 2 O reveal that there is no preferred lateral organization of the C 8 E 4 adsorption layers. For amphiphilic triblock copolymers (PEO-PPO-PEO) it is found that under equilibrium conditions they form solvent-swollen brushes both at the air/water and the solid/water interface. In the latter case, the brushes transform to uniform, dense layers after extensive rinsing with water and subsequent solvent evaporation. The primary adsorption layers maintain properties of the precursor brushes. In particular, their thickness scales with the number of ethylene oxide units (EO) of the block copolymer. In the case of dip-coating without

  13. Occupational asthma in the furniture industry: is it due to styrene?

    Science.gov (United States)

    Oner, Ferda; Mungan, Dilşad; Numanoglu, Numan; Demirel, Yavuz

    2004-01-01

    Styrene, a volatile monomer, has been reported as a cause of occupational asthma in a few case reports. The aim of this study was to investigate the risk for asthma in relation to exposure to styrene in a large number of workers. A total of 47 workers with a history of exposure to styrene were included in the study. To establish whether asthma was present, each patient underwent a clinical interview, pulmonary function testing and bronchial challenge with methacholine. Specific bronchial challenges with styrene and serial peak expiratory flow (PEF) measurement at home and at work were carried out in subjects with a diagnosis of asthma to evaluate the relationship between their asthma and exposure to styrene in the workplace. Among the 47 subjects, 5 workers had given a history of work-related symptoms, and 3 of them had a positive methacholine challenge test. Specific bronchial challenges with styrene and serial PEF measurement were subsequently carried out in these 3 subjects. Although provocation tests with styrene were negative in the 3 workers, 1 worker had PEF rate records compatible with occupational asthma. We established one patient with occupational asthma from a group of people who have excessive styrene exposure. This finding may be suggestive but is not conclusive about the causative role of styrene in occupational asthma. Since styrene is a frequently used substance in the furniture industry, it is worth performing further studies to investigate the relationship between styrene and occupational asthma. Copyright 2004 S. Karger AG, Basel

  14. Occupational Styrene Exposure on Auditory Function Among Adults: A Systematic Review of Selected Workers

    Directory of Open Access Journals (Sweden)

    Francis T. Pleban

    2017-12-01

    Full Text Available A review study was conducted to examine the adverse effects of styrene, styrene mixtures, or styrene and/or styrene mixtures and noise on the auditory system in humans employed in occupational settings. The search included peer-reviewed articles published in English language involving human volunteers spanning a 25-year period (1990–2015. Studies included peer review journals, case–control studies, and case reports. Animal studies were excluded. An initial search identified 40 studies. After screening for inclusion, 13 studies were retrieved for full journal detail examination and review. As a whole, the results range from no to mild associations between styrene exposure and auditory dysfunction, noting relatively small sample sizes. However, four studies investigating styrene with other organic solvent mixtures and noise suggested combined exposures to both styrene organic solvent mixtures may be more ototoxic than exposure to noise alone. There is little literature examining the effect of styrene on auditory functioning in humans. Nonetheless, findings suggest public health professionals and policy makers should be made aware of the future research needs pertaining to hearing impairment and ototoxicity from styrene. It is recommended that chronic styrene-exposed individuals be routinely evaluated with a comprehensive audiological test battery to detect early signs of auditory dysfunction. Keywords: auditory system, human exposure, ototoxicity, styrene

  15. Inner Stucture of Thin Films of Lamellar Poly(styrene-em>b>-butadiene) Diblock Copolymers as revealed by Grazing-Incidence Small-Angle Scattering

    DEFF Research Database (Denmark)

    Busch, Peter; Posselt, Dorthe; Smilgies, Detlef-Matthias

    2007-01-01

    The lamellar orientation in supported, thin films of poly(styrene-b-butadiene) (P(S-b-B)) depends on block copolymer molar mass. We have studied films from nine block copolymer samples with molar masses between 13.9 and 183 kg/mol using grazing-incidence small-angle X-ray scattering (GISAXS) and ...... quantitatively in the framework of our recently developed distorted-wave Born approximation model (Busch, P.; et al. J. Appl. Crystallogr. 2006, 39, 433). The results cannot be explained from enthalpic considerations alone but point to the importance of entropic factors....

  16. Polymer films

    Science.gov (United States)

    Granick, Steve; Sukhishvili, Svetlana A.

    2004-05-25

    A film contains a first polymer having a plurality of hydrogen bond donating moieties, and a second polymer having a plurality of hydrogen bond accepting moieties. The second polymer is hydrogen bonded to the first polymer.

  17. Smart ampholytic ABC block copolypeptide

    Czech Academy of Sciences Publication Activity Database

    Schlaad, H.; Sun, J.; Černoch, Peter; Ruokolainen, J.

    2017-01-01

    Roč. 254, 20 August (2017), s. 79 ISSN 0065-7727. [ACS National Meeting & Exposition /254./. 20.08.2017-24.08.2017, Washington] Institutional support: RVO:61389013 Keywords : block copolypeptide * smart ampholytic Subject RIV: CD - Macromolecular Chemistry OBOR OECD: Polymer science

  18. New aspects in the biomonitoring of occupational exposure to styrene

    Czech Academy of Sciences Publication Activity Database

    Vodička, Pavel; Štětina, R.; Koskinen, M.; Souček, P.; Vodičková, L.; Hlaváč, P.; Kuricová, M.; Nečasová, R.; Hemminki, K.

    2002-01-01

    Roč. 75, - (2002), s. S75-S85 ISSN 0340-0131 R&D Projects: GA ČR GA313/99/1460; GA ČR GA310/01/0802 Institutional research plan: CEZ:AV0Z5039906 Keywords : styrene * biological monitoring * DNA adducts Subject RIV: FM - Hygiene Impact factor: 1.352, year: 2002

  19. Styrene vapor control systems in FRP yacht plants.

    Science.gov (United States)

    Todd, W F

    1985-01-01

    The production of large (greater than 25-ft) fiber-reinforced plastic (FRP) yachts has presented problems of styrene exposure in excess of the Occupational Safety and Health Administration permissible exposure level (OSHA PEL) of 100 ppm. Also, the National Institute for Occupational Safety and Health (NIOSH) is currently recommending a 10-hour workshift, 40-hour workweek time weighted average (TWA) of 50 ppm for styrene. Meeting this challenge will require a system of engineering, work practice, personal protective equipment, and monitoring control measures. NIOSH has performed a study of the engineering controls in three FRP yacht plants. Work practices and the use of personal protective equipment (PPE) were also considered in the evaluation. The three systems evaluated included a dilution system, a local ventilation system, and a push-pull ventilation system. The cost of constructing and operating these systems was not evaluated in this study. Study results indicated that each type of ventilation system can meet the present PEL of 100 ppm styrene; however, it is not certain that these systems can meet a lower PEL of 50 ppm styrene.

  20. Highly selective cobalt-catalyzed hydrovinylation of styrene

    NARCIS (Netherlands)

    Grutters, M.M.P.; Müller, C.; Vogt, D.

    2006-01-01

    The hydrovinylation reaction is a codimerization of a 1,3-diene or vinyl arene and ethene with great potential for fine chemicals and pharmaceuticals. For the first time, enantioselective cobalt-catalyzed hydrovinylations of styrene were achieved with a cobalt-based system bearing a chiral

  1. Comparing in situ removal strategies for improving styrene bioproduction.

    Science.gov (United States)

    McKenna, Rebekah; Moya, Luis; McDaniel, Matthew; Nielsen, David R

    2015-01-01

    As an important conventional monomer compound, the biological production of styrene carries significant promise with respect to creating novel sustainable materials. Since end-product toxicity presently limits styrene production by previously engineered Escherichia coli, in situ product removal by both solvent extraction and gas stripping were explored as process-based strategies for circumventing its inhibitory effects. In solvent extraction, the addition of bis(2-ethylhexyl)phthalate offered the greatest productivity enhancement, allowing net volumetric production of 836 ± 64 mg/L to be reached, representing a 320 % improvement over single-phase cultures. Gas stripping rates, meanwhile, were controlled by rates of bioreactor agitation and, to a greater extent, aeration. A periodic gas stripping protocol ultimately enabled up to 561 ± 15 mg/L styrene to be attained. Lastly, by relieving the effects of styrene toxicity, new insight was gained regarding subsequent factors limiting its biosynthesis in E. coli and strategies for future strain improvement are discussed.

  2. Polymer architecture and drug delivery.

    Science.gov (United States)

    Qiu, Li Yan; Bae, You Han

    2006-01-01

    Polymers occupy a major portion of materials used for controlled release formulations and drug-targeting systems because this class of materials presents seemingly endless diversity in topology and chemistry. This is a crucial advantage over other classes of materials to meet the ever-increasing requirements of new designs of drug delivery formulations. The polymer architecture (topology) describes the shape of a single polymer molecule. Every natural, seminatural, and synthetic polymer falls into one of categorized architectures: linear, graft, branched, cross-linked, block, star-shaped, and dendron/dendrimer topology. Although this topic spans a truly broad area in polymer science, this review introduces polymer architectures along with brief synthetic approaches for pharmaceutical scientists who are not familiar with polymer science, summarizes the characteristic properties of each architecture useful for drug delivery applications, and covers recent advances in drug delivery relevant to polymer architecture.

