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Sample records for hyperbranched azobenzene-containing polymeric

  1. HYPERBRANCHED POLYMERIC DISPERSANTS AND NON-AQUEOUS PIGMENT DISPERSIONS

    NARCIS (Netherlands)

    ANDRE, XAVIER; Bernaerts, Katrien

    2011-01-01

    A polymeric dispersant having a hyperbranched polyurethane architecture obtained by reacting a polyisocyanate core with a mixture of a) 40 to 65 mol% of an anchor represented by Formula (I) and/or (II) wherein n represents an integer selected from 0 to 7; and X and Y each independently represent a p

  2. Hyperbranched polymeric dispersants and non-aqueous pigment dispersions

    NARCIS (Netherlands)

    ANDRE, XAVIER; Bernaerts, Katrien

    2012-01-01

    The invention discloses a polymeric dispersant having a hyperbranched polyurethane architecture obtained by reacting a polyisocyanate core with a mixture of a) 40 to 65 mol% of an anchor represented by Formula (I) and/or (II) wherein n represents an integer selected from 0 to 7; and X and Y each ind

  3. HYPERBRANCHED POLYMERIC DISPERSANTS AND NON-AQUEOUS PIGMENT DISPERSIONS

    NARCIS (Netherlands)

    ANCRE, XAVIER; BERNAERTS, KATRIEN; ANDRE, XAVIER

    2012-01-01

    A polymeric dispersant having a hyperbranched polyurethane architecture obtained by reacting a polyisocyanate core with a mixture of: a) 40 to 65 mol % of an anchor represented by Formula (I) and/or (II): wherein n represents an integer selected from 0 to 7; and X and Y each independently represent

  4. Hyperbranched Polymers by Type II Photoinitiated Self-Condensing Vinyl Polymerization.

    Science.gov (United States)

    Aydogan, Cansu; Ciftci, Mustafa; Yagci, Yusuf

    2016-04-01

    Type II photoinitiated self-condensing vinyl polymerization for the preparation of hyperbranched polymers is explored using 2-hydroxyethyl methacrylate (HEMA) or 2-(dimethylamino)ethyl methacrylate (DMAEMA), and methyl methacrylate as hydrogen donating inimers and comonomer, respectively, in the presence of benzophenone and camphorquinone under UV and visible light. Upon irradiation at the corresponding wavelength, the excited photoinitiator abstracts hydrogen from HEMA or DMAEMA leading to the formation of initiating radicals. Depending on the concentration of inimers, type of the photoinitiator, and irradiation time, hyperbranched polymers with different branching densities and cross-linked polymers are formed.

  5. The Volume Holographic Optical Storage Potential in Azobenzene Containing Polymers

    DEFF Research Database (Denmark)

    Hvilsted, Søren; Sanchez, Carlos; Alcalá, Rafael

    2009-01-01

    Volume holographic data storage is one of the most promising techniques to improve both the storage capacity of devices and the transfer data rate. Among the materials proposed as storage data media, azobenzene containing polymers have received much attention. Some of their properties seem to be ...

  6. Rheology of Hyperbranched Poly(triglyceride)-Based Thermoplastic Elastomers via RAFT polymerization

    Science.gov (United States)

    Yan, Mengguo; Cochran, Eric

    2014-03-01

    In this contribution we discuss how melt- and solid-state properties are influenced by the degree of branching and molecular weight in a family of hyperbranched thermoplastics derived from soybean oil. Acrylated epoxidized triglycerides from soybean oils have been polymerized to hyperbranched thermoplastic elastomers using reversible addition-fragmentation chain transfer (RAFT) polymerization. With the proper choice of chain transfer agent, both homopolymer and block copolymer can be synthesized. By changing the number of acrylic groups per triglycerides, the chain architectures can range from nearly linear to highly branched. We show how the fundamental viscoelastic properties (e.g. entanglement molecular weight, plateau modulus, etc.) are influenced by chain architecture and molecular weight.

  7. Synthesis of hyperbranched copolymers by combining enzymatic ring-opening polymerization and A TRP from a novel bifunctional initiator

    Institute of Scientific and Technical Information of China (English)

    Al Peng; CHEN Liang; HU Dehua; CHEN Yanhua; LI Dongshuang; ZHANG Bao; SHA Ke; WANG Jingyuan

    2006-01-01

    The hyperbranched aliphatic polyester P(ε-CL) was synthesized by means of Novozyme435-catalyzed ring-opening polymerization (ROP) of BHB (2, 2-bis(hydroxymethyl) butyric acid). The chains ended with hydroxyl of P(ε-CL) were modified by the esterification of α-bromopropionyl bromide to obtain hyperbranched difunctional macroinitiator, which was used in the ATRP of St. CuCI/HMTETA was used as the catalyst system in the reaction of ATRP to acquire the hyperbranched copolymers polystyrene-blockpoly(2,2-bis(hydroxymethyl) butyric acid). The copolymer was confirmed by NMR and GPC.

  8. HYPERBRANCHED EPOXY RESINS PREPARED BY PROTON TRANSFER POLYMERIZATION FROM AN A2 + B3 SYSTEM

    Institute of Scientific and Technical Information of China (English)

    Li-jie Ma; Hai-qiao Wang; Li fan He; Xiao-yu Li

    2011-01-01

    Epoxy-terminated hyperbranched polymers (EHBPs) were prepared by proton transfer polymerization and characterized by FT-IR, 1H-NMR and GPC. The solution and thermal properties of the uncured samples and mechanical properties of cured samples were examined. The thermo-stable products had good solubility in polar solvents, low solution viscosity and Tgs ranging from 15℃ to 33℃ depending on their molecular weights. The mechanical properties of cured films were studied and compared with those of a bisphenol-A type epoxy resin. The films of EHBPs had good impact resistance and high gloss values without sacrificing hardness and adhesion.

  9. Branched polymeric media: Perchlorate-selective resins from hyperbranched polyethyleneimine

    KAUST Repository

    Chen, Dennis P.

    2012-10-02

    Perchlorate (ClO4 -) is a persistent contaminant found in drinking groundwater sources in the United States. Ion exchange (IX) with selective and disposable resins based on cross-linked styrene divinylbenzene (STY-DVB) beads is currently the most commonly utilized process for removing low concentrations of ClO4 - (10-100 ppb) from contaminated drinking water sources. However, due to the low exchange capacity of perchlorate-selective STY-DVB resins (∼0.5-0.8 eq/L), the overall cost becomes prohibitive when treating groundwater with higher concentration of ClO4 - (e.g., 100-1000 ppb). In this article, we describe a new perchlorate-selective resin with high exchange capacity. This new resin was prepared by alkylation of branched polyethyleneimine (PEI) beads obtained from an inverse suspension polymerization process. Batch and column studies show that our new PEI resin with mixed hexyl/ethyl quaternary ammonium chloride exchange sites can selectively extract trace amounts of ClO4 - from a makeup groundwater (to below detection limit) in the presence of competing ions. In addition, this resin has a strong-base exchange capacity of 1.4 eq/L, which is 1.75-2.33 times larger than those of commercial perchlorate-selective STY-DVB resins. The overall results of our studies suggest that branched PEI beads provide versatile and promising building blocks for the preparation of perchlorate-selective resins with high exchange capacity. © 2012 American Chemical Society.

  10. Synthesis of Conjugated Hyperbranched Polytriazoles Containing Truxene Units by Click Polymerization

    Institute of Scientific and Technical Information of China (English)

    李冬至; 王欣; 贾玉涛; 王爱卿; 武永刚

    2012-01-01

    It has been a challenge to synthesize high molecular weight and soluble conjugated hyperbranched poly(1,2,3-triazole)s (hb-PTAs). In this paper a series of soluble hyperbranched polytriazoles, whose num- ber-average molecular weight (Mn) and polydispersity index ranged in (1.2--3.3)× 104 and 1.7--3.0, respectively, were synthesized with A2 d-B3 approach. In the polymerization process, diazides A1--A4 and triyne B1 were used as A2 and B3 monomers; Cu(I)-catalyst, THF and water were used as their reaction system. At room temperature the final molecular weight could be controlled through reaction time, so finally we obtained soluble conjugated hyper- branched poly(1,2,3-triazole)s hb-PTAs (1--4). The polymers were soluble in common organic solvents, and all emitted blue light; the films of polymers emitted yellow and blue light, due to the difference in the aggregation of their chromophoric units in the solid state. The thermal properties of the final copolymers were analyzed by differ- ential scanning calorimetry (DSC) and thermogravimetric analysis (TGA).

  11. 4-Dimethylaminopyridine promoted interfacial polymerization between hyperbranched polyesteramide and trimesoyl chloride for preparing ultralow-pressure reverse osmosis composite membrane.

    Science.gov (United States)

    Qin, Jiaxu; Lin, Saisai; Song, Shuqin; Zhang, Lin; Chen, Huanlin

    2013-07-24

    We have presented a concept of ultralow-pressure reverse osmosis membrane based on hyperbranched polyesteramide through interfacial reaction promoted by pyridine derivate. In this strategy, a key catalyst of 4-dimethylaminopyridine, which can both eliminate the steric hindrance of acyl transfer reaction and facilitate the phase transfer in interfacial polymerization, is adopted to drive the formation of a thin film composite membrane from the hyperbranched polyesteramide and trimesoyl chloride. The results of the characterization demonstrate that a dense, rough, and hydrophilic active layer with a thickness of about 100 nm is formed when the 4-dimethylaminopyridine catalyst is used. The salt rejections for Na2SO4, NaCl, and MgSO4 of the as-prepared composite membrane are higher than 92%, especially for Na2SO4 with 98% rejection. The water fluxes reach about 30-40 L·m(-2)·h(-1) even at an operation pressure of 0.6 MPa. The membrane exhibits good chlorine-resistance ability but poor resistance abilities to acidic and alkaline solutions in the physical-chemical stability experiment. It is also found that the resultant membrane possesses excellent separation performance for PEG-200, showing a promising way to separate small organic molecules from water.

  12. Light-Switchable Azobenzene-Containing Macromolecules: From UV to Near Infrared.

    Science.gov (United States)

    Weis, Philipp; Wu, Si

    2017-06-23

    Azobenzene-containing macromolecules (azo-macromolecules) such as azobenzene-containing polymers (azopolymers) and azobenzene-functionalized biomacromolecules are photoswitchable macromolecules. Trans-to-cis photoisomerization in conventional azo-macromolecules is induced by ultraviolet (UV) light. However, UV light cannot penetrate deeply into issue and has a very small fraction in sunlight. Therefore, conventional azo-macromolecules are problematic for biomedical and solar-energy-related applications. In this Feature Article, the strategies for constructing visible and near-infrared (NIR) light-responsive azo-macromolecules are reviewed, and the potential applications of visible- and NIR-light-responsive azo-macromolecules in biomedicine and solar energy conversion are highlighted. The remaining challenges in the field of photoswitchable azo-macromolecules are discussed. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Light propagation through photoinduced chiral structures in azobenzene-containing polymers

    DEFF Research Database (Denmark)

    Nedelchev, L; Nikolova, L; Todorov, T

    2001-01-01

    (o) of the exciting light. In amorphous azopolymers, light induces a macroscopic chiral structure comprising the whole illuminated region. The pitch depends on the value of e(o): no chirality is induced if e(o) = 1 (circular polarization). In liquid-crystalline azopolymers circularly polarized light induces......We investigate light propagation through azobenzene-containing polymers with photoinduced chiral structures. The structures have large pitch but the Mauguin condition is not fulfilled. The eigenmodes are shown to be elliptical and their ellipticity is determined by the ellipticity e...

  14. Optical and Physical Applications of Photocontrollable Materials: Azobenzene-Containing and Liquid Crystalline Polymers

    Directory of Open Access Journals (Sweden)

    Takashi Fukuda

    2012-01-01

    Full Text Available Photocontrol of molecular alignment is an exceptionally-intelligent and useful strategy. It enables us to control optical coefficients, peripheral molecular alignments, surface relief structure, and actuation of substances by means of photoirradiation. Azobenzene-containing polymers and functionalized liquid crystalline polymers are well-known photocontrollable materials. In this paper, we introduce recent applications of these materials in the fields of mechanics, self-organized structuring, mass transport, optics, and photonics. The concepts in each application are explained based on the mechanisms of photocontrol. The interesting natures of the photocontrollable materials and the conceptual applications will stimulate novel ideas for future research and development in this field.

  15. MORPHOLOGY STUDY OF A SERIES OF AZOBENZENE-CONTAINING SIDE-ON LIQUID CRYSTALLINE TRIBLOCK COPOLYMERS

    Institute of Scientific and Technical Information of China (English)

    Wei Deng; Annie Br(u)let; Pierre-antoine Albouy; Patrick Keller; Xiao-gong Wang; Min-hui Li

    2012-01-01

    A series of azobenzene containing side-on liquid crystalline ABA triblock copolymers were investigated.This triblock series possesses the same central liquid crystal block B and various lengths of the amorphous block A.Transmission electron microscopy (TEM),small angle X-rays and neutron scattering (SAXS and SANS) were used to study their morphologies.Aider annealing the samples over weeks at a temperature within the nematic temperature range of block B,different morphologies (disordered,lamellar,perforated layer and hexagonal cylinder) were observed by TEM.The alignment behavior of these azo triblock copolymers in the magnetic field for artificial muscle application,as well as the phase period and the order-disorder transition (ODT) were studied in situ by SANS.

  16. Waterborne hyperbranched alkyd-acrylic resin obtained by mini emulsion polymerization

    Energy Technology Data Exchange (ETDEWEB)

    Murillo, Edwin, E-mail: edwinalbertomurillo@gmail.com [Grupo de Investigacion en Materiales Polimericos (GIMAPOL), Universidad Francisco de Paula Santander, San Jose de Cucuta (Colombia); Lopez, Betty [Grupo de Investigacion en Ciencia de los Materiales, Universidad de Antioquia, Calle, Medellin (Colombia)

    2016-10-15

    Four waterborne hyper branched alkyd-acrylic resins (HBRAA) were synthesized by mini emulsion polymerization from a hyper branched alkyd resin (HBR), methyl methacrylate (MMA), butyl acrylate (BA) and acrylic acid (AA), by using benzoyl peroxide (BPO) and ammonium persulfate (AP) as initiators. The reaction between HBR and acrylic monomers was evidenced by differential scanning calorimetric (DSC), nuclear magnetic resonance (NMR) and gel permeation chromatography (GPC). The conversion percentage, glass transition temperature (T{sub g}), content of acrylic polymer (determined by soxhlet extraction) and molecular weight increased with the content of acrylic monomers used in the synthesis. The main structure formed during the synthesis was the HBRAA. The analysis by dynamic light scattering (DLS) showed that the particle size distribution of HBRAA2, HBRAA3 and HBRAA4 resins were mainly mono modal. The film properties (gloss, flexibility, adhesion and drying time) of the HBRAA were good. (author)

  17. Photo-orientation of azobenzene-containing liquid-crystalline materials by means of domain structure rearrangement.

    Science.gov (United States)

    Bogdanov, Alexey V; Vorobiev, Andrey Kh

    2013-11-07

    A novel mechanism of photo-orientation of azobenzene-containing liquid-crystalline materials is proposed. This mechanism is based on the notion of photochemically induced domain rearrangement driven by destabilization of liquid-crystalline phase in light absorbing domains due to photochemical formation of non-mesogenic cis-azobenzene moieties. The experimental evidence of photoinduced movement of a domain boundary is presented, and the velocity of this movement is measured. A mathematical model for photo-orientation of a polydomain azobenzene-containing material is formulated. The values of model parameters for a liquid-crystalline azopolymer have been measured in separate experiments. Theoretical predictions demonstrate quantitative agreement with the experimental observations.

  18. Hyperbranched Polysiloxysilanes

    Institute of Scientific and Technical Information of China (English)

    Masa-aki Kakimoto

    2005-01-01

    @@ 1Introduction Hyperbranched polymers have been paid attention because of their unique structures. Especially, they have many terminals whose number is the same as that of repeating units as far as they are synthesized from AB2 type monomers. These characteristics of the hyperbranched polymers make them new functionalized polymers. Polysiloxanes have unique properties such as low Tg, high decomposition temperature, water repulsion, and good dielectric property. They are widely fabricated from liquid (oil) to solid (resin) by changing the extent of crosslinking. We have studied dendrimers and hyperbrached polymers possessing polysiloxane structure. These materials have the amphiphilic nature when they have amine functional group at the terminal position.

  19. Ultrasensitive electrochemical biosensor for specific detection of DNA based on molecular beacon mediated circular strand displacement polymerization and hyperbranched rolling circle amplification.

    Science.gov (United States)

    Li, Xiaolu; Guo, Jing; Zhai, Qian; Xia, Jing; Yi, Gang

    2016-08-31

    Using a cascade signal amplification strategy, an ultrasensitive electrochemical biosensor for specific detection of DNA based on molecular beacon (MB) mediated circular strand displacement polymerization (CSDP) and hyperbranched rolling circle amplification (HRCA) was proposed. The hybridization of MB probe to target DNA resulted in a conformational change of the MB and triggered the CSDP in the presence of bio-primer and Klenow fragment (KF exo(-)), leading to multiple biotin-tagged DNA duplex. Furthermore, the HRCA was implemented to product amounts of double-stranded DNA (ds-DNA) fragments using phi29 DNA polymerase via biotin-streptavidin interaction. After the product of HRCA binded numerous biotinylated detection probes, an ultrasensitive electrochemical readout by further employing the streptavidin-alkaline phosphatase. The proposed biosensor exhibited excellent detection sensitivity and specificity with a log-linear response to target DNA from 0.01 fM to 10 pM as low as 8.9 aM. The proposed method allowed DNA detection with simplicity, rapidness, low cost and high specificity, which might have the potential for application in clinical molecular diagnostics and environmental monitoring.

  20. SYNTHESIS OF A HYPERBRANCHED POLYETHER EPOXY THROUGH ONESTEP PROTON TRANSFER POLYMERIZATION AND ITS APPLICATION AS A TOUGHENER FOR EPOXY RESIN DGEBA

    Institute of Scientific and Technical Information of China (English)

    Jian-yong Lv; Yan Meng; Li-fan He; Xiao-yu Li; Hai-qiao Wang

    2012-01-01

    A novel liquid hyperbranched polyether epoxy (HBPEE) based on commercially available hydroquinone (HQ) and 1,1,1-trihydroxymethylpropane triglycidyl ether (TMPGE) was synthesized through an A2 + B3 one-step proton transfer polymerization.In order to improve the toughness,the synthesized HBPEE was mixed with diglycidyl ether of bisphenol A (DGEBA) in different ratios to form hybrids and cured with triethylenetetrarnine (TETA).Thermal and mechanical properties of the cured hybrids were evaluated.Results show that addition of HBPEE can improve the toughness of cured hybrids remarkably at < 20 wt% loading,without compromising the tensile strength.However,the glass transition temperature (Tg) of the cured hybrids decreases with increasing HBPEE content.Fracture surface images from scanning electron microscope show oriented fibrils in hybrids containing HBPEE.The formation and orientation of the fibrils can absorb energy under impact and lead to an improvement of toughness.Furthermore,based on the morphology of fractured surfaces and the single Tg in each hybrid,no sign of phase separation was found in the cured hybrid systems.As a result,the toughening mechanism could be explained by in situ homogeneous toughening mechanism rather than phase separation mechanism.

  1. Monte Carlo simulation on kinetic behavior of one-pot hyperbranched polymerization based on AA*+CB2

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Monte Carlo simulation was applied to investigate the kinetic behavior of AA*+CB2 system.The algorithm consisted of two procedures to simulate the in-situ synthesis of AB2-like intermediate and the subsequent polymerization,respectively.In order to improve the accuracy of the prediction,the mobility distinction between different scale molecules in polymerization was taken into account by relating the reaction rate constants to the collision possibility of each pair of species.The feed ratio of initial monomers and the activity difference between the two functional groups within AA* were studied systematically to catch the essential features of the reaction.Simulation results have revealed that the achievable maximum conversion primarily depends on the extent of the reactivity difference between A and A*-groups,and it is suggested that A*-group should be at least 10 times more active than A-group to achieve high number-average degree of polymerization.

  2. Tuning the Solubility of Copper Complex in Atom Transfer Radical Self-Condensing Vinyl Polymerizations to Control Polymer Topology via One-Pot to the Synthesis of Hyperbranched Core Star Polymers

    Directory of Open Access Journals (Sweden)

    Zong-Cheng Chen

    2014-09-01

    Full Text Available In this paper, we propose a simple one-pot methodology for proceeding from atom transfer reaction-induced conventional free radical polymerization (AT-FRP to atom transfer self-condensing vinyl polymerization (AT-SCVP through manipulation of the catalyst phase homogeneity (i.e., CuBr/2,2'-bipyridine (CuBr/Bpy in a mixture of styrene (St, 4-vinyl benzyl chloride (VBC, and ethyl 2-bromoisobutyrate. Tests of the solubilities of CuBr/Bpy and CuBr2/Bpy under various conditions revealed that both temperature and solvent polarity were factors affecting the solubility of these copper complexes. Accordingly, we obtained different polymer topologies when performing AT-SCVP in different single solvents. We investigated two different strategies to control the polymer topology in one-pot: varying temperature and varying solvent polarity. In both cases, different fractions of branching revealed the efficacy of varying the polymer topology. To diversify the functionality of the peripheral space, we performed chain extensions of the resulting hyperbranched poly(St-co-VBC macroinitiator (name as: hbPSt MI with either St or tBA (tert-butyl acrylate. The resulting hyperbranched core star polymer had high molecular weights (hbPSt-g-PSt: Mn = 25,000, Đ = 1.77; hbPSt-g-PtBA: Mn = 27,000, Đ = 1.98; hydrolysis of the tert-butyl groups of the later provided a hyperbranched core star polymer featuring hydrophilic poly(acrylic acid segments.

  3. Photo-responsive and thermoreversible networks from the self-assembly of azobenzene-containing liquid crystal triblock copolymers (Conference Presentation)

    Science.gov (United States)

    Kurji, Zuleikha; Kornfield, Julia A.; Kuzyk, Mark G.

    2016-09-01

    We report the synthesis of azobenzene-containing coil-liquid crystal-coil triblock copolymers that can serve as mechano-optic actuators for applications that include non-invasively steering fiber optics. The coil (polystyrene) end-blocks phase segregate from the liquid crystal midblock forming of uniform and uniformly-spaced physical crosslinks, resulting in highly reproducible and thermoreversible networks by self-assembly. These polymers are elastic in the melt (at room temperature) and can be easily spun, coated or molded. Mechanical stretching results in a temporary monodomain alignment. Starting from identical triblock prepolymers (with polystyerene end blocks and 1,2-polybutadiene midblocks), a matched pair (azobenzene-containing, and non-azobenzene-containing) of liquid crystal triblock copolymers was synthesized. These triblocks were then be blended to prepare a series of elastomers with 0 to 5% azobenzene groups, while matching in nearly all other physical properties (cross-link density, modulus, birefringence, etc.), allowing the effect of concentration of photo-responsive groups to be unambiguously determined. Results will be presented that demonstrate this approach to independent control of optical density and photo-mechanical sensitivity.

  4. 预聚-酶催化缩聚法合成超支化聚酯及其结构表征%Synthesis of Hyperbranched Polyester by Combination of Prepolymerization with Enzymatic Condensation Polymerization and Its Characterization

    Institute of Scientific and Technical Information of China (English)

    林智健; 李光吉; 龙俊元; 宗敏华

    2011-01-01

    A new route for hyperbranched aliphatic polyester by the prepolymerization of comonomers followed by the enzymatic condensation polymerization in organic media was developed using glycerol, 1,6-hexanediol, and adipic acid as comonomers and using immobilized lipase Novozym 435 as a biocatalyst. The organic solvents, such as isooctane, toluene. tert-butanol. tetrahydrofuran. and acetone. were used as the reaction medium for enzymatic condensation polymerization. The effects of reaction medium and reaction temperature on the enzymatic condensation polymerization were investigated. The molecular mass and the structure of the prepared polyesters were characterized by gel permeation chromatography and NMR. The results indicated that the hyperbranched aliphatic polyester could be successfully synthesized under the mild conditions by the combination of prepolymerization of comonomers with enzymatic condensation polymerization in organic media. Toluene was the best reaction medium among the examined ones. and the lipase Novozym 435 exhibited the highest activity at 70 oC within the temperature range from 50 to 90 oC. The polyester prepared by prepolymerization and the enzymatic condensation polymerization in toluene at 70 ℃ possessed the maximal molecular mass of up to 1.3 lx 104 and the branching degree of about 0.27.%以丙三醇、1,6-己二醇和己二酸为共聚单体,以固定化脂肪酶Novozym435为催化剂,尝试先进行共聚单体的预聚后在有机介质中进行酶催化直接缩聚反应合成脂肪族超支化聚酯的新途径,考察了反应介质和反应温度对酶催化缩聚反应的影响,并采用凝胶渗透色谱和核磁共振确定产物的分子量和结构.结果表明,将单体的预聚与酶催化缩聚反应相结合,可在温和的反应条件下合成超支化脂肪族聚酯;在所考察的有机介质中以甲苯的效果最佳,且在70℃时脂肪酶Novozym435催化活性最高,所得产物的支化度为0.27,重均分子量为1

  5. SYNTHESIS OF AN EPOXY-TERMINATED HYPERBRANCHED AROMATIC POLYESTER

    Institute of Scientific and Technical Information of China (English)

    Xia Wang; W.J. Feast

    2002-01-01

    An epoxy-terminated hyperbranched aromatic polyester (P3) was synthesized from a hyperbranched aromaticpolyester containing carboxylic acid end groups (P1), which was derived from the condensation polymerization of the AB2monomer, 5-acetoxyisophthalic acid. Polymer P1 was converted into the polymeric acid chloride by reaction with thionylchloride. The acid chloride was reacted with ethanol and glycidol to form a poly(ethyl ester) (P2) and an epoxy terminatedmaterial (P3), respectively. The reaction conditions in each step of these processes had to be controlled very carefully toavoid unwanted cross-linking reactions. The characterization of products and intermediates, including molecular weightdistributions and thermal properties, are reported.

  6. Using 2D NMR to determine the degree of branching of complicated hyperbranched polymers

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Degree of branching (DB) is a crucial structure parameter of hyperbranched polymers, which can be determined by 1H NMR, quantitative 13C NMR, degradative method, etc. However, for complicated hy-perbranched polymers, intricate structure and severe overlap of spectral signals hinder the determina-tion of DB using traditional methods. In this work, the architecture of complicated hyperbranched polymers has been elucidated with the help of 2D NMR techniques. Using such a method, overlapped NMR signals can be well separated into a two-dimensional space, and additional structural information is also available. Correspondingly, quantitative analysis for complicated systems can be realized. De-termination of DBs for three types of complicated hyperbranched polymers synthesized from step-polymerization, self-condensation vinyl polymerization and self-condensation ring-opening po-lymerization is shown as examples.

  7. Multifunctional hyperbranched glycoconjugated polymers based on natural aminoglycosides.

    Science.gov (United States)

    Chen, Mingsheng; Hu, Mei; Wang, Dali; Wang, Guojian; Zhu, Xinyuan; Yan, Deyue; Sun, Jian

    2012-06-20

    Multifunctional gene vectors with high transfection, low cytotoxicity, and good antitumor and antibacterial activities were prepared from natural aminoglycosides. Through the Michael-addition polymerization of gentamycin and N,N'-methylenebisacrylamide, cationic hyperbranched glycoconjugated polymers were synthesized, and their physical and chemical properties were analyzed by FTIR, (1)H NMR, (13)C NMR, GPC, ζ-potential, and acid-base titration techniques. The cytotoxicity of these hyperbranched glycoconjugated polycations was low because of the hydrolysis of degradable glycosidic and amide linkages in acid conditions. Owing to the presence of various primary, secondary, and tertiary amines in the polymers, hyperbranched glycoconjugated polymers showed high buffering capacity and strong DNA condensation ability, resulting in the high transfection efficiency. In the meantime, due to the introduction of natural aminoglycosides into the polymeric backbone, the resultant hyperbranched glycoconjugated polymers inhibited the growth of cancer cells and bacteria efficiently. Combining the gene transfection, antitumor, and antibacterial abilities together, the multifunctional hyperbranched glycoconjugated polymers based on natural aminoglycosides may play an important role in protecting cancer patients from bacterial infections.

  8. Synthesis and characterization of hyperbranched poly(glycidol) modified with pH- and temperature-sensitive groups.

    Science.gov (United States)

    Kojima, Chie; Yoshimura, Kohei; Harada, Atsushi; Sakanishi, Yuichi; Kono, Kenji

    2009-05-20

    Hyperbranched poly(glycidol)s with varying degrees of polymerization were modified by reaction with succinic anhydride and isopropylamine to obtain novel pH- and thermosensitive polymers. These polymers exhibited phase transitions in response to decreasing pH and/or increasing temperature, depending on the degree of polymerization and the ratio of succinyl group to N-isopropylamide. It was possible to harvest a bioactive molecule, rose bengal, from solution using the phase transition of thermosensitive hyperbranched poly(glycidol).

  9. Toward Spatiotemporally Controlled Synthesis of Photoresponsive Polymers: Computational Design of Azobenzene-Containing Monomers for Light-Mediated ROMP.

    Science.gov (United States)

    Zhou, Qunfei; Fursule, Ishan; Berron, Brad J; Beck, Matthew J

    2016-09-15

    Density functional theory calculations have been used to identify the optimum design for a novel, light-responsive ring monomer expected to allow spatial and temporal control of ring-opening metathesis polymerization (ROMP) via light-mediated changes in ring strain energy. The monomer design leverages ring-shaped molecules composed of 4,4'-diaminoazobenzene (ABn) closed by alkene-α,ω-dioic acid linkers. The atomic geometries, formation enthalpies and ring strain energies of azobenzene (AB)-containing rings with various length linkers have been calculated. The AB(2,2) monomer is identified as having optimal properties for light-mediated ROMP, including high thermodynamic stability, low ring strain energy (RSE) with cis-AB, and high RSE with trans-AB. Time-dependent DFT calculations have been used to explore the photoisomerization mechanism of isolated AB and AB-containing rings, and calculations show that trans-to-cis and cis-to-trans photoisomerization of the optimal AB(2,2) ring molecule can be achieved with monochromatic green and blue light, respectively. The AB(2,2) monomer identified here is expected to allow precise, reversible, spatial and temporal light-mediated control of ROMP through AB photoisomerization, and to have promising potential applications in the fabrication of patterned and/or responsive AB-containing polymer materials.