  3. Kinetics of styrene biodegradation by Pseudomonas sp. E-93486.

    Science.gov (United States)

    Gąszczak, Agnieszka; Bartelmus, Grażyna; Greń, Izabela

    2012-01-01

    The research into kinetics of styrene biodegradation by bacterial strain Pseudomonas sp. E-93486 coming from VTT Culture Collection (Finland) was presented in this work. Microbial growth tests in the presence of styrene as the sole carbon and energy source were performed both in batch and continuous cultures. Batch experiments were conducted for initial concentration of styrene in the liquid phase changed in the range of 5-90 g m(-3). The Haldane model was found to be the best to fit the kinetic data, and the estimated constants of the equation were: μ (m) = 0.1188 h(-1), K(S) = 5.984 mg l(-1), and K (i) = 156.6 mg l(-1). The yield coefficient mean value [Formula in text] for the batch culture was 0.72 g(dry cells weight) (g(substrate))(-1). The experiments conducted in a chemostat at various dilution rates (D = 0.035-0.1 h(-1)) made it possible to determine the value of the coefficient for maintenance metabolism m (d) = 0.0165 h(-1) and the maximum yield coefficient value [Formula in text]. Chemostat experiments confirmed the high value of yield coefficient [Formula in text] observed in the batch culture. The conducted experiments showed high activity of the examined strain in the styrene biodegradation process and a relatively low sensitivity to inhibition of its growth at higher concentrations of styrene in the solution. Such exceptional features of Pseudomonas sp. E-93486 make this bacterial strain the perfect candidate for technical applications.

  4. Mechanical behavior of styrene grafted PVC films by electron beam irradiation

    International Nuclear Information System (INIS)

    Cardoso, Jessica R.; Moura, Eduardo; Somessari, Elisabeth S.R.; Silveira, Carlos G.; Paes, Helio A.; Souza, Carlos A.; Manzoli, Jose E.; Geraldo, Aurea B.C.

    2011-01-01

    The polyvinyl chloride (PVC) is a technological and low cost polymer, however it presents high sensitivity to high energy irradiation because of the weakness of carbon-chloride bond face to carbon-carbon and carbon-hydrogen bonds. Grafting is a type of co-polymerization process that can allow it an increase of mechanical characteristics. The aim of this work is to evaluate the mechanical properties of styrene grafted PVC by electron beam irradiation using mutual and pre-irradiation methods to verify the mechanical resistance changes of obtained product whether grafting process is applied from non-irradiated or from pre-irradiated substrates. The irradiation procedures were performed in atmosphere air or inert atmosphere and the irradiation conditions comprised doses from 10 kGy to 100 kGy and dose rates of 2.2 kGy/s and 22.4 kGy/s. The styrene grafted samples were analyzed by gravimetry to determinate the grafting yield; the final values have been averaged from a series of three measurements. The Mid-A TR-FTIR was the spectrophotometer technique used for qualitative/semi-quantitative analysis of grafted samples. The Young's module and tensile strength of pre-irradiated and grafted PVC samples at both methods were measured at a Lloyd LXR tensile tester at a cross-head speed of 10.00 mm/min. We observed the decrease of Young's module and tensile strength with the increase of absorbed dose at pre-irradiated PVC samples. These mechanical parameters results are discussed. (author)

  5. Ionizing radiation effect study by electron beam on acrylonitrile butadiene styrene - ABS terpolymer

    International Nuclear Information System (INIS)

    Landi, Tania Regina Lourenco

    2003-01-01

    The great advantage in the researches involving development has as objective to increase significantly the quality of the products. The ABS (acrylonitrile, butadiene, styrene) resins are terpolymers formed by an elastomer and two thermoplastics amorphous components. The three different monomeric units from the terpolymer ABS contribute separately to the material characteristics exhibited. The molecular stiffness originating from polystyrene and the benzene ring hanging on the chain is responsible for the flexion module ABS. The acrylonitrile and the styrene incorporated butadiene exercises strong influence in the resistance to the impact because it reduces the bonding among them. The engineering use of this terpolymer became important due their mechanical properties and mainly, for the responses of this to tensions or deformations applied. The polymeric materials, when submitted to the ionizing radiation are modified by the transference of energy to these materials, introducing excitation and ionization of the molecules, generating chemical reactions that can produce permanent modifications in the polymeric physicochemical structure. The induced modifications can result in the polymeric material degradation or crosslinking, which can result in the improvement of some properties. This work has, as objective, to study the electron beam ionizing radiation effect, at different doses, in the properties of the polymer ABS. The studied properties were: tensile strength at break, elongation at break, Izod impact strength, flexural strength, melt flow index, Vicat softening temperature and the thermic distortion temperature. Also researches on Differential Scanning Calorimetry (DSC) and Thermogravimetric Analyses (TGA) were accomplished. From the experimental results, it was showed that for doses until 500 kGy, at 22.6 kGy/s dose rate, in the presence of air, the crosslinking process of ABS prevails. (author)

  6. Mechanical behavior of styrene grafted PVC films by electron beam irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Cardoso, Jessica R.; Moura, Eduardo; Somessari, Elisabeth S.R.; Silveira, Carlos G.; Paes, Helio A.; Souza, Carlos A.; Manzoli, Jose E.; Geraldo, Aurea B.C., E-mail: ageraldo@ipen.br, E-mail: jmanzoli@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2011-07-01

    The polyvinyl chloride (PVC) is a technological and low cost polymer, however it presents high sensitivity to high energy irradiation because of the weakness of carbon-chloride bond face to carbon-carbon and carbon-hydrogen bonds. Grafting is a type of co-polymerization process that can allow it an increase of mechanical characteristics. The aim of this work is to evaluate the mechanical properties of styrene grafted PVC by electron beam irradiation using mutual and pre-irradiation methods to verify the mechanical resistance changes of obtained product whether grafting process is applied from non-irradiated or from pre-irradiated substrates. The irradiation procedures were performed in atmosphere air or inert atmosphere and the irradiation conditions comprised doses from 10 kGy to 100 kGy and dose rates of 2.2 kGy/s and 22.4 kGy/s. The styrene grafted samples were analyzed by gravimetry to determinate the grafting yield; the final values have been averaged from a series of three measurements. The Mid-A TR-FTIR was the spectrophotometer technique used for qualitative/semi-quantitative analysis of grafted samples. The Young's module and tensile strength of pre-irradiated and grafted PVC samples at both methods were measured at a Lloyd LXR tensile tester at a cross-head speed of 10.00 mm/min. We observed the decrease of Young's module and tensile strength with the increase of absorbed dose at pre-irradiated PVC samples. These mechanical parameters results are discussed. (author)

  7. Characterization of poly(Sodium Styrene Sulfonate) Thin Films Grafted from Functionalized Titanium Surfaces

    Science.gov (United States)

    Zorn, Gilad; Baio, Joe E.; Weidner, Tobias; Migonney, Veronique; Castner, David G.

    2011-01-01

    Biointegration of titanium implants in the body is controlled by their surface properties. Improving surface properties by coating with a bioactive polymer is a promising approach to improve the biological performance of titanium implants. To optimize the grafting processes, it is important to fully understand the composition and structure of the modified surfaces. The main focus of this study is to provide a detailed, multi-technique characterization of a bioactive poly(sodium styrene sulfonate) (pNaSS) thin film grafted from titanium surfaces via a two-step procedure. Thin titanium films (~50 nm thick with an average surface roughness of 0.9±0.2nm) prepared by evaporation onto silicon wafers were used as smooth model substrates. X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS) showed that the titanium film was covered with a TiO2 layer that was at least 10nm thick and contained hydroxyl groups present at the outermost surface. These hydroxyl groups were first modified with a 3-methacryloxypropyltrimethoxysilane (MPS) cross linker. XPS and ToF-SIMS showed that a monolayer of the MPS molecules were successfully attached onto the titanium surfaces. The pNaSS film was grafted from the MPS modified titanium through atom transfer radical polymerization. Again, XPS and ToF-SIMS were used to verify that the pNaSS molecules were successfully grafted onto the modified surfaces. Atomic force microscopy analysis showed that the film was smooth and uniformly covered the surface. Fourier transform infrared spectroscopy indicated an ordered array of grafted NaSS molecules were present on the titanium surfaces. Sum frequency generation vibration spectroscopy and near edge X-ray absorption fine structure spectroscopy illustrated that the NaSS molecules were grafted onto the titanium surface with a substantial degree of orientational order in the styrene rings. PMID:21892821

  8. Water Soluble Polymers for Pharmaceutical Applications

    Directory of Open Access Journals (Sweden)

    Veeran Gowda Kadajji

    2011-11-01

    Full Text Available Advances in polymer science have led to the development of novel drug delivery systems. Some polymers are obtained from natural resources and then chemically modified for various applications, while others are chemically synthesized and used. A large number of natural and synthetic polymers are available. In the present paper, only water soluble polymers are described. They have been explained in two categories (1 synthetic and (2 natural. Drug polymer conjugates, block copolymers, hydrogels and other water soluble drug polymer complexes have also been explained. The general properties and applications of different water soluble polymers in the formulation of different dosage forms, novel delivery systems and biomedical applications will be discussed.