  10. Direct Synthesis of Hyperbranched Poly(acrylic acid-co-3-hydroxypropionate

    Directory of Open Access Journals (Sweden)

    Efkan Çatıker

    2015-01-01

    Full Text Available Hyperbranched poly(acrylic acid-co-3-hydroxypropionate (PAcHP was synthesized by base-catalyzed hydrogen transfer polymerization of acrylic acid through one step. The copolymers obtained through solution and bulk polymerization were insoluble in water and all organic solvents tried. Structural and compositional characterizations of hyperbranched PAcHP were performed by using FTIR, solid 13C-NMR, TGA, and titrimetric analysis. Acrylate fraction of the hyperbranched PAcHP obtained via bulk polymerization was determined as 60–65% by comparing TGA curves of hyperbranched PAcHP and pure poly(3-hydroxy propionate (PHP. However, analytical titration of the same sample revealed that acrylic acid units were about 47.3%. The results obtained from TGA and analytical titration were used to evaluate the chemical structure of the copolymer. Hyperbranched PAcHP exhibited hydrogel properties. Swelling behavior of the copolymer was investigated at a wide pH range and ionic strength. The dynamic swelling profiles of hyperbranched PAcHP exhibited a fast swelling behavior in the first hour and achieved the equilibrium state within 12 h in PBS. Depending on the conditions, the copolymers exhibited swelling ratios up to 2100%. As the copolymer has easily biodegradable propionate and versatile functional acrylic acid units, it can be used as not only biodegradable material in medical applications but also raw material in personal care commodities.

  11. Hyperbranched polyphosphates: synthesis, functionalization and biomedical applications.

    Science.gov (United States)

    Liu, Jinyao; Huang, Wei; Pang, Yan; Yan, Deyue

    2015-06-21

    Hyperbranched polyphosphates (HBPPs) are newly emerged polymeric biomaterials with repeating phosphate bonds in a highly branched framework over the past 5 years. Due to the integration of the advantages of both hyperbranched polymers and polyphosphates, HBPPs are versatile in chemical structure, flexible in physicochemical properties, water soluble, biocompatible and biodegradable in biological features. On the basis of their excellent water solubility, biocompatibility, biodegradability and potential functionalization as well as their simple preparation in one-pot synthesis, HBPPs have fascinating biomedical applications, especially for drug delivery. In this tutorial review, the recent advances of HBPPs are summarized. HBPPs with different topological structures and various functionalities were synthesized via adjusting the side group of cyclic phosphate monomers, which have shown promising biomedical applications, for example, using as a macromolecular anticancer agent and constructing advanced drug delivery systems, including site-specific delivery systems, self-delivery systems, and stimuli-responsive delivery systems. Such progress may promote the further development of interdisciplinary research between polymer chemistry, material science and biomedicine.

  12. Hyperbranched urethane-acrylates

    Directory of Open Access Journals (Sweden)

    Tasić Srba

    2004-01-01

    Full Text Available The synthesis, characterization and UV-curing of hyperbranched urethaneacrylates (HB-UA were investigated in this study. They were evaluated as oli-gomers in model UV curable coatings. HB-UAs were synthesized by reaction of an aliphatic hyperbranched polyester of the second generation (HBRG2 and an isocyanate adduct, obtained by the reaction of isophoronediisocyana-te and different hydroxy alkyl acrylates. Their thermal properties and viscosities depend on the degree of modification of HBRG2 and the type of hydroxy alkyl acrylate used. The introduction of a flexible alkoxylated spacer between the HBP core and acrylate end groups reduces steric hindrance by moving the cross linkable acrylate groups away from the HBP core and increase its reactivity. Due to the presence of abstractable H-atoms in the α-position to the ether links, HB-UAs based on poly(ethylene oxide monoacrylate are very reactive and do not show oxygen inhibition. The obtained coatings combine a high cross linking density with flexible segments between the cross links, which results in a good compromise between hardness and flexibility and have the potential to be used in different UV-curing applications.

  13. INVESTIGATION OF SPECIFIC AB2 TYPE HYPERBRANCHED POLYESTERIFICATION REACTION WITH MONTE CARLO SIMULATION

    Institute of Scientific and Technical Information of China (English)

    Long Wang; Xiao-mei Yang; Xue-hao He

    2013-01-01

    The AB2 type bulk polymerization of 3,5-bis(trimethylsiloxy)benzoyl chloride is studied by the reactive 3d bond fluctuation lattice model (3d-BFLM).Through tuning the reactivity parameters,the experimental data are fitted well via an iterative dichotomy method.By using the optimized reactivity parameters,the number-average degree of polymerization and degree of branching obtained in simulation are very close to experimental data.Meanwhile,the information about the weight-average degree of polymerization and the polydispersity index is provided,and the internal structural properties of hyperbranched polyesters are investigated.Simulation results demonstrate that the 3d-BFLM can be used to study specific hyperbranched polymerizations semi-quantitatively which is helpful to deep understand the kinetics of reactions and make predictions for specific polymerization systems.

  14. Stainless steel grafting of hyperbranched polymer brushes with an antibacterial activity: synthesis, characterization, and properties.

    Science.gov (United States)

    Ignatova, Milena; Voccia, Samule; Gabriel, Sabine; Gilbert, Bernard; Cossement, Damien; Jerome, Robert; Jerome, Christine

    2009-01-20

    Two strategies were used for the preparation of hyperbranched polymer brushes with a high density of functional groups: (a) the cathodic electrografting of stainless steel by poly[2-(2-chloropropionate)ethyl acrylate] [poly(cPEA)], which was used as a macroinitiator for the atom transfer radical polymerization of an inimer, 2-(2-bromopropionate)ethyl acrylate in the presence or absence of heptadecafluorodecyl acrylate, (b) the grafting of preformed hyperbranched poly(ethyleneimine) onto poly(N-succinimidyl acrylate) previously electrografted onto stainless steel. The hyperbranched polymer, which contained either bromides or amines, was quaternized because the accordingly formed quaternary ammonium or pyridinium groups are known for antibacterial properties. The structure, chemical composition, and morphology of the quaternized and nonquaternized hyperbranched polymer brushes were characterized by ATR-FTIR reflectance, Raman spectroscopy, X-ray photoelectron spectroscopy, and atomic force microscopy. The peeling test confirmed that the grafted hyperbranched polymer films adhered much more strongly to stainless steel than the nongrafted solvent-cast films. The quaternized hyperbranched polymer brushes were more effective in preventing both protein adsorption and bacterial adhesion than quaternary ammonium containing poly(cPEA) primary films, more likely because of the higher hydrophilicity and density of cationic groups.

  15. Nanoplugging Performance of Hyperbranched Polyamine as Nanoplugging Agent in Oil-Based Drilling Fluid

    Directory of Open Access Journals (Sweden)

    Gang Xie

    2015-01-01

    Full Text Available A hyperbranched polyamine was synthesized by self-condensing vinyl polymerization with divinyl sulfone, N-phenyl-p-phenylenediamine, by A2 + BB2' approach. The hyperbranched polyamine was characterized by FT-IR, TGA, and phase analysis light scanning. Average grain diameter of hyperbranched polyamine was 36.7 nm. Hyperbranched polyamine has good thermal stability. Hyperbranched polyamine (HBPA was employed successfully as nanoplugging agent in oil-based drilling fluid system, which could plug nanopore formation in shale formation. HBPA has a little effect on rheological properties of oil-based drilling fluid and the FLAPI and FLHTHP decreased dramatically with an increase of hyperbranched polyamine. Emulsion-breaking voltage has a slight increase, which is beneficial to maintain stability of oil-based drilling fluid. When the HBPA concentration is greater than 1 wt%, plugging rate of oil-based drilling fluid for artificial core is close to 100% and the permeability recovery value can reach 99.7% after adding 1 wt% HBPA, which prove that HBPA has an excellent plugging performance.

  16. Hyperbranched Polyarylenes from Copolycyclotrimerization

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    High molecular weight hyperbranched polyarylenes were synthesized in high yields by one-pot copolycyclotrimerizations of 2,5-diethynylthiophene (1), 4,4'-biphenyldiyne (2) and 2,7-diethynylfluorenes (3) with 1-heptyne (4) and 1-dodecyne (5) using TaCl5*Ph4Sn catalysts in toluene.The structures and properties of the polymers were characterized and evaluated by IR,NMR,TGA,UV,fluorescence and optical limiting analyses.All the polymers possess high thermal stability and emit strong blue light upon UV irradiation, whose intensities are higher than that from poly(1-phenyl-1-octyne) (PPO),a well-known highly luminescent disubstituted polyacetylene.Little aggregation-induced red shift in the photoluminescence is observed in the thin films of the polymers.

  17. Hyperbranched Polycarbosilanes via Nucleophilic Substitution Reactions

    Science.gov (United States)

    Interrante, L.; Shen, Q.

    Nucleophilic substitution reactions involving organomagnesium (Grignard) [1] and organolithium reagents have been used extensively for many years to form Si—C bonds (see Reaction Scheme 12.1). However, their use for the construction of hyperbranched polymers whose backbone contains, as a major structural component, silicon—carbon bonds, i.e., polycarbosilanes [2] is relatively more recent. (12.1) begin{array}{l} {{R}}_3 {{SiX + MR'}} to {{R}}_3 {{SiR' + MX}} \\ left({{{R,R' = alkyl}} {{or aryl;}} {{M = Mg(X),}} {{Li,}} {{Na}};{{X = halogen, OR''}}} right) \\ This chapter focuses on the application of such nucleophilic substitution reactions toward the synthesis of hyperbranched polycarbosilanes, with particular emphasis on those preparations that have resulted in relatively well characterized products. These syntheses are organized by the type of ABn monomer unit used (see Section 1.2), where A and B refer to the (C)X and (Si)Xn, respectively, functional ends of the monomer unit and where the nature of the coupling reaction leads to entirely or primarily Si—C bond formation. In most cases, these are “one-pot” reactions that employ monomers that bear halogen or alkoxy groups on the C and Si ends of the unit. Indeed, hyperbranched polycarbosilanes have been described, in general, as “obtained in one synthetic step via a random, one-pot polymerization of multifunctional monomers of AB n type” [2]. Treatment of the ABn monomer with either elemental Mg or an organolithium reagent, ideally (but not always) forms a complexed carbanion (the nucleophile) by reaction with the C-X end of the monomer unit, resulting in an intermediate of the type, (XxM)CSiXn, where M = Mg or Li, X = halogen or alkoxy, and x = 1 (Mg) or 0 (Li). Self-coupling of this reagent via reactions of the type shown in Reaction Scheme 12.1 leads to oligomeric and polymeric products that are connected primarily through Si—C bonds and yield an inorganic MXx by-product.

  18. POLYCYCLOTRIMERIZATION OF DIYNES, A NEW APPROACH TO HYPERBRANCHED POLYPHENYLENES

    Institute of Scientific and Technical Information of China (English)

    Kai-tian Xu; Ben-zhong Tang

    1999-01-01

    Polycyclotrimerization of diynes was explored as a new route to hyperbranched polymers in this investigation.Polymerization of terminal diynes of 1,8-nonadiyne and 1,9-decadiyne was studied using TaCl5, NbCl5, Mo(CO)4(nbd) and [Mo(CO)3cp]2 as catalysts (where nbd = 2,5-norbornadiene, cp = cyclo-pentadiene). A soluble polymer was obtained when the polymerization of 1,9-decadiyne was initiated by TaCl5 at low temperature (0℃). The polymer, however, became partially soluble after purification, possibly due to the postpolymerization-induced crosslinking. NbCl5-catalyzed polymerization of 1,9-bis(trimethylsilyl)-1,8-nonadiyne gave a completely soluble polymer. Soluble polymers were also obtained from the polymerization of 3,9-dodecadiyne initiated by NbCl5, Mo(CO)4(nbd), [Mo(CO)3cp]2, PdCl2-ClSiMe3 and Pd/C-ClSiMe3. IR, UV, and NMR spectroscopic analysis revealed that different catalysts gave polymers with different structures, ranging from linear polyenes to hyperbranched polyphenylenes. The polymers absorb UV light at around 250 nm and emit fluorescence at 340 nm when they are excited at 248 nm.

  19. Is the polydispersity exponent of the hyperbranched polymers the 3/2 or 5/2?

    Institute of Scientific and Technical Information of China (English)

    BA Xinwu; LIU Ying; WANG Sujuan; WANG Haijun

    2006-01-01

    The number of the hyperbranched polymers in the system is investigated for the polymerization process to give the asymptotic form of the concentration of the n-mer. The polydispersity exponent is calculated, which coincides with that of the classical result. Finally, the asymptotic forms of the number, the weight and the z-average degrees of the polymerization were evaluated analytically to obtain polydispersity index, which is close to 1 as the reaction is quantitatively completed.

  20. Enhanced dispersion of carbon nanotubes in hyperbranched polyurethane and properties of nanocomposites.

    Science.gov (United States)

    Rana, Sravendra; Karak, Niranjan; Cho, Jae Whan; Kim, Young Ho

    2008-12-10

    Hyperbranched polyurethane (HBPU) nanocomposites with multi-walled carbon nanotubes (MWNTs) were prepared by in situ polymerization on the basis of poly(ε-caprolactone)diol as the soft segment, 4,4'-methylene bis(phenylisocyanate) as the hard segment, and castor oil as the multifunctional group for the hyperbranched structure. A dominant improvement in the dispersion of MWNTs in the HBPU matrix was found, and good solubility of HBPU-MWNT nanocomposites in organic solvents was shown. Due to the well-dispersed MWNTs, the nanocomposites resulted in achieving excellent shape memory properties as well as enhanced mechanical properties compared to pure HBPU.

  1. Cinnamate-functionalized hyperbranched polymer as liquid crystal photo-alignment layer

    Institute of Scientific and Technical Information of China (English)

    Bin Jun Shen; Zheng Xie; Ya Ning He; Yan Qing Lian

    2008-01-01

    In this work, 4-methoxylcirmamoyl chloride was reacted with a commercial hyperbranched polymer (Boltom~TM H30) to prepare a hyperbranched photosensitive polymer (H30-Ci). The polymer was characterized by UV absorption spectrum and 1H-NMR spectrum. After processed by Linearly Polarized Polymerization (LPP) method, the spin-coated films of H30-Ci were used as photo-alignment layers to assemble liquid crystal (LC) cells containing nematic liquid crystal (5CB). The observation by polarized microscope showed that the H30-Ci blended with a linear polymer (BP-AN-Ci) photo-alignment layers could align LC molecules in a very uniform way.

  2. Photoinduced dichroism and surface-relief-gratings of hyperbranched azo polymers synthesized by azo-coupling reaction

    Institute of Scientific and Technical Information of China (English)

    CHE Pengchao; HE Yaning; WANG Xiaogong

    2007-01-01

    This article reports the synthesis and photoresponsive properties of a hyperbranched azo polymer containing electron donor-acceptor type azo chromophores both in backbone and peripheral positions.For the synthesis,a hyperbranched azo precursor polymer was synthesized by step-growth polymerization of an AB2 monomer,bis[2-(N-ethylanilino)ethyl] 5-aminoisophthalate,through azocoupling reaction.The hyperbranched precursor polymer was then reacted with the diazonium salt from 4-cyanoaniline to introduce donor-acceptor azo chromophores in the peripheral groups.The resulting azo polymers were characterized by the spectroscopic methods and thermal analysis.The photo-induced dichroism of the hyperbranched polymer was studied and its orientation order parameter was estimated to be 0.063.Thin films of the hyperbranched azo polymers were used to fabricate surface-relief-gratings (SRGs) by exposing them to an interference pattern of Ar+ laser beam at modest intensities (150 mW/cm2).The azo chromophores introduced by postazo-coupling reaction at the para-positions of the peripheral azobenzenes shows a significant effect on the SRG inscription rate.The hyperbranched azo polymers can potentially be used for applications such as reversible optical data storage,photoswitch,sensors,and other photo-driven devices.

  3. Hyperbranched red light-emitting phosphorescent polymers based on iridium complex as the core

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Ting; Yu, Lei; Yang, Yong; Li, Yanhu; Tao, Yun [Institute of Polymer Optoelectronic Materials and Devices, State Key Laboratory of Luminescent Materials and Devices, South China University of Technology, Guangzhou 510640 (China); Hou, Qiong [School of Chemistry & Environment, South China Normal University, Guangzhou 510006 (China); Ying, Lei, E-mail: msleiying@scut.edu.cn [Institute of Polymer Optoelectronic Materials and Devices, State Key Laboratory of Luminescent Materials and Devices, South China University of Technology, Guangzhou 510640 (China); Yang, Wei; Wu, Hongbin; Cao, Yong [Institute of Polymer Optoelectronic Materials and Devices, State Key Laboratory of Luminescent Materials and Devices, South China University of Technology, Guangzhou 510640 (China)

    2015-11-15

    A series of hyperbranched π-conjugated light-emitting polymers containing an iridium complex as the branched core unit and polyfluorene or poly(fluorene-alt-carbazole) as the branched segments were synthesized via a palladium catalyzed Suzuki polymerization. Apparent Förster energy transfer in the photoluminescent spectra as thin films was observed, while no discernible characteristic absorbance and photoluminescence of the iridium complex can be realized in dilute solutions. Copolymers based on poly(fluorene-alt-carbazole) as the branched segments demonstrated enhanced highest occupied molecular orbital energy levels relative to those based on polyfluorene. The electroluminescent spectra of these copolymers exclusively showed the characteristic emission of the iridium complex, with corresponding CIE coordinates of (0.67±0.01, 0.31). All devices exhibited relatively slow roll-off of efficiency, and the best device performance with the maximum luminous efficiency of 5.33 cd A{sup −1} was attained by using PFCzTiqIr3 as the emissive layer. These results indicated that the hyperbranched conjugated architectures can be a promising molecular design strategy for efficient electrophosphorescent light-emitting polymers. - Highlights: • Hyperbranched red light-emitting polymers are synthesized. • Red light-emitting iridium complex is used as the branched core unit. • Hyperbranched polymers based on PFCz exhibit higher luminescence. • The highest luminous efficiency of 5.33 cd A{sup −1} is attained.

  4. Aliphatic Hyperbranched Poly(amido amine)s(PAMAMs): Preparation and Modification

    Institute of Scientific and Technical Information of China (English)

    LIU Cui-hua; GAO Chao; YAN De-yue

    2005-01-01

    A series of water soluble aliphatic hyperbranched poly(amido amine)s(PAMAMs) with the same or similar chemical structure of poly(amido amine) dendrimer was successfully synthesized from commercially available AB and Cn types of monomers by one-pot polymerization via the couple-monomer methodology(CMM). The AB type monomer used in this paper was methyl acrylate, and Cn monomers were multi-amino compounds such as ethylenediamine(EDA), diethylenetriamine(DETA), triethylenetetraamine(TETA), tetraethylenepentaamine(TEPA) and pentaethylenehexamine(PEHA). The reaction mechanism was investigated by means of the mass spectra of the reaction intermediates. Adjusting the feed ratio of AB to Cn, hyperbranched polymers with different terminal groups and properties were obtained. FTIR, NMR, DSC, and TGA were used to characterize the polymers. It was found that the polymers' properties such as solubility, thermal behaviour and encapsulation capability varied with changing the feed ratio of AB to Cn. Benzoyl and palmitoyl groups were introduced into these macromolecules by acidylation to form amphiphilic hyperbranched polymers which have a high capability to encapsulate water soluble dyes such as Congo red. It is expected that the hyperbranched PAMAMs can play an important role in the industrial applications, such as coatings, cross-linking and phase-transferring agents because of their versatility and availability.

  5. Protein adhesion on silicon-supported hyperbranched poly(ethylene glycol) and poly(allylamine) thin films.

    Science.gov (United States)

    Dyer, Maureen A; Ainslie, Kristy M; Pishko, Michael V

    2007-06-19

    Hyperbranching poly(allylamine) (PAAm) and poly(ethylene glycol) (PEG) on silicon and its effect on protein adhesion was investigated. Hyperbranching involves sequential grafting of polymers on a surface with one of the components having multiple reactive sites. In this research, PAAm provided multiple amines for grafting PEG diacrylate. Current methodologies for generating PEG surfaces include PEG-silane monolayers or polymerized PEG networks. Hyperbranching combines the nanoscale thickness of monolayers with the surface coverage afforded by polymerization. A multistep approach was used to generate the silicon-supported hyperbranched polymers. The silicon wafer surface was initially modified with a vinyl silane followed by oxidation of the terminal vinyl group to present an acid function. Carbodiimide activation of the surface carboxyl group allowed for coupling to PAAm amines to form the first polymer layer. The polymers were hyperbranched by grafting alternating PEG and PAAm layers to the surface using Michael addition chemistry. The alternating polymers were grafted up to six total layers. The substrates remained hydrophilic after each modification. Static contact angles for PAAm (32-44 degrees) and PEG (33-37 degrees) were characteristic of the corresponding individual polymer (30-50 degrees for allylamine, 34-42 degrees for PEG). Roughness values varied from approximately 1 to 8 nm, but had no apparent affect on protein adhesion. Modifications terminating with a PEG layer reduced bovine serum albumin adhesion to the surface by approximately 80% as determined by ELISA and radiolabel binding studies. The hyperbranched PAAm and PEG surfaces described in this paper are nanometer-scale, multilayer films capable of reducing protein adhesion.

  6. Vegetable Oil-Based Hyperbranched Thermosetting Polyurethane/Clay Nanocomposites

    Directory of Open Access Journals (Sweden)

    Deka Harekrishna

    2009-01-01

    Full Text Available Abstract The highly branched polyurethanes and vegetable oil-based polymer nanocomposites have been showing fruitful advantages across a spectrum of potential field of applications.Mesua ferreaL. seed oil-based hyperbranched polyurethane (HBPU/clay nanocomposites were prepared at different dose levels by in situ polymerization technique. The performances of epoxy-cured thermosetting nanocomposites are reported for the first time. The partially exfoliated structure of clay layers was confirmed by XRD and TEM. FTIR spectra indicate the presence of H bonding between nanoclay and the polymer matrix. The present investigation outlines the significant improvement of tensile strength, scratch hardness, thermostability, water vapor permeability, and adhesive strength without much influencing impact resistance, bending, and elongation at break of the nanocomposites compared to pristine HBPU thermoset. An increment of two times the tensile strength, 6 °C of melting point, and 111 °C of thermo-stability were achieved by the formation of nanocomposites. An excellent shape recovery of about 96–99% was observed for the nanocomposites. Thus, the formation of partially exfoliated clay/vegetable oil-based hyperbranched polyurethane nanocomposites significantly improved the performance.

  7. Vegetable Oil-Based Hyperbranched Thermosetting Polyurethane/Clay Nanocomposites

    Science.gov (United States)

    Deka, Harekrishna; Karak, Niranjan

    2009-07-01

    The highly branched polyurethanes and vegetable oil-based polymer nanocomposites have been showing fruitful advantages across a spectrum of potential field of applications. Mesua ferrea L. seed oil-based hyperbranched polyurethane (HBPU)/clay nanocomposites were prepared at different dose levels by in situ polymerization technique. The performances of epoxy-cured thermosetting nanocomposites are reported for the first time. The partially exfoliated structure of clay layers was confirmed by XRD and TEM. FTIR spectra indicate the presence of H bonding between nanoclay and the polymer matrix. The present investigation outlines the significant improvement of tensile strength, scratch hardness, thermostability, water vapor permeability, and adhesive strength without much influencing impact resistance, bending, and elongation at break of the nanocomposites compared to pristine HBPU thermoset. An increment of two times the tensile strength, 6 °C of melting point, and 111 °C of thermo-stability were achieved by the formation of nanocomposites. An excellent shape recovery of about 96-99% was observed for the nanocomposites. Thus, the formation of partially exfoliated clay/vegetable oil-based hyperbranched polyurethane nanocomposites significantly improved the performance.

  8. Carboxylated Polyurethanes Containing Hyperbranched Polyester Soft Segments

    Directory of Open Access Journals (Sweden)

    Žigon, M.

    2006-09-01

    Full Text Available hyperbranched polyester soft segments (HB PU with functional carboxylic groups in order to enable the preparation of stable HB PU dispersions. Carboxylated hyperbranched polyurethanes were synthesized using a hyperbranched polyester based on 2,2-bis(methylolpropionic acid of the fourth pseudo-generation (Boltorn H40 and hexamethylene (HDI or isophorone diisocyanate (IPDI. The reactivity of hyperbranched polyester with HDI was lower than expected, possibly due to the presence of less reactive hydroxyl groups in the linear repeat units. A gel was formed at mole ratios rNCO/OH = 1:2 or 1:4. The synthesis of HB PU was performed with partly esterified hyperbranched polyester with lowered hydroxyl functionality. The carboxyl groups were incorporated in the HB PU backbone by reaction of residual hydroxyl groups with cis-1,2-cyclohexanedicarboxylic anhydride. HB PU aqueous dispersions were stable at least for two months, although their films were brittle. The tensile strength and Young's modulus of blends of linear and HB PU decreased with increasing content of HB PU whereas elongation at break remained nearly constant, which was explained in terms of looser chain packing due to more open tree-like hyperbranched structures.

  9. Preparation of Hyperbranched Polyethyleneimine Composite Membrane Using Interfacial Polymerization Catalyzed by 4-Dimethylamiopryidine%4-二甲氨基吡啶催化的界面聚合法制备超支化聚乙烯亚胺复合膜

    Institute of Scientific and Technical Information of China (English)

    张林; 林赛赛; 魏平; 程丽华; 陈欢林

    2012-01-01

    The promoting effect of 4-dimethylaminopyridine (DMAP) on the interfacial polymerization between trimesoyl chloride (TMC) and hyperbranched polyethyleneimine (PEI) was investigated. The solubility of DMAP in organic phase and aqueous phase was examined and the mass fraction of DMAP to PEI was optimized to 8%. Fourier transform infrared spectroscopy and scanning electron microscopy results showed that when catalyzed by DMAP, almost all the amino groups of PEI were cross-linked with TMC into amide groups, and thus a smooth and integrated layer was formed on the polysulfone support membrane. The rejection of PEI/TMC composite membrane against NaCl was improved to 85.4% as compared with 45.2%. Combined with the donating electron effects of 1-tertiary amine and 4-methylamino groups, the catalytic mechanism for DMAP in this PEI-based interfacial polymerization was proposed.%为了提高超支化聚合物在界面聚合反应中的成膜性能,选择4-二甲氨基吡啶(DMAP)作为空间位阻催化剂,用于催化超支化聚乙烯亚胺(PEI)与均苯三甲酰氯(TMC)界面聚合成膜.研究了DMAP在水油两相中的溶解性能,发现DMAP的适宜用量为底物PEI的8%.傅里叶红外光谱和扫描电镜表征结果表明,DMAP能够催化PEI上更多氨基参与酰化交联,在聚砜底膜上形成光滑连续的网络状结构.该复合分离膜对NaCl的截留率由无DMAP催化成膜的45.2%提高至85.4%,水通量高达60.8 L/(m2·h).结合吡啶环上1-叔胺基团及环外的4-二甲氨基团,推测了DMAP在PEI界面聚合反应过程中消除强空间位阻效应的催化机理.

  10. Promotion of Surface Free Energy of Azobenzene Containing Side-Chain Liquid Crystalline Polysiloxane Film by Polarized Light%偏振光照对偶氮苯侧链聚硅氧烷膜表面能的提高

    Institute of Scientific and Technical Information of China (English)

    刘剑; 王明乐; 李园园; 罗海波

    2011-01-01

    采用硅氢加成法合成了含偶氮苯侧链的聚硅烷液晶聚合物,用FTIR、DSC和偏光显微镜对聚合物结构及液晶特性进行了表征.采用473 nm偏振光对聚合物膜进行了光致取向,用偏光显微镜对取向结果进行了表征,发现偏振光倾斜照射后侧链偶氮苯基团发生了面外垂直取向.采用量高法测量了取向前后膜的接触角,根据接触角计算了膜的表面能.聚合物膜在取向前接触角为94.5°,偏振光照射取向后降低为76.5°,表明光照使聚合物膜从疏水变为亲水,膜的表面能明显增加.结合锥光显微镜观察到的干涉图结果,提出了极性偶氮苯基团面外垂直排列取向提升膜表面能的机理.%Azobenzene containing side-chain liquid crystalline polymer was synthesized by hydrosilation reaction of poly (methylhydrosiloxane) with the azo monomer. The chemical structure and its liquid crystalline properties were investigated by FITR, DSC and POM with a hot stage. Photo-alignment treatment was performed on the polysiloxane film by using a linearly polarized light source with the wavelength of 473 nm. A static contact angle measurement was carried out and the surface free energy was also calculated from the contact angles of a drop of water on the polymer film. The water contact angles was decreased from 94. 5° to 76. 5° after the light irradiation. We conclude that the changes in the hydrophilic of LC polymer were influenced by the surface compositions upon the photoinduced reorientation of the azobenzene side groups perpendicularly towards the film surface, which was confirmed by conoscopic POM observation results.

  11. Hyperbranched polyglycerols at the biointerface

    Science.gov (United States)

    Moore, Eli; Thissen, Helmut; Voelcker, Nicolas H.

    2013-08-01

    The control over biointerfacial interactions is the key to a broad range of biomedical applications, ranging from implantable devices to drug delivery and nanomedicine. In many of these applications, coatings are required that reduce or prevent non-specific interactions with the biological environment, while at the same time presenting specific bioactive signals. Whilst surface coatings based on polymers such as poly(ethylene glycol) (PEG) have been used successfully, many limitations persist in regard to the biocompatibility, stability and functionality of state-of-the-art polymer coatings. Most of these limitations are related to the fact that, typically, linear polymers are used with associated limited chemical functionality. Here, we examine the development of hyperbranched polyglycerols (HPGs) as promising candidates for the replacement of traditional linear polymers, such as the chemically analogous PEG, for the control of biointerfacial interactions. HPGs are highly branched globular molecules that exhibit a high valency, allow easy access to a variety of functionalities and can present biologically active signals. In this review, a comprehensive overview is provided with respect to the history, synthetic strategies, modifications and applications of HPGs.

  12. Supramolecular self-assembly and controllable drug release of thermosensitive hyperbranched multiarm copolymers

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    A novel temperature-responsive hyperbranched multiarm copolymer with a hydrophobic hyperbranched poly(3-ethyl-3-(hydroxymethyl)oxetane)(HBPO) core and thermosensitive poly(N-isopropylacrylamide)(PNIPAM) arms was synthesized via the atom transfer radical polymerization(ATRP) of NIPAM monomers from a hyperbranched HBPO macroinitiator.It was found that HBPO-star-PNIPAM self-assembled into multimolecular micelles(around 60 nm) in water at room temperature according to pyrene probe fluorescence spectrometry,1H NMR,TEM,and DLS measurements.The micelle solution showed a reversible thermosensitive phase transition at a lower critical solution temperature(LCST)(around 32°C) observed by variable temperature optical absorbance measurements.Variable temperature NMR and DLS analyses demonstrated that the LCST transition originated from the secondary aggregation of the micelles driven by increasing hydrophobic interaction due to the dehydration of PNIPAM shells upon heating.The drug loading and release properties of HBPO-star-PNIPAM micelles were also investigated using prednisone acetate as a model drug.The micelles showed a much improved drug encapsulation efficiency and temperature-dependent sustainable release behavior due to the special micellar structure.The micelles exhibited no apparent cytotoxicity against human HeLa cells.

  13. RHEOLOGY OF CONCENTRATED SOLUTIONS OF HYPERBRANCHED POLYESTERS

    Science.gov (United States)

    The solution rheology of different generations of hyperbranched polyesters in N-methyl-2- pyrrolidinone (NMP) solvent was examined in this study. The solutions exhibited Newtonian behavior over a wide range of polyester concentrations. Also, the relative viscosities of poly(amido...

  14. RHEOLOGY OF CONCENTRATED SOLUTIONS OF HYPERBRANCHED POLYESTERS

    Science.gov (United States)

    The solution rheology of different generations of hyperbranched polyesters in N-methyl-2- pyrrolidinone (NMP) solvent was examined in this study. The solutions exhibited Newtonian behavior over a wide range of polyester concentrations. Also, the relative viscosities of poly(amido...

  15. Probing the molecular design of hyper-branched aryl polyesters towards lubricant applications

    Science.gov (United States)

    Robinson, Joshua W.; Zhou, Yan; Bhattacharya, Priyanka; Erck, Robert; Qu, Jun; Bays, J. Timothy; Cosimbescu, Lelia

    2016-01-01

    We report novel polymeric materials that may be used as viscosity index improvers (VII) for lubricant applications. Our efforts included probing the comb-burst hyper-branched aryl polyester architecture for beneficial viscosity and friction behavior when utilized as an additive in a group I oil. The monomer was designed as to undergo polymerization via polycondensation within the architectural construct (AB2), typical of hyperbranched polymers. The monomer design was comprised of aliphatic arms (12 or 16 methylenes) to provide the necessary lipophilicity to achieve solubility in a non-polar medium. Once polymerized, via catalyst and heat, the surface alcohols were functionalized with fatty acids (lauric and palmitic). Controlling the aliphatic nature of the internal arms and peripheral end-groups provided four unique flexible polymer designs. Changing the reaction time and concentration provided opportunities to investigate the influence of molecular weight and branching density on oil-solubility, viscosity, and friction. Oil-solubility was found to decrease with fewer internal carbons, but the number of internal carbons appears to have little influence on the bulk solution viscosity. At concentrations of 2 wt % in a group I base oil, these polymer additives demonstrated an improved viscosity index and reduced friction coefficient, validating the basic approach.

  16. Probing the molecular design of hyper-branched aryl polyesters towards lubricant applications.

    Science.gov (United States)

    Robinson, Joshua W; Zhou, Yan; Bhattacharya, Priyanka; Erck, Robert; Qu, Jun; Bays, J Timothy; Cosimbescu, Lelia

    2016-01-01

    We report novel polymeric materials that may be used as viscosity index improvers (VII) for lubricant applications. Our efforts included probing the comb-burst hyper-branched aryl polyester architecture for beneficial viscosity and friction behavior when utilized as an additive in a group I oil. The monomer was designed as to undergo polymerization via polycondensation within the architectural construct (AB2), typical of hyperbranched polymers. The monomer design was comprised of aliphatic arms (12 or 16 methylenes) to provide the necessary lipophilicity to achieve solubility in a non-polar medium. Once polymerized, via catalyst and heat, the surface alcohols were functionalized with fatty acids (lauric and palmitic). Controlling the aliphatic nature of the internal arms and peripheral end-groups provided four unique flexible polymer designs. Changing the reaction time and concentration provided opportunities to investigate the influence of molecular weight and branching density on oil-solubility, viscosity, and friction. Oil-solubility was found to decrease with fewer internal carbons, but the number of internal carbons appears to have little influence on the bulk solution viscosity. At concentrations of 2 wt % in a group I base oil, these polymer additives demonstrated an improved viscosity index and reduced friction coefficient, validating the basic approach.

  17. AZIDE-ALKYNE CLICK POLYMERIZATION: AN UPDATE

    Institute of Scientific and Technical Information of China (English)

    Hong-kun Li; Jing-zhi Sun; An-jun Qin; Ben Zhong Tang

    2012-01-01

    The great achievements of click chemistry have encouraged polymer scientists to use this reaction in their field.This review assembles an update of the advances of using azide-alkyne click polymerization to prepare functional polytriazoles (PTAs) with linear and hyperbranched structures.The Cu(Ⅰ)-mediated click polymerization furnishes 1,4-regioregular PTAs,whereas,the metal-free click polymerization of propiolates and azides produces PTAs with 1,4-regioisomer contents up to 90%.The PTAs display advanced functions,such as aggregation-induced emission,thermal stability,biocompatibility and optical nonlinearity.

  18. Trapping in dendrimers and regular hyperbranched polymers

    CERN Document Server

    Wu, Bin; Zhang, Zhongzhi; Chen, Guanrong

    2012-01-01

    Dendrimers and regular hyperbranched polymers are two classic families of macromolecules, which can be modeled by Cayley trees and Vicsek fractals, respectively. In this paper, we study the trapping problem in Cayley trees and Vicsek fractals with different underlying geometries, focusing on a particular case with a perfect trap located at the central node. For both networks, we derive the exact analytic formulas in terms of the network size for the average trapping time (ATT)---the average of node-to-trap mean first-passage time over the whole networks. The obtained closed-form solutions show that for both Cayley trees and Vicsek fractals, the ATT display quite different scalings with various system sizes, which implies that the underlying structure plays a key role on the efficiency of trapping in polymer networks. Moreover, the dissimilar scalings of ATT may allow to differentiate readily between dendrimers and hyperbranched polymers.

  19. Thermal stability of aliphatic hyperbranched polyesters

    Directory of Open Access Journals (Sweden)

    Vuković Jasna

    2002-01-01

    Full Text Available The influence of the molar mass (generation, number and type of end groups on the thermal stability of aliphatic hyperbranched polyesters are presented in this study. Different end groups were obtained by modification of the samples with chlorides of propionic acid and stearic acid. The thermal stability of the hyperbranched polyesters was determined by thermogravimetry using a NET-ZSCH TG 209 instrument in nitrogen atmosphere at a heating rate of 10°C/min. A comparison of the temperatures obtained for mass losses of 5 20 and 40 wt% for unmodified samples showed that the thermal stability increased up to the fourth generation and then remained practically constant. An increase in the thermal stability of modified samples of the second, third and fourth generation was observed.

  20. Phase Diagrams for Systems Containing Hyperbranched Polymers

    Directory of Open Access Journals (Sweden)

    Tim Zeiner

    2012-01-01

    Full Text Available Hyperbranched polymers show an outstanding potential for applications ranging from chemistry over nanotechnology to pharmacy. In order to take advantage of this potential, the underlying phase behaviour must be known. From the thermodynamic point of view, the modelling of these phase diagrams is quite challenging, because the thermodynamic properties depend on the architecture of the hyperbranched polymer as well as on the number and kind of present functional end groups. The influence of architecture can be taken into account via the lattice cluster theory (LCT as an extension of the well-known Flory–Huggins theory. Whereas the Flory–Huggins theory is limited to linear polymer chains, the LCT can be applied to an arbitrary chain architecture. The number and the kind of functional groups can be handled via the Wertheim perturbation theory, applicable for directed forces between the functional groups and the surrounding solvent molecules. The combination of the LCT and the Wertheim theory can be established for the modelling or even prediction of the liquid-liquid equilibria (LLE of polymer solutions in a single solvent or in a solvent mixture or polymer blends, where the polymer can have an arbitrary structure. The applied theory predicts large demixing regions for mixtures of linear polymers and hyperbranched polymers, as well as for mixtures made from two hyperbranched polymers. The introduction of empty lattice sites permits the theoretical investigation of pressure effects on phase behaviour. The calculated phase diagrams were compared with own experimental data or to experimental data taken from literature.

  1. Novel Hyperbranched Polyurethane Brushes for Biomedical Applications

    Institute of Scientific and Technical Information of China (English)

    Ton; Loontjens; Bart; Plum

    2007-01-01

    1 Results The objective was to make hyperbranched (HB) polyurethane brushes with reactive end groups, to coat biomedical devices and to enable the introduction of various functionalities that are needed to fulfill biomedical tasks.Biomedical materials should fulfill at least three requirements: (1) good mechanical properties, (2) good biocompatibility and (3) provided with functionalities to perform the required tasks. Since polyurethanes are able to fulfill the first 2 requirements we focused in this w...

  2. SYNTHESES AND CHARACTERIZATIONS OF HYPERBRANCHED POLYPHENYLENES

    Institute of Scientific and Technical Information of China (English)

    Han Peng; Hong-chen Dong; Yu-ping Dong; De-min Jia; Ben-zhong Tang

    2004-01-01

    New hyperbranched polyphenylenes with high molecular weights are synthesized by the copolycyclotrimerizations of 1,4-diethynylbenzene (I) with phenylacetylene (A), 1-octyne (B), and 1-dodecyne (C) catalyzed by TaCl5-Ph4Sn. The polymers are completely soluble in common solvents such as toluene, THF, chloroform, and dichloromethane. The polymers are characterized by spectroscopic methods and all of the polymers give satisfactory analysis data corresponding to their expected molecular structures.

  3. One-Pot Synthesis for Biocompatible Amphiphilic Hyperbranched Polyurea Micelles

    NARCIS (Netherlands)

    Xiang, Fei; Stuart, Marc; Vorenkamp, Joop; Roest, Steven; Timmer-Bosscha, Hetty; Fokkink, Remco; Loontjens, Ton

    2013-01-01

    Here we report, for the first time to our knowledge, a method to synthesize AB(2) monomers, the corresponding hyperbranched and the corresponding amphiphilic hyperbranched polymers in a one-pot procedure, starting from two commercial available compounds. Since the B groups were blocked isocyanates

  4. Effect of support structure on CO2 adsorption properties of pore-expanded hyperbranched aminosilicas

    KAUST Repository

    Drese, Jeffrey H.

    2012-03-01

    Hyperbranched aminosilica (HAS) CO 2 adsorbents are prepared by the ring-opening polymerization of aziridine from SBA-15 mesoporous silica, as in the original synthesis of HAS materials, as well as over an array of new support materials with substantially larger average pore diameters to elucidate the effect of support porosity on final adsorbent properties. Pore-expanded hyperbranched aminosilica (PEHAS) CO 2 adsorbents are prepared from several different pore-expanded, ordered mesoporous silicas including pore-expanded SBA-15, mesocellular foam, and a large-pore commercial silica. The effect of the nature of the silica support is determined by examining the degree of aziridine polymerization and the CO 2 adsorption kinetics and capacities of the resulting organic/inorganic hybrid materials. Comparisons are made to non-pore-expanded SBA-15 based HAS adsorbents, reported previously, where pores become blocked at higher amine loadings. The PEHAS materials unexpectedly possess lower amine loadings than the previously reported HAS materials and do not exhibit pore blocking. The use of acetic acid as a catalyst during PEHAS synthesis only marginally increases amine loading. The adsorption kinetics of PEHAS adsorbents are similar to HAS adsorbents with low amine loadings and do not show the detrimental effects of pore-blocking. However, the inability to synthesize PEHAS adsorbents with high amine loadings via this approach limits the total amount of CO 2 captured per gram of material, compared to HAS adsorbents with high amine loadings. © 2011 Elsevier Inc. All rights reserved.

  5. Drug release property of a pH-responsive double-hydrophilic hyperbranched graft copolymer

    Institute of Scientific and Technical Information of China (English)

    SUN XiaoYi; ZHOU YongFeng; YAN DeYue

    2009-01-01

    In this paper, we report the synthesis and self-assembly of double-hydrophilie hyperbranched graft copolymers of HPG-g-PDMAEMA, which consist of a hyperbranched polyglycerol (HPG) core and several grafted poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) arms. HPG was synthesized by cationic polymerization. Then HPG-Br macroinitiator was obtained by esterification of HPG with 2-bromoisobutyryl bromide, which was subsequently used in the preparation of HPG-g-PDMAEMA graft copolymers through atom transfer radical polymerization (ATRP) of DMAEMA monomers. The molecular structures were studied by 1H NMR arid GPC. The pyrene-based fluorescent probe method, 1H NMR and DLS were used to study the self-assembly behavior of HPG-g-PDMAEMA. The drug loading and pH-responsive release properties of HPG-g-PDMAEMA were also investigated by using coumarin 102 as a model drug. The results show that the HPG-g-PDMAEMA micelles can continuously release and re-encapsulate coumarin 102 as the pH continuously changes from 11.5 to 2.5; however, this process is not totally reversible.

  6. Drug release property of a pH-responsive double-hydrophilic hyperbranched graft copolymer

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    In this paper, we report the synthesis and self-assembly of double-hydrophilic hyperbranched graft copolymers of HPG-g-PDMAEMA, which consist of a hyperbranched polyglycerol (HPG) core and several grafted poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) arms. HPG was synthesized by cationic polymerization. Then HPG-Br macroinitiator was obtained by esterification of HPG with 2-bromoisobutyryl bromide, which was subsequently used in the preparation of HPG-g-PDMAEMA graft copolymers through atom transfer radical polymerization (ATRP) of DMAEMA monomers. The molecular structures were studied by 1H NMR and GPC. The pyrene-based fluorescent probe method, 1H NMR and DLS were used to study the self-assembly behavior of HPG-g-PDMAEMA. The drug loading and pH-responsive release properties of HPG-g-PDMAEMA were also investigated by using coumarin 102 as a model drug. The results show that the HPG-g-PDMAEMA micelles can continuously release and re-encapsulate coumarin 102 as the pH continuously changes from 11.5 to 2.5; however, this process is not totally reversible.

  7. Synthesis and swelling behavior of polyurethane networks based on hyperbranched polymer

    Directory of Open Access Journals (Sweden)

    Džunuzović Jasna V.

    2011-01-01

    Full Text Available A series of six polyurethane (PU networks was synthesized from BoltornR hydroxy-functional hyperbranched polyester (HBP of the second pseudo generation as a crosslinking agent, α,ω- dihydroxy-(ethylene oxide-poly(dimethylsiloxane-ethylene oxide (EO-PDMS-EO and 4,4’- methylenediphenyl diisocyanate, by a two-step polymerization in solution. Each sample of the prepared PUs had different EO-PDMS-EO content. The chemical structure of the synthesized networks was analyzed by FTIR spectroscopy. The influence of the EO-PDMS-EO content and type of the solvent on the swelling behavior of the PUs in 2-propanol and toluene was investigated. During the swelling measurements certain amount of sol fractions was extracted from the PUs by solvents. According to the 1H NMR results, sol fractions are mainly composed of the soluble hyperbranched PU, formed during the polymerization by partial modification of the end hydroxyl groups of HBP with NCO-terminated prepolymer synthesized in the first step of the reaction. Chains of the so reacted prepolymer can then fold back and form cyclic products by reaction of the free -NCO group from the NCO-terminated prepolymer with free -OH group of HBP. As the EO-PDMS-EO content increases the amount of the sol fractions and swelling degree also increased, indicating that networks with lower EO-PDMS-EO content are more crosslinked and have higher solvent resistance.

  8. Stimuli-Responsive Biodegradable Hyperbranched Polymer-Gadolinium Conjugates as Efficient and Biocompatible Nanoscale Magnetic Resonance Imaging Contrast Agents.

    Science.gov (United States)

    Sun, Ling; Li, Xue; Wei, Xiaoli; Luo, Qiang; Guan, Pujun; Wu, Min; Zhu, Hongyan; Luo, Kui; Gong, Qiyong

    2016-04-27

    The efficacy and biocompatibility of nanoscale magnetic resonance imaging (MRI) contrast agents depend on optimal molecular structures and compositions. Gadolinium [Gd(III)] based dendritic macromolecules with well-defined and tunable nanoscale sizes are excellent candidates as multivalent MRI contrast agents. Here, we propose a novel alternate preparation of biodegradable hyperbranched polymer-gadolinium conjugates via a simple strategy and report potentially efficient and biocompatible nanoscale MRI contrast agents for cancer diagnosis. The enzyme-responsive hyperbranched poly(oligo-(ethylene glycol) methacrylate)-gadolinium conjugate (HB-POEGMA-Gd) was prepared via one-step reversible addition-fragmentation chain transfer (RAFT) polymerization and Gd(III) chelating, and the cRGDyK functionalized polymer (HB-POEGMA-cRGD-Gd) was obtained via click chemistry. By using an enzyme similar to lysosomal cathepsin B, hyperbranched conjugates of high molecular weights (MW) (180 and 210 kDa) and nanoscale sizes (38 and 42 nm) were degraded into low MW (25 and 30 kDa) and smaller products (4.8 and 5.2 nm) below the renal threshold. Conjugate-based nanoscale systems had three-fold more T1 relaxivity compared to clinical agent diethylenediaminepentaacetic acid (DTPA)-Gd. Animal studies with the nanoscale system offered greater tumor accumulation and enhanced signal intensity (SI) in mouse U87 tumors of which the greatest activity was conferred by the cRGDyK moiety functionalized hyperbranched conjugate. In vitro cytotoxicity, hemocompatibility and in vivo toxicity studies confirmed no adverse events. This design strategy for multifunctional Gd(III)-labeled biodegradable dendritic macromolecules may have significant potential as future efficient, biocompatible polymeric nanoscale MRI diagnostic contrast agents for cancer.

  9. HBP Builder: A Tool to Generate Hyperbranched Polymers and Hyperbranched Multi-Arm Copolymers for Coarse-grained and Fully Atomistic Molecular Simulations

    Science.gov (United States)

    Yu, Chunyang; Ma, Li; Li, Shanlong; Tan, Haina; Zhou, Yongfeng; Yan, Deyue

    2016-05-01

    Computer simulation has been becoming a versatile tool that can investigate detailed information from the microscopic scale to the mesoscopic scale. However, the crucial first step of molecular simulation is model building, particularly for hyperbranched polymers (HBPs) and hyperbranched multi-arm copolymers (HBMCs) with complex and various topological structures. Unlike well-defined polymers, not only the molar weight of HBPs/HBMCs with polydispersity, but the HBPs/HBMCs with the same degree of polymerization (DP) and degree of branching (DB) also have many possible topological structures, thus making difficulties for user to build model in molecular simulation. In order to build a bridge between model building and molecular simulation of HBPs and HBMCs, we developed HBP Builder, a C language open source HBPs/HBMCs building toolkit. HBP Builder implements an automated protocol to build various coarse-grained and fully atomistic structures of HBPs/HBMCs according to user’s specific requirements. Meanwhile, coarse-grained and fully atomistic output structures can be directly employed in popular simulation packages, including HOOMD, Tinker and Gromacs. Moreover, HBP Builder has an easy-to-use graphical user interface and the modular architecture, making it easy to extend and reuse it as a part of other program.

  10. The effects of hyperbranched poly(siloxysilane)s on conductive polymer aluminum solid electrolytic capacitors

    Energy Technology Data Exchange (ETDEWEB)

    Nogami, Katsunori [Graduate School of Tokyo Institute Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550 (Japan); Nippon Chemi-Con Co., 185-1, Marunouchi, Yabuki-machi, Nishi-Shirakawa-gun, Fukushima 969-0235 (Japan); Sakamoto, Kiyoshi [Nippon Chemi-Con Co., 185-1, Marunouchi, Yabuki-machi, Nishi-Shirakawa-gun, Fukushima 969-0235 (Japan); Hayakawa, Teruaki; Kakimoto, Masa-aki [Graduate School of Tokyo Institute Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550 (Japan)

    2007-04-15

    An aluminum solid electrolytic capacitor, using poly-(3,4-ethylenedioxythiophene) (PEDOT) as a counter electrode, was prepared with hyperbranched poly(siloxysilane)s (HBPSi) that has a large number of vinyl groups to improve the interfacial properties between aluminum oxide and PEDOT. Capacitance and equivalent series resistance (Rs) were significantly improved compared to untreated oxide film and vinyl terminated polydimethylsiloxane coated interfaces. From electrochemical measurement of the withstand voltage, damage to the oxide film from chemical polymerization of PEDOT was less with the HBPSi treatment. Frequency characteristics and electrical conductivity measurements of the polymer indicated that the resistance inside the etched porous layer was greatly reduced. These results show that the HBPSi pre-coating layer inhibited degradation of the oxide film by chemical polymerization of PEDOT and the conductivity of PEDOT in the etched porous oxide layer, and also enlarges the contact area by improving interfacial adhesion. (author)

  11. Hyperbranched Poly(amide-ester) Mildly Synthesized and Its Characterization

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    AB2-type-prepolymerized monomer was rapidly (2 h) prepared atIoom temperature (25℃) using commercially available maleic anhydride (MA) and diethanolamine (DEA) as raw materials.By employing toluene-p-sulfonic acid as a catalyzer, a series of hyperbranched poly(amide-ester) (HBPAE) were successfully synthesized from prepared AB2 monomer by solution condensation polymerization through "one-step process" or "pseudo one-step process" (using pen taerythritol as a center core).The processes were carried out at high temperature of 120 C for 6 h in air atmosphere (inert protection free) with reduced pressure distillation (0.08~0.096 MPa).The results of FT-IR, UV-Vis, TGA, and intrinsic viscosity testing by Ubbelodhe viscometer showed that the prepared HBPAEspossess three-dimensional configuration with unsaturated conjugate structure,large numbers of branches and numerous terminal hydroxyl groups.These result in their lowviscosity, high solubility and thermal stability.

  12. Synthesis and Characterization of Aliphatic-Aromatic Hyperbranched Polyesters

    Institute of Scientific and Technical Information of China (English)

    唐黎明; 张晓龙; 邱藤; 刘德山

    2002-01-01

    Hyperbranched polymers possess special architectures and have potential applications in various areas. In this study, two AB2 monomers, dipropyl 5-(hydroxyethoxy) isophthalate (I) and 5-hydroxyethoxyisophthaic acid (II), were prepared. By bulk polycondensation of each monomer, two aliphatic-aromatic hyperbranched polyesters were prepared and characterized by 1H-nuclear magnetic resonance (1H-NMR), differential scanning calorimetry (DSC), thermogravimetry analysis (TGA), and scanning electron microscopy (SEM). Compared with all-aromatic hyperbranched polyesters, the prepared polymers showed lower glass transition temperatures in connection with the moderate decrease in their decomposition temperatures.

  13. 超支化聚己内酯的制备与表征%Preparation and Characterization of Hyperbranched Polycaprolactone

    Institute of Scientific and Technical Information of China (English)

    刘啸天; 范洪波; 刘传生; 罗群

    2014-01-01

    This work is directed to developing a method for the synthesis and characterisation of hyperbranched polymers combining enzymatic Ring-opening Polymerization ( ROP) and self-condensing vinyl polymerization ( SCVP) .Macromer is pre-pared by Novozyme 435 catalyzed ROP of ε-CL, and subsequently converted to AB* macroinimer by the esterification with α-bromoisobutyryl bromide .The target of hyperbranched polycaprolactone is obtained by SCVP of AB * macroinimer via atom transfer radical polymerization ( ATRP) .%在Novozyme 435固定化脂肪酶催化下,甲基丙烯酸羟乙酯( HEMA)引发己内酯(ε-CL)开环聚合反应,得到分别以双键和羟基封端的直链聚己内酯( PCL )产物;利用α-溴代异丁酰溴与开环聚合产物的端羟基发生酯化反应,得到大分子型AB*单体;再以CuCl/bpy (联吡啶)为催化体系,令大分子型AB*单体通过自缩合乙烯基聚合反应(利用原子转移自由基聚合反应形式),成功合成了超支化聚己内酯目标产物。

  14. Nano-Bio Engineered Carbon Dot-Peptide Functionalized Water Dispersible Hyperbranched Polyurethane for Bone Tissue Regeneration.

    Science.gov (United States)

    Gogoi, Satyabrat; Maji, Somnath; Mishra, Debasish; Devi, K Sanjana P; Maiti, Tapas Kumar; Karak, Niranjan

    2017-03-01

    The present study delves into a combined bio-nano-macromolecular approach for bone tissue engineering. This approach relies on the properties of an ideal scaffold material imbued with all the chemical premises required for fostering cellular growth and differentiation. A tannic acid based water dispersible hyperbranched polyurethane is fabricated with bio-nanohybrids of carbon dot and four different peptides (viz. SVVYGLR, PRGDSGYRGDS, IPP, and CGGKVGKACCVPTKLSPISVLYK) to impart target specific in vivo bone healing ability. This polymeric bio-nanocomposite is blended with 10 wt% of gelatin and examined as a non-invasive delivery vehicle. In vitro assessment of the developed polymeric system reveals good osteoblast adhesion, proliferation, and differentiation. Aided by this panel of peptides, the polymeric bio-nanocomposite exhibits in vivo ectopic bone formation ability. The study on in vivo mineralization and vascularization reveals the occurrence of calcification and blood vessel formation. Thus, the study demonstrates carbon dot/peptide functionalized hyperbranched polyurethane gel for bone tissue engineering application.

  15. Micro-hydrogel Particles Consisting of Hyperbranched Polyamidoamine for the Removal of Heavy Metal Ions from Water.

    Science.gov (United States)

    Lee, Sanghwa; Eom, Youngsik; Park, Jeyoung; Lee, Jinhee; Kim, Sang Youl

    2017-08-30

    A series of micro-hydrogel particles consisting of hyperbranched polyamidoamine (HPAMAM) without any supporting core materials was synthesized via the inverse suspension condensation polymerization of A2 and B4 monomers, N,N'-methylenebisacrylamide (MBA) and ethylenediamine (EDA). The particles were found to be highly effective when used to remove heavy metal ions, such as cadmium, copper, lead, nickel, zinc, and cobalt, from water, and they could be separated from the water by a simple filtration process. The results of this study demonstrate that crosslinked HPAMAM particles, which can be prepared by a simple and environmentally friendly process, are an attractive absorbent for water purification.

  16. Chain dimension of polystyrene-like hyperbranched polymers with various chain end groups in THF

    Energy Technology Data Exchange (ETDEWEB)

    Kikuchi, Moriya; Kobayashi, Motoyasu; Takahara, Atsushi [Institute for Materials Chemistry and Engineering, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka, 819-0385 (Japan); Tanaka, Akihiro, E-mail: takahara@cstf.kyushu-u.ac.j [Synthesis Research Department, Chemical Reserch Laboratories, Nissan Chemical Industries, Ltd., 722-1 tsuboi, Funabashi 274-8507 (Japan)

    2009-08-01

    A hyperbranched polymer (HPS-DC) synthesized using N,N-diethylamino -dithiocarbamoylstyrene as an inimer and a hyperbranched poly(4-methylstyrene) (HPS-H) prepared by hydrogenation of the HPS-DC are characterized in tetrahydrofuran (THF) solutions by static and dynamic light scattering measurements. The experimental values of z-averaged mean-square radius of gyration ({sub z}{sup 1/2}) and hydrodynamic radius (R{sub H}) of the HPS-H have smaller dimensions than those of the linear polystyrene (PS) at the same degree of polymerization (N{sub w}), whereas the R{sub H} of the HPS-DC in the region of N{sub w} < 700 is larger than that of the linear PS at the same N{sub w}. The N{sub w}-dependence of {sub z}{sup 1/2} and R{sub H} for the HPS-H are described by a randomly trifunctional branched polymer model with the molecular weight per a branch point (4.55 x 10{sup 3} g/mol) and the chain dimensions of the linear PS in THF at 25 {sup 0}C.

  17. Synthesis and Gas Transport Properties of Hyperbranched Polyimide–Silica Hybrid/Composite Membranes

    Directory of Open Access Journals (Sweden)

    Masako Miki

    2013-12-01

    Full Text Available Hyperbranched polyimide–silica hybrids (HBPI–silica HBDs and hyperbranched polyimide–silica composites (HBPI–silica CPTs were prepared, and their general and gas transport properties were investigated to clarify the effect of silica sources and preparation methods. HBPI–silica HBDs and HBPI–silica CPTs were synthesized by two-step polymerization of A2 + B3 monomer system via polyamic acid as precursor, followed by hybridizing or blending silica sources. Silica components were incorporated by the sol-gel reaction with tetramethoxysilane (TMOS or the addition of colloidal silica. In HBPI-silica HBDs, the aggregation of silica components is controlled because of the high affinity of HBPI and silica caused by the formation of covalent bonds between HBPI and silica. Consequently, HBPI-silica HBDs had good film formability, transparency, and mechanical properties compared with HBPI-silica CPTs. HBPI-silica HBD and CPT membranes prepared via the sol-gel reaction with TMOS showed specific gas permeabilities and permselectivities for CO2/CH4 separation, that is, both CO2 permeability and CO2/CH4 selectivity increased with increasing silica content. This result suggests that gas transport can occur through a molecular sieving effect of the porous silica network derived from the sol-gel reaction and/or through the narrow interfacial region between the silica networks and the organic matrix.

  18. Hyperbranched Polyurethane Acrylate Applied to UV Curable Flame Retardant Coatings

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    @@ UV curable hyperbranched prepolymers based on amine-ester, ester-amide and ether-amide started with AB2-type monomers have been prepared by the authors[1~3]. A se-ries of work on allyl ether maleate hyperbranched polyesters for UV curing coatings by Hult and his colleagues has been reported[4]. However, the UV cured films from those materials are all flammable when attached to fire without addition of flame retardants.

  19. Effect of Chemical Structure on Molecular Properties of Hyperbranched Polycarbosilanes

    Institute of Scientific and Technical Information of China (English)

    E.Tarabukina; A.Shpyrkov; A.Amirova; E.Tarasova; N.Shumilkina; A.Filippov; A.Muzafarov

    2007-01-01

    1 Results In spite of the increased interest to the synthesis of hyperbranched polymers,there is a lack of studies of conformational properties of their macromolecules.Structural features of hyperbranched polymers are responsible for new properties that distinguish them from linear compounds and open unique possibilities for their applications.The knowledge of the "structure-properties" relationships is of fundamental value,it also can be helpful when developing new technologies and new materials. The g...