  9. Micro- and nanophase separations in hierarchical self-assembly of strongly amphiphilic block copolymer-based ionic supramolecules

    DEFF Research Database (Denmark)

    Ayoubi, Mehran Asad; Zhu, Kaizheng; Nyström, Bo

    2013-01-01

    block), a class of ionic supramolecules are successfully synthesized whose molecular architecture consists of a poly(styrene) PS block (Linear block) covalently connected to a strongly amphiphilic comb-like block (AmphComb block), i.e. Linear-b-AmphComb. In the melt state, these ionic supramolecules can.......20 (SLL/C and SBCC/C) and ∼0.28 (C/L). Finally, the specific influences of the strongly amphiphilic nature of the AmphComb blocks on the observed morphological and hierarchical behaviours of our system are discussed. For reference, stoichiometric strongly amphiphilic comb-like (AmphComb) ionic...

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

    Science.gov (United States)

    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.

  11. Detection block

    International Nuclear Information System (INIS)

    Bezak, A.

    1987-01-01

    A diagram is given of a detection block used for monitoring burnup of nuclear reactor fuel. A shielding block is an important part of the detection block. It stabilizes the fuel assembly in the fixing hole in front of a collimator where a suitable gamma beam is defined for gamma spectrometry determination of fuel burnup. The detector case and a neutron source case are placed on opposite sides of the fixing hole. For neutron measurement for which the water in the tank is used as a moderator, the neutron detector-fuel assembly configuration is selected such that neutrons from spontaneous fission and neutrons induced with the neutron source can both be measured. The patented design of the detection block permits longitudinal travel and rotation of the fuel assembly to any position, and thus more reliable determination of nuclear fuel burnup. (E.S.). 1 fig

  12. CONJUGATED BLOCK-COPOLYMERS FOR ELECTROLUMINESCENT DIODES

    NARCIS (Netherlands)

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

    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

  13. Substrate tolerant direct block copolymer nanolithography

    DEFF Research Database (Denmark)

    Li, Tao; Wang, Zhongli; Schulte, Lars

    2016-01-01

    Block copolymer (BC) self-assembly constitutes a powerful platform for nanolithography. However, there is a need for a general approach to BC lithography that critically considers all the steps from substrate preparation to the final pattern transfer. We present a procedure that significantly sim...... plasma treatment enables formation of the oxidized PDMS hard mask, PS block removal and polymer or graphene substrate patterning....

  14. Modification of polymer blends by irradiation

    International Nuclear Information System (INIS)

    Zuchowska, D.; Zagorski, Z.P.

    1999-01-01

    Modification of polymers, especially of polyolefin-elastomer blends (e. g. ethylene/propylene/diene terpolymer, ethylene propylene copolymer, ethylene/vinyl acetate copolymer etc.), by irradiation with a beam of fast electrons is discussed. Irradiation of polymer blends usually results in enhanced interactions between the constituents, caused among other things, by grafting induced at the polymer interphase. As a result, mechanical properties are affected to an extent depending on the proportion and type of constituent polymers, stabilizer content and radiation dose. Breaking strength (σ) relative elongation at break (ε) and melt flow rate (MFR), were examined for a triblock styrene/butadiene/styrene (SBS) copolymer, polypropylene (PP), and a PP-SBS blend (50:50 by wt.). In PP, the content of the crystal phase was determined. Irradiation was found to make SBS crosslink, as a result, σ rose by 25% and ε remained unaffected. PP was found to become degraded upon irradiation (MFR rose as much as 16 times), thereby σ and ε decreased considerably. In pure PP, the content of the crystal phase was found to increase. The variations of σ and ε in the irradiated PP-SBS blend follow a tendency similar to that in the SBS copolymer examined. This fact suggests the SBS copolymer to have a decisive effect on the macroscopic properties of the PP-SBS blend. (author)

  15. Green polymer chemistry: biocatalysis and biomaterials

    Science.gov (United States)

    This overview briefly surveys the practice of green chemistry in polymer science. Eight related themes can be discerned from the current research activities: 1) biocatalysis, 2) bio-based building blocks and agricultural products, 3) degradable polymers, 4) recycling of polymer products and catalys...

  16. Occupational Styrene Exposure on Auditory Function Among Adults: A Systematic Review of Selected Workers.

    Science.gov (United States)

    Pleban, Francis T; Oketope, Olutosin; Shrestha, Laxmi

    2017-12-01

    A review study was conducted to examine the adverse effects of styrene, styrene mixtures, or styrene and/or styrene mixtures and noise on the auditory system in humans employed in occupational settings. The search included peer-reviewed articles published in English language involving human volunteers spanning a 25-year period (1990-2015). Studies included peer review journals, case-control studies, and case reports. Animal studies were excluded. An initial search identified 40 studies. After screening for inclusion, 13 studies were retrieved for full journal detail examination and review. As a whole, the results range from no to mild associations between styrene exposure and auditory dysfunction, noting relatively small sample sizes. However, four studies investigating styrene with other organic solvent mixtures and noise suggested combined exposures to both styrene organic solvent mixtures may be more ototoxic than exposure to noise alone. There is little literature examining the effect of styrene on auditory functioning in humans. Nonetheless, findings suggest public health professionals and policy makers should be made aware of the future research needs pertaining to hearing impairment and ototoxicity from styrene. It is recommended that chronic styrene-exposed individuals be routinely evaluated with a comprehensive audiological test battery to detect early signs of auditory dysfunction.

  17. New improved polymer electrolyte membrane for PEM fuel cell. Final Report, 1. Documentation synthesis and test of proton exchange membranes

    Energy Technology Data Exchange (ETDEWEB)

    Lund, Peter B.; Dimitrov, I. (IRD A/S, Svendborg (Denmark)); Jankova, K.; Hvilsted, S. (Technical Univ. of Denmark. Chemical Engineering, Kgs. Lyngby (Denmark)); Juul Larsen, M.; Skou, E. (Univ. of Southern Denmark. Institute of Chemical Engineering, Biotechnology and Environmental Technology, Odense (Denmark))

    2010-07-15

    A novel concept for preparation of sulfonate containing fluorinated block co-polystyrenes have been developed based on initial ATRP of fluorinated styrene monomers. The strategy depends on well defined macroinitiatiors that after conversion to block copolymers can be post functionalized in two steps with propyl sulfonate groups in different ratios. Thermal investigations have demonstrated that addition of a PFS block to the sulfonate containing block improves the materials' thermal stability. (Author)

  18. Pulmonary function and oxidative stress in workers exposed to styrene in plastic factory: occupational hazards in styrene-exposed plastic factory workers.

    Science.gov (United States)

    Sati, Prakash Chandra; Khaliq, Farah; Vaney, Neelam; Ahmed, Tanzeel; Tripathi, Ashok K; Banerjee, Basu Dev

    2011-11-01

    Styrene is a volatile organic compound used in factories for synthesis of plastic products. The pneumotoxicity of styrene in experimental animals is known. The aim of the present study was to study the effect of styrene on lung function and oxidative stress in occupationally exposed workers in plastic factory. Thirty-four male workers, between 18 and 40 years of age, exposed to styrene for atleast 8 hours a day for more than a year were studied, while 30 age- and sex-matched healthy subjects not exposed to styrene served as controls. Assessment of lung functions showed a statistically significant reduction (p volumes, capacities (FVC, FEV(1), VC, ERV, IRV, and IC) and flow rates (PEFR, MEF(75%), and MVV) in the study group (workers) as compared to controls. Malondialdehyde (MDA) was observed to be significantly high (p < 0.05) while ferric-reducing ability of plasma (FRAP) was significantly low (p < 0.05) in styrene-exposed subjects. Reduced glutathione (GSH) level was significantly depleted in exposed subjects as compared to control group. The mean value of serum cytochrome c in styrene-exposed subjects was found to be 1.1 ng/ml (0.89-1.89) while in control its levels were under detection limit (0.05 ng/ml). It shows that styrene inhalation by workers leads to increased level of oxidative stress, which is supposed to be the cause of lung damage.

  19. Compatibility, Morphology, Mechanical Properties and Biodegradability of Poly(styrene-ethylene-propylenestyrene/ Modified Thermoplastic Starch Blends

    Directory of Open Access Journals (Sweden)

    Saaid Rahimi Bandarabadi

    2016-09-01

    Full Text Available The effect of modified starch on the properties of poly(styrene-ethylenepropylene- styrene tri-block copolymer was studied. Chemical treatment of starch with maleic anhydride was accomplished in an internal mixer in the presence of glycerol. The reaction was confirmed using Fourier infrared spectroscopy (FTIR and titration. The blend samples containing 10, 20, 30 and 50 wt% were obtained by melt blending and their mechanical, morphological and dynamic-mechanical properties were studied. Scanning electron microscopy (SEM images displayed droplet-matrix morphology and with increases in modified starch up to 50 wt% some partial co-continuous morphology was also observed. With increase of modified starch in the compound, the size of dispersed phase increased. DMTA results revealed that the partial compatibility was obtained because of slight difference between glass transition temperatures of two phases in the presence of modified starch. The peak of modified starch shifted to higher values and the differences between the two peaks decreased, indicating partial compatibility. Mechanical properties including tensile, elongation-at-break and modulus were also determined and the results showed that the mechanical properties of the sample were higher than those of neat TPS because of the higher compatibility. Tensile strength was decreased with increase in modified starch content due to the absence of strong interfacial adhesion. Moduli of the samples were increased with increase in modified starch content due to higher stiffness of starch. Biodegradability of the samples was evaluated by weight loss percentage using compost test. A rapid degradation was observed in the first 45 days and with increase of the modified starch content the degree of degradation was increased.