  20. SOLUTION RHEOLOGY OF HYPERBRANCHED POLYESTERS AND THEIR BLENDS WITH LINEAR POLYMERS

    Science.gov (United States)

    In this study, the rheological properties of different generations of hyperbranched polyesters in 1-methyl-2-pyrrolidinone solvent and their blends with poly(2-hydroxyethyl methacrylate) have ben investigated. All the hyperbranched polyester solutions exhibited Newtonian behavior...

  1. SOLUTION RHEOLOGY OF HYPERBRANCHED POLYESTERS AND THEIR BLENDS WITH LINEAR POLYMERS

    Science.gov (United States)

    In this study, the rheological properties of different generations of hyperbranched polyesters in 1-methyl-2-pyrrolidinone solvent and their blends with poly(2-hydroxyethyl methacrylate) have ben investigated. All the hyperbranched polyester solutions exhibited Newtonian behavior...

  2. Formation of hyperbranched polymers in atom transfer radical copolymerization of MMA and DVB

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Hyperbranched poly(methyl methacrylate)s (HPMMAs) have been successfully prepared by atom transfer radical copolymerization of MMA and divinylbenzene (DVB).Kinetic study shows complete consumption of the initiator in 0.5 h,and relatively low polymerization rate when DVB content in the feed was high.By analyzing MALDI-TOF spectra of the resulting copolymers,the linear A n B (n=0,1,2,3) oligomers were formed in 0.5 h of polymerization,and then the oligomers reacted each other to form dimers,further reactions produced HPMMA.The SEC and NMR spectroscopies were used to trace the polymerization,and the results demonstrate that small amount of the branching reactions occur in the initial polymerization,and the branched polymers are significantly generated past a certain conversion depending upon the feed ratios.Raising the content of DVB in the monomer mixture can increase the pendent vinyl groups of the linear oligo-inimers,leading to gelation at low MMA conversion.

  3. Linear-g-hyperbranched and cyclodextrin-based amphiphilic block copolymer as a multifunctional nanocarrier

    Directory of Open Access Journals (Sweden)

    Yamei Zhao

    2014-11-01

    Full Text Available In this paper, a novel, multifunctional polymer nanocarrier was designed to provide adequate volume for high drug loading, to afford a multiregion encapsulation ability, and to achieve controlled drug release. An amphiphilic, triblock polymer (ABC with hyperbranched polycarbonsilane (HBPCSi and β-cyclodextrin (β-CD moieties were first synthesized by the combination of a two-step reversible addition-fragmentation transfer polymerization into a pseudo-one-step hydrosilylation and quaternization reaction. The ABC then self-assembled into stable micelles with a core–shell structure in aqueous solution. These resulting micelles are multifunctional nanocarriers which possess higher drug loading capability due to the introduction of HBPCSi segments and β-CD moieties, and exhibit controlled drug release based on the diffusion release mechanism. The novel multifunctional nanocarrier may be applicable to produce highly efficient and specialized delivery systems for drugs, genes, and diagnostic agents.

  4. Local orientational mobility in regular hyperbranched polymers

    CERN Document Server

    Dolgushev, Maxim; Fürstenberg, Florian; Guérin, Thomas

    2016-01-01

    We study the dynamics of local bond orientation in regular hyperbranched polymers modeled by Vicsek fractals. The local dynamics is investigated through the temporal autocorrelation functions of single bonds and the corresponding relaxation forms of the complex dielectric susceptibility. We show that the dynamic behavior of single segments depends on their remoteness from the periphery rather than on the size of the whole macromolecule. Remarkably, the dynamics of the core segments (which are most remote from the periphery) shows a scaling behavior that differs from the dynamics obtained after structural average. We analyze the most relevant processes of single segment motion and provide an analytic approximation for the corresponding relaxation times. Furthermore, we describe an iterative method to calculate the orientational dynamics in the case of very large macromolecular sizes.

  5. Crosslinked polyurethanes based on hyperbranched polymers

    Directory of Open Access Journals (Sweden)

    Vuković Jasna

    2008-01-01

    Full Text Available In this paper, two samples of polyurethane (PU crosslinked with hydroxy -functonal hyperbranched aliphatic polyester of the second pseudo generation were investigated. For the synthesis of these crosslinked PUs two different macrodiols were used: poly(tetramethyleneoxide (PTMO for PUPTMO and ethylene oxide-poly(dimethylsiloxane-ethylene oxide (PDMS-EO for PUPDMS-EO sample. Synthesized samples behave as elastomers and have yellow color. Obtained results show that swelling degree of the sample PUPDMS-EO in N-methyl-2-pyrrolidinon (NMP determined at room temperature is higher than for the sample PUPTMO. It has been also observed that thermal properties of these polyurethane networks can be changed by incorporation of siloxane sequences in their structure.

  6. Dynamics of Hyperbranched Polymers under Confinement

    Science.gov (United States)

    Androulaki, Krystallenia; Chrissopoulou, Kiriaki; Anastasiadis, Spiros H.; Prevosto, Daniele; Labardi, Massimiliano

    2015-03-01

    The effect of severe confinement on the dynamics of three different generations of hyperbranched polyesters (Boltorns) is investigated by Dielectric Spectroscopy. The polymers are intercalated within the galleries of natural Na+-MMT, thus, forming 1nm polymer films confined between solid walls. The Tg's of the polymers determined by DSC show a clear dependence on the generation whereas the transition is completely suppressed when all the polymer chains are intercalated. The dynamic investigation of the bulk polymers reveals two sub-Tg processes, with similar behavior for the three polymers with the segmental relaxation observed above the Tg of each. For the nanocomposites, where all polymers are severely confined, the dynamics show significant differences compared to that of the bulk polymers. The sub-Tg processes are similar for the three generations but significantly faster and with weaker temperature dependence than those in the bulk. The segmental process appears at temperatures below the bulk polymer Tg, it exhibits an Arrhenius temperature dependence and shows differences for the three generations. A slow process that appears at higher temperatures is due to interfacial polarization. Co-financed by the EU and Greek funds through the Operational Program ``Education and Lifelong Learning'' of the NSRF-Research Funding Program: THALES-Investing in knowledge society through the Eur. Social Fund (MIS 377278) and COST Action MP0902-COINAPO.

  7. Peroxidase-like activity of gold nanoparticles stabilized by hyperbranched polyglycidol derivatives over a wide pH range

    Science.gov (United States)

    Drozd, Marcin; Pietrzak, Mariusz; Parzuchowski, Paweł; Mazurkiewicz-Pawlicka, Marta; Malinowska, Elżbieta

    2015-12-01

    The aim of this work was to carry out comparative studies on the peroxidase-like activity of gold nanoparticles (AuNPs) stabilized with low molecular weight hyperbranched polyglycidol (HBPG-OH) and its derivative modified with maleic acid residues (HBPG-COOH). The influence of the stabilizer to gold precursor ratio on the size and morphology of nanoparticles obtained was checked, and prepared nanoparticles were characterized by means of transmission electron microscopy and UV-Vis spectroscopy. The results indicated the divergent effect of increasing the concentration of stabilizers (HBPG-OH or HBPG-COOH) on the size of the nanostructures obtained. The gold nanoparticles obtained were characterized as having intrinsic peroxidase-like activity and the mechanism of catalysis in acidic and alkaline mediums was consistent with the standard Michaelis-Menten kinetics, revealing a strong affinity of AuNPs with 2, 2‧-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and 3, 3‧, 5, 5‧-tetramethylbenzidine (TMB), and significantly lower affinity towards phenol. By comparing the kinetic parameters, a negligible effect of polymeric ligand charge on activity against various types of substrates (anionic or cationic) was indicated. The superiority of steric stabilization via the application of tested low-weight hyperbranched polymers over typical stabilizers in preventing salt-induced aggregation and maintaining high catalytic activity in time was proved. The applied hyperbranched stabilizers provide a good tool for manufacturing gold-based nanozymes, which are highly stable and active over a wide pH range.

  8. Poly(urethane-siloxanes based on hyperbranched polyester as crosslinking agent: Synthesis and characterization

    Directory of Open Access Journals (Sweden)

    Pergal Marija V.

    2012-01-01

    Full Text Available A series of novel polyurethane crosslinked structures (PUs was prepared from α,ω-dihydroxy-(ethylene oxide-poly(dimethylsiloxane-ethylene oxide (EO-PDMS-EO, 4,4’-methylenediphenyl diisocyanate and Boltorn® hyperbranched polyester of the third pseudo generation. The hydroxyfunctional hyperbranched aliphatic polyester with 26 end groups was used as crosslinking agent. In order to improve the compatibility of all reactants during the synthesis, PU samples were prepared by a step-growth polymerization in two stages in solution. The soft EO-PDMS-EO segment content was varied in the range from 15 to 40 wt.%. The influence of the EO-PDMS-EO content on the swelling behavior, crosslinking density, hardness, thermal and surface properties of the synthesized PUs was investigated. The structure of the synthesized polyurethanes was confirmed by the presence of specific bands in Fourier transform infrared spectra. Swelling studies were carried out to determine the crosslinking density and polyurethane networks with lower EOPDMS- EO content revealed higher crosslinking density. The glass transition temperature of the synthesized PUs, determined by differential scanning calorimetry, slightly increased from 50 to 58°C by decreasing EO-PDMS-EO content as a consequence of higher crosslinking density of samples. The increase of EO-PDMS-EO content leads to the better thermal stability, as it was confirmed by the value of the starting temperature of thermal degradation. The surface of the polyurethane networks became more hydrophobic with increasing EO-PDMS-EO content. The surface morphology of synthesized polyurethanes was analyzed by scanning electron microscopy.

  9. Preparation and Post-Functionalization of Hyperbranched Polyurea Coatings

    NARCIS (Netherlands)

    Xiang, Fei; Asri, Lia; Ivashenko, Oleksii; Rudolf, Petra; Loontjens, Ton

    2015-01-01

    Postfunctionalizable hyperbranched polyurea coatings were prepared by the bulk polycondensation of AB(2) monomers on preactivated silicon substrates. As previously shown, AB(2) monomers were prepared, comprising a secondary amino group (A) and two blocked isocyanates (B) connected by hexyl spacers,

  10. Blends of Amphiphilic, Hyperbranched Polyesters and Different Polyolefins

    NARCIS (Netherlands)

    Schmaljohann, D.; Pötschke, P.; Hässler, R.; Voit, B.I.; Froehling, P.E.; Mostert, B.; Loontjens, J.A.

    1999-01-01

    A hyperbranched polyester based on 3,5-dihydroxybenzoic acid was completely modified with dodecanoyl chloride to result in an amphiphilic, globular polymer, which has a polar core and a nonpolar outer sphere with the ability both to incorporate an organic dye and to interact with a nonpolar matrix.

  11. Microcellular processing of polylactide-hyperbranched polyester-nanoclay composites

    Science.gov (United States)

    Srikanth Pilla; Adam Kramschuster; Jungjoo Lee; Craig Clemons; Shaoqin Gong; Lih-Sheng Turng

    2010-01-01

    The effects of addition of hyperbranched polyesters (HBPs) and nanoclay on the material properties of both solid and microcellular polylactide (PLA) produced via a conventional and microcellular injection-molding process, respectively, were investigated. The effects of two different types of HBPs (i.e., Boltorn H2004® and Boltorn H20®) at the same...

  12. Long-term active antimicrobial coatings for surgical sutures based on silver nanoparticles and hyperbranched polylysine.

    Science.gov (United States)

    Ho, Chau Hon; Odermatt, Erich K; Berndt, Ingo; Tiller, Joerg C

    2013-01-01

    The goal of this study was to develop a long-term active antimicrobial coating for surgical sutures. To this end, two water-insoluble polymeric nanocontainers based on hyperbranched polylysine (HPL), hydrophobically modified by either using glycidyl hexadecyl ether, or a mixture of stearoyl/palmitoyl chloride, were synthesized. Highly stabilized silver nanoparticles (AgNPs, 2-5 nm in size) were generated by dissolving silver nitrate in the modified HPL solutions in toluene followed by reduction with L-ascorbic acid. Poly(glycolic acid)-based surgical sutures were dip-coated with the two different polymeric silver nanocomposites. The coated sutures showed high efficacies of more than 99.5% reduction of adhesion of living Staphylococcus aureus cells onto the surface compared to the uncoated specimen. Silver release experiments were performed on the HPL-AgNP modified sutures by washing them in phosphate buffered saline for a period of 30 days. These coatings showed a constant release of silver ions over more than 30 days. After this period of washing, the sutures retained their high efficacies against bacterial adhesion. Cytotoxicity tests using L929 mouse fibroblast cells showed that the materials are basically non-cytotoxic.

  13. Proton-conducting electrolyte membranes based on hyperbranched polymer with a sulfonic acid group for high-temperature fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Itoh, Takahito, E-mail: itoh@chem.mie-u.ac.j [Division of Chemistry for Materials, Graduate School of Engineering, Mie University, 1577 Kurima Machiya-cho, Tsu, Mie 514-8507 (Japan); Sakakibara, Takahiro; Takagi, Yuki; Tamura, Masashi; Uno, Takahiro; Kubo, Masataka [Division of Chemistry for Materials, Graduate School of Engineering, Mie University, 1577 Kurima Machiya-cho, Tsu, Mie 514-8507 (Japan); Aihara, Yuichi [Samsung Yokohama Research Institute, 2-7 Sugasawa-cho, Tsurumi-ku, Yokohama 230-0027 (Japan)

    2010-01-25

    The hyperbranched polymers (HBP-SA-Acs) with both a sulfonic acid group as a functional group and an acryloyl group as a cross-linker at terminals in different ratios of sulfonic acid group/acryloyl group (SO{sub 3}H/Ac) were successfully synthesized as a new thermally stable proton-conducting electrolyte. The cross-linked hyperbranched polymer electrolyte membranes (CL-HBP-SAs) were prepared by thermal polymerizations of the HBP-SA-Acs using benzoyl peroxide, and their ionic conductivities under dry condition and thermal properties were investigated. The ionic conductivities of the CL-HBP-SAs were found to be in the range of 2.2 x 10{sup -4} to 3.3 x 10{sup -6} S/cm, depending upon the SO{sub 3}H unit contents, at 150 deg. C under dry condition, and showed the Vogel-Tamman-Fulcher (VTF) type temperature dependence, indicating that proton transfer is cooperated by local polymer chain motion. All CL-HBP-SAs were thermally stable up to 260 deg. C, and they had suitable thermal stability as electrolyte membranes for the high-temperature fuel cells under dry condition. Fuel cell measurement using a single membrane electrode assembly cell with a cross-linked electrolyte membrane was successfully performed under non-humidified condition. It was demonstrated that applying the concept of dry polymer system to proton conduction is one possible approach toward high-temperature fuel cells.

  14. An efficient nonviral gene-delivery vector based on hyperbranched cationic glycogen derivatives

    Directory of Open Access Journals (Sweden)

    Liang X

    2014-01-01

    Full Text Available Xuan Liang,1,* Xianyue Ren,2,* Zhenzhen Liu,1 Yingliang Liu,1 Jue Wang,2 Jingnan Wang,2 Li-Ming Zhang,1 David YB Deng,2 Daping Quan,1 Liqun Yang1 1Institute of Polymer Science, School of Chemistry and Chemical Engineering, Key Laboratory of Designed Synthesis and Application of Polymer Material, Key Laboratory for Polymeric Composite and Functional Materials of Ministry of Education, Sun Yat-Sen University, Guangzhou, People's Republic of China; 2Research Center of Translational Medicine, The First Affiliated Hospital, Sun Yat-Sen University, Guangzhou, People's Republic of China *Both these authors contributed equally to this work Background: The purpose of this study was to synthesize and evaluate hyperbranched cationic glycogen derivatives as an efficient nonviral gene-delivery vector. Methods: A series of hyperbranched cationic glycogen derivatives conjugated with 3-(dimethylamino-1-propylamine (DMAPA-Glyp and 1-(2-aminoethyl piperazine (AEPZ-Glyp residues were synthesized and characterized by Fourier-transform infrared and hydrogen-1 nuclear magnetic resonance spectroscopy. Their buffer capacity was assessed by acid–base titration in aqueous NaCl solution. Plasmid deoxyribonucleic acid (pDNA condensation ability and protection against DNase I degradation of the glycogen derivatives were assessed using agarose gel electrophoresis. The zeta potentials and particle sizes of the glycogen derivative/pDNA complexes were measured, and the images of the complexes were observed using atomic force microscopy. Blood compatibility and cytotoxicity were evaluated by hemolysis assay and MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide assay, respectively. pDNA transfection efficiency mediated by the cationic glycogen derivatives was evaluated by flow cytometry and fluorescence microscopy in the 293T (human embryonic kidney and the CNE2 (human nasopharyngeal carcinoma cell lines. In vivo delivery of pDNA in model animals (Sprague Dawley

  15. Synthesis of cationic hyperbranched multiarm copolymer and its application in self-reducing and stabilizing gold nanoparticles

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    A novel hyperbranched multiarm copolymer of HBPO-star-PDEAEMA with a hydrophobic poly(3-ethyl-3-(hydroxymethyl) oxetane)(HBPO) core and many cationic poly(2-(N,N-diethylamino) ethyl methacrylate)(PDEAEMA) arms has been synthesized through an atom transfer radical polymerization(ATRP) method,and been applied to spontaneously reduce and stabilize gold nanoparticles(AuNPs) in water without other additional agents.The size of the nanoparticles could be effectively controlled at about 4 nm,and the nanoparticles are extremely stable in solution without aggregation even for one year.It was found that solution pH and the molar ratio of N/Au have certain effects on the size and stability of AuNPs.This work provides a simple method for the synthesis of uniform and highly stable AuNPs.

  16. Aptamer-Functionalized and Backbone Redox-Responsive Hyperbranched Polymer for Targeted Drug Delivery in Cancer Therapy.

    Science.gov (United States)

    Zhuang, Yuanyuan; Deng, Hongping; Su, Yue; He, Lin; Wang, Ruibin; Tong, Gangsheng; He, Dannong; Zhu, Xinyuan

    2016-06-13

    A novel type of backbone redox-responsive hyperbranched poly(2-((2-(acryloyloxy)ethyl)disulfanyl)ethyl 4-cyano-4-(((propylthio)carbonothioyl)-thio)-pentanoate-co-poly(ethylene glycol) methacrylate) (HPAEG) has been designed and prepared successfully via the combination of reversible addition-fragmentation chain-transfer (RAFT) polymerization and self-condensing vinyl polymerization (SCVP). Owing to the existence of surface vinyl groups, HPAEG could be efficiently functionalized by DNA aptamer AS1411 via Michael addition reaction to obtain an active tumor targeting drug delivery carrier (HPAEG-AS1411). The amphiphilic HPAEG-AS1411 could form nanoparticles by macromolecular self-assembly strategy. Cell Counting Kit-8 (CCK-8) assay illustrated that HPAEG-AS1411 nanoparticles had low cytotoxicity to normal cell line. Flow cytometry and confocal laser scanning microscopy (CLSM) results demonstrated that HPAEG-AS1411 nanoparticles could be internalized into tumor cells via aptamer-mediated endocytosis. Compared with pure HPAEG nanoparticles, HPAEG-AS1411 nanoparticles displayed enhanced tumor cell uptake. When the HPAEG-AS1411 nanoparticles loaded with anticancer drug doxorubicin (DOX) were internalized into tumor cells, the disulfide bonds in the backbone of HPAEG-AS1411 were cleaved by glutathione (GSH) in the cytoplasm, so that DOX was released rapidly. Therefore, DOX-loaded HPAEG-AS1411 nanoparticles exhibited a high tumor cellular proliferation inhibition rate and low cytotoxicity to normal cells. This aptamer-functionalized and backbone redox-responsive hyperbranched polymer provides a promising platform for targeted drug delivery in cancer therapy.

  17. [Modification of the composite resin with the hyperbranched polyester and evaluation of the mechanical properties of the modified composite resin].

    Science.gov (United States)

    Luo, Y C; Sun, S; Xiao, Y H

    2016-04-09

    To study the effect of hyperbranched polyester(HBP)on mechanical properties of the conventional resin matrix. Two hyperbranched monomers(HBP2-X and HBP2-Y)were synthesized and incorporated at 40%(by mass)into a 2∶1(by mass)bisphenol-A diglycidyl methacrylate(Bis-GMA): triethylene glycol dimethacrylate(TEGDMA)resin. Bis-GMA/TEGDMA without the incorporation of hyperbranched polyester was used as control(n=8 per group). The mechanical properties of the modified neat resin, including polymerization volumetric shrinkage, Vickers hardness, water absorption and dissolution rate, as well as the flexural strength, compressive strength and diametral tensile strength of the composite resin with different content of filler(0%, 30%, 50%, 70%)were measured. Mechanical properties of the composite resin were measured by universal testing machine. The results were analyzed by the ANOVA and LSD-t-test. The resin with HBP greatly decreased the polymerization shrinkage of the composite resin, and the value of group X was(6.32±0.49)%, and that of group Y was(6.31±0.68)%, whereas that of the control group was(8.14 ± 0.53)%. The value of volumetric shrinkage of the modified groups were significantly lower than that of the control group(Presin(Pcomposite materials, with 70% inorganic filler, there were no significant difference in the value of flexural strength among the groups(P>0.05). There was no significant difference in the value of compressive strength, between group X([244 ± 13]MPa)and the standard group([234 ± 17]MPa)(P>0.05). However, they were significantly higher than that in group Y([204 ± 24]MPa)(P0.05), but both were significantly lower than that in group X([41.1 ± 3.0]MPa)(Presin that was modified with the HBP, we should make further analysis and study based on the property of low volumetric shrinkage, to strive for the development of low volumetric shrinkage of HBP, without affecting its mechanical properties.

  18. Hyperbranched PEG by random copolymerization of ethylene oxide and glycidol.

    Science.gov (United States)

    Wilms, Daniel; Schömer, Martina; Wurm, Frederik; Hermanns, M Iris; Kirkpatrick, C James; Frey, Holger

    2010-10-18

    The synthesis of hyperbranched poly(ethylene glycol) (hbPEG) in one step was realized by random copolymerization of ethylene oxide and glycidol, leading to a biocompatible, amorphous material with multiple hydroxyl functionalities. A series of copolymers with moderate polydispersity ($\\overline {M} _{{\\rm w}} /\\overline {M} _{{\\rm n}} $ < 1.8) was obtained with varying glycidol content (3-40 mol-%) and molecular weights up to 49 800 g mol(-1) . The randomly branched structure of the copolymers was confirmed by (1) H and (13) C NMR spectroscopy and thermal analysis (differential scanning calorimetry). MTS assay demonstrated low cell toxicity of the hyperbranched PEG, comparable to the highly established linear PEG.

  19. Stimulus responsive fluorescent hyperbranched polymers and their applications

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Fluorescent hyperbranched polymers (FHBPs),which combine the versatile fluorescent property with unique characteristics of hyperbranched architecture,are desirable candidates for stimulus responsive materials.This review demonstrates the structure and environment-dependent emission behaviors of a series of FHBPs.AEE active FHBPs showing opposite performance to ACQ effect are used to sensitively detect explosives and a superamplification effect is found.Specially designed FHBPs can complex with metal ions,leading to fluorescence turn-off due to complex quenching effect.The protonation of amino-containing FHBPs exhibits pH-dependent fluorescence responses to solution acidity.Some FHBPs containing responsive moieties are photo-and thermo-sensitive,and show potential applications as smart materials.

  20. Adsorption mechanism and valency of catechol-functionalized hyperbranched polyglycerols

    Directory of Open Access Journals (Sweden)

    Stefanie Krysiak

    2015-05-01

    Full Text Available Nature often serves as a model system for developing new adhesives. In aqueous environments, mussel-inspired adhesives are promising candidates. Understanding the mechanism of the extraordinarily strong adhesive bonds of the catechol group will likely aid in the development of adhesives. With this aim, we study the adhesion of catechol-based adhesives to metal oxides on the molecular level using atomic force microscopy (AFM. The comparison of single catechols (dopamine with multiple catechols on hyperbranched polyglycerols (hPG at various pH and dwell times allowed us to further increase our understanding. In particular, we were able to elucidate how to achieve strong bonds of different valency. It was concluded that hyperbranched polyglycerols with added catechol end groups are promising candidates for durable surface coatings.

  1. Adsorption mechanism and valency of catechol-functionalized hyperbranched polyglycerols.

    Science.gov (United States)

    Krysiak, Stefanie; Wei, Qiang; Rischka, Klaus; Hartwig, Andreas; Haag, Rainer; Hugel, Thorsten

    2015-01-01

    Nature often serves as a model system for developing new adhesives. In aqueous environments, mussel-inspired adhesives are promising candidates. Understanding the mechanism of the extraordinarily strong adhesive bonds of the catechol group will likely aid in the development of adhesives. With this aim, we study the adhesion of catechol-based adhesives to metal oxides on the molecular level using atomic force microscopy (AFM). The comparison of single catechols (dopamine) with multiple catechols on hyperbranched polyglycerols (hPG) at various pH and dwell times allowed us to further increase our understanding. In particular, we were able to elucidate how to achieve strong bonds of different valency. It was concluded that hyperbranched polyglycerols with added catechol end groups are promising candidates for durable surface coatings.

  2. Modification of polylactide bioplastic using hyperbranched polymer based nanostructures

    Science.gov (United States)

    Bhardwaj, Rahul

    Polylactide (PLA) is the most well known renewable resource based biodegradable polymer. The inherent brittleness and poor processability of PLA pose considerable technical challenges and limit its range of commercial applications. The broad objective of this research was to investigate novel pathways for polylactide modification to enhance its mechanical and rheological properties. The focus of this work was to tailor the architecture of a dendritic hyperbranched polymer (HBP) and study its influence on the mechanical and rheological properties of PLA bioplastic. The hyperbranched polymers under consideration are biodegradable aliphatic hydroxyl-functional hyperbranched polyesters having nanoscale dimensions, unique physical properties and high peripheral functionalities. This work relates to identifying a new and industrially relevant research methodology to develop PLA based nanoblends having outstanding stiffness-toughness balance. In this approach, a hydroxyl functional hyperbranched polymer was crosslinked in-situ with a polyanhydride (PA) in the PLA matrix during melt processing, leading to the generation of new nanoscale hyperbranched polymer based domains in the PLA matrix. Transmission electron microscopy and atomic force microscopy revealed the "sea-island" morphology of PLA-crosslinked HBP blends. The domain size of a large portion of the crosslinked HBP particles in PLA matrix was less than 100 nm. The presence of crosslinked hyperbranched polymers exhibited more than 500% and 800% improvement in the tensile toughness and elongation at break values of PLA, respectively, with a minimal sacrifice of tensile strength and modulus as compared to unmodified PLA. The toughening mechanism of PLA in the presence of crosslinked HBP particles was comprised of shear yielding and crazing. The volume fraction of crosslinked HBP particles and matrix ligament thickness (inter-particle distance) were found to be the critical parameters for the toughening of PLA. The

  3. Conformation and intramolecular relaxation dynamics of semiflexible randomly hyperbranched polymers

    Science.gov (United States)

    Kumar, Amit; Rai, Gobind Ji; Biswas, Parbati

    2013-03-01

    The conformational and dynamic properties of semiflexible randomly hyperbranched polymers are investigated in dilute solutions within the framework of optimized Rouse-Zimm formalism. Semiflexibility is incorporated by restricting the directions and orientations of the respective bond vectors, while hydrodynamic interactions are modeled through the preaveraged Oseen tensor. The effect of semiflexibility is typically reflected in the intermediate frequency regime of the viscoelastic relaxation moduli where the bond orientation angle restores the characteristic power-law scaling in fractal structures, as in randomly hyperbranched polymers. Despite the absence of this power-law scaling regime in flexible randomly hyperbranched polymers and in earlier models of semiflexible randomly branched polymers due to weak disorder [C. von Ferber and A. Blumen, J. Chem. Phys. 116, 8616 (2002)], 10.1063/1.1470198, this power-law behavior may be reinstated by explicitly modeling hyperbranched polymers as a Vicsek fractals. The length of this power-law zone in the intermediate frequency region is a combined function of the number of monomers and the degree of semiflexibility. A clear conformational transition from compact to open structures is facilitated by changing the bond orientation angle, where the compressed conformations are compact, while the expanded ones are relatively non-compact. The extent of compactness in the compressed conformations are much less compared to the semiflexible dendrimers, which resemble hard spheres. The fractal dimensions of the compressed and expanded conformations calculated from the Porod's scaling law vary as a function of the bond orientation angle, spanning the entire range of three distinct scaling regimes of linear polymers in three-dimensions. The results confirm that semiflexibility exactly accounts for the excluded volume interactions which are expected to be significant for such polymers with complex topologies.

  4. Hyperbranched Polymer-Based Electrolyte for Lithium Polymer Batteries

    Institute of Scientific and Technical Information of China (English)

    Takahito Itoh

    2005-01-01

    @@ 1Introduction Solid polymer electrolytes have attracted much attention as electrolyte materials for all solid-state recharge able lithium batteries, and poly ( ethylene oxide) ( PEO)-based polymer electrolytes are among the most intensively studied systems[1-3]. Hyperbranched polymers have unique properties such as completely amorphous, highly soluble in common organic solvent and processible because of the highly branched nature[4,5].

  5. Triazatruxene-containing hyperbranched polymers:Microwave-assisted synthesis and optoelectronic properties

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Hyperbranched polymer structures represent a class of high-functionality building blocks with excellent three-dimensional topology for the construction of highly substituted conjugated polymers.In this contribution,an efficient microwave synthesis protocol toward the synthesis of conjugated hyperbranched polymers is presented.A novel series of soluble hyperbranched polyfluorenes (PTF1-PTF3) incorporating triazatruxene moiety as the branch units with various branching degrees have thus been successfully constructed with good yields and high molecular weight via a facile "A2+B2+C3" approach.The structures of the hyperbranched polymers were confirmed by NMR and GPC.Their thermal,optical,and electrochemical properties of the hyperbranched polymers were also investigated.The results showed that introduction of triazatruxene units into the hyperbranched structure endowed the polymer with good thermal stability and highly amorphous properties.Photophysical investigation of PTFx revealed strong blue emission in both solution and solid states.Hyperbranched polymers with higher degree of branching and proper content of linear fluorene units exhibited better photophysical properties in terms of narrow emission spectra and relatively high quantum efficiency as well as improved thermal spectral stability.The triazatruxene branching unit also played a role in raising the HOMO energy levels relative to those of polyfluorenes that would help to improve the charge injection and transport properties.The incorporation of triazatruxene unit into hyperbranched polymers has thus explored an effective avenue for constructing optoelectronic polymers with improved functional characteristics.