  20. STABLE SILICA-GRAFTED POLYMER-BOUND BULKY-PHOSPHITE MODIFIED RHODIUM HYDROFORMYLATION CATALYSTS

    NARCIS (Netherlands)

    JONGSMA, T; VANAERT, H; FOSSEN, M; CHALLA, G; VANLEEUWEN, PWNM

    1993-01-01

    The present study demonstrates that silica-grafted polymer-bound phosphite modified rhodium complexes can be used in continuous flow reactors. The hydroformylation of styrene was carried out at moderate pressure (p(CO/H-2) = 30 bar) and temperature (T = 100-degrees-C), yielding constant conversions

  1. Studies for methods to improve thermostability of the functionalized butadiene styrene rubbers

    Directory of Open Access Journals (Sweden)

    A. L. Rumyantseva

    2018-01-01

    Full Text Available It is well known that the tire performance properties can deteriorate in the processes of production, processing, storage and operation. One of the reasons for that is a series of processes occurring in the polymer under the influence of different factors: thermal, mechanical or chemical. This problem is particularly relevant for functionalized polymers, as functional groups can interact with each other, causing side cross linking reactions that lead to a deterioration of consumer properties of the products. The main purpose of this work was to study influence of several key factors on the thermostability of functionalized rubbers in order to find a solution: different types of antioxidants, rubber polymerizate stripping conditions and rubber processing. In accordance with the problem, solutions were found and work was carried out in several directions: changing the pH of the medium in the rubber stripping and using antioxidants containing carbonyl groups located in ?-positions to methylene groups, namely Irganox 1520 and Irganox 1076. As an evaluation factor, thermal treatment was selected in two modes: at 100 °C for 48 hours and after extruder at 130 °C for 5 minutes + 100 °C for 48 hours. At the same time, the following parameters were determined: molecular weight characteristics and Mooney viscosity of the starting polymers and after thermal aging. During the experiments, it was found that the acidity of the medium in the water degasser does not affect the crosslinking of the functionalized rubber during storage. In addition, a study was made of the effect of the type of antioxidant and its quantity on the thermal stability of functionalized styrene butadiene rubbers, as well as the study of the effect of the content of the modifying agent on the thermal stability of the product. It has been found that the use, as antioxidants, of carbonyl compounds containing a methylene group at the ?-position, leads to inhibition of the cross

  2. Preparation of Fe 3O 4/poly(styrene-butyl acrylate-[2-(methacryloxy)ethyl]trimethylammonium chloride) by emulsifier-free emulsion polymerization and its interaction with DNA

    Science.gov (United States)

    Li, Xiaolong; Liu, Guoqiang; Yan, Wei; Chu, Paul K.; Yeung, Kelvin W. K.; Wu, Shuilin; Yi, Changfeng; Xu, Zushun

    2012-04-01

    Cationic magnetic polymer particles Fe3O4/poly(styrene-butyl acrylate-[2-(methacryloxy)ethyl]trimethylammonium chloride), a type of potential gene carrier, were prepared by emulsifier-free emulsion polymerization with oleic acid modified magnetite Fe3O4, styrene, butyl acrylate and [2-(methacryloxy)ethyl]trimethylammonium chloride) (METAC). The morphology of the particles was characterized by transmission electron microscopy and the composites of particles were characterized by FT-IR spectroscopy, X-ray diffraction. These results showed that magnetic particles were well dispersed in polymers with the content of about 15%(wt/wt). The composites exhibited superparamagnetism and possessed a certain level of magnetic response. The interactions between the particles with calf-thymus DNA (ct DNA) were confirmed by zeta potential measurement, UV-vis spectroscopy and fluorescence spectroscopy. The DNA-binding capacity determined by the agarose gel electrophoresis showed good binding capacity of the emulsion to DNA. These results suggested the potential of the cationic magnetic polymer emulsion as gene target delivery carrier.

  3. Formal description of styrene conversion in ionized air

    International Nuclear Information System (INIS)

    Novoselov, Yu.N.; Filatov, I.E.

    2002-01-01

    The styrene conversion in the air flow under the effect of the electron beam with the energy of 180 keV and the streamer corona charge is studied with the purpose of searching the general criterion of the efficiency of the air purification from the toxic aromatic unsaturated compounds with application of the electrophysical methods. It is established, that dependence of the styrene concentration on the radiation pulse number have the character of the falling curves specific for the first order reactions. It is shown that it is advisable to use as the criterion of the efficiency of the electrophysical air purification methods the initial characteristic energy, the numerical value whereof corresponds to the energy quantity, removed substance concentration by e = 2.718 times [ru

  4. Recycling cycle of materials applied to acrylonitrile-butadiene-styrene/policarbonate blends with styrene-butadiene-styrene copolymer addition

    Science.gov (United States)

    Cândido, L. H. A.; Ferreira, D. B.; Júnior, W. Kindlein; Demori, R.; Mauler, R. S.

    2014-05-01

    The scope of this research is the recycling of polymers from mobile phones hulls discarded and the performance evaluation when they are submitted to the Recycling Cycle of Materials (RCM). The studied material was the ABS/PC blend in a 70/30 proportion. Different compositions were evaluated adding virgin material, recycled material and using the copolymer SBS as impact modifier. In order to evaluate the properties of material's composition, the samples were characterized by TGA, FTIR, SEM, IZOD impact strength and tensile strength tests. At the first stage, the presented results suggest the composition containing 25% of recycled material and 5% of SBS combines good mechanical performance to the higher content of recycled material and lower content of impact modifier providing major benefits to recycling plans. Five cycles (RCM) were applied in the second stage; they evidenced a decrease trend considering the impact strength. At first and second cycle the impact strength was higher than reference material (ABS/PC blend) and from the fourth cycle it was lower. The superiority impact strength in the first and second cycles can be attributed to impact modifier effect. The thermal tests and the spectrometry didn't show the presence of degradation process in the material and the TGA curves demonstrated the process stability. The impact surface of each sample was observed at SEM. The microstructures are not homogeneous presenting voids and lamellar appearance, although the outer surface presents no defects, demonstrating good moldability. The present work aims to assess the life cycle of the material from the successive recycling processes.

  5. Fast and robust method for the determination of microstructure and composition in butadiene, styrene-butadiene, and isoprene rubber by near-infrared spectroscopy.

    Science.gov (United States)

    Vilmin, Franck; Dussap, Claude; Coste, Nathalie

    2006-06-01

    In the tire industry, synthetic styrene-butadiene rubber (SBR), butadiene rubber (BR), and isoprene rubber (IR) elastomers are essential for conferring to the product its properties of grip and rolling resistance. Their physical properties depend on their chemical composition, i. e., their microstructure and styrene content, which must be accurately controlled. This paper describes a fast, robust, and highly reproducible near-infrared analytical method for the quantitative determination of the microstructure and styrene content. The quantitative models are calculated with the help of pure spectral profiles estimated from a partial least squares (PLS) regression, using (13)C nuclear magnetic resonance (NMR) as the reference method. This versatile approach allows the models to be applied over a large range of compositions, from a single BR to an SBR-IR blend. The resulting quantitative predictions are independent of the sample path length. As a consequence, the sample preparation is solvent free and simplified with a very fast (five minutes) hot filming step of a bulk polymer piece. No precise thickness control is required. Thus, the operator effect becomes negligible and the method is easily transferable. The root mean square error of prediction, depending on the rubber composition, is between 0.7% and 1.3%. The reproducibility standard error is less than 0.2% in every case.

  6. EFFECTS OF IMPREGNATION WITH STYRENE AND NANO-ZINC OXIDE ON FIRE-RETARDING, PHYSICAL, AND MECHANICAL PROPERTIES OF POPLAR WOOD

    Directory of Open Access Journals (Sweden)

    Siroos Habibzade

    2016-12-01

    Full Text Available Nanoparticles have been vastly applied in wood polymer composites (WPCs in the recent years to improve some of the drawbacks of solid wood species. In the present study, the effects of ZnO nanoparticles on fire retarding, physical, and mechanical properties of polymerized poplar wood were investigated. Poplar specimens were impregnated with styrene monomer, containing four different contents of nano-zinc oxide (ZnO (0, 0.5, 1 and 1.5%, based on the dry weight of monomer. Results of the scanning electron microscopy (SEM showed homogeneous dispersion of ZnO nanoparticles in the WPC matrix. Nano-zinc oxide improved physical properties such as dimensional stability and water absorption. Moreover, mechanical properties increased in comparison to the control specimens. The impregnation process also significantly improved some of the fire-retarding properties, including the ignition time; however, the flammability nature of styrene aggravated some others, such as carbonized area. It was concluded that, although most of the properties were improved, the final application of WPC should be taken in to consideration before making decision on whether or not to impregnate populus wood with styrene.

  7. The immobilization of anion exchange resins in polymer modified cements

    International Nuclear Information System (INIS)

    Dyer, A.; Morgan, P.D.

    1991-09-01

    Organic anion exchange resins, loaded with 99-Tc as the pertechnate ion, were incorporated into polymer modified cements (Flexocrete Ltd, Preston). BFS/OPC (9:1 mix) also was modified by three polymers from the same source (styrene acrylic (2) styrene butadiene) and loaded with anion exchanger containing the pertechnate. Composites were tested for initial compressive strengths, under water and radiation stability and leach rate. IAEA standard leach testing was with simulated sea and ground waters. Ground water leaching also was carried out on composites subjected to 1.10 9 rads (γ). Leach testing correlated well with compressive strength. Modified composites performed better than the BFS/OPC mix under all conditions studied and were able to encapsulate higher resin loadings. (author)

  8. Positron annihilation lifetime study of interfaces in ternary polymer blends

    International Nuclear Information System (INIS)

    Meghala, D; Ramya, P; Pasang, T; Raj, J M; Ranganathaiah, C; Williams, J F

    2013-01-01

    A new method based on positron lifetime spectroscopy is developed to characterize individual interfaces in ternary polymer blends and hence determine the composition dependent miscibility level. The method owes its origin to the Kirkwood-Risemann-Zimm (KRZ) model for the evaluation of the hydrodynamic interaction parameters (α ij ) which was used successfully for a binary blend with a single interface. The model was revised for the present work for ternary polymer blends to account for three interfaces. The efficacy of this method is shown for two ternary blends namely poly(styrene-co-acrylonitrile)/poly (ethylene-co-vinylacetate)/poly(vinyl chloride) (SAN/EVA/PVC) and polycaprolactone /poly(styrene-co-acrylonitrile)/poly(vinyl chloride) (PCL/SAN/PVC) at different compositions. An effective hydrodynamic interaction parameter, α eff , was introduced to predict the overall miscibility of ternary blends.

  9. STYRENE/STYRENE-DERIVATIVE COPOLYMERIZATION BY PH2Zn-METALLOCENE-MAO SYSTEMS: HOMO- AND COPOLYMERIZATION OF á-METHYLSTYRENE WITH STYRENE

    OpenAIRE

    RABAGLIATI, FRANCO M; MUÑOZ, HÉCTOR E; MARDONES, GABRIELA V

    2010-01-01

    The copolymerization of styrene with á-methylstyrene has been tested using combined metallocene-MAO initiator systems with and without diphenylzinc. The metallocenes used were biscyclopentadienyltitanium dichloride, Cp2TiCl2, bis(n-butylcyclopentadienyl)titanium dichloride, (n-BuCp)2TiCl2, and the half-sandwich metallocene indenyltitanium trichloride, IndTiCl3. The results indicate that both binary metallocene-MAO, and ternary Ph2Zn-metallocene-MAO systems are capable of polymerizing á-methyl...

  10. New powder compaction method using a styrene foam

    International Nuclear Information System (INIS)

    Kinemuchi, Y.; Takata, A.; Ishizaki, K.

    1999-01-01

    In general, metallic and ceramic powder compacts for sintering are shaped by uni-axial pressing or cold isostatic pressing (CIPing). Since metal or rubber is used as dies or moulds, it is difficult to form complicated shapes and flat disks, i.e., the ratio of diameter / thickness more than 50, by using uni-axial or CIPing. Rubber moulding, a moulding method with a rubber bag, can not press powder uniformly into flat disks because rubber deforms significantly. To solve this problem, we developed a new shaping technique to obtain complicated or thin flat shape by using styrene foam, which is cheap and has good machinability. Plastic foams such as styrene and acrylic foam contain many pores, and shrink uniformly by applying external pressure when the pores are collapsed. In this study, shrinking behavior of styrene and acrylic rubber moulds related to CIPing pressure was investigated. The experimental results show that the plastic foams shrink uniformly and the plastic deformation is linearly increased as CIP pressure increases. Copyright (1999) AD-TECH - International Foundation for the Advancement of Technology Ltd

  11. Beyond benzyl grignards: facile generation of benzyl carbanions from styrenes.

    Science.gov (United States)

    Grigg, R David; Rigoli, Jared W; Van Hoveln, Ryan; Neale, Samuel; Schomaker, Jennifer M

    2012-07-23

    Benzylic functionalization is a convenient approach towards the conversion of readily available aromatic hydrocarbon feedstocks into more useful molecules. However, the formation of carbanionic benzyl species from benzyl halides or similar precursors is far from trivial. An alternative approach is the direct reaction of a styrene with a suitable coupling partner, but these reactions often involve the use of precious-metal transition-metal catalysts. Herein, we report the facile and convenient generation of reactive benzyl anionic species from styrenes. A Cu(I)-catalyzed Markovnikov hydroboration of the styrenic double bond by using a bulky pinacol borane source is followed by treatment with KOtBu to facilitate a sterically induced cleavage of the C-B bond to produce a benzylic carbanion. Quenching this intermediate with a variety of electrophiles, including CO(2), CS(2), isocyanates, and isothiocyanates, promotes C-C bond formation at the benzylic carbon atom. The utility of this methodology was demonstrated in a three-step, two-pot synthesis of the nonsteroidal anti-inflammatory drug (±)-flurbiprofen. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Site-Specific Antibody Functionalization Using Tetrazine-Styrene Cycloaddition.

    Science.gov (United States)

    Umlauf, Benjamin J; Mix, Kalie A; Grosskopf, Vanessa A; Raines, Ronald T; Shusta, Eric V

    2018-05-03

    Biologics, such as antibody-drug conjugates, are becoming mainstream therapeutics. Consequently, methods to functionalize biologics without disrupting their native properties are essential for identifying, characterizing, and translating candidate biologics from the bench to clinical practice. Here, we present a method for site-specific, carboxy-terminal modification of single-chain antibody fragments (scFvs). ScFvs displayed on the surface of yeast were isolated and functionalized by combining intein-mediated expressed protein ligation (EPL) with inverse electron-demand Diels-Alder (IEDDA) cycloaddition using a styrene-tetrazine pair. The high thiol concentration required to trigger EPL can hinder the subsequent chemoselective ligation reactions; therefore, the EPL reaction was used to append styrene to the scFv, limiting tetrazine exposure to damaging thiols. Subsequently, the styrene-functionalized scFv was reacted with tetrazine-conjugated compounds in an IEDDA cycloaddition to generate functionalized scFvs that retain their native binding activity. Rapid functionalization of yeast surface-derived scFv in a site-directed manner could find utility in many downstream laboratory and preclinical applications.

  13. Styrene biofiltration in a trickle-bed reactor

    Directory of Open Access Journals (Sweden)

    V. Novak

    2008-04-01

    Full Text Available The biological treatment of styrene waste gas in a trickle-bed filter (TBF was investigated. The bioreactor consisted of a two-part glass cylinder (ID 150 mm filled with 25 mm polypropylene Pall rings serving as packing material. The bed height was 1m. Although the laboratory temperature was maintained at 22 ºC, the water temperature in the trickle-bed filter was slightly lower (about 18 ºC.The main aim of our study was to observe the effect of empty-bed residence time (EBRT on bioreactor performance at a constant pollutant concentration over an extended time period. The bioreactor was inoculated with a mixed microbial consortium isolated from a styrene-degrading biofilter that had been running for the previous two years. After three weeks of acclimation period, the bioreactor was loaded with styrene (100 mg.m-3. EBRT was in the range of 53 s to 13 s. A maximum elimination capacity (EC of 11.3 gC.m-3.h-1 was reached at an organic loading (OL rate of 18.6 gC.m-3.h-1.

  14. Polystyrene Backbone Polymers Consisting of Alkyl-Substituted Triazine Side Groups for Phosphorescent OLEDs

    OpenAIRE

    Salert, Beatrice Ch. D.; Wedel, Armin; Grubert, Lutz; Eberle, Thomas; Anémian, Rémi; Krueger, Hartmut

    2012-01-01

    This paper describes the synthesis of new electron-transporting styrene monomers and their corresponding polystyrenes all with a 2,4,6-triphenyl-1,3,5-triazine basic structure in the side group. The monomers differ in the alkyl substitution and in the meta-/paralinkage of the triazine to the polymer backbone. The thermal and spectroscopic properties of the new electron-transporting polymers are discussed in regard to their chemical structures. Phosphorescent OLEDs were prepared using the obta...

  15. The Recent Developments in Biobased Polymers toward General and Engineering Applications: Polymers that Are Upgraded from Biodegradable Polymers, Analogous to Petroleum-Derived Polymers, and Newly Developed

    OpenAIRE

    Nakajima, Hajime; Dijkstra, Peter; Loos, Katja

    2017-01-01

    The main motivation for development of biobased polymers was their biodegradability, which is becoming important due to strong public concern about waste. Reflecting recent changes in the polymer industry, the sustainability of biobased polymers allows them to be used for general and engineering applications. This expansion is driven by the remarkable progress in the processes for refining biomass feedstocks to produce biobased building blocks that allow biobased polymers to have more versati...