  6. SYNTHESIS AND CHARACTERIZATION OF SURFACE-HYPERBRANCHED MAGNETITE NANOPARTICLE FOR BOVINE SERUM ALBUMIN IMMOBILIZATION

    Institute of Scientific and Technical Information of China (English)

    Bifeng Pan; Feng Gao; Hongchen Gu

    2004-01-01

    A hyperbranched polyamidoamine polymer was synthesized on the surface of magnetite nanoparticles to enhance bovine serum albumin (BSA) immobilization efficiency. The amount of immobilized bovine serum albumin (BSA)on the surface-hyperbranched magnetite nanoparticle was up to 2.5 times as much as that of magnetite nanoparticle modified with only amino silane.

  7. HYPERBRANCHED CONJUGATIVE MACROMOLECULES CONSTRUCTED FROM TRIPLE-BOND BUILDING BLOCKS

    Institute of Scientific and Technical Information of China (English)

    Matthias H(a)uβler; Hong-chen Dong; Jacky Wing Yip Lam; Rong-hua Zheng; An-jun Qin; Ben-zhong Tang

    2005-01-01

    Polycyclotrimerization and polycoupling of acetylenic monomers respectively furnish hyperbranched polyarylenes and polyynes with high molecular weights (up to 1 × 106) in high yields (up to 99.9%). The polymers possess low intrinsic viscosities and high thermal stabilities, losing little of their weights when heated to > 400℃. Upon pyrolysis at > 800℃, the polymers graphitize with high char yields (up to 86%). Hyperbranched polyarylenes efficiently emit deep-blue to blue-green lights with fluorescence quantum yields up to 98% and strongly attenuate intense laser pulses with optical power-limiting performances superior to that of C60, a well-known optical limiter. Poly(alkenephenylenes), poly(aroylarylenes) and polyynes are readily cross-linkable by UV irradiation, serving as excellent photoresist materials for the generation of patterns with nanometer resolution. Thin films of hyperbranched polyynes exhibit very high refractive indexes (n up to 1.86). The internal and terminal acetylene moieties of the polyynes readily form complexes with cobalt carbonyls, which can be transformed into soft ferromagnetic ceramics with high magnetic susceptibilities (Ms up to ca. 118 emu/g) and near-zero magnetic losses.

  8. Polymeric microspheres

    Science.gov (United States)

    Walt, David R.; Mandal, Tarun K.; Fleming, Michael S.

    2004-04-13

    The invention features core-shell microsphere compositions, hollow polymeric microspheres, and methods for making the microspheres. The microspheres are characterized as having a polymeric shell with consistent shell thickness.

  9. Carboxylated hyperbranched poly(glycidol)s for preparation of pH-sensitive liposomes.

    Science.gov (United States)

    Yuba, Eiji; Harada, Atsushi; Sakanishi, Yuichi; Kono, Kenji

    2011-01-05

    Previous reports by the authors described intracellular delivery using liposomes modified with various carboxylated poly(glycidol) derivatives. These linear polymer-modified liposomes exhibited a pH-dependent membrane fusion behavior in cellular acidic compartments. However, the effect of the backbone structure on membrane fusion activity remains unknown. Therefore, this study specifically investigated the backbone structure to obtain pH-sensitive polymers with much higher fusogenic activity and to reveal the effect of the polymer backbone structure on the interaction with the membrane. Hyperbranched poly(glycidol) (HPG) derivatives were prepared as a new type of pH-sensitive polymer and used for the modification of liposomes. The resultant HPG derivatives exhibited high hydrophobicity and intensive interaction with the membrane concomitantly with the increasing degree of polymerization (DP). Furthermore, HPG derivatives showed a stronger interaction with the membrane than the linear polymers show. Liposomes modified with HPG derivatives of high DP delivered contents into the cytosol of DC2.4 cells, a dendritic cell line, more effectively than the linear polymer-modified liposomes do. Results show that the backbone structure of pH-sensitive polymers affected their pH-sensitivity and interaction with liposomal and cellular membranes.

  10. Reversible hemostatic properties of sulfabetaine/quaternary ammonium modified hyperbranched polyglycerol.

    Science.gov (United States)

    Wen, Jiying; Weinhart, Marie; Lai, Benjamin; Kizhakkedathu, Jayachandran; Brooks, Donald E

    2016-04-01

    A library of hyperbranched polyglycerols (HPGs) functionalized with different mole fractions of zwitterionic sulfabetaine and cationic quaternary ammonium ligands was synthesized and characterized. A post-polymerization method was employed that utilized double bond moieties on the dendritic HPG for the coupling of thiol-terminated ligands via UV initiated thiol-ene "click" chemistry. The proportions of different ligands were precisely controlled by varying the ligand concentration during the irradiation process. The effect of the polymer library on hemostasis was investigated using whole human blood. It was found that polymer with ≥40% of alkenes converted to positive charges and the remainder to sulfabetaines caused hemagglutination at ≥1 mg/mL, without causing red blood cell lysis. The quaternary ammonium groups can interact with the negative charged sites on the membranes of erythrocytes, which provides the bioadhesion. The zwitterionic sulfabetaine evidently provides a hydration layer to partially mask the adverse effects that are likely to be caused by cationic moieties. The polymer was also found able to enhance platelet aggregation and activation in a concentration and positive charge density-dependent manner, which would contribute to initiating hemostasis. In a variety of other assays the material was found to be largely biocompatible. The polymer-induced hemostasis is obtained by a process independent of the normal blood clotting cascade but dependent on red blood cell agglutination, where the polymers promote hemostasis by linking erythrocytes together to form a lattice to entrap the cells.

  11. Solid, double-metal cyanide catalysts for synthesis of hyperbranched polyesters and aliphatic polycarbonates

    Indian Academy of Sciences (India)

    Joby Sebastian; Srinivas Darbha

    2014-03-01

    Fe-Zn and Co-Zn double-metal cyanide (DMC) complexes exhibit highly efficient and selective catalytic activity for synthesis of hyperbranched polyesters (glycerol-succinic acid (G-SA) and glycerol-adipic acid (G-AA)) and aliphatic polycarbonates (via., alternative co-polymerization of cyclohexene oxide and CO2), respectively. The influence of method of preparation of DMC, in particular the mode of addition of reagents, on its physicochemical and catalytic properties was investigated. Co-Zn DMC was found highly selective for polycarbonate (than polyethers) formation. Catalysts prepared using tert-butanol and PEG-4000 as complexing and co-complexing agents, respectively, were found superior to those prepared without these agents. Apart from its role as a coordinating ligand, tert-butanol activated the Lewis acidic Zn2+ sites for reactions in polyester and polycarbonate formation. Hydrophobicity, micro-mesoporosity, acid strength and the amount of coordinated complexing agent are some of the crucial factors influenced the catalytic activity of DMC complexes.

  12. THE AMPHIPHILIC MULTIARM COPOLYMERS BASED ON HYPERBRANCHED POLYESTER AND LYSINE: SYNTHESIS AND SELF-ASSEMBLY

    Institute of Scientific and Technical Information of China (English)

    Jing Wang; Yuan Yao; Bing Ji; Wei Huang; Yong-feng Zhou; De-yue Yan

    2011-01-01

    The amphiphilic multiarm copolymers were synthesized through the modification of commercially available hyperbranched polyesters (Boltom H40) with N-ε-carbobenzoxy-L-Lysine N-carboxyanhydride (ZLys-NCA). After being condensed with N-Boc-phenylalanine (Boc-NPhe) and deprotected the Boc-groups in trifluoroacetic acid (TFA), the original terminal hydroxyl groups were transformed into the amino groups and then initiated the ring-opening polymerization of ZLys-NCA. The hydrophilic poly(L-lysine) was grafted to the surface of Boltorn H40 successfully after the protecting benzyl groups were removed by the HBr solution in glacial acetic acid (33 wt%). The resulting multiarm copolymers were characterized by the 1H-NMR, GPC and FTIR. The arm length calculated by NMR and GPC analysis was about 3 and 13 lysine-units for H40-Phe-PLysl and H40-Phe-PLys2 respectively. Due to the amphiphilic molecular structure, they displayed ability to self-assemble into spherical micelles in aqueous solution with the average diameter in the range from 70 nm to 250 nm. The CMC of H40-Phe-PLysl and H40-Phe-PLys2 was 0.013 mg/mL and 0.028 mg/mL, respectively,indicating that H40-Phe-PLysl with shorter arm length is easier to self-assemble than H40-Phe-PLys2 with longer arm length.

  13. Fabrication and mechanical properties of single-wall carbon nanotubes and hyperbranched diazonium salt multilayers

    Institute of Scientific and Technical Information of China (English)

    Xinyang LI; Pengwei FAN; Xinlin TUO; Xiaogong WANG

    2008-01-01

    Acidized single-wall carbon nanotubes (SWNTs) were fabricated into multilayers with a hyperbranched azo-benzene-containing polymeric diazonium salt (PDAS) using the layer-by-layer adsorption technique.The fabrication process,multilayer thickness variation,multilayer surface morphology,and the interaction between SWNTs and PDAS were monitored by UV-Vis absorption spectroscopy,optical ellipsometry,Atomic Force Microscopy,Scanning Electron Microscopy and Raman spectroscopy.Moreover,the nanomechanical properties of the multilayer films were measured by nanoindentation.All results show that SWNTs and PDAS can be fabricated into multilayers based on the cooperation of electrostatic absorption and chemical cross-linkage between SWNTs and PDAS.Further,this cooperation endows the SWNT/PDAS multilayer films with outstanding nanomechanical properties.The hardness and modulus are about 2.0GPa and 10.0GPa,respectively.Finally,the SWNT/PDAS multilayer film can be peeled off to be a free-standing film.

  14. Advanced Polymeric Materials for High-tech Innovations

    Institute of Scientific and Technical Information of China (English)

    TANG; BenZhong

    2001-01-01

    High technology is advancing our society and modernizing our life and advanced materials play an important role in the technological innovations. My research group has been working on the development of advanced polymeric materials and in this talk I will report our recent work on the creation of new conjugated polymers with novel molecular structures and unique materials properties.1-18 Our work include the design of molecular structures of monomeric building blocks, development of stable, effective and environmentally benign "green” polymerization catalysts, discovery of new polymerization reactions, synthesis of functional macromolecules, fabrication of nanodimensional composites, assembly and control of hierarchical structures, and construction of electrooptical devices. We have revealed the liquid crystallinity, light emission, photoconductivity, optical limiting, nano-hybridization, solvatochromism, optical activity, self-organization, and biological activity of the linear polyacetylenes and hyperbranched polyarylenes. The utilization of the advanced polymers and their interesting materials properties for high-tech innovations will be discussed.  ……

  15. Advanced Polymeric Materials for High-tech Innovations

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    @@ High technology is advancing our society and modernizing our life and advanced materials play an important role in the technological innovations. My research group has been working on the development of advanced polymeric materials and in this talk I will report our recent work on the creation of new conjugated polymers with novel molecular structures and unique materials properties.1-18 Our work include the design of molecular structures of monomeric building blocks, development of stable, effective and environmentally benign "green” polymerization catalysts, discovery of new polymerization reactions, synthesis of functional macromolecules, fabrication of nanodimensional composites, assembly and control of hierarchical structures, and construction of electrooptical devices. We have revealed the liquid crystallinity, light emission, photoconductivity, optical limiting, nano-hybridization, solvatochromism, optical activity, self-organization, and biological activity of the linear polyacetylenes and hyperbranched polyarylenes. The utilization of the advanced polymers and their interesting materials properties for high-tech innovations will be discussed.

  16. Kinetic theory of self-condensing vinyl polymerization

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    This review introduces the kinetic theory of self-condensing vinyl polymerization (SCVP),including the SCVP of AB inimers,the SCVP with non-equal reactivity between A and B groups,the SCVP in the presence of a small amount of multifunctional initiators,also the SCVP of both inimers and comonomers.The analytical expressions of various molecular parameters for the resulting hyperbranched polymers,such as the molecular size distribution function,the average molecular weight,the polydispersity index and the degree of branching,are reviewed systematically.

  17. Improving of Mechanical and Shape-Memory Properties in Hyperbranched Epoxy Shape-Memory Polymers

    Science.gov (United States)

    Santiago, David; Fabregat-Sanjuan, Albert; Ferrando, Francesc; De la Flor, Silvia

    2016-09-01

    A series of shape-memory epoxy polymers were synthesized using an aliphatic amine and two different commercial hyperbranched poly(ethyleneimine)s with different molecular weights as crosslinking agents. Thermal, mechanical, and shape-memory properties in materials modified with different hyperbranched polymers were analyzed and compared in order to establish the effect of the structure and the molecular weight of the hyperbranched polymers used. The presence of hyperbranched polymers led to more heterogeneous networks, and the crosslinking densities of which increase as the hyperbranched polymer content increases. The transition temperatures can be tailored from 56 to 117 °C depending on the molecular weight and content of the hyperbranched polymer. The mechanical properties showed excellent values in all formulations at room temperature and, specially, at T_{{g}}^{{E^' with stress at break as high as 15 MPa and strain at break as high as 60 %. The shape-memory performances revealed recovery ratios around 95 %, fixity ratios around 97 %, and shape-recovery velocities as high as 22 %/min. The results obtained in this study reveal that hyperbranched polymers with different molecular weights can be used to enhance the thermal and mechanical properties of epoxy-based SMPs while keeping excellent shape-memory properties.

  18. Improving of Mechanical and Shape-Memory Properties in Hyperbranched Epoxy Shape-Memory Polymers

    Science.gov (United States)

    Santiago, David; Fabregat-Sanjuan, Albert; Ferrando, Francesc; De la Flor, Silvia

    2016-03-01

    A series of shape-memory epoxy polymers were synthesized using an aliphatic amine and two different commercial hyperbranched poly(ethyleneimine)s with different molecular weights as crosslinking agents. Thermal, mechanical, and shape-memory properties in materials modified with different hyperbranched polymers were analyzed and compared in order to establish the effect of the structure and the molecular weight of the hyperbranched polymers used. The presence of hyperbranched polymers led to more heterogeneous networks, and the crosslinking densities of which increase as the hyperbranched polymer content increases. The transition temperatures can be tailored from 56 to 117 °C depending on the molecular weight and content of the hyperbranched polymer. The mechanical properties showed excellent values in all formulations at room temperature and, specially, at T_{g}^{{E^' with stress at break as high as 15 MPa and strain at break as high as 60 %. The shape-memory performances revealed recovery ratios around 95 %, fixity ratios around 97 %, and shape-recovery velocities as high as 22 %/min. The results obtained in this study reveal that hyperbranched polymers with different molecular weights can be used to enhance the thermal and mechanical properties of epoxy-based SMPs while keeping excellent shape-memory properties.

  19. Hyperbranched polymer-cored star polyfluorenes as blue light-emitting materials

    Institute of Scientific and Technical Information of China (English)

    HAN Yang; SUN MingHao; FEI ZhuPing; BO ZhiShan

    2008-01-01

    Hyperbranched polymer-cored star polyfluorenes with high molecular weights and narrow molecular weight distribution were prepared by palladium-catalyzed one-pot Suzuki polycondensation of multi-functional cores and an AB-type monomer. The optical, electrochemical and thermal properties of the hyperbranched polymer-cored star polymers were investigated. These polymers exhibited good ther-mal and color stability in solid state, and there was no significant blue-green emission after the poly-mers had been annealed in air for 2.5 h. Their three-dimensional hyperbranched structures could ef-fectively reduce the aggregation of the peripheral rigid linear conjugated polyfluorene chains.

  20. Solution-Stable Colloidal Gold Nanoparticles via Surfactant-Free, Hyperbranched Polyglycerol-b-polystyrene Unimolecular Templates.

    Science.gov (United States)

    Iocozzia, James; Lin, Zhiqun

    2016-07-19

    Hyperbranched polyglycerol-block-polystyrene copolymers, denoted HPG-b-PS, are synthesized and employed as a new and effective unimolecular template for synthesizing colloidal gold (Au) nanoparticles. The coordination of noble metal precursors with polyether within the inner HPG core and subsequent in situ reduction enables the formation of well-dispersed and stable PS-capped Au nanoparticles. The inner HPG core is produced via ring opening multibranching polymerization (ROMBP) and subsequently converted into atom transfer radical polymerization (ATRP) macroinitiators for the controlled growth of polystyrene (PS) arms possessing low polydispersity (PDI < 1.31). An initial investigation into the templating parameters of HPG-b-PS was undertaken by producing templates with different arm numbers (98 and 117) and different PS chain lengths (i.e., molecular weight = 3500-13400 g/mol). It was found that the PS chain length and solvent conditions affect the quality of the resulting PS-capped colloidal Au nanoparticles. This work demonstrates, for the first time, a simple, lower-cost approach for templating nonpolar solvent-soluble PS-capped Au nanoparticles on the order of 10-30 nm in diameter.

  1. “Controlled” and “Living” Cationic Polymerizations:Another Way Towards Well Defined Polymer Architectures and Materials

    Institute of Scientific and Technical Information of China (English)

    Jean-Pierre; Vairon; Michel; Moreau; Rudolf; Faust

    2007-01-01

    1 Results No doubt that one of the major breakthroughs in polymer chemistry was the discovery and the progressive implementation of the "living" and "controlled" polymerizations.These now widely used techniques allow not only to control with an extreme precision the molar masses and their distributions but also to synthesise easily a broad variety of architectures from block and graft copolymers,miktoarms stars,to polymer brushes,hyperbranched polymers,dendrimers,etc....They opened an immense domain of ...

  2. Synthesis and Mechanism Insight of a Peptide-Grafted Hyperbranched Polymer Nanosheet with Weak Positive Charges but Excellent Intrinsically Antibacterial Efficacy.

    Science.gov (United States)

    Gao, Jingyi; Wang, Mingzhi; Wang, Fangyingkai; Du, Jianzhong

    2016-06-13

    Antimicrobial resistance is an increasingly problematic issue in the world and there is a present and urgent need to develop new antimicrobial therapies without drug resistance. Antibacterial polymers are less susceptible to drug resistance but they are prone to inducing serious side effects due to high positive charge. Herein we report a peptide-grafted hyperbranched polymer which can self-assemble into unusual nanosheets with highly effective intrinsically antibacterial activity but weak positive charges (+ 6.1 mV). The hyperbranched polymer was synthesized by sequential Michael addition-based thiol-ene and free radical mediated thiol-ene reactions, and followed by ring-opening polymerization of N-carboxyanhydrides (NCAs). The nanosheet structure was confirmed by transmission electron microscopy (TEM) and atomic force microscopy (AFM) studies. Furthermore, a novel "wrapping and penetrating" antibacterial mechanism of the nanosheets was revealed by TEM and it is the key to significantly decrease the positive charges but have a very low minimum inhibitory concentration (MIC) of 16 μg mL(-1) against typical Gram-positive and Gram-negative bacteria. Overall, our synthetic strategy demonstrates a new insight for synthesizing antibacterial nanomaterials with weak positive charges. Moreover, the unique antibacterial mechanism of our nanosheets may be extended for designing next-generation antibacterial agents without drug resistance.

  3. Studies on the Self-condensing Vinyl Living Radical Polymerization of a Novel Acrylate Inimer

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    A novel acrylate inimer, 2-(2-chloroacetyloxy) ethyl acrylate, was prepared by the reaction of 2-hydroxyethyl acrylate with chloroacetyl chloride in the presence of triethylamine. The self-condensing vinyl living radical polymerization of the inimer was studied and the hyperbranched macromolecules containing ester linkages on their backbone were prepared. All the polymerization products were characterized by 1H NMR. The polymerization degree and the branching parameter were calculated based on the 1H NMR spectra. It has been shown that this inimer exhibits a very distinctive polymerization behavior. Similar to step-growth polymerization, the polymerization degree of the products formed increased exponentially during the early stage of the polymerization, and then the increasing rate slowed down. However, the inimer remained present throughout the polymerization consistent with conventional free radical polymerization. Also, if much longer polymerization time was used, the polymerization system would become gel due to the crosslinking reaction derived from radical-radical recombination. As a result of the unequal reactivity of -CH2Cl and >CHCl, an almost linear product was obtained at a molar ratio of bipy to inimer=0.05, while a relatively high ratio of bipy to inimer 1 favored the formation of the branched structure. The macromolecules formed at a high ratio of bipy to inimer 1 exhibited an excellent solubility in organic solvents such as acetone.

  4. Thermoresponsive and Reducible Hyperbranched Polymers Synthesized by RAFT Polymerisation

    Directory of Open Access Journals (Sweden)

    Anna Tochwin

    2017-09-01

    Full Text Available Here, we report the synthesis of new thermoresponsive hyperbranched polymers (HBPs via one-pot reversible addition-fragmentation chain transfer (RAFT copolymerisation of poly(ethylene glycolmethyl ether methacrylate (PEGMEMA, Mn = 475 g/mol, poly(propylene glycolmethacrylate (PPGMA, Mn = 375 g/mol, and disulfide diacrylate (DSDA using 2-cyanoprop-2-yl dithiobenzoate as a RAFT agent. DSDA was used as the branching agent and to afford the HBPs with reducible disulfide groups. The resulting HBPs were characterised by Nuclear Magnetic Resonance Spectroscopy (NMR and Gel Permeation Chromatography (GPC. Differential Scanning Calorimetry (DSC was used to determine lower critical solution temperatures (LCSTs of these copolymers, which are in the range of 17–57 °C. Moreover, the studies on the reducibility of HBPs and swelling behaviours of hydrogels synthesized from these HBPs were conducted. The results demonstrated that we have successfully synthesized hyperbranched polymers with desired dual responsive (thermal and reducible and crosslinkable (via thiol-ene click chemistry properties. In addition, these new HBPs carry the multiplicity of reactive functionalities, such as RAFT agent moieties and multivinyl functional groups, which can afford them with the capacity for further bioconjugation and structure modifications.

  5. A room temperature cured low dielectric hyperbranched epoxy adhesive with high mechanical strength

    Indian Academy of Sciences (India)

    Bibekananda De; Niranjan Karak

    2014-05-01

    A low dielectric constant hyperbranched epoxy thermoset with excellent adhesive and mechanical strength is the demand for advanced electronics and engineering applications. The present investigation provided a room temperature, curable hyperbranched epoxy, obtained by an A2 + B3 polycondensation reaction. The synthesized hyperbranched epoxy was cured by a combined hardener system consisting of a commercial poly(amido-amine) and a first generation aliphatic poly(amido-amine) dendrimer (PAD) prepared by Michael addition reaction of methyl acrylate and aliphatic amines. The thermoset exhibited high mechanical strength, excellent adhesive strength, low dielectric constant, good thermal stability and excellent weather resistance along with very good moisture resistance. The results showed the influence of the amount of PAD on the performance of the thermoset. Thus, the study revealed that the combined poly(amido-amine) cured hyperbranched epoxy has high potential in advanced electrical packaging and microelectronic devices.

  6. Catalytic water dissociation using hyperbranched aliphatic polyester (Boltorn series) as the interface of a bipolar membrane.

    Science.gov (United States)

    Xue, Yanhong; Xu, Tongwen; Fu, Rongqiang; Cheng, Yiyun; Yang, Weihua

    2007-12-15

    The effect of hyperbranched aliphatic polyester (Boltorn series) on the water dissociation in bipolar membranes was firstly investigated in this paper. The bipolar membranes were prepared by immersing the anion exchange layer in a hyperbranched aliphatic polyester solution and then coating on the layer a polyphenylene oxide (SPPO) solution. The SEM observations proved the existence of hyperbranched aliphatic polyester at the membrane intermediate layer. The adsorption amount was evaluated by the oxygen content via XPS. The junction thickness of the prepared bipolar membrane was determined by electrochemical impedance spectroscopy (EIS), and the membrane performances were evaluated by current-voltage curves. The results showed that the amount and generation of Boltorn series, and temperature all affected I-V behaviors of the fabricated bipolar membranes, and the former two played the critical role. These effects were explained on the basis of the water dissociation theory and the characteristics of hyperbranched aliphatic polyester.

  7. Convenient Synthesis and Enhanced Second-order Nonlinear Optical Property of a Novel Hyperbranched Polymer

    Institute of Scientific and Technical Information of China (English)

    ZHU Zhi-Chao; LI Zhong-An; LI Qian-Qian; ZENG Qi; LI Zhen; YE Cheng; QIN Jin-Gui

    2007-01-01

    A novel hyperbranched polymer (3) was prepared by copolymerization of tri-aldehyde moieties with azo chromophores having two active methelene groups, from "A2+B3" approach based on simple Kneovenagel reaction.For comparison, its analogue linear polymer (5) was also synthesized. The two polymers are soluble in common organic solvents, and exhibit good thermal stability. Interestingly, the hyperbranched polymer demonstrates dramatically enhanced second-order nonlinear optical property with comparison to its linear analogue.

  8. Synthesis of novel tempera ture/pH responsive polymer via oxyanionic polymerization

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Hyperbranched poly(3-ethyl-3-oxetanemethanol)-graft-poly(2-dimethylaminoethyl methacrylate) (HP-gDMA) with a three-demensional structure was synthesized via oxyanionic polymerization. The hydroxyl groups of hyperbranched poly(3-ethyl-3-oxetanemethanol) (HP) reacted with KH and conversed into potassium alcoholate macroinitiators with high initiating efficiencies. High monomer conversion (>95%) was obtained and no residual macroinitiators or monomer was observed. UV-visible spectra indicate that the aqueous solution of the HP-g-DMA exhibited the lowermost critical solution temperature (LCST). The LCST was influenced by the chain length of DMA and pH condition of solution. It is found that LCST decreased with increasing DMA chain length or increasing pH value of solution.

  9. Preparation of fluorescent hyperbranched polymer materials by end-capping approach

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Two kinds of novel fluorescent hyperbranched polymers were synthesized by the end-capping approach.The fluorescent hyperbranched polyether (FPEOTM) was obtained by end capping the hyperbranched poly(hydroxyl ether) (PEOTM) with guest molecules N,N- dimethylaminobenzaldehyde (DMABA).In addition,in the presence of triethylamine,the hyperbranched polysulfone-amine with terminal double bonds (HPSA) was synthesized by polyaddition of a new AB2 type monomer (SAP,sulfone amine piperazine) at 40℃ for 60 h in chloroform solution.Then the fluorescent hyperbranched polysulfone-amine (FHPSA) was prepared by addition of guest molecules N,N-dimethylaminoanilines (DMAA) with the terminal double bonds of HPSA.The two resulting polymers fluoresce yellow-green color in both solid and solution states.The maximum emission wavelength is (460±10) nm and (470±10) nm,respectively.A novel "complex quenching effect" for hyperbranched polymer was observed.The fluorescence can be quenched by transition metal cations such as Ag+,Cu2+ and Fe3+,while alkali and alkaline earth metal cations almost have no influence on the fluorescence intensity.

  10. Antimicrobial hyperbranched poly(ester amide)/polyaniline nanofiber modified montmorillonite nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Pramanik, Sujata [Advanced Polymer and Nanomaterial Laboratory, Department of Chemical Sciences, Tezpur University, Tezpur 784028 (India); Bharali, Pranjal; Konwar, B.K. [Department of Molecular Biology and Biotechnology, Tezpur University, Tezpur 784028 (India); Karak, Niranjan, E-mail: karakniranjan@yahoo.com [Advanced Polymer and Nanomaterial Laboratory, Department of Chemical Sciences, Tezpur University, Tezpur 784028 (India)

    2014-02-01

    There has been growing interest in the use of nanomaterials featuring potent of antimicrobial activity in the biomedical domain. It still remains a challenge for the researchers to develop an efficient nanocomposite possessing antimicrobial efficacy against broad spectrum microbes including bacteria, fungi as well as algal consortium, posing serious challenges for the human survival. In addressing the above problem, we report the fabrication of bio-based hyperbranched poly(ester amide) (HBPEA)/polyaniline nanofiber modified montmorillonite (MMT) nanocomposites by an ex-situ polymerization technique at varied weight percentages (1, 2.5, 5 wt.%) of the modified MMT (nanohybrid). The Fourier transform infrared spectroscopy confirmed the structural changes upon interaction of the nanohybrid with HBPEA. A probable mechanism is proposed for the formation of nanocomposites with partially exfoliated nanoplatelet structure, which was further confirmed from the high resolution transmission electron microscopic analyses. The prepared nanocomposites exhibited potent efficacy against gram positive bacteria like Bacillus subtilis and Staphylococcus aureus as compared to the gram negative ones like Pseudomonas aeruginosa and Escherichia coli. The nanocomposites showed significant antifungal activity against Aspergillus niger, Fusarium oxysporum and Coleotricum capcii and antialgal activity against algal consortium comprising of Chlorella, Hormidium and Cladophorella species. The formation of thermosetting nanocomposites resulted in the acceptable improvement of desired physico-chemical and mechanical properties including thermostability. Thus pronounced antimicrobial activity of the nanocomposites against a spectrum of bacterial and fungal strains as well as a consortium of algal species along with other desired performance vouched them as potent antimicrobial materials in the realm of health and biomedical industry. - Highlights: • A possible approach for fabrication of the

  11. Antimicrobial hyperbranched poly(ester amide)/polyaniline nanofiber modified montmorillonite nanocomposites.

    Science.gov (United States)

    Pramanik, Sujata; Bharali, Pranjal; Konwar, B K; Karak, Niranjan

    2014-02-01

    There has been growing interest in the use of nanomaterials featuring potent of antimicrobial activity in the biomedical domain. It still remains a challenge for the researchers to develop an efficient nanocomposite possessing antimicrobial efficacy against broad spectrum microbes including bacteria, fungi as well as algal consortium, posing serious challenges for the human survival. In addressing the above problem, we report the fabrication of bio-based hyperbranched poly(ester amide) (HBPEA)/polyaniline nanofiber modified montmorillonite (MMT) nanocomposites by an ex-situ polymerization technique at varied weight percentages (1, 2.5, 5 wt.%) of the modified MMT (nanohybrid). The Fourier transform infrared spectroscopy confirmed the structural changes upon interaction of the nanohybrid with HBPEA. A probable mechanism is proposed for the formation of nanocomposites with partially exfoliated nanoplatelet structure, which was further confirmed from the high resolution transmission electron microscopic analyses. The prepared nanocomposites exhibited potent efficacy against gram positive bacteria like Bacillus subtilis and Staphylococcus aureus as compared to the gram negative ones like Pseudomonas aeruginosa and Escherichia coli. The nanocomposites showed significant antifungal activity against Aspergillus niger, Fusarium oxysporum and Coleotricum capcii and antialgal activity against algal consortium comprising of Chlorella, Hormidium and Cladophorella species. The formation of thermosetting nanocomposites resulted in the acceptable improvement of desired physico-chemical and mechanical properties including thermostability. Thus pronounced antimicrobial activity of the nanocomposites against a spectrum of bacterial and fungal strains as well as a consortium of algal species along with other desired performance vouched them as potent antimicrobial materials in the realm of health and biomedical industry.

  12. Synthesis of functionalized CNTs/hyperbranched polyester nanocomposites

    Science.gov (United States)

    Pan, Yufeng; Cui, Xiaokun; Zhang, Yue

    2017-01-01

    Carbon nanotubes (CNTs) were unzipped using the modified Hummer method to prepare the CNTs-GO microstructure (see Fig. 1). A new type of CNTs-GO-H20 nanocomposite has been synthesized by grafting hyperbranched (HB) polyester (Boltorn H20) brushes on the CNTs-GO by coupling agent (KH560). The morphology of CNTs-GO-H20 was characterized by FTIR, TEM, XPS and TGA. The FT-IR data and XPS data evidenced that CNTs-GO-H20 nanocomposites were synthesized successfully. The addition of CNTs improved the thermal stability of the nanocomposites. The TEM data showed that the CNTs-GO microstructure was also prepared. These electrochemical measurements results indicated that coatings provided greater protection against corrosion behavior. Moreover, the nanocomposite material improved corrosion resistance of the coating.

  13. Unimolecular micelles and electrostatic nanoassemblies stemming from hyperbranched polyethyleneimine

    Energy Technology Data Exchange (ETDEWEB)

    Picco, A.; Azzaroni, O.; Ceolin, M. [Instituto de Investigaciones Fisicoquimicas Teoricas y Aplic, La Plata, BA (Argentina); Silbestri, G.F. [Universidad Nacional del Sur, Bahia Blanca Bueno (Argentina)

    2012-07-01

    Full text: Hyperbranched polyethyleneimine (HPEI) was used as a building block to construct different self-assembled soft nanomaterials. This was accomplished via covalent linkage of carboxylic acids (CA) of different chain lengths to terminal amino groups of HPEI, thus leading to the formation of reverse unimolecular micelles constituted of a hydrophilic core and a hydrophobic shell. On the other hand, acid base interactions in organic solvents between CAs and peripheral amino groups of HPEI also facilitated the formation of electrostatic assemblies with reverse micellar properties. In this work we describe the formation of both structures as well as their characterization using diverse techniques including SAXS, NMR, IR, and fluorescence spectroscopy, among others. Unimolecular micelles were synthesized through the reaction of HPEI (Mn= 10 KDa) and acyl chlorides with different chain lengths (C8, C10, C12, C14, C16, C18). Depending on the chain length, the solvent and the temperature, a broad variety of supra macromolecular assemblies can be observed by SAXS measurements, including structured aggregation, and gelation. Hyperbranched electrostatic assemblies were simply produced by mixing HPEI with selected carboxylic acids (C8, C10, C12, C14, C16, C18) in an appropriate solvent, which dissolves the CA, or both reactants, i.e. chloroform, toluene or THF. The formation of the assemblies was corroborated using FT-IR by monitoring the appearance of the carboxylate bands. SAXS experiments of electrostatically assembled micelles showed globular, core-shell structures, whose characteristics are similar, in many cases, to their covalent counterparts prepared using the same chain length CA shells. (author)

  14. Hydrogen storing and electrical properties of hyperbranched polymers-based nanoporous materials

    Energy Technology Data Exchange (ETDEWEB)

    Abdel Rehim, Mona H., E-mail: monaabdelrehim@yahoo.com [Packing and Packaging Materials Department, Center of Excellence for advanced Science, Renewable Energy Group, National Research Center, Cairo (Egypt); Ismail, Nahla; Badawy, Abd El-Rahman A.A. [Physical Chemistry Department, Center of Excellence for advanced Science, Renewable Energy Group, National Research Center, Cairo (Egypt); Turky, Gamal [Microwave Physics and Dielectrics Department, National Research Center, Cairo (Egypt)

    2011-09-15

    Highlights: {center_dot} The hydrogen storage capacity of hyperbranched P-Urea, PAMAM and PAMAM and VO{sub x} is studied and electrical properties of the samples are also investigated; the measurements showed complete insulating behavior at hydrogenation measuring temperature. These investigations ensure that the polymer conductivity does not play a role in hydrogen uptake, also hyperbranched polymers are promising materials for hydrogen storage. {center_dot} Electrical properties measurements for the samples showed complete insulating behavior at hydrogenation measuring temperature. {center_dot} These investigations ensure that the polymer conductivity does not play a role in hydrogen uptake, also hyperbranched polymers are promising materials for hydrogen storage. - Abstract: Hydrogen storage and electrical properties of different hyperbranched polymer systems beside a nanocomposite are studied. The polymers examined are aliphatic hyperbranched poly urea (P-Urea), polyamide amine (PAMAM) and polyamide amine/vanadium oxide (PAMAM/VO{sub x}) nanocomposite. At 80 K and up to 20 bar hydrogen pressure, the hydrogen storage capacity of hyperbranched P-Urea reached 1.6 wt%, 0.9 wt% in case of PAMAM and 0.6 wt% for VO{sub x}. The hydrogen storage capacity significantly enhanced when PAMAM and VO{sub x} form a nanocomposite and increased up to 2 wt%. At 298 K and up to 20 bar, all the samples did not show measurable hydrogen uptake. Electrical properties of the samples are also investigated; the measurements showed complete insulating behavior at hydrogenation measuring temperature. These investigations ensure that the polymer conductivity does not play a role in hydrogen uptake, also hyperbranched polymers are promising materials for hydrogen storage.

  15. Condensation Polymerization

    Indian Academy of Sciences (India)

    S Ramakrishnan

    2017-04-01

    The very idea that large polymer molecules can indeed existwas hotly debated during the early part of the 20th century.As highlighted by Sivaram in his articles on Carothersand Flory, Staudinger’s macromolecular hypothesis was finallyaccepted, and the study of polymers gained momentumbecause of the remarkable efforts of the these two individualswho laid down the foundations concerning the processes thatled to the formation of large polymer molecules, and to thosethat led to an understanding of many of their extraordinaryphysical properties. Condensation polymerizations, as thename suggests, utilizes bond-forming reactions that generatea small molecule condensate, which often needs to be continuouslyremoved to facilitate the formation of the polymer. Inthis article, I shall describe some of the essential principles ofcondensation polymerizations or more appropriately calledstep-growth polymerizations; and I will also describe someinteresting extensions that lead to the formation of polymernetworks and highly branched polymers.

  16. Progesterone binding nano-carriers based on hydrophobically modified hyperbranched polyglycerols

    Science.gov (United States)

    Alizadeh Noghani, M.; Brooks, D. E.

    2016-02-01

    Progesterone (Pro) is a potent neurosteroid and promotes recovery from moderate Traumatic Brain Injury but its clinical application is severely impeded by its poor water solubility. Here we demonstrate that reversibly binding Pro within hydrophobically modified hyperbranched polyglycerol (HPG-Cn-MPEG) enhances its solubility, stability and bioavailability. Synthesis, characterization and Pro loading into HPG-Cn-MPEG is described. The release kinetics are correlated with structural properties and the results of Differential Scanning Calorimetry studies of a family of HPG-Cn-MPEGs of varying molecular weight and alkylation. While the maximum amount of Pro bound correlates well with the amount of alkyl carbon per molecule contributing to its hydrophobicity, the dominant first order rate constant for Pro release correlates strongly with the amount of structured or bound water in the dendritic domain of the polymer. The results provide evidence to justify more detailed studies of interactions with biological systems, both single cells and in animal models.Progesterone (Pro) is a potent neurosteroid and promotes recovery from moderate Traumatic Brain Injury but its clinical application is severely impeded by its poor water solubility. Here we demonstrate that reversibly binding Pro within hydrophobically modified hyperbranched polyglycerol (HPG-Cn-MPEG) enhances its solubility, stability and bioavailability. Synthesis, characterization and Pro loading into HPG-Cn-MPEG is described. The release kinetics are correlated with structural properties and the results of Differential Scanning Calorimetry studies of a family of HPG-Cn-MPEGs of varying molecular weight and alkylation. While the maximum amount of Pro bound correlates well with the amount of alkyl carbon per molecule contributing to its hydrophobicity, the dominant first order rate constant for Pro release correlates strongly with the amount of structured or bound water in the dendritic domain of the polymer. The

  17. Synthesis of Cu/SiO2 Core-Shell Particles Using Hyperbranched Polyester as Template and Dispersant

    Science.gov (United States)

    Han, Wensong

    2017-07-01

    Third-generation hyperbranched polyester (HBPE3) was synthesized by stepwise polymerization with N, N-diethylol-3-amine methylpropionate as AB2 monomer and pentaerythritol as core molecule. Then, Cu particles were prepared by reduction of copper nitrate with ascorbic acid in aqueous solution using HBPE3 as template. Finally, Cu/SiO2 particles were prepared by coating silica on the surface of Cu particles. The structure and morphology of the samples were characterized by Fourier-transform infrared (FT-IR) spectrometry, x-ray diffraction (XRD) analysis, transmission electron microscopy (TEM), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). The results confirmed the formation of the silica coating on the surface of Cu and that the Cu/SiO2 particles had spherical shape with particle size in the range of 0.8 μm to 2 μm. Compared with pure Cu, the synthesized Cu/SiO2 core-shell particles exhibited better oxidation resistance at high temperature. Moreover, the oxidation resistance of the Cu/SiO2 particles increased significantly with increasing tetraethyl orthosilicate (TEOS) concentration.

  18. Study on the morphology and thermomechanical properties of poly(urethane-siloxane networks based on hyperbranched polyester

    Directory of Open Access Journals (Sweden)

    Pergal Marija V.

    2013-01-01

    Full Text Available Two series of polyurethane films based on hyperbranched polyester of the second pseudogeneration (Boltorn®, 4,4'-methylenediphenyl diisocyanate and two different siloxane prepolymers, α,ω-dihydroxy-(ethylene oxide-poly(dimethylsiloxane-ethylene oxide (EO-PDMS-EO and α,ω-dihydroxypropyl-poly(dimethylsiloxane (HP-PDMS, were prepared by two-step polymerization in solution. The influence of the type and content of soft segment on the morphology, thermomechanical and surface properties of the synthesized polyurethanes was studied by atomic force microscopy (AFM, small-angle X-ray scattering (SAXS, scanning electron microscopy (SEM, dynamic mechanical thermal analysis (DMTA and water absorption measurements. It was found that these techniques confirmed existence of microphase separated morphology. Synthesized polyurethanes exhibited two glass transition temperatures and one second relaxation process. The results showed that polyurethanes based on HP-PDMS had higher surface roughness, better microphase separation and waterproof performances. Samples synthesized with lower PDMS content had less hydrophobic surface, but higher crosslinking density and better thermomechanical properties. (Projekat Ministarstva nauke Republike Srbije, br. 172062

  19. Anhydrous proton-conducting electrolyte membranes based on hyperbranched polymer with phosphonic acid groups for high-temperature fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Itoh, Takahito; Hirai, Keita; Tamura, Masashi; Uno, Takahiro; Kubo, Masataka [Division of Chemistry for Materials, Graduate School of Engineering, Mie University, 1577 Kurima Machiya-cho, Tsu, Mie 514-8507 (Japan); Aihara, Yuichi [Samsung Yokohama Research Institute, 2-7 Sugasawa-cho, Tsurumi-ku, Yokohama 230-0027 (Japan)

    2008-04-01

    The two different molecular weight hyperbranched polymers (HBP(L)-PA-Ac and HBP(H)-PA-Ac) with both phosphonic acid group as a functional group and acryloyl group as a cross-linker at the chain ends were successfully synthesized as a new thermally stable proton-conducting electrolyte. The cross-linked electrolyte membranes (CL-HBP-PA) were prepared by their thermal polymerizations using benzoyl peroxide and their ionic conductivities under dry condition and thermal properties were investigated. The ionic conductivities of the low molecular weight CL-HBP(L)-PA membrane and the high molecular weight CL-HBP(H)-PA membrane were found to be 1.2 x 10{sup -5} and 2.6 x 10{sup -6} S cm{sup -1}, respectively, at 150 C under dry condition, and showed the Vogel-Tamman-Fulcher (VTF) type temperature dependence. Both membranes were thermally stable up to 300 C, and they had suitable thermal stability as electrolyte membranes for the high-temperature fuel cells under dry condition. Fuel cell measurements using a single membrane electrode assembly cell with both cross-linked membranes were successfully performed. (author)

  20. STUDY OF NANOSIZED SILICA GRAFIED WITH HYPERBRANCHED POLY(AMINE-ESTER)

    Institute of Scientific and Technical Information of China (English)

    ZHAO Hui; YANG Shu; LUO Yunjun

    2006-01-01

    A new method to chemically modify the surface of nanosized-SiO2 was studied in this paper. Nanosized-SiO2 was grafted with hyperbranched poly(amin ester) through one-spot polycondensation between AB2 monomer and active hydroxyl on silica surface in present of catalyst.Compared with the results of FTIR and TEM, it is found hyperbranched poly(amin ester) is successfully grafted on the surface of nanosized-SiO2 and the surface properties have been changed with an expected way. The results indicate that nanosized-SiO2 grafted with hyperbranched poly(amin ester) has better dispersion in the ethanol or chloroform than that unmodified.

  1. Perfluoroalkyl-Functionalized Hyperbranched Polyglycerol as Pore Forming Agents and Supramolecular Hosts in Polymer Microspheres

    Directory of Open Access Journals (Sweden)

    Olaf Wagner

    2015-08-01

    Full Text Available Perfluoroalkyl-functionalized, hyperbranched polyglycerols that produce stable microbubbles are integrated into a microfluidic emulsion to create porous microspheres. In a previously-presented work a dendrimer with a perfluorinated shell was used. By replacing this dendrimer core with a hyperbranched core and evaluating different core sizes and degrees of fluorinated shell functionalization, we optimized the process to a more convenient synthesis and higher porosities. The new hyperbranched polyglycerol porogens produced more pores and can be used to prepare microspheres with porosity up to 12% (v/v. The presented preparation forms pores with a perfluoroalkyl-functionalized surface that enables the resulting microspheres to act as supramolecular host systems. The microspheres can incorporate gases into the pores and actives in the polymer matrix, while the perfluoroalkylated pore surface can be used to immobilize perfluoro-tagged molecules onto the pores by fluorous-fluorous interaction.

  2. Synthesis and characterization of a hyper-branched water-soluble β-cyclodextrin polymer

    Directory of Open Access Journals (Sweden)

    Francesco Trotta

    2014-11-01

    Full Text Available A new hyper-branched water-soluble polymer was synthesized by reacting β-cyclodextrin with pyromellitic dianhydride beyond the critical conditions that allow the phenomenon of gelation to occur. The molar ratio between the monomers is a crucial parameter that rules the gelation process. Nevertheless, the concentration of monomers in the solvent phase plays a key role as well. Hyper-branched β-cyclodextrin-based polymers were obtained performing the syntheses with excess of solvent and cross-linking agent, and the conditions for critical dilution were determined experimentally. A hyper-branched polymer with very high water solubility was obtained and fully characterized both as for its chemical structure and for its capability to encapsulate substances. Fluorescein was used as probe molecule to test the complexation properties of the new material.

  3. Synthetic methodologies and spatial organization of metal chelate dendrimers and star and hyperbranched polymers.

    Science.gov (United States)

    Dzhardimalieva, Gulzhian I; Uflyand, Igor E

    2017-08-08

    The synthetic methodologies, physico-chemical peculiarities, properties, and structure of metal chelate dendrimers and star and hyperbranched polymers are considered. These compounds are subdivided into molecular, intracomplex, and macrocyclic types which in turn are classified depending on the nature of the donor atoms (N,N-, N,O-, N,S-, O,O-, O,S-, S,S-, P,P-chelates, etc.). Special attention is paid to the features of the preparation of metal chelate star polymers by "arm-first", "core-first" and click-to-chelate approaches. The main data on the synthesis, spatial structure and properties of the metal chelate hyperbranched polymers are summarized. The basic concepts and synthetic strategies leading to the different types of supramolecular metal chelate dendrimers are analyzed. The problems and future prospects of metal chelate dendrimers and star and hyperbranched polymers are outlined. The bibliography includes papers published after 2010.

  4. Graphene oxide and hyperbranched polymer-toughened hydrogels with improved absorption properties and durability

    DEFF Research Database (Denmark)

    Yu, Yang; De Andrade, Leandro Carvalho Xavier; Fang, Liming

    2015-01-01

    Hyperbranched polymers or/and graphene oxide nanosheets were used to synthesize poly(acrylic acid)-based hybrid hydrogels with high water absorption ability, excellent mechanical properties, and environmental remediation abilities through a novel one-step, cost-effective, and environmentally...... friendly method. The combination of hyperbranched polymers and graphene oxide nanosheets had synergistic effects on the final hybrid hydrogel, especially on the mechanical behaviors of the hydrogels, with Young's modulus, tensile strength at break and elongation at break increasing by 69, 308, and 848...

  5. Ductile electroactive biodegradable hyperbranched polylactide copolymers enhancing myoblast differentiation.

    Science.gov (United States)

    Xie, Meihua; Wang, Ling; Guo, Baolin; Wang, Zhong; Chen, Y Eugene; Ma, Peter X

    2015-12-01

    Myotube formation is crucial to restoring muscular functions, and biomaterials that enhance the myoblast differentiation into myotubes are highly desirable for muscular repair. Here, we report the synthesis of electroactive, ductile, and degradable copolymers and their application in enhancing the differentiation of myoblasts to myotubes. A hyperbranched ductile polylactide (HPLA) was synthesized and then copolymerized with aniline tetramer (AT) to produce a series of electroactive, ductile and degradable copolymers (HPLAAT). The HPLA and HPLAAT showed excellent ductility with strain to failure from 158.9% to 42.7% and modulus from 265.2 to 758.2 MPa. The high electroactivity of the HPLAAT was confirmed by UV spectrometer and cyclic voltammogram measurements. These HPLAAT polymers also showed improved thermal stability and controlled biodegradation rate compared to HPLA. Importantly, when applying these polymers for myotube formation, the HPLAAT significantly improved the proliferation of C2C12 myoblasts in vitro compared to HPLA. Furthermore, these polymers greatly promoted myogenic differentiation of C2C12 cells as measured by quantitative analysis of myotube number, length, diameter, maturation index, and gene expression of MyoD and TNNT. Together, our study shows that these electroactive, ductile and degradable HPLAAT copolymers represent significantly improved biomaterials for muscle tissue engineering compared to HPLA. Copyright © 2015 Elsevier Ltd. All rights reserved.

  6. 新型超支化环氧丙烯酸酯的合成及表征%Synthesis and characterization of a novel hyperbranched epoxy acrylate

    Institute of Scientific and Technical Information of China (English)

    靳奇峰; 薛蕾; 陈欣; 佟丽娜; 姜冬月

    2015-01-01

    采用质子转移聚合法成功制备了超支化环氧树脂,并通过丙烯酸对其端基进行化学改性合成了一种新型的超支化环氧丙烯酸酯,采用 FTIR、1 H NMR 对产物结构进行了表征。通过控制投料比及测定产物酸值来监测反应进行的程度,使生成的超支化环氧丙烯酸酯中既含有环氧基又含有碳碳双键,使之兼具阳离子型光聚合与自由基型光聚合的协同作用。测试了超支化聚合物在氯仿中的紫外-可见光谱和荧光发射光谱,超支化环氧树脂和超支化环氧丙烯酸酯的荧光发射波谱出峰位置分别为314 nm 和311 nm。研究表明,超支化聚合物具有较强的荧光性能,作为光固化材料在光学、医疗器件、防伪等领域具有潜在的应用价值。%Hyperbranched epoxy resin(HBEP)was synthesized by proton transfer polymerization. And a novel structure hyperbranched epoxy acrylate(HBEA)containing both epoxy group and carbon-carbon double bond was synthesized by acrylic modified the HBEP. The structures of the polymer were character-ized by FTIR and 1 H NMR. The extent of the reaction was monitored by controlling the molar ratio and measuring the acid value. The results showed that the HBEA contained both epoxy group and carbon-car-bon double bond which can improve the performance of the material by the synergistic effect of the cation-ic photopolymerization and the radical photopolymerization. Hyperbranched polymers were characterized in chloroform by UV-Vis spectra and fluorescence emission spectra. The photoluminescent behavior renders these materials highly interesting as UV curing films in optical devices like light-emitting diodes and UV light detection systems as well as in anticounterfeiting applications.

  7. 脂肪族超支化聚酯的合成与性能研究%STUDY ON SYNTHESIS AND PROPERTIES OF HYPERBRANCHED ALIPHATIC POLYESTER

    Institute of Scientific and Technical Information of China (English)

    肖文清; 程万里; 胡剑青; 涂伟萍

    2008-01-01

    The different generation hyperbranched aliphatic polyesters were synthesized based upon 2,2-Bis(methylol)propionic acid as a AB2 monomer, and Neopentyl glycol as a core molecule through one step polymerization process. The structure and properties of the product were characterized by FTIR, 1H NMR, GPC and TGA. It was shown that the third generation hyperbranched polyester has narrow molecular weight distribution with Mw=2 615 g/mol, Mn=1 536 g/mol, PDI=1.41 by GPC. The degree of branching, as determined by quantitative 1H NMR spectroscopy, was found to be 0.49. TGA analysis showed that the polymer exhibited high thermal stability, the decomposition temperature is more than 300 ℃. The conversion of carboxyl groups of the third generation hyperbranched polyeste was discussed. Because the water which is produced in this reaction could't be emitted totally, as a result, the final carboxyl groups conversation rate still could't get to 100% .%以新戊二醇为核,2,2-二羟甲基丙酸为支化单体,通过准一步熔融缩聚法合成了不同代数的脂肪族超支化聚酯.采用FT-IR、1H NMR、GPC及TGA方法对所合成的超支化聚酯的结构与性能进行了表征和分析.对第三代超支化聚酯而言,GPC分析测得重均分子量为2 615 g/mol,质均分子量为1 536 g/mol,分子量分布为1.41;1H NMR分析测得其支化度为0.49,热重分析表明温度高达300 ℃该聚酯才失重5wt%.此外还讨论了第三代脂肪族超支化聚酯熔融缩聚过程羧基的变化,结果表明,由于反应生成的水不能完全除去,羧基的最终转化率不可能达到100%.

  8. Mesomorphic ionic hyperbranched polymers: effect of structural parameters on liquid-crystalline properties and on the formation of gold nanohybrids

    Science.gov (United States)

    Nguyen, Hong Hanh; Serrano, Clara Valverde; Lavedan, Pierre; Goudounèche, Dominique; Mingotaud, Anne-Françoise; Viguerie, Nancy Lauth-De; Marty, Jean-Daniel

    2014-03-01

    Branched thermotropic liquid crystals were successfully obtained from ionic interactions between hyperbranched polyamidoamine and sodium dodecylsulfate. These complexes present columnar rectangular and lamellar thermotropic mesophases as demonstrated by polarized optical microscopy, differential scanning calorimetry, and small-angle X-ray scattering. The relationships between the structural characteristics of the polymers (size of the hyperbranched core, hyperbranched or dendritic nature of the core, and substitution ratio) and the mesomorphic properties were studied. In situ formation of gold nanoparticles was then performed. The templating effect of the liquid crystal mesophase resulted in the formation of isotropic nanoparticles, the size of which was dictated by the local organization of the mesophase and by the molar mass of the hyperbranched complex.Branched thermotropic liquid crystals were successfully obtained from ionic interactions between hyperbranched polyamidoamine and sodium dodecylsulfate. These complexes present columnar rectangular and lamellar thermotropic mesophases as demonstrated by polarized optical microscopy, differential scanning calorimetry, and small-angle X-ray scattering. The relationships between the structural characteristics of the polymers (size of the hyperbranched core, hyperbranched or dendritic nature of the core, and substitution ratio) and the mesomorphic properties were studied. In situ formation of gold nanoparticles was then performed. The templating effect of the liquid crystal mesophase resulted in the formation of isotropic nanoparticles, the size of which was dictated by the local organization of the mesophase and by the molar mass of the hyperbranched complex. Electronic supplementary information (ESI) available: NMR, DSC, POM and SAXS data for hyperbranched complexes and associated hybrids. See DOI: 10.1039/c3nr05913h

  9. 超支化聚合物修饰碳纳米管的研究进展%Research Progress of Carbon Nanotubes Modified by Hyperbranched Polymer

    Institute of Scientific and Technical Information of China (English)

    张梓军; 颜红侠; 管兴华; 刘超

    2012-01-01

    碳纳米管( CNTs)具有极高的杨氏模量、硬度和韧性、良好的导电性和导热性,但由于其分散性差,限制了其应用范围.超支化聚合物( HBP)具有低粘度、高流变性和良好的溶解性,特别是末端含有大量的活性官能团.用HBP修饰CNTs,不仅可以提高CNTs在聚合物基体中的分散性,改善CNTs与基体之间的相容性和界面粘接性能,还可以赋予CNTs新的功能.因此,综述了超支化聚合物改性CNTs的方法,包括直接改性法,表面引发聚合法等方法,并指出了每种改性方法的优缺点及其发展前景.%Although carbon nanotubes (CNTs) have many good properties, such as high Young modulus, hardness and toughness, good electrical conductivity and thermal conductivity, its poor dispersibility have imposed great limitations to its applications and development Hyperbranched polymer (HBP) has low viscosity, high rheologi-cal behaviour and good solubility, especially its terminal end with lots of active functional groups. So CNTs modified by HBP can not only improve dispersibility of CNTs, enhance the compatibility and interface adhesion between polymer matrix and CNTs, but also endow CNTs with new properties. So in this article, methods of hyperbranched-poly-mer-modified CNTs are summarized, including direct modification and surface-initiated polymerization and so on. The merit and demerit of each method and its prospects in the future are also pointed out.

  10. The Lewis-acid-catalyzed synthesis of hyperbranched poly(glycerol-diacid)s in toluene

    Science.gov (United States)

    The first examples of monomeric glycerol-derived hyperbranched polyesters produced in a non-polar solvent system are reported here. The polymers were made by the Lewis acid (dibutyltin(IV)oxide)-catalyzed polycondensation of glycerol with either succinic acid (n (aliphatic chain length)=2), glutari...

  11. Synthesis of a Chloroamide-Hyperbranched Polymer Additive for Self-Decontaminating Surfaces

    Science.gov (United States)

    2012-04-01

    groups to the surface. Boltorn H20 polymer was insoluble in most organic solvents but soluble in high boiling solvents such as dimethylsulfoxide ...oxidative chlorine DCM dichloromethane DMF N,N-dimethylformamide DMSO dimethylsulfoxide HBP hyperbranched polymer IPA isopropyl alcohol IR

  12. New Phase Transfer Agent for Dye:Application for Hyperbranched Poly(ester-amine)

    Institute of Scientific and Technical Information of China (English)

    Teng QIU; Li Ming TANG; Xin Lin TUO; De Shan LIU

    2004-01-01

    Hydrophilic hyperbranched poly(ester-amine) (HPEA) synthesized from diethanolamine and methyl acrylate was used as phase transfer agent for the first time to transfer methyl orange (MO) from water into chloroform.This process was quantified by UV-Vis spectra.A possible mechanism was put forward based on the formation of amphiphilic aggregates.

  13. Hyperbranched-polymer dispersed nanocomposite volume gratings for holography and diffractive optics

    Science.gov (United States)

    Tomita, Yasuo; Takeuchi, Shinsuke; Oyaizu, Satoko; Urano, Hiroshi; Fukamizu, Taka-aki; Nishimura, Naoya; Odoi, Keisuke

    2016-10-01

    We review our experimental investigations of photopolymerizable nanoparticle-polymer composites (NPCs) for holography and diffractive optics. Various types of hyperbranched polymer (HBP) were systhesized and used as transporting organic nanoparticles. These HBPs include hyperbranched poly(ethyl methacrylate) (HPEMA), hyperbranched polystyrene (HPS) and hyperbranched triazine/aromatic polymer units (HTA) whose refractive indices are 1.51, 1.61 and 1.82, respectively. Each HBP was dispersed in (meth)acrylate monomer whose refractive index was so chosen that a refractive index difference between HBP and the formed polymer was large. Such monomer-HBP syrup was mixed with a titanocene photoinitiator for volume holographic recording in the green. We used a two-beam interference setup to write an unslanted transmission volume grating at grating spacing of 1 μm and at a wavelength of 532 nm. It is shown that NPC volume gratings with the saturated refractive index modulation amplitudes as large as 0.008, 0.004 and 0.02 can be recorded in NPCs incorporated with HPEMA, HPS and HTA at their optimum concentrations of 34, 34 and 25 vol.%, respectively. We show the usefulness of HBP-dispersed NPC volume gratings for holographic applications such as holographic data storage and diffractive optical devices.

  14. New coating systems based on vinyl ether- and oxetane-modified hyperbranched polyesters

    NARCIS (Netherlands)

    Schmaljohann, D.; Voit, B.I.; Jansen, J.F.G.A.; Hendriks, Peter; Loontjens, J.A.

    2000-01-01

    A series of hyperbranched aliphatic-aromatic polyesters has been synthesized which contain vinyl ether or oxetane functionalities as curable groups. We investigated the curing behavior of these multifunctional polymers in the presence of reactive diluents in order to analyze the possibility of their

  15. Intercalation Study of Low-Molecular-Weight Hyperbranched Polyethyleneimine into Graphite Oxide

    NARCIS (Netherlands)

    Tsoufis, Theodoros; Katsaros, Fotios; Sideratou, Zili; Kooi, Bart J.; Karakassides, Michael. A.; Siozios, Anastasios

    2014-01-01

    We report for the first time the intercalation of low-molecular-weight hyperbranched polyethyleneimine (PEI) into graphite oxide (GO) for the facile, bulk synthesis of novel graphene-based hybrid (GO-PEI) materials exhibiting tailored interlayer galleries. The size of the intercalant as well as the

  16. Production of CaCO3/hyperbranched polyglycidol hybrid films using spray-coating technique.

    Science.gov (United States)

    Malinova, Kalina; Gunesch, Manfred; Montero Pancera, Sabrina; Wengeler, Robert; Rieger, Bernhard; Volkmer, Dirk

    2012-05-15

    Biomineralizing organisms employ macromolecules and cellular processing strategies in order to produce highly complex composite materials such as nacre. Bionic approaches translating this knowledge into viable technical production schemes for a large-scale production of biomimetic hybrid materials have met with limited success so far. Investigations presented here thus focus on the production of CaCO(3)/polymer hybrid coatings that can be applied to huge surface areas via reactive spray-coating. Technical requirements for simplicity and cost efficiency include a straightforward one-pot synthesis of low molecular weight hyperbranched polyglycidols (polyethers of 2,3-epoxy-1-propanol) as a simple mimic of biological macromolecules. Polymers functionalized with phosphate monoester, sulfate or carboxylate groups provide a means of controlling CaCO(3) particle density and morphology in the final coatings. We employ reactive spray-coating techniques to generate CaCO(3)/hybrid coatings among which vaterite composites can be prepared in the presence of sulfate-containing hyperbranched polyglycidol. These coatings show high stability and remained unchanged for periods longer than 9 months. By employing carboxylate-based hyperbranched polyglycidol, it is possible to deposit vaterite-calcite composites, whereas phosphate-ester-based hyperbranched polyglycidol leads to calcite composites. Nanoindentation was used to study mechanical properties, showing that coatings thus obtained are slightly harder than pure calcite. Copyright © 2012 Elsevier Inc. All rights reserved.