  16. Fluorescent Pressure Response of Protein-Nanocluster Polymer Composites

    Science.gov (United States)

    2016-05-01

    composites as pressure sensitive indicators of brain damage. The PNC composites are made up of protein coated gold nanoclusters and a styrene-ethylene...enhancement of the BSA- protected gold nanoclusters and the corresponding conformational changes of protein, J Phys Chem C. 2013;117:639–647...public release; distribution is unlimited. 13. SUPPLEMENTARY NOTES 14. ABSTRACT This research focuses on the uses of polymer gold nanocluster (PNC

  17. Bacterial degradation of styrene in waste gases using a peat filter

    Energy Technology Data Exchange (ETDEWEB)

    Arnold, M.; Reittu, A. [Kuopio Univ. (Finland). Dept. of Environmental Sciences; Wright, A. von; Suihko, M.L. [VTT Biotechnology and Food Research (Finland); Martikainen, P.J. [Kuopio Univ. (Finland). Dept. of Environmental Sciences]|[National Public Health Inst., Lab. of Environmental Microbiology, Kuopio (Finland)

    1997-12-31

    A biofiltration process was developed for styrene-containing off-gases using peat as filter material. The average styrene reduction ratio after 190 days of operation was 70% (max. 98%) and the mean styrene elimination capacity was 12 g m{sup -3} h{sup -1} (max. 30 g m{sup -3} h{sup -1}). Efficient styrene degradation required addition of nutrients to the peat, adjustment of the pH to a neutral level and efficient control of the humidity. Maintenance of the water balance was easier in a down-flow than in an up-flow process, the former consequently resulting in much better filtration efficiency. The optimum operation temperature was around 23 C, but the styrene removal was still satisfactory at 12 C. Seven different bacterial isolates belonging to the genera Tsukamurella, Pseudomonas, Sphingomonas, Xanthomonas and an unidentified genus in the {gamma} group of the Proteobacteria isolated from the microflora of active peat filter material were capable of styrene degradation. The isolates differed in their capacity to decompose styrene to carbon dioxide and assimilate it to biomass. No toxic intermediate degradation products of styrene were detected in the filter outlet gas or in growing cultures of isolated bacteria. The use of these isolates in industrial biofilters is beneficial at low styrene concentrations and is safe from both the environmental and public health points of view. (orig.)

  18. Bacterial degradation of styrene in waste gases using a peat filter.

    Science.gov (United States)

    Arnold, M; Reittu, A; von Wright, A; Martikainen, P J; Suihko, M L

    1997-12-01

    A biofiltration process was developed for styrene-containing off-gases using peat as filter material. The average styrene reduction ratio after 190 days of operation was 70% (max. 98%) and the mean styrene elimination capacity was 12 g m-3 h-1 (max. 30 g m-3 h-1). Efficient styrene degradation required addition of nutrients to the peat, adjustment of the pH to a neutral level and efficient control of the humidity. Maintenance of the water balance was easier in a down-flow than in an up-flow process, the former consequently resulting in much better filtration efficiency. The optimum operation temperature was around 23 degrees C, but the styrene removal was still satisfactory at 12 degrees C. Seven different bacterial isolates belonging to the genera Tsukamurella, Pseudomonas, Sphingomonas, Xanthomonas and an unidentified genus in the gamma group of the Proteobacteria isolated from the microflora of active peat filter material were capable of styrene degradation. The isolates differed in their capacity to decompose styrene to carbon dioxide and assimilate it to biomass. No toxic intermediate degradation products of styrene were detected in the filter outlet gas or in growing cultures of isolated bacteria. The use of these isolates in industrial biofilters is beneficial at low styrene concentrations and is safe from both the environmental and public health points of view.

  19. Cooperative effects for CYP2E1 differ between styrene and its metabolites

    Science.gov (United States)

    Hartman, Jessica H.; Boysen, Gunnar; Miller, Grover P.

    2014-01-01

    Cooperative interactions are frequently observed in the metabolism of drugs and pollutants by cytochrome P450s; nevertheless, the molecular determinants for cooperativity remain elusive. Previously, we demonstrated that steady-state styrene metabolism by CYP2E1 exhibits positive cooperativity.We hypothesized that styrene metabolites have lower affinity than styrene toward CYP2E1 and limited ability to induce cooperative effects during metabolism. To test the hypothesis, we determined the potency and mechanism of inhibition for styrene and its metabolites toward oxidation of 4-nitrophenol using CYP2E1 Supersomes® and human liver microsomes.Styrene inhibited the reaction through a mixed cooperative mechanism with high affinity for the catalytic site (67 μM) and lower affinity for the cooperative site (1100 μM), while increasing substrate turnover at high concentrations. Styrene oxide and 4-vinylphenol possessed similar affinity for CYP2E1. Styrene oxide behaved cooperatively like styrene, but 4-vinylphenol decreased turnover at high concentrations. Styrene glycol was a very poor competitive inhibitor. Among all compounds, there was a positive correlation with binding and hydrophobicity.Taken together, these findings for CYP2E1 further validate contributions of cooperative mechanisms to metabolic processes, demonstrate the role of molecular structure on those mechanisms and underscore the potential for heterotropic cooperative effects between different compounds. PMID:23327532

  20. Infrared and ultraviolet spectroscopic studies of low-temperature radiolysis of ethylene - styrene copolymers

    International Nuclear Information System (INIS)

    Mal'tseva, A.P.; Golikov, V.P.; Leshchenko, S.S.; Karpov, V.L.

    1977-01-01

    Certain features of low-temperature radiolysis of statistic ethylene-styrene copolymers have been studied by infrared and ultraviolet spectroscopy. It is shown that the nature of the accumulation and decay of trans-vinylene, vinyl and vinylidene double bonds in an ethylene-styrene copolymer is essentially influenced by both the dose absorbed and copolymer composition. A suggestion is made that the ethylene-styrene copolymer is formed when structures are irradiated containing double bonds conjugated with the phenyl rings of styrene groups - which more effectively dissipate the absorbed energy than solitary phenyl rings

  1. Stabilization of polypropylene, polypropylene blends with poly (styrene-b-(ethylene-co-butylene)-b-styrene) under irradiation: A comparative investigation

    International Nuclear Information System (INIS)

    Luan Shifang; Yang Huawei; Shi Hengchong; Zhao Jie; Wang Jianwei; Yin Jinghua

    2011-01-01

    The aim of this paper is to investigate the stabilization of polypropylene in the poly (styrene-b-(ethylene-co-butylene)-b-styrene) (SEBS)/polypropylene (PP) blends under irradiation with respect to PP. The PP films, SEBS/PP films were subjected to electron beam irradiation and characterized by wide angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC), gel permeation chromatography (GPC), and dynamic mechanical thermal analysis (DMTA). It demonstrated that upon irradiation, the molecular weight of PP had a pronounced decrease due to the major chain scission, and the minor chain cross-linking or chain branching occurred at the higher irradiation dose. Stabilization of PP was improved in the presence of SEBS, exhibiting an enhanced irradiation resistance.

  2. Stabilization of polypropylene, polypropylene blends with poly (styrene-b-(ethylene-co-butylene)-b-styrene) under irradiation: A comparative investigation

    Energy Technology Data Exchange (ETDEWEB)

    Luan Shifang; Yang Huawei; Shi Hengchong; Zhao Jie [State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China); Wang Jianwei [Shandong Weigao Group Medical Polymer Company Limited, Weihai 264209 (China); Yin Jinghua, E-mail: yinjh@ciac.jl.c [State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China)

    2011-01-15

    The aim of this paper is to investigate the stabilization of polypropylene in the poly (styrene-b-(ethylene-co-butylene)-b-styrene) (SEBS)/polypropylene (PP) blends under irradiation with respect to PP. The PP films, SEBS/PP films were subjected to electron beam irradiation and characterized by wide angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC), gel permeation chromatography (GPC), and dynamic mechanical thermal analysis (DMTA). It demonstrated that upon irradiation, the molecular weight of PP had a pronounced decrease due to the major chain scission, and the minor chain cross-linking or chain branching occurred at the higher irradiation dose. Stabilization of PP was improved in the presence of SEBS, exhibiting an enhanced irradiation resistance.

  3. Biodegradable Polymers

    OpenAIRE

    Vroman, Isabelle; Tighzert, Lan

    2009-01-01

    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. ...

  4. Radiation induced, raft mediated grafting of styrene onto poly(ethylene-alt-tetrafluoroethylene) (ETFE)

    International Nuclear Information System (INIS)

    Celik, G.; Barsbay, M.; Gueven, O.

    2011-01-01

    Complete text of publication follows. The development of cost-effective proton exchange membranes to replace the state-of-the-art and expensive perfluorinated membranes such as Nafion, Flemion, and Aciplex is one of the main challenges for commercialization of polymer electrolyte fuel cell technology. Recently, partially fluorinated poly(ethlyene-alt-tetrafluoroethylene) (ETFE) has been identified as a promising alternative base polymer film to prepare low-cost polymer electrolyte membranes because of its advantageous characters like superior mechanical properties and high resistance to radiation-induced damage. The radiation-induced grafting technique, based on the utilization of a polymer material such as ETFE in combination with further chemical modification steps (sulfonation) allows the functionalization of the base material and the introduction of the desired property (proton conductivity) for preparing a fuel cell membrane. However this simple conventional method suffers from one simple flaw: The molecular weight and the polydispersity of the grafted chains cannot be controlled. Predetermined molecular weights and low dispersities as well as homogeneous composition and desired architecture can be achieved by grafting of monomer onto base polymer under living/controlled free radical polymerization (CRP) conditions. Among the CRP methods, Reversible Addition Fragmentation-Chain Transfer (RAFT) is of particular interest as a very wide range of functional monomers can be polymerized in a controlled manner under non-demanding reaction conditions (e.g., tolerance to oxygen and low temperatures). The present study deals with the RAFT mediated radiation-induced (0.032 kGyh -1 , 60 Co) grafting of styrene on ETFE films followed by the sulfonation of the polystyrene grafts. The effect of monomer concentration, absorbed dose and RAFT agent concentration on the grafting were investigated. The synthesized films were characterized by ATR-FTIR, XPS, DSC and TGA methods

  5. Amphiphilic glycosylated block copolypeptides as macromolecular surfactants in the emulsion polymerization of styrene

    NARCIS (Netherlands)

    Jacobs, Jaco; Gathergood, N.; Heuts, J.P.A.; Heise, A.

    2015-01-01

    Diblock copolymers consisting of poly(L-phenyl alanine) and poly(benzyl-L-glutamate) or poly(CBZ-L-lysine), respectively, were synthesized via sequential NCA polymerization. After deprotection, subsequent partial glycosylation of the glutamic acid and lysine units with galactosamine hydrochloride or

  6. Nanoparticle self-assembly in mixtures of phospholipids with styrene/maleic acid copolymers or fluorinated surfactants

    Science.gov (United States)

    Vargas, Carolyn; Arenas, Rodrigo Cuevas; Frotscher, Erik; Keller, Sandro

    2015-12-01

    Self-assembling nanostructures in aqueous mixtures of bilayer-forming lipids and micelle-forming surfactants are relevant to in vitro studies on biological and synthetic membranes and membrane proteins. Considerable efforts are currently underway to replace conventional detergents by milder alternatives such as styrene/maleic acid (SMA) copolymers and fluorinated surfactants. However, these compounds and their nanosized assemblies remain poorly understood as regards their interactions with lipid membranes, particularly, the thermodynamics of membrane partitioning and solubilisation. Using 19F and 31P nuclear magnetic resonance spectroscopy, static and dynamic light scattering, and isothermal titration calorimetry, we have systematically investigated the aggregational state of a zwitterionic bilayer-forming phospholipid upon exposure to an SMA polymer with a styrene/maleic acid ratio of 3 : 1 or to a fluorinated octyl phosphocholine derivative called F6OPC. The lipid interactions of SMA(3 : 1) and F6OPC can be thermodynamically conceptualised within the framework of a three-stage model that treats bilayer vesicles, discoidal or micellar nanostructures, and the aqueous solution as distinct pseudophases. The exceptional solubilising power of SMA(3 : 1) is reflected in very low membrane-saturating and solubilising polymer/lipid molar ratios of 0.10 and 0.15, respectively. Although F6OPC saturates bilayers at an even lower molar ratio of 0.031, this nondetergent does not solubilise lipids even at >1000-fold molar excess, thus highlighting fundamental differences between these two types of mild membrane-mimetic systems. We rationalise these findings in terms of a new classification of surfactants based on bilayer-to-micelle transfer free energies and discuss practical implications for membrane-protein research.Self-assembling nanostructures in aqueous mixtures of bilayer-forming lipids and micelle-forming surfactants are relevant to in vitro studies on biological and

  7. Electrically conductive poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate)/polyacrylonitrile fabrics for humidity sensors

    International Nuclear Information System (INIS)

    Panapoy, Manop; Singsang, Witawat; Ksapabutr, Bussarin

    2010-01-01

    Humidity sensors based on poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate) (PEDOT-PSS)/polyacrylonitrile (PAN) nanofiber fabric were fabricated by a dip coating of nonwoven PAN nanofiber mat, which was prepared via an electrospinning method, in PEDOT-PSS solution. The influence of PAN solution concentration on their responsiveness to humidity on dynamic testing was monitored as the device was exposed to humidity. With the relative humidity (RH) changing from 0 to 100%, a resistance device response over 110% was achieved, and the curve of the resistance response with RH is of high linearity at the humidity working range of 0-100% RH. The high device reproducibility was demonstrated by carrying out vapor adsorption-desorption dynamic cycles, and the response and recovery times were determined to be of the order of 2-46 and 7-34 s, respectively. These hybrid polymer sensors can be used as disposable handheld instruments due to low cost and light weight.

  8. Preparation of Paraffin@Poly(styrene-co-acrylic acid) Phase Change Nanocapsules via Combined Miniemulsion/Emulsion Polymerization.

    Science.gov (United States)

    Zhang, Feng; Liu, Tian-Yu; Hou, Gui-Hua; Guan, Rong-Feng; Zhang, Jun-Hao

    2018-06-01

    The fast development of solid-liquid phase change materials calls for nanomaterials with large specific surface area for rapid heat transfer and encapsulation of phase change materials to prevent potential leakage. Here we report a combined miniemulsion/emulsion polymerization method to prepare poly(styrene-co-acrylic acid)-encapsulated paraffin (paraffin@P(St-co-AA)) nanocapsules. The method could suppress the shortcomings of common miniemulsion polymerization (such as evaporation of monomer and decomposition of initiator during ultrasonication). The paraffin@P(St-co-AA) nanocapsules are uniform in size and the polymer shell can be controlled by the weight ratio of St to paraffin. The phase change behavior of the nanocapsules is similar to that of pure paraffin. We believe our method can also be utilized to synthesize other core-shell phase change materials.

  9. Grafting amino drugs to poly(styrene-alt-maleic anhydride) as a potential method for drug release

    Energy Technology Data Exchange (ETDEWEB)

    Khazaei, Ardeshir; Saednia, Shahnaz; Saien, Javad; Abbasi, Fatemeh, E-mail: Khazaei_1326@yahoo.com, E-mail: ssaednia@gmail.com [Faculty of Chemistry, Bu-Ali Sina University, Hamedan (Iran, Islamic Republic of); Kazem-Rostami, Masoud [Young Researchers Club and Elite, Takestan Branch, Islamic Azad University, Takestan (Iran, Islamic Republic of); Sadeghpour, Mahdieh [Department of Chemistry, Takestan Branch, Islamic Azad University, Takestan (Iran, Islamic Republic of); Borazjani, Maryam Kiani [Faculty of Science, Department of Chemistry, Bushehr Payame Noor University (PNU), Bushehr (Iran, Islamic Republic of)

    2013-07-15

    Drug delivery systems based on polymer-drug conjugates give an improved treatment with lower toxicity or side effects and be used for the treatment of different diseases. Conjugates of biodegradable poly(styrene-alt-maleic anhydride) (PSMA), with a therapeutic agents such as amantadine hydrochloride, amlodipine, gabapentin, zonisamide and mesalamine, were afforded by the formation of the amide bonds of the amino drugs that reacted with the PSMA anhydride groups. The amounts of covalently conjugated drugs were determined by a {sup 1}H NMR spectroscopic method, and the in vitro release rate in buffer solution (pH 1.3) was studied at body temperature 37 Degree-Sign C. In kinetic studies, different dissolution models were examined to obtain drug release data and the collected data were well-fitted to the Korsmeyer-Peppas equation, revealing a dominant Fickian diffusion mechanism for drug release under the in vitro conditions. (author)

  10. Coarse-grained simulations of polyelectrolyte complexes: MARTINI models for poly(styrene sulfonate) and poly(diallyldimethylammonium)

    International Nuclear Information System (INIS)

    Vögele, Martin; Holm, Christian; Smiatek, Jens

    2015-01-01

    We present simulations of aqueous polyelectrolyte complexes with new MARTINI models for the charged polymers poly(styrene sulfonate) and poly(diallyldimethylammonium). Our coarse-grained polyelectrolyte models allow us to study large length and long time scales with regard to chemical details and thermodynamic properties. The results are compared to the outcomes of previous atomistic molecular dynamics simulations and verify that electrostatic properties are reproduced by our MARTINI coarse-grained approach with reasonable accuracy. Structural similarity between the atomistic and the coarse-grained results is indicated by a comparison between the pair radial distribution functions and the cumulative number of surrounding particles. Our coarse-grained models are able to quantitatively reproduce previous findings like the correct charge compensation mechanism and a reduced dielectric constant of water. These results can be interpreted as the underlying reason for the stability of polyelectrolyte multilayers and complexes and validate the robustness of the proposed models

  11. Coarse-grained simulations of polyelectrolyte complexes: MARTINI models for poly(styrene sulfonate) and poly(diallyldimethylammonium)

    Energy Technology Data Exchange (ETDEWEB)

    Vögele, Martin [Institute for Computational Physics, University of Stuttgart, Stuttgart (Germany); Department of Theoretical Biophysics, Max Planck Institute of Biophysics, Frankfurt a. M. (Germany); Holm, Christian; Smiatek, Jens, E-mail: smiatek@icp.uni-stuttgart.de [Institute for Computational Physics, University of Stuttgart, Stuttgart (Germany)

    2015-12-28

    We present simulations of aqueous polyelectrolyte complexes with new MARTINI models for the charged polymers poly(styrene sulfonate) and poly(diallyldimethylammonium). Our coarse-grained polyelectrolyte models allow us to study large length and long time scales with regard to chemical details and thermodynamic properties. The results are compared to the outcomes of previous atomistic molecular dynamics simulations and verify that electrostatic properties are reproduced by our MARTINI coarse-grained approach with reasonable accuracy. Structural similarity between the atomistic and the coarse-grained results is indicated by a comparison between the pair radial distribution functions and the cumulative number of surrounding particles. Our coarse-grained models are able to quantitatively reproduce previous findings like the correct charge compensation mechanism and a reduced dielectric constant of water. These results can be interpreted as the underlying reason for the stability of polyelectrolyte multilayers and complexes and validate the robustness of the proposed models.