  17. Modification with alkyl chains and the influence on thermal and mechanical properties of aromatic hyperbranched polyesters

    NARCIS (Netherlands)

    Schmaljohann, Dirk; Häußler, Liane; Pötschke, Petra; Voit, Brigitte I.; Loontjens, Ton J.A.

    2000-01-01

    All-aromatic hyperbranched polyesters with hydroxy endgroups were functionalized with aliphatic n-alkyl carboxylic acids. The length of the n-alkyl chain as well as the degree of modification were varied and the resulting, partially amphiphilic polymers were characterized by differential scanning ca

  18. The Synthesis of Backbone Thermo and pH Responsive Hyperbranched Poly(Bis(N,N-Propyl Acryl Amides by RAFT

    Directory of Open Access Journals (Sweden)

    Shijiao Zhou

    2016-04-01

    Full Text Available Hyperbranched poly(methylene-bis-acrylamide, poly(bis(N,N-propyl acryl amide (HPNPAM and poly(bis(N,N-butyl acryl amide were synthesized by reversible addition-fragmentation chain transfer polymerization. HPNPAMs showed lower critical solution temperature (LCST due to an appropriate ratio between hydrophilic and hydrophobic groups. The effects of reaction conditions on polymerization were investigated in detail. The structure of HPNPAM was characterized by 1H NMR, FT-IR, Muti detector-size exclusion chromatography (MDSEC and Ultravioletvisble (UV-Vis. The α value reached 0.20 and DB was 90%, indicating HPNPAMs with compact topology structure were successfully prepared. LCSTs were tuned by Mw and the pH value of the solution. The change of molecular size was assayed by dynamic light scattering and scanning electron microscope. These results indicated that the stable uniform nanomicelles were destroyed and macromolecules aggregated together, forming large particles as temperature exceeded LCST. In addition, after the cells were incubated for 24 h, the cell viability reached 80%, which confirmed this new dual responsive HPNPAM had low cytotoxicity.

  19. Biokompatible Polymere

    Science.gov (United States)

    Ha, Suk-Woo; Wintermantel, Erich; Maier, Gerhard

    Der klinische Einsatz von synthetischen Polymeren begann in den 60-er Jahren in Form von Einwegartikeln, wie beispielsweise Spritzen und Kathetern, vor allem aufgrund der Tatsache, dass Infektionen infolge nicht ausreichender Sterilität der wiederverwendbaren Artikel aus Glas und metallischen Werkstoffen durch den Einsatz von sterilen Einwegartikeln signifikant reduziert werden konnten [1]. Die Einführung der medizinischen Einwegartikel aus Polymeren erfolgte somit nicht nur aus ökonomischen, sondern auch aus hygienischen Gründen. Wegen der steigenden Anzahl synthetischer Polymere und dem zunehmenden Bedarf an ärztlicher Versorgung reicht die Anwendung von Polymeren in der Medizin von preisgünstigen Einwegartikeln, die nur kurzzeitig intrakorporal eingesetzt werden, bis hin zu Implantaten, welche über eine längere Zeit grossen Beanspruchungen im menschlichen Körper ausgesetzt sind. Die steigende Verbreitung von klinisch eingesetzten Polymeren ist auf ihre einfache und preisgünstige Verarbeitbarkeit in eine Vielzahl von Formen und Geometrien sowie auf ihr breites Eigenschaftsspektrum zurückzuführen. Polymere werden daher in fast allen medizinischen Bereichen eingesetzt.

  20. Nuclear entry of hyperbranched polylysine nanoparticles into cochlear cells

    Directory of Open Access Journals (Sweden)

    Weikai Zhang

    2011-03-01

    Full Text Available Weikai Zhang1, Ya Zhang1, Marian Löbler2, Klaus-Peter Schmitz2, Aqeel Ahmad3, Ilmari Pyykkö1, Jing Zou11Department of Otolaryngology, University of Tampere, Medical School, Tampere, Finland; 2University of Rostock, Institute for Biomedical Engineering, Rostock, Germany; 3Department of Biomedical Engineering and Computational Science, Aalto University, Espoo, FinlandBackground: Gene therapy is a potentially effective therapeutic modality for treating sensorineural hearing loss. Nonviral gene delivery vectors are expected to become extremely safe and convenient, and nanoparticles are the most promising types of vectors. However, infrequent nuclear localization in the cochlear cells limits their application for gene therapy. This study aimed to investigate the potential nuclear entry of hyperbranched polylysine nanoparticles (HPNPs for gene delivery to cochlear targets.Methods: Rat primary cochlear cells and cochlear explants generated from newborn rats were treated with different concentrations of HPNPs. For the in vivo study, HPNPs were administered to the rats' round window membranes. Subcellular distribution of HPNPs in different cell populations was observed with confocal microscope 24 hours after administration.Results: Nuclear entry was observed in various cochlear cell types in vitro and in vivo. In the primary cochlear cell culture, concentration-dependent internalization was observed. In the cochlear organotypic culture, abundant HPNPs were found in the modiolus, including the spiral ganglion, organ of Corti, and lateral wall tissues. In the in vivo study, a gradient distribution of HPNPs through different layers of the round window membrane was observed. HPNPs were also distributed in the cells of the middle ear tissue. Additionally, efficient internalization of HPNPs was observed in the organ of Corti and spiral ganglion cells. In primary cochlear cells, HPNPs induced higher transfection efficiency than did Lipofectamine

  1. Novel hot-melting hyperbranched poly(ester-amine) bearing self-complementary quadruple hydrogen bonding units

    Institute of Scientific and Technical Information of China (English)

    Yi Peng Qiu; Li Ming Tang; Yu Wang; Shi You Guan

    2008-01-01

    Hyperbranched poly(amine-ester)s bearing serf-complementary quadruple hydrogen bonding units display excellent mechanical and temperature-dependent melt rheological properties,which make them suitable as novel hot-melting materials.

  2. Architecture of Star-block Copolymers Consisting of Triblock Arms via a N,N-diethyldi-thiocarbamate-mediated Living Radical Photo-polymerization and Application for Nanocomposites by Using as Fillers

    Institute of Scientific and Technical Information of China (English)

    K.Ishizu

    2007-01-01

    1 Results Highly branched poly(methyl methacrylate) (PMMA) stars were prepared by one-pot approach based on N,N-diethyldithiocarbamate-(DC) mediated living radical photo-polymerization.Soluble alternating hyperbranched microgel formation was initiated fast with preferential consumption of inimer 4-vinylbenzyl N,N-diethyldithiocarbamate (VBDC) and 4,4′-bismaleimidediphenylmethane (BMIM) in the presence of an excess of methyl methacrylate (MMA),PMMA arms could then grow from DC groups of microgel as macro...

  3. Amine-catalyzed polycyclotrimerization of arylene bipropiolate: A metal-free and regioselective route to hyperbranched polymer

    Institute of Scientific and Technical Information of China (English)

    JIM Cathy K W; QIN AnJun; LAM Jacky W Y; LIU JianZhao; HAEUSSLER Matthias; TANG Ben Zhong

    2008-01-01

    This paper presents a new synthetic route to hyperbranched polymer. An arylene bipropiolete monomer, dimethylmethylenebis(1,4-phenylene) bipropiolate, was prepared by a one-step esterification reaction of bisphenol A with propiolic acid. Polycyclotrimrtization of the monomer was effected by reflux in di-methylformamide (DMF), producing a soluble hyperbranched poly(aroxycarbonylphenylene) in a good yield. The polymer was perfectly branched with a degree of branching of 100%.

  4. Amine-catalyzed polycyclotrimerization of arylene bipropiolate:A metal-free and regioselective route to hyperbranched polymer

    Institute of Scientific and Technical Information of China (English)

    JIM; Cathy; K; W; LAM; Jacky; W; Y; HAEUSSLER; Matthias

    2008-01-01

    This paper presents a new synthetic route to hyperbranched polymer. An arylene bipropiolate monomer,dimethylmethylenebis(1,4-phenylene) bipropiolate,was prepared by a one-step esterification reaction of bisphenol A with propiolic acid. Polycyclotrimrtization of the monomer was effected by reflux in dimethylformamide(DMF),producing a soluble hyperbranched poly(aroxycarbonylphenylene) in a good yield. The polymer was perfectly branched with a degree of branching of 100%.

  5. Polymerization of Ethylene Oxide, Propylene Oxide, and Other Alkylene Oxides: Synthesis, Novel Polymer Architectures, and Bioconjugation.

    Science.gov (United States)

    Herzberger, Jana; Niederer, Kerstin; Pohlit, Hannah; Seiwert, Jan; Worm, Matthias; Wurm, Frederik R; Frey, Holger

    2016-02-24

    The review summarizes current trends and developments in the polymerization of alkylene oxides in the last two decades since 1995, with a particular focus on the most important epoxide monomers ethylene oxide (EO), propylene oxide (PO), and butylene oxide (BO). Classical synthetic pathways, i.e., anionic polymerization, coordination polymerization, and cationic polymerization of epoxides (oxiranes), are briefly reviewed. The main focus of the review lies on more recent and in some cases metal-free methods for epoxide polymerization, i.e., the activated monomer strategy, the use of organocatalysts, such as N-heterocyclic carbenes (NHCs) and N-heterocyclic olefins (NHOs) as well as phosphazene bases. In addition, the commercially relevant double-metal cyanide (DMC) catalyst systems are discussed. Besides the synthetic progress, new types of multifunctional linear PEG (mf-PEG) and PPO structures accessible by copolymerization of EO or PO with functional epoxide comonomers are presented as well as complex branched, hyperbranched, and dendrimer like polyethers. Amphiphilic block copolymers based on PEO and PPO (Poloxamers and Pluronics) and advances in the area of PEGylation as the most important bioconjugation strategy are also summarized. With the ever growing toolbox for epoxide polymerization, a "polyether universe" may be envisaged that in its structural diversity parallels the immense variety of structural options available for polymers based on vinyl monomers with a purely carbon-based backbone.

  6. Influence of Reactive Diluent on UV-curing of Acrylate Terminated Hyperbranched Polymers

    Institute of Scientific and Technical Information of China (English)

    TANG Li-ming; FANG Yu; YAN Liang; FU Zhi-wei

    2004-01-01

    A Aeries of hydroxylic hyperbranched polymers were derived from 2,2-bis(methylol) propionic acid and tris (methylol) propane reacted with acrylic acid to various extents. The obtained acrylated hyperbranched polymers alone or with a monofunctional diluent, isobornylene acrylate(IBOA) were further cured by UV radiation. The cured films based on the modified polymers alone all demonstrated poor mechanical properties due to their high network densities and low moving ability of polymer chains. For the composite systems, the cured films demonstrated improved mechanical properties due to the low network densities and high chain moving ability. With more IBOA included in the systems, acrylate groups can react to a higher extent during the curing process.

  7. Hyperbranched polycarbonate-based multimolecular micelle with enhanced stability and loading efficiency.

    Science.gov (United States)

    Su, Wei; Luo, Xiao-Hua; Wang, Hua-Fen; Li, Lei; Feng, Jun; Zhang, Xian-Zheng; Zhuo, Ren-Xi

    2011-02-16

    We herein develop a facile catalyst-free method to prepare hyperbranched hydroxyl-enriched aliphatic polycarbonate according to SCROP strategy. PEG-attached multiarm hyperbranched copolymer HEHDO-star-mPEG was further designed. It was found that HEHDO-star-mPEG can self-assemble into supramolecular multimolecular micelles in water. HEHDO-star-mPEG micelle showed excellent stability with respect to micellar size upon dilution, and displayed good cell-biocompatibility. An anticancer drug of doxorubicin with hydrogen-bonding functionality was incorporated into obtained micelles to establish a drug delivery system model. A high drug-loading content as well as sustained release pattern for HEHDO-star-mPEG based delivery system was achieved.

  8. Facile synthesis of dendritic gold nanostructures with hyperbranched architectures and their electrocatalytic activity toward ethanol oxidation.

    Science.gov (United States)

    Huang, Jianshe; Han, Xinyi; Wang, Dawei; Liu, Dong; You, Tianyan

    2013-09-25

    Gold dendritic nanostructures with hyperbranched architectures were synthesized by the galvanic replacement reaction between nickel wire and HAuCl4 in aqueous solution. The study revealed that the morphology of the obtained nanostructures strongly depended on experimental parameters such as the HAuCl4 solution concentration, reaction temperature, and time, as well as stirring or not. According to the investigation of the growth process, it was proposed that gold nanoparticles with rough surfaces were first deposited on the nickel substrate and that subsequent growth preferentially occurred on the preformed gold nanoparticles, finally leading to the formation of hyperbranched gold dendrites via a self-organization process under nonequilibrium conditions. The electrochemical experiment results demonstrated that the as-obtained gold dendrites exhibited high catalytic activity toward ethanol electrooxidation in alkaline solution, indicating that this nanomaterial may be a potential catalyst for direct ethanol fuel cells.

  9. Novel Method of Hyperbranched Polymer Modified Nano-SiO2-Grafting Hyperbranched Poly (amide-ester) from Nano-SiO2 by One-Step Polycondensation

    Institute of Scientific and Technical Information of China (English)

    ZHAO Hui; LI Jie; SUN Rui-min; LUO Yun-jun

    2008-01-01

    A new method of surface chemical modification of nano-SiO2 is proposed in this paper. In the presence of catalyst, the active hydroxyl groups on the surface of nano-SiO2 reacted with AB2-type monomer (N, N-dihydroxyethyl-3-amino methyl propionate) by one-step polycondensation. And the product's Fourer transform infrared (FTIR) graphs and transmission electron microscopy(TEM) images proved that hyperbranched poly (amine-ester) was grafted on nano-SiO2 surface successfully. Results show that the modified nano-SiO2 exhibits excellent dispersion and stability in some solvents such as alcohol and chloroform.

  10. Hybrid epoxy networks from ethoxysilyl-modified hyperbranched poly(ethyleneimine) and inorganic reactive precursors

    OpenAIRE

    Acebo Gorostiza, Cristina; Fernández Francos, Xavier; Santos, Jose-Ignacio; Messori, Massimo; Ramis Juan, Xavier; Serra Albet, Àngels

    2015-01-01

    New epoxy-silica hybrid coatings were prepared by a dual process consisting of a sol-gel process using tetraethoxysilane (TEOS) or 3-glycidyloxypropyl trimethoxysilane (GPTMS) in the presence of hyperbranched poly(ethyleneimine) with ethoxysilyl groups at the chain ends (PEI-Si) followed by a homopolymerization of diglycidylether of bisphenol A (DGEBA) using 1-methylimidazole (1-MI) as anionic initiator. The influence of the amount of TEOS and GPTMS in the characteristics of the coating was e...

  11. Layer-by-layer deposition of rhenium-containing hyperbranched polymers and fabrication of photovoltaic cells.

    Science.gov (United States)

    Tse, Chui Wan; Man, Ka Yan Kitty; Cheng, Kai Wing; Mak, Chris S K; Chan, Wai Kin; Yip, Cho Tung; Liu, Zheng Tong; Djurisić, Aleksandra B

    2007-01-01

    Multilayer thin films were prepared by the layer-by-layer (LBL) deposition method using a rhenium-containing hyperbranched polymer and poly[2-(3-thienyl)ethoxy-4-butylsulfonate] (PTEBS). The radii of gyration of the hyperbranched polymer in solutions with different salt concentrations were measured by laser light scattering. A significant decrease in molecular size was observed when sodium trifluoromethanesulfonate was used as the electrolyte. The conditions of preparing the multilayer thin films by LBL deposition were studied. The growth of the multilayer films was monitored by absorption spectroscopy and spectroscopic ellipsometry, and the surface morphologies of the resulting films were studied by atomic force microscopy. When the pH of a PTEBS solution was kept at 6 and in the presence of salt, polymer films with maximum thickness were obtained. The multilayer films were also fabricated into photovoltaic cells and their photocurrent responses were measured upon irradiation with simulated air mass (AM) 1.5 solar light. The open-circuit voltage, short-circuit current, fill factor, and power conversion efficiency of the devices were 1.2 V, 27.1 mu A cm(-2), 0.19, and 6.1x10(-3) %, respectively. The high open-circuit voltage was attributed to the difference in the HOMO level of the PTEBS donor and the LUMO level of the hyperbranched polymer acceptor. A plot of incident photon-to-electron conversion efficiency versus wavelength also suggests that the PTEBS/hyperbranched polymer junction is involved in the photosensitization process, in which a maximum was observed at approximately 420 nm. The relatively high capacitance, determined from the measured photocurrent rise and decay profiles, can be attributed to the presence of large counter anions in the polymer film.

  12. New improved thermosets obtained from DGEBA and a hyperbranched poly(ester-amide)

    OpenAIRE

    Morell, Mireia; Ramis Juan, Xavier; Ferrando Piera, Francesc; Yu, Yingfeng; Serra Albet, Àngels

    2009-01-01

    The influence on the curing process of a commercial hydroxy-functionalized hyperbranched poly(ester-amide) (HBP) Hybrane® S1200 on diglycidylether of bisphenol A (DGEBA) was studied. By Differential Scanning Calorimetry (DSC) and Fourier Transform Infrared Spectroscopy (FTIR) the curing reaction was studied and the covalent incorporation of the modifier in the matrix was proved. By Thermomechanical Analysis (TMA) the reduction of the contraction after gelation on changing the S1200 proportio...

  13. Spiro-linked hyperbranched architecture in electrophosphorescent conjugated polymers for tailoring triplet energy back transfer.

    Science.gov (United States)

    Shao, Shiyang; Ma, Zhihua; Ding, Junqiao; Wang, Lixiang; Jing, Xiabin; Wang, Fosong

    2012-04-17

    A spiro-linked hyperbranched architecture has been incorporated into electrophosphorescent conjugated polymers for the first time, aiming at simultaneously tailoring the intra- and intermolecular triplet energy back transfer from the phosphorescent guest to the conjugated polymer host. Based on a prototype with this unique structure, slower decay of triplet excitons, and 5-8 fold enhancement of device efficiencies are obtained compared with the conventional blending counterpart.

  14. Hyperbranched-linear poly(ether sulfone) blend films for proton exchange membranes

    Energy Technology Data Exchange (ETDEWEB)

    Grunzinger, Stephen J.; Watanabe, Masatoshi; Fukagawa, Kiyotaka; Kikuchi, Ryohei; Tominaga, Yoichi; Hayakawa, Teruaki; Kakimoto, Masa-aki [Department of Organic and Polymeric Materials, Tokyo Institute of Technology, 2-12-1 O-okayama, Meguro-ku, Tokyo 152-8552 (Japan)

    2008-01-03

    Hyperbranched poly(ether sulfone) polymers having sulfonyl chloride end-groups is blended at up to 30 w% with linear poly(ether ether ether sulfone)s and a two-phase system is generated via spinodal decomposition upon drying from a DMAc solution. Conversion of the end-groups from sulfonyl chloride to sulfonic acid is accomplished using 16 M H{sub 2}SO{sub 4} that is also believed to introduce additional sulfonic acid groups at the interface of the linear polymer. The blend films before and after conversion to sulfonic acid have similar tensile strengths as films composed of solely linear polymer (yield stress >40 MPa and Young's modulus >3 GPa m). These films are designed to test the viability of hyperbranched polymers as fuel cell membranes. Proton conductivities of up to 0.03 S cm{sup -1} are observed at 80 C and 90% R.H indicating a good potential for use of hyperbranched polymers as a proton conduction material. (author)

  15. Metal catalyzed synthesis of hyperbranched ethylene and/or .alpha.-olefin polymers

    Science.gov (United States)

    Sen, Ayusman; Kim, Jang Sub; Pawlow, James H.; Murtuza, Shahid; Kacker, Smita; Wojcinski, III, Louis M.

    2001-01-01

    Oily hyperbranched polymers derived from ethylene, propylene, butene and/or a C.sub.5 -C.sub.24 .alpha.-olefin, and a method for their synthesis, are disclosed. The polymers have non-regular microstructures and are characterized by a ratio ({character pullout})of methyl hydrogens centered around 0.85 ppm on the 1H-NMR spectra of the polymers relative to total aliphatic hydrogens of from about 0.40 to about 0.65 for polymers derived from ethylene or butene, and a ratio ({character pullout})of from greater than 0.50 to about 0.65 for polymers derived from propylene. A method for grafting hyperbranched polymers derived from ethylene, propylene, butene and/or a C.sub.5 -C.sub.24 .alpha.-olefin onto aromatic rings in organic molecules and polymers, and the resulting grafted materials, are also disclosed. The hyperbranched polymers and grafted materials are useful, for example, as lubricants and lubricant additives.

  16. Conducting Polymeric Materials

    DEFF Research Database (Denmark)

    Hvilsted, Søren

    2016-01-01

    The overall objective of this collection is to provide the most recent developments within the various areas of conducting polymeric materials. The conductivity of polymeric materials is caused by electrically charged particles, ions, protons and electrons. Materials in which electrons...

  17. Tethering of hyperbranched polyols using PEI as a building block to synthesize antifouling PVDF membranes

    Science.gov (United States)

    Wang, Xushan; Wang, Zihong; Wang, Zhe; Cao, Yu; Meng, Jianqiang

    2017-10-01

    Antifouling PVDF membranes were prepared by grafting hyperbranched polyols on the membrane surface via a three-step modification method. The membrane was first prepared by alkaline treatment to introduce alkenyl groups, then chemically immobilizing hyperbranched poly(ethyleneimine) (HPEI) on membrane surface through Michael reaction followed by ring opening reaction of the glycidol with amine groups. Chemical compositions, surface morphology and physicochemical properties of the original and modified membranes were characterized via attenuated total refection-Fourier transform infrared spectroscopy (ATR-FTIR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), water contact angle (WCA) and zeta potential measurements. The antifouling property of the modified membrane was assessed by the static bovine serum albumin (BSA) and lysozyme (LZM) adsorption as well as cross-flow filtration of BSA aqueous solution. The results explicate that surface modification using hyperbranched polymers can alter membrane chemistry and morphology significantly. In contrast to the original PVDF membrane, the modified membrane shows superhydrophilic property and relatively high capability to resist nonspecific protein adsorption. Three HPEIs were used for modification and the obtained PVDFA-g-PG60,000 membrane has a static BSA protein adsorption of 45 μg/cm2 and shows the highest protein resistance. However, the PVDF-g-PG membrane is positively charged due to the unreacted amine groups. As a result, the PVDF-g-PG membranes also show high flux decline during the filtration of BSA aqueous solution due to the electrostatic interaction. In spite of that, the PVDF-g-PG membranes still maintain high flux recovery ratio and good washing properties.

  18. A novel chain-extended urea containing hyperbranched polymer used as toughening modifier for epoxy resin

    Institute of Scientific and Technical Information of China (English)

    LU Shao-rong; WEI Chun; YANG Xiao-wang

    2006-01-01

    A new kind of reactive toughening accelerator for epoxy resin,amine-teminated hyperbranched polymer (H2O-NMe2) was synthesized and characterized by FT-IR spectroscopy. Dynamic mechanical analysis (DMA) was used to study the glass transition temperature (Tg),loss factor (tanδ) and activation energy (Ea) by using multiplexing frequency. The results show that the Ea at glassy relaxation process of modified system is about 70-80 kJ/mol higher than that of unmodified system,and the high modulus and good thermal properties are still maintained.

  19. SYNTHESIS AND PHOTOLUMINESCENCE OF AN ANTHRACENE-CONTAINING HYPERBRANCHED POLY(ARYLENEETHYNYLENE)

    Institute of Scientific and Technical Information of China (English)

    Yong-qiang Dong; Zhen Li; Jacky W. Y. Lam; Yu-ping Dong; Xin-de Feng; Ben-zhong Tang

    2005-01-01

    A hyperbranched poly(aryleneethynylene) containing anthracene chromophore was synthesized by palladiumcatalyzed cross-coupling reaction of 2,4,6-triiodophenyl 9-anthracenylcarboxylate with 9,9-bis[4-(2-propynyloxy)phenyl]-9H-fluorene. The structure and properties of the polymer are characterized and evaluated by NMR, IR, UV, PL and TGA analyses. The polymer is soluble in common organic solvents, possesses high thermal stability (Td > 330℃), and emits a strong blue light of 465 nm in both solution and solid states.

  20. Using of Hyperbranched Poly(amidoamine as Pretanning Agent for Leather

    Directory of Open Access Journals (Sweden)

    Amal Amin Ibrahim

    2013-01-01

    Full Text Available Although chrome is considered as the major tanning agent in the production of all types of hides and leather worldwide, it represents a serious source of environmental pollution. Therefore, polyamidoamine hyperbranched polymer (HPAM was involved in pretanning of the depickled hides to enhance the chromium uptake during the tanning process. The key parameters which affect the exhaustion and fixation of chrome tan including shrinkage temperature of the tanned leather were studied. The results showed a significant improvement in the chrome exhaustion, the shrinkage temperature, and the texture and softness of the leather treated by HPAM.

  1. NOVEL HYPERBRANCHED POLY(AMINE-ESTER) FILMS: PREPARATION, CHARACTERIZATION AND PROPERTIES

    Institute of Scientific and Technical Information of China (English)

    Xiu-zhen Wei; Bao-ku Zhu; Ling Xiao; You-yi Xu

    2006-01-01

    Crosslinked film of hyperbranched poly(amine-ester) (HPAE) was prepared by crosslinking its terminal hydroxyl groups with glutaraldehyde (GA). Atom force microscope (AFM) and scanning electron microscope (SEM) reveals that they have smooth surfaces, dense and homogenous matrices. It was found that the water static contact angle is smaller than 41.7°,the tensile strength is higher than 8.9 MPa, the elongation at break is higher than 5.1%, the swelling degree is higher than42% in water, and the Bovine hemoglobin (Hb) adsorption is relatively low. These results indicate that the crosslinked HPAE films might have some potential applications in many areas.

  2. Self-Induced Light Polarization Rotation in Azobenzene-Containing Polymers

    DEFF Research Database (Denmark)

    Nikolova, L.; Nedelchev, L.; Todorov, T.

    2000-01-01

    We report here a light-induced phenomenon--a self-induced rotation of the azimuth of elliptically polarized light passing through photobirefringent azopolymers. The experiments are carried out with films of amorphous and liquid-crystalline polymers. It has been shown that the induced rotation angle...... depends on the ellipticity of the input light. A theoretical analysis of the phenomenon has been done and it has been shown that light induces chiral structure in the polymer films. (C) 2000 American Institute of Physics. [S0003-6951(00)02731-5]....

  3. Optical storage in azobenzene-containing epoxy polymers processed as Langmuir Blodgett films.

    Science.gov (United States)

    Fernández, Raquel; Mondragon, Iñaki; Sanfelice, Rafaela C; Pavinatto, Felippe J; Oliveira, Osvaldo N; Oyanguren, Patricia; Galante, María J

    2013-04-01

    In this study, azocopolymers containing different main-chain segments have been synthesized with diglycidyl ether of bisphenol A (DGEBA, DER 332, n=0.03) and the azochromophore Disperse Orange 3 (DO3) cured with two monoamines, viz. benzylamine (BA) and m-toluidine (MT). The photoinduced birefringence was investigated in films produced with these azopolymers using the spin coating (SC) and Langmuir Blodgett (LB) techniques. In the LB films, birefringence increased with the content of azochromophore and the film thickness, as expected. The nanostructured nature of the LB films led to an enhanced birefringence and faster dynamics in the writing process, compared to the SC films. In summary, the combination of azocopolymers and the LB method may allow materials with tuned properties for various optical applications, including in biological systems were photoisomerization may be used to trigger actions such as drug delivery.

  4. Optical storage in azobenzene-containing epoxy polymers processed as Langmuir Blodgett films

    Energy Technology Data Exchange (ETDEWEB)

    Fernández, Raquel; Mondragon, Iñaki [‘Materials - Technologies’ Group, Department of Chemical and Environmental Engineering, Polytechnic School, Universidad País Vasco/Euskal Herriko Unibertsitatea, Pza Europa 1, 20018 Donostia-San Sebastián (Spain); Sanfelice, Rafaela C.; Pavinatto, Felippe J.; Oliveira, Osvaldo N. [Instituto de Física de São Carlos, Universidade de São Paulo, Av. Trabalhador São Carlense, 400, Centro, CEP 13560-970, São Carlos (Brazil); Oyanguren, Patricia [Institute of Materials Science and Technology (INTEMA), University of Mar del Plata and National Research Council (CONICET), J. B. Justo 4302, 7600 Mar del Plata (Argentina); Galante, María J., E-mail: galant@fi.mdp.edu.ar [Institute of Materials Science and Technology (INTEMA), University of Mar del Plata and National Research Council (CONICET), J. B. Justo 4302, 7600 Mar del Plata (Argentina)

    2013-04-01

    In this study, azocopolymers containing different main-chain segments have been synthesized with diglycidyl ether of bisphenol A (DGEBA, DER 332, n = 0.03) and the azochromophore Disperse Orange 3 (DO3) cured with two monoamines, viz. benzylamine (BA) and m-toluidine (MT). The photoinduced birefringence was investigated in films produced with these azopolymers using the spin coating (SC) and Langmuir Blodgett (LB) techniques. In the LB films, birefringence increased with the content of azochromophore and the film thickness, as expected. The nanostructured nature of the LB films led to an enhanced birefringence and faster dynamics in the writing process, compared to the SC films. In summary, the combination of azocopolymers and the LB method may allow materials with tuned properties for various optical applications, including in biological systems were photoisomerization may be used to trigger actions such as drug delivery. Highlights: ► Langmuir Blodgett (LB) films of epoxy-based azopolymers were obtained and analyzed. ► Optical properties of LB and spin coated (SC) films were compared. ► Azo content, structure, laser power and number of layers were main factors studied. ► LB films had larger free volume for the azobenzenes isomerization than SC. ► LB films led to higher birefringence and faster dynamics compared to SC.