  12. Investigation of the adsorption of polymer chains on amine-functionalized double-walled carbon nanotubes.

    Science.gov (United States)

    Ansari, R; Ajori, S; Rouhi, S

    2015-12-01

    Molecular dynamics (MD) simulations were used to study the adsorption of different polymer chains on functionalized double-walled carbon nanotubes (DWCNTs). The nanotubes were functionalized with two different amines: NH2 (a small amine) and CH2-NH2 (a large amine). Considering three different polymer chains, all with the same number of atoms, the effect of polymer type on the polymer-nanotube interaction was studied. In general, it was found that covalent functionalization considerably improved the polymer-DWCNT interaction. By comparing the results obtained with different polymer chains, it was observed that, unlike polyethylene and polyketone, poly(styrene sulfonate) only weakly interacts with the functionalized DWCNTs. Accordingly, the smallest radius of gyration was obtained with adsorbed poly(styrene sulfonate). It was also observed that the DWCNTs functionalized with the large amine presented more stable interactions with polyketone and poly(styrene sulfonate) than with polyethylene, whereas the DWCNTs functionalized with the small amine showed better interfacial noncovalent bonding with polyethylene.

  13. Perfluorinated polymer grafting: influence of preirradiation conditions

    International Nuclear Information System (INIS)

    Moura, E.; Somessari, E.S.R.; Silveira, C.G.; Paes, H.A.; Sousa, C.A.; Fernandes, W.; Manzoli, J.E; Geraldo, A.B.; Cardozo, P.

    2009-01-01

    The technological interest of perfluorinated polymers is related to its specific properties like low chemical reactivity and high mechanical and temperature resistance. The development of polymeric membranes for PEM fuel cell dispositives requires beyond these characteristics, a long-life time performance and low cost compared to Nafion membranes. By these material have high crystallinity, the radiation grafting indeed occurs but this process generate a low mechanical resistance aggregate. In this way, it is necessary to render the polymer with a low crystallinity or even amorphous. Generally, irradiation under polymer melt temperatures makes the crystallinity breaking and polymer crosslinking. The main objective of this work was promoting the crosslinking process into perfluorinated polymers by pre-irradiation method and to precede styrene grafting by electron beam irradiation in a second step. The experimental methodology consists in pre-irradiate perfluorinated polymers films like PTFE and PFA under high temperature (> 300 deg C) and vacuum conditions by electron beam irradiation at 5 kGy to 30 kGy doses and 2,85 kGy/s to 22,4 kGy/s dose rates. To obtain temperatures above 300 deg C, it was necessary construct a vacuum chamber with a heating system where temperature process could be follow up in real time. Some molecular alterations in polymeric matrix were analyzed by Mid-ATR-FTIR spectroscopy; macroscopic changes are verified by gravimetry. The styrene grafting onto these samples is realized by electron beam irradiation at doses between 30 and 100 kGy. These results are discussed. (author)

  14. Binary and ternary LLE data of the system (ethylbenzene + styrene + 1-ethyl-3-methylimidazolium thiocyanate) and binary VLE data of the system (styrene + 1-ethyl-3-methylimidazolium thiocyanate)

    International Nuclear Information System (INIS)

    Jongmans, Mark T.G.; Schuur, Boelo; Haan, André B. de

    2012-01-01

    Highlights: ► LLE data have been measured for the system {ethylbenzene + styrene + [EMIM][SCN]}. ► VLE was determined for the system {styrene + [EMIM][SCN]} at vacuum conditions. ► All experimental data were correlated well with the NRTL model. ► [EMIM][SCN] has a much larger selectivity than the benchmark solvent sulfolane. - Abstract: The distillation of close boiling mixtures may be improved by adding a proper affinity solvent, and thereby creating an extractive distillation process. An example of a close boiling mixture that may be separated by extractive distillation is the mixture ethylbenzene/styrene. The ionic liquid 1-ethyl-3-methylimidazolium thiocyanate ([EMIM][SCN]) is a promising solvent to separate ethylbenzene and styrene by extractive distillation. In this study, (vapour + liquid) equilibrium data have been measured for the binary system (styrene + [EMIM][SCN]) over the pressure range of (3 to 20) kPa and binary and ternary (liquid + liquid) equilibrium data of the system (ethylbenzene + styrene + [EMIM][SCN]) at temperatures (313.2, 333.2 and 353.2) K. Due to the low solubility of ethylbenzene in [EMIM][SCN], it was not possible to measure accurately VLE data of the binary system (ethylbenzene + [EMIM][SCN]) and of the ternary system (ethylbenzene + styrene + [EMIM][SCN]) using the ebulliometer. Because previous work showed that the LLE selectivity is a good measure for the selectivity in VLE, we determined the selectivity with LLE. The selectivity of [EMIM][SCN] to styrene in LLE measurements ranges from 2.1 at high styrene raffinate purity to 2.6 at high ethylbenzene raffinate purity. The NRTL model can properly describe the experimental results. The rRMSD in temperature, pressure and mole fraction for the binary VLE data are respectively (0.1, 0.12 and 0.13)%. The rRMSD is only 0.7% in mole fraction for the LLE data.

  15. Synthesis of amylose-block-polystyrene rod-coil block copolymers

    NARCIS (Netherlands)

    Loos, Katja; Stadler, Reimund

    1997-01-01

    In the present communication we demonstrate the synthesis of a hybrid block copolymer based on the combination of a biopolymer (amylose) with a synthetic block (polystyrene). To obtain such materials, amino-functionalized polymers were modified with maltoheptaose moieties that serve as initiators

  16. Lithium-Assisted Copolymerization of CO 2 /Cyclohexene Oxide: A Novel and Straightforward Route to Polycarbonates and Related Block Copolymers

    KAUST Repository

    Zhang, Dongyue; Zhang, Hefeng; Hadjichristidis, Nikolaos; Gnanou, Yves; Feng, Xiaoshuang

    2016-01-01

    of this initiating system also resides in the easy access to PSt-b-PCHC (PSt: polystyrene) and PI-b-PCHC (PI: polyisoprene) block copolymers which can be derived by mere one-pot sequential addition of styrene or dienes first and then of CO2 and CHO under the same

  17. Surprising transformation of a block copolymer into a high performance polystyrene ultrafiltration membrane with a hierarchically organized pore structure

    KAUST Repository

    Shevate, Rahul; Kumar, Mahendra; Karunakaran, Madhavan; Canlas, Christian; Peinemann, Klaus-Viktor

    2018-01-01

    ) block from self-assembled poly(styrene)-b-poly(4-vinyl pyridine) (PS-b-P4VP) membranes through the formation of an unstable pyridinium intermediate in an alkaline medium. During this process, the confined swelling and controlled degradation produced a

  18. Studies on interfaces between immiscible polymers by neutron reflectivity

    International Nuclear Information System (INIS)

    Torikai, Naoya; Noda, Ichiro; Matsushita, Yushu; Tasaki, Seiji; Ebisawa, Toru; Karim, Alamgir; Han, C.C.

    1995-01-01

    Segment distributions of partially deuterium-labeled styrene-2-vinylpyridine block copolymers in lamellar microphase-separated structure were investigated by neutron reflectivity (NR) measurements. Each component lamellae were alternatively stacked in spin-coated thin films and interfacial thickness between those lamellae was about 45 A. Also, it was found that the segments of block chains near a chemical junction point connecting different component blocks are strongly localized in the vicinity of lamellar interface, while those on the free ends are localized at the center of lamellar microdomain with a fairly wide distribution. (author)

  19. Studies on interfaces between immiscible polymers by neutron reflectivity

    Energy Technology Data Exchange (ETDEWEB)

    Torikai, Naoya; Noda, Ichiro [Nagoya Univ. (Japan). School of Engineering; Matsushita, Yushu; Tasaki, Seiji; Ebisawa, Toru; Karim, Alamgir; Han, C.C.

    1995-06-01

    Segment distributions of partially deuterium-labeled styrene-2-vinylpyridine block copolymers in lamellar microphase-separated structure were investigated by neutron reflectivity (NR) measurements. Each component lamellae were alternatively stacked in spin-coated thin films and interfacial thickness between those lamellae was about 45 A. Also, it was found that the segments of block chains near a chemical junction point connecting different component blocks are strongly localized in the vicinity of lamellar interface, while those on the free ends are localized at the center of lamellar microdomain with a fairly wide distribution. (author).

  20. Radiation preparation of interpenetrating polymer networks

    International Nuclear Information System (INIS)

    Sheikh, N.; Ahmadi, M.; Afshar Taromi, F.

    2002-01-01

    Sequential interpenetrating polymer netwoks were prepared using gamma radiation. Styrene-butadiene rubber (SBR) and polymethyl methacrylate (PMMA) were used as elastomer and plastomer components respectively. Dicumyl peroxide (DCP) and ethylene glycol dimethacrylate (EGDMA) were also used as the curing agent of SBR and crosslinker for MMA monomer. The resulting IPNs were characterized by evaluating their mechanical properties. The effect of the amount of DCP on the final properties of product was examined. It was found that amount of curing agent had an important role on the properties of obtained IPNS. The results of the mechanical properties of IPNs showed very good synergistic behavior. (Author)