  5. Synthesis of azobenzene-containing liquid crystalline gelator for use in liquid crystal gels

    Institute of Scientific and Technical Information of China (English)

    Guang Wang; Xiao Liang Zhao; Yue Zhao

    2008-01-01

    A liquid crystalline gelator containing the azobenzene chromophore was synthesized for the first time; it was used to form self-assembled network in nematic liquid crystals resulting in liquid crystal gels with distinct features.? 2008 Guang Wang. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.

  6. Switching Thin Films of Azobenzene-Containing Metal-Organic Frameworks with Visible Light.

    Science.gov (United States)

    Müller, Kai; Knebel, Alexander; Zhao, Fangli; Bléger, David; Caro, Jürgen; Heinke, Lars

    2017-04-24

    Stimuli-responsive molecules change their properties when exposed to external signals, such as light, and enable the preparation of smart materials. UV light, which often destroys organic materials, is typically required for activating the desired response of photoswitchable compounds, significantly limiting the potential applications of light-operated smart materials. Herein, we present the first metal-organic framework (MOF), which enables reversible modulation of key properties upon irradiation with visible light only. The fluorinated azobenzene side groups in the MOF structure can be reversibly switched between the trans and cis state by green and violet light, avoiding UV light. It was demonstrated that the uptake of guest molecules by these MOF films can be switched in a fully remote-controlled way. The membrane separation of hydrogen/hydrocarbon mixtures was investigated. The light-induced changes of the MOF pore size result in the switching of the permeation and of the selection factor. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Response function for the characterization of photo-induced anisotropy in azobenzene containing polymers

    DEFF Research Database (Denmark)

    Sajti, S.; Kerekes, Á.; Ramanujam, P.S.;

    2002-01-01

    A response function is derived for the description of photo-induced birefringence and dichroism in case of materials where the underlying process is photo-isomerization. Our result explains the usefulness of the theoretical formulae derived earlier by Kakichashvili for photo-anisotropic materials...

  8. Straightforward synthesis of hyperbranched polymer/graphene nanocomposites from graphite oxide via in situ grafting from approach

    Indian Academy of Sciences (India)

    Qiuhong Xu; Yiwen Gong; Yuan Fang; Guohua Jiang; Yin Wang; Xinke Sun; Rijing Wang

    2012-10-01

    The grafting of graphite oxide (GO) with cyclic ether monomers, directly affords grafting with hyperbranched polymers. The resulting nanocomposites show good solubility in the solvents of polymers, exfoliation of graphene in the polymer matrix and excellent mechanical properties and robustness under bending.

  9. Application research progress of hyperbranched polyesteramide%超支化聚酰胺酯应用研究进展

    Institute of Scientific and Technical Information of China (English)

    张新荔; 张可青

    2009-01-01

    Hyperbranched polyesteramide(PEA) was applied in many fields due to their unique structure and performances, and was one of commercialized hyperbranched polymers (HBP) at present. The application research progresses of hyperbranched PEA were reviewed in coat bonding, fibre dyeing, plastic modified and pigment dispersing. Meanwhile,the research directions of hyperbranched PEA was expected for the future.%超支化聚酰胺酯(PEA)因其独特的结构和性能特点,已成为目前商业化生产的超支化聚合物(HBP)之一,并已在许多领域中获得应用.综述了超支化PEA在涂层粘接、纤维染色、塑料改性和颜料分散等方面的应用研究进展,同时对超支化PEA今后的研究方向作了展望.

  10. Polymerization Using Phosphazene Bases

    KAUST Repository

    Zhao, Junpeng

    2015-09-01

    In the recent rise of metal-free polymerization techniques, organic phosphazene superbases have shown their remarkable strength as promoter/catalyst for the anionic polymerization of various types of monomers. Generally, the complexation of phosphazene base with the counterion (proton or lithium cation) significantly improves the nucleophilicity of the initiator/chain end resulting in highly enhanced polymerization rates, as compared with conventional metalbased initiating systems. In this chapter, the general features of phosphazenepromoted/catalyzed polymerizations and the applications in macromolecular engineering (synthesis of functionalized polymers, block copolymers, and macromolecular architectures) are discussed with challenges and perspectives being pointed out.

  11. Synthesis and intrinsic blue fluorescence study of hyperbranched poly(ester-amide-ether)

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    A series of hyperbranched poly(ester-amide-ether)s (H-PEAEs) were synthesized via the A2+CB3 approach by the self-transesterification of ethyl ester-amide-ethers end-capped with three hydroxyl groups and ethyl ester group at two terminals.The molecular structures were characterized with 1H NMR and FT-IR spectroscopy.The number average molecular weights were estimated by GPC analysis to possess bimodal wide distribution from 1.57 to 2.09.The strong inherent blue fluorescence was observed at 330 nm for excitation and 390 nm for emission.Moreover,the emission intensity and fluorescence quantum yield increased along with the incorporated ether chain length,as well as almost linearly with the H-PEAE concentration in an aqueous solution.For comparing the fluorescence performance,the linear poly(ester-amide-ether) (L-PEAE) and hyperbranched poly(ester-amide) (H-PEA) were synthesized.The results showed that the coexistence of ether bond and carboxyl group in the molecular chain was essential for generating the strong fluorescence.However,the compact backbone of H-PEAE would be propitious to the enhancement of fluorescence properties.

  12. Incorporation of Hyperbranched Supramolecules into Nafion Ionic Domains via Impregnation and In-Situ Photopolymerization

    Directory of Open Access Journals (Sweden)

    Hiruto Kudo

    2011-11-01

    Full Text Available Nafion membranes were impregnated with photocurable supramolecules, viz., hyperbranched polyester having pendant functional carboxylic acid groups (HBPEAc-COOH by swelling in methanol and subsequently photocured in-situ after drying. Structure-property relationships of the HBPEAc-COOH impregnated Nafion membranes were analyzed on the basis of Fourier transform infrared (FTIR spectroscopy, solid-state nuclear magnetic resonance (SSNMR and dynamic mechanical analysis (DMA. FTIR and SSNMR investigations revealed that about 7 wt % of HBPEAc-COOH was actually incorporated into the ionic domains of Nafion. The FTIR study suggests possible complexation via inter-species hydrogen bonding between the carboxylic groups of HBPEAc-COOH and the sulfonate groups of Nafion. The α-relaxation peak corresponding to the glass transition temperature of the ionic domains of the neat Nafion-acid form was found to increase from ~100 to ~130 °C upon impregnation with enhanced modulus afforded by the cured polyester network within the ionic domains. The AC impedance fuel cell measurement of the impregnated membrane exhibited an increasing trend of proton conductivity with increasing temperature, which eventually surpassed that of neat Nafion above 100 °C. Of particular importance is that the present paper is the first to successfully incorporate polymer molecules/networks into the Nafion ionic domains by means of impregnation with hyperbranched supramolecules followed by in-situ photopolymerization.

  13. Transparent luminescent hyperbranched epoxy/carbon oxide dot nanocomposites with outstanding toughness and ductility.

    Science.gov (United States)

    De, Bibekananda; Voit, Brigitte; Karak, Niranjan

    2013-10-23

    A luminescent transparent hyperbranched epoxy nanocomposite with previously unachieved outstanding toughness and elasticity has been created by incorporation of a very small amount of carbon oxide nanodots. The nanocomposites of the hyperbranched epoxy with carbon oxide dots at different dose levels (0.1, 0.5, and 1.0 wt %) have been prepared by an ex situ solution technique followed by curing with poly(amido-amine) at 100 °C. Different characterizations and evaluations of mechanical and optical properties of the nanocomposites have been performed. The toughness (area under the stress-strain curve) of the pristine system has been improved dramatically by 750% with only 0.5 wt % carbon oxide dots. The tensile strength has been enhanced from 38 to 46 MPa, whereas the elongation at break improved noticeably from 15 to 45%. Excellent adhesive strength combined with transparency and photoluminescent behavior renders these materials highly interesting as functional films in optical devices like light-emitting diodes and UV light detection systems as well as in anticounterfeiting applications.

  14. Synthesis of New Hyperbranched α-Glucans from Sucrose by Lactobacillus reuteri 180 Glucansucrase Mutants.

    Science.gov (United States)

    Meng, Xiangfeng; Dobruchowska, Justyna M; Pijning, Tjaard; Gerwig, Gerrit J; Dijkhuizen, Lubbert

    2016-01-20

    α-Glucans produced by glucansucrase enzymes of lactic acid bacteria attract strong attention as novel ingredients and functional biopolymers in the food industry. In the present study, α-helix 4 amino acid residues D1085, R1088, and N1089 of glucansucrase GTF180 of Lactobacillus reuteri 180 were targeted for mutagenesis both jointly and separately. Analysis of the mutational effects on enzyme function revealed that all D1085 and R1088 mutants catalyzed the synthesis of hyperbranched α-glucans with 15-22% branching (α1→3,6) linkages, compared to 13% in the wild-type GTF180. In addition, besides native (α1→6) and (α1→3) linkages, all of the mutations introduced a small amount of (α1→4) linkages (5% at most) in the polysaccharides produced. We conclude that α-helix 4 residues, especially D1085 and R1088, constituting part of the +2 acceptor binding subsite, are important determinants for the linkage specificity. The new hyperbranched α-glucans provide very interesting structural diversities and may find applications in the food industry.

  15. Highly efficient hyperbranched CNT surfactants: influence of molar mass and functionalization.

    Science.gov (United States)

    Bertels, Ellen; Bruyninckx, Kevin; Kurttepeli, Mert; Smet, Mario; Bals, Sara; Goderis, Bart

    2014-10-21

    End-group-functionalized hyperbranched polymers were synthesized to act as a carbon nanotube (CNT) surfactant in aqueous solutions. Variation of the percentage of triphenylmethyl (trityl) functionalization and of the molar mass of the hyperbranched polyglycerol (PG) core resulted in the highest measured surfactant efficiency for a 5000 g/mol PG with 5.6% of the available hydroxyl end-groups replaced by trityl functions, as shown by UV-vis measurements. Semiempirical model calculations suggest an even higher efficiency for PG5000 with 2.5% functionalization and maximal molecule specific efficiency in general at low degrees of functionalization. Addition of trityl groups increases the surfactant-nanotube interactions in comparison to unfunctionalized PG because of π-π stacking interactions. However, at higher functionalization degrees mutual interactions between trityl groups come into play, decreasing the surfactant efficiency, while lack of water solubility becomes an issue at very high functionalization degrees. Low molar mass surfactants are less efficient compared to higher molar mass species most likely because the higher bulkiness of the latter allows for a better CNT separation and stabilization. The most efficient surfactant studied allowed dispersing 2.85 mg of CNT in 20 mL with as little as 1 mg of surfactant. These dispersions, remaining stable for at least 2 months, were mainly composed of individual CNTs as revealed by electron microscopy.

  16. Succinate Functionalization of Hyperbranched Polyglycerol-Coated Magnetic Nanoparticles as a Draw Solute During Forward Osmosis.

    Science.gov (United States)

    Yang, Hee-Man; Choi, Hye Min; Jang, Sung-Chan; Han, Myeong Jin; Seo, Bum-Kyoung; Moon, Jei-Kwon; Lee, Kune-Woo

    2015-10-01

    Hyperbranched polyglycerol-coated magnetic nanoparticles (SHPG-MNPs) were functionalized with succinate groups to form a draw solute for use in a forward osmosis (FO). After the one-step synthesis of hyperbranched polyglycerol-coated magnetic nanoparticles (HPG-MNPs), the polyglycerol groups on the surfaces of the HPG-MNPs were functionalized with succinic anhydride moieties. The resulting SHPG-MNPs showed no change of size and magnetic property compared with HPG-MNPs and displayed excellent dispersibility in water up to the concentration of 400 g/L. SHPG-MNPs solution showed higher osmotic pressure than that of HPG-MNPs solution due to the presence of surface carboxyl groups in SHPG-MNPs and could draw water from a feed solution across an FO membrane without any reverse draw solute leakage during FO process. Moreover, the water flux remained nearly constant over several SHPG-MNP darw solute regeneration cycles applied to the ultrafiltration (UF) process. The SHPG-MNPs demonstrate strong potential for use as a draw solute in FO processes.

  17. 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.

  18. SYNTHESIS AND MAGNETIC PROPERTIES OF COMPLEXES OF A CONJUGATED HYPERBRANCHED POLYMER CONTAINING BITHIAZOLE RINGS

    Institute of Scientific and Technical Information of China (English)

    Neng-wen Ding; Wei-lin Sun; Yan Lin; Zhi-quan Shen

    2012-01-01

    A novel conjugated hyperbranched polymer containing bithiazole rings (PBTADB) was synthesized by polycondensation of 1,3,5-benzenetricarboxaldehyde and 2,2′-diamino-4,4′-bithiazole (DABT).The structure of the hyperbranched polymer was confirmed by FT-IR and 1H-NMR.PBTADB dissolved in organic polar solvents such as DMSO and NMP.Bithiazole rings were introduced to provide bidentate N-donor sites for binding metal ions.The metal complexes were prepared by chelation of the polymer with Co2+ and Sm3+.The magnetic behavior of coordination compounds was measured as a function of magnetic field strength (0-4.8 × l06 A/m) at 5 K and as a function of temperature (5-300 K) at magnetic field strength of 2.4 × 106 A/m.The magnetic hysteresis loops of PBTADB-Sm3+ and PBTADB-Co2+ showed the typical ‘S' shape at 5 K with the Curie-Weiss temperature Tθ =96 K and 41 K respectively.The results show that they exhibit properties of soft ferromagnetic materials.

  19. Controlled synthesis of hyper-branched inorganic nanocrystals withrich three-dimensional structures

    Energy Technology Data Exchange (ETDEWEB)

    Kanaras, Antonios G.; Sonnichsen, Carsten; Liu, Haitao; Alivisatos, A. Paul

    2005-07-27

    Studies of crystal growth kinetics are tightly integrated with advances in the creation of new nanoscale inorganic building blocks and their functional assemblies 1-11. Recent examples include the development of semiconductor nanorods which have potential uses in solar cells 12-17, and the discovery of a light driven process to create noble metal particles with sharp corners that can be used in plasmonics 18,19. In the course of studying basic crystal growth kinetics we developed a process for preparing branched semiconductor nanocrystals such as tetrapods and inorganic dendrimers of precisely controlled generation 20,21. Here we report the discovery of a crystal growth kinetics regime in which a new class of hyper-branched nanocrystals are formed. The shapes range from 'thorny balls', to tree-like ramified structures, to delicate 'spider net'-like particles. These intricate shapes depend crucially on a delicate balance of branching and extension. The multitudes of resulting shapes recall the diverse shapes of snowflakes 22.The three dimensional nature of the branch points here, however, lead to even more complex arrangements than the two dimensionally branched structures observed in ice. These hyper-branched particles not only extend the available three-dimensional shapes in nanoparticle synthesis ,but also provide a tool to study growth kinetics by carefully observing and modeling particle morphology.

  20. Hard and flexible nanocomposite coatings using nanoclay-filled hyperbranched polymers.

    Science.gov (United States)

    Fogelström, Linda; Malmström, Eva; Johansson, Mats; Hult, Anders

    2010-06-01

    The combination of hardness, scratch resistance, and flexibility is a highly desired feature in many coating applications. The aim of this study is to achieve this through the introduction of an unmodified nanoclay, montmorillonite (Na(+)MMT), in a polymer resin based on the hyperbranched polyester Boltorn H30. Smooth and transparent films were prepared from both the neat and the nanoparticle-filled hyperbranched resins. X-ray diffraction (XRD) and transmission electron microscopy (TEM) corroborated a mainly exfoliated structure in the nanocomposite films, which was also supported by results from dynamic mechanical analysis (DMA). Furthermore, DMA measurements showed a 9-16 degrees C increase in Tg and a higher storage modulus-above and below the T(g)-both indications of a more cross-linked network, for the clay-containing film. Thermogravimetric analysis (TGA) demonstrated the influence of the nanofiller on the thermal properties of the nanocomposites, where a shift upward of the decomposition temperature in oxygen atmosphere is attributed to the improved barrier properties of the nanoparticle-filled materials. Conventional coating characterization methods demonstrated an increase in the surface hardness, scratch resistance and flexibility, with the introduction of clay, and all coatings exhibited excellent chemical resistance and adhesion.

  1. A hyperbranched β-d-glucan with compact coil conformation from Lignosus rhinocerotis sclerotia.

    Science.gov (United States)

    Hu, Ting; Huang, Qilin; Wong, Kahing; Yang, Hong; Gan, Jingsi; Li, Yanru

    2017-06-15

    An alkali-soluble polysaccharide was extracted from Lignosus rhinocerotis sclerotia (LRP). Its structural characteristics were determined by GC-MS, FT-IR, GC, 1D and 2D NMR combined with Smith degradation and methylation analysis. The LRP had a (1→3)-β-d-Glcp backbone with every three residues bearing a (1→6)-linked and hyperbranched side chain that contained three (1→6)-β-d-Glcp residues as secondary main chain and two terminal β-d-Glcp residues linked at O3. The degree of branching was 0.76 from GC-MS analysis, implying a highly branched structure for LRP. The Mw, z(1/2), Rh and [η] values of LRP in 0.25M LiCl/DMSO were measured by SEC-MALLS-Vis-RI combination technology to be 2.88×10(5)g/mol, 30.36nm, 22.34nm and 131.50ml/g, respectively. Furthermore, the exponent α of [η]-Mw, β of z(1/2)-Mw, the fractal dimension df and molecular parameter ρ were determined to be 0.20, 0.33, 2.50 and 1.36, demonstrating that the LRP was a hyperbranched polysaccharide and adopted a compact coil conformation in LiCl/DMSO.

  2. 超支化预聚物的合成及对聚合物分散液晶膜电光性能的影响%Synthesis of Hyperbranched Pre-Polymers and Its Influence on Electro-Optical Properties of Polymer-Dispersed Liquid Crystals

    Institute of Scientific and Technical Information of China (English)

    杨志刚; 潘翠红; 汪映寒

    2011-01-01

    Polymer has a great influence on electro-optical properties of polymer dispersed liquid crystals(PDLC).In present work,different ratios of monovinyl monomer and divinyl monomer were adopted to synthesize series of hyperbranched polymers via reversible addition-fragmentation transfer(RAFT) polymerization.These hyperbranched polymers,served as "living" pre-polymers,then were used in photopolymerization induced phase separation(PIPS) process for preparing hyperbranched polymer matrix–based PDLC films.Different pre-polymers result in varied morphology of PDLC film and further affect threshold voltage.Meanwhile,the driving voltage shows certain dependence on molecular weight of polymer matrix.Moreover,it is found hysteresis and memory effect decrease with the increase of level of branching,this may be attributed to hyperbranched structure strengthening the interactions between liquid crystal molecules and polymer.%聚合物基体对聚合物分散液晶(PDLC)膜电光性能影响很大。文中,用不同比例单乙烯基和二乙烯基单体通过可逆加成-断裂链转移自由基聚合(RAFT)得到了一系列超支化聚合物。这些超支化聚合物可作为"活性"预聚物用于聚合诱导相分离(PIPS)来制备超支化树脂基PDLC膜。结果表明,添加不同预聚物导致不同的表面形貌,进而影响到阈值电压大小。驱动电压对聚合物基体分子量有一定的依赖性,分子量高的基体驱动电压相对较高。此外,滞后和记忆效应随基体支化度提高而减小,这可能与超支化结构增强了聚合物与液晶间的相互作用力有关。

  3. Making Polymeric Microspheres

    Science.gov (United States)

    Rhim, Won-Kyu; Hyson, Michael T.; Chung, Sang-Kun; Colvin, Michael S.; Chang, Manchium

    1989-01-01

    Combination of advanced techniques yields uniform particles for biomedical applications. Process combines ink-jet and irradiation/freeze-polymerization techniques to make polymeric microspheres of uniform size in diameters from 100 to 400 micrometer. Microspheres used in chromatography, cell sorting, cell labeling, and manufacture of pharmaceutical materials.

  4. Applied bioactive polymeric materials

    CERN Document Server

    Carraher, Charles; Foster, Van

    1988-01-01

    The biological and biomedical applications of polymeric materials have increased greatly in the past few years. This book will detail some, but not all, of these recent developments. There would not be enough space in this book to cover, even lightly, all of the major advances that have occurred. Some earlier books and summaries are available by two of this book's Editors (Gebelein & Carraher) and these should be consul ted for additional information. The books are: "Bioactive Polymeric Systems" (Plenum, 1985); "Polymeric Materials In Medication" (Plenum, 1985); "Biological Acti vi ties of Polymers" (American Chemical Society, 1982). Of these three, "Bioacti ve Polymeric Systems" should be the most useful to a person who is new to this field because it only contains review articles written at an introductory level. The present book primarily consists of recent research results and applications, with only a few review or summary articles. Bioactive polymeric materials have existed from the creation of life...

  5. 一种超支化聚酯的合成及反应动力学%Synthesis and Reaction Kinetics of Hyperbranched Polyester

    Institute of Scientific and Technical Information of China (English)

    张新荔

    2011-01-01

    以等物质的量比的间苯二甲酸(A2型单体)和三羟甲基丙烷(B3型单体)为原料,采用熔融聚合工艺制备了一种具有芳香-脂肪骨架的新型超支化聚酯(HBPE)。利用红外光谱、核磁共振、凝胶渗透色谱和热分析等手段对HBPE进行了表征。同时对合成HBPE的反应动力学进行了研究,建立了适合该体系的反应动力学方程,实验结果与理论研究符合良好。研究结果表明,该缩聚反应为外加酸的催化反应过程,反应级数为二级,反应速率由羧基浓度和羟基浓度共同决定。%A new hyperbranched polyester(HBPE) with aromatic-aliphatic skeleton was prepared by melt polymerization of isophthalic acid(A2 type monomer) and trimethylolpropane(B3 type monomer) with equimolar ratio,and the HBPE was characterized using Fourier transform infrared spectroscopy,nuclear magnetic resonance,gel permeation chromatography and thermal analyzer.A suitable kinetics equation of the system was established.It is found that the experimental results are in good agreement with theory.The research results show that the reaction is a second order.The condensation reaction is a acid-catalyzed process,and reaction rate is decided by the concentrations of carboxyl and hydroxyl together.

  6. Thermally stable hyperbranched polyether-based polymer electrolyte for lithium-ion batteries

    Science.gov (United States)

    Wu, Feng; Feng, Ting; Wu, Chuan; Bai, Ying; Ye, Lin; Chen, Junzheng

    2010-01-01

    A thermally stable polymer matrix, comprising hyperbranched polyether PHEMO (poly(3-{2-[2-(2-hydroxyethoxy) ethoxy] ethoxy}methyl-3'-methyloxetane)) and PVDF-HFP (poly(vinylidene fluoride-hexafluoropropylene)), has been successfully prepared for applications in lithium-ion batteries. This type of polymer electrolyte has been made by adding different amounts of lithium bis(oxalate)borate (LiBOB) to the polymer matrix. Its thermal and structural properties were measured using differential scanning calorimetry and x-ray diffraction. Experimental results show that the polymer electrolyte system possesses good thermal stability, with a decomposition temperature above 420 °C. The ionic conductivity of the polymer electrolyte system is dependent on the lithium salt content, reaching a maximum of 1.1 × 10-5 S cm-1 at 30 °C and 2.3 × 10-4 S cm-1 at 80 °C when doped with 10 wt% LiBOB.

  7. Hyperbranched Acrylated Aromatic Polyester Used as a Modifier in UV-Curable Epoxy Acrylate Resins

    Institute of Scientific and Technical Information of China (English)

    KOU,Hui-Guang; ASIF,Anila; SHI,Wen-Fang

    2003-01-01

    The viscosity, the shrinkage degree and the photoplymerization rate of the epoxy acrylate (EB600 ) blended with hyperbranched acrylated aromatic polyester ( HAAPE ) were investigated. The addition of HAAPE into EB600 largely reduces the viscosity of the blend formulation and the shrinkage degree. For example, EB600resin with 50% weight fraction of HAAPE has the 1250 cps of the viscosity and 2.0% of shrinkage degree, while the pure EB600 resin has 3000 cps of the viscosity and 10.5% of shrinkage degree. The photopolymerization rate of the rein is also promoted by HAAPE addition. The good miscibility between HAAPE and EB600 was also observed from the dynamic mechanical analysis. The tensile, flexural and compressive strength, and the thermal properties of the UVcured films are greatly improved.

  8. Non-enzymatic glucose biosensor based on hyperbranched pine-like gold nanostructure.

    Science.gov (United States)

    Heli, H; Amirizadeh, O

    2016-06-01

    Hyperbranched pine-like gold nanostructure was electrodeposited on the polycrystalline gold surface at 0 mV (vs. AgCl) with the assistance of histidine as a soft template. The nanostructure was then applied as a highly sensitive nonenzymatic sensor for glucose. The catalytic activity and sensitivity of the gold nanostructure toward the electrooxidation of glucose was excellent without surface fouling and deterioration effects. The current related to the oxidation of glucose rapidly and linearly depended on its concentration with a sensitivity of 776.8 μA cm(-2)mmol(-1)dm(3), a detection limit of 3.39 μmol dm(-3) with a relative standard deviation of 2.32%.

  9. Catalytic hyperbranched polymers as enzyme mimics; exploiting the principles of encapsulation and supramolecular chemistry.

    Science.gov (United States)

    Kirkorian, Katerina; Ellis, Adam; Twyman, Lance J

    2012-09-21

    Nature uses the principles of encapsulation and supramolecular chemistry to bind and orientate substrates within active catalytic sites. Over the years, synthetic chemistry has generated a number of small molecule active site mimics capable of catalysing reactions involving bound substrates. Another approach uses larger molecules that better represent an enzymes globular structure. These molecules mimic an enzymes structure by incorporating binding/catalytic sites within the globular structure of the polymer. As such, the electronic and steric properties around the binding/catalytic site(s) can be controlled and fine-tuned. One class of polymer that is particularly adept at mimicking the globular structure of enzymes are dendritic polymers. This review will concentrate on the use of hyperbranched polymers as synthetic enzyme mimics.

  10. The Time Evolution of the Surface Segregation of Hyperbranched Molecules from a Linear Matrix

    Science.gov (United States)

    Swader, Onome; Dadmun, Mark; Hutchings, Lian; Thompson, Richard

    2010-03-01

    Modification of a surface by the selective surface segregation of an additive in a mixture is a process with many commercial applications including biocompatibility, wettability, and anti-fouling in coatings. In a blend of branched and linear polymers, there exists an entropic driving force for the selective surface segregation of the branched polymer. Unfortunately, a systematic study of the impact of the branched copolymer structure on the dynamics and thermodynamics of this surface segregation is not currently available. Neutron reflectivity experiments that seek to fill this void have been completed and will be discussed. High molecular weight poly(styrene) (PS) hyperbranched molecules, hypermacs (HM) and dendrimacs (DM), with 10 % HM or DM and 90 % deuterated PS are the model systems studied. Reflectivity profiles for all blends were obtained as a function of annealing time from 30 minutes up to 48 hours.

  11. Hybrid solar cells with prescribed nanoscale morphologies based on hyperbranched semiconductor nanocrystals.

    Science.gov (United States)

    Gur, Ilan; Fromer, Neil A; Chen, Chih-Ping; Kanaras, Antonios G; Alivisatos, A Paul

    2007-02-01

    In recent years, the search to develop large-area solar cells at low cost has led to research on photovoltaic (PV) systems based on nanocomposites containing conjugated polymers. These composite films can be synthesized and processed at lower costs and with greater versatility than the solid state inorganic semiconductors that comprise today's solar cells. However, the best nanocomposite solar cells are based on a complex architecture, consisting of a fine blend of interpenetrating and percolating donor and acceptor materials. Cell performance is strongly dependent on blend morphology, and solution-based fabrication techniques often result in uncontrolled and irreproducible blends, whose composite morphologies are difficult to characterize accurately. Here we incorporate three-dimensional hyperbranched colloidal semiconductor nanocrystals in solution-processed hybrid organic-inorganic solar cells, yielding reproducible and controlled nanoscale morphology.

  12. Thermo-/pH-dual responsive properties of hyperbranched polyethylenimine grafted by phenylalanine.

    Science.gov (United States)

    Chen, Jie; Xia, Jialiang; Tian, Huayu; Tang, Zhaohui; He, Chaoliang; Chen, Xuesi

    2014-01-01

    Novel thermo- and pH-dual responsive amphiphilic copolymers were synthesized based on hyperbranched polyethylenimine (PEI) by grafting L-phenylalanine. The phenylalanine-modified PEI exhibited lower cytotoxicity than commercial PEI. These copolymers showed the phenomena of phase transitions in response to pH and temperature. The dilute copolymer solution at lower pH displayed the higher LCST. Furthermore, LCST increased with the increasing of phenylalanine grafting density. LCST of these copolymers were tunable from 7.2 to 59.6 °C by the degree of amidation and pH of solution. DLS and TEM experiments certified that the copolymer chains aggregated to form small size particles as increasing the temperature above LCST. For these reasons, the obtained smart copolymers were considered to be potential gene/drug carriers in biomedical field.

  13. Hyperbranched poly(epsilon-caprolactone) as a nonmigrating alternative plasticizer for phthalates in flexible PVC.

    Science.gov (United States)

    Choi, Jeongsoo; Kwak, Seung-Yeop

    2007-05-15

    Hyperbranched (dendritic) poly(epsilon-caprolactone)s (HPCLs) were synthesized to have architectural variations, which are the different lengths of linear segments and different numbers of branches, and were used as plasticizers for flexible poly(vinyl chloride) (PVC). The plasticization efficiency estimated by the lowering of glass transition temperature and the enhancement in ultimate elongation indicated that the HPCLs with the shorter linear segments and the larger number of branches imparted as high flexibility as di(ethylhexyl) phthalate (DEHP) and much higher flexibility than their linear analogue, linear poly(epsilon-caprolactone), which is one of currently used polymer plasticizers. Volatility, extractability, and exudation tests for PVC/HPCL samples showed that there was no plasticizer migration even at very harsh condition, while ca. 7-78% of additives in PVC/DEHP was migrated out of samples, indicating that the HPCL can be used as an alternative plasticizer to remove the potential health risk from migrating phthalates during end use.

  14. Effect of Hyperbranched Polyester on Modification of Epoxy Resins Cured with Anhydride

    Institute of Scientific and Technical Information of China (English)

    Xiu Xia WANG; Zhi Gang JIANG; Yi Feng ZHANG

    2006-01-01

    The synthesis and characterization of hyperbranched polyester (HBP) with different molecular weight are studied. The effect of HBP on the modification of epoxy resins cured with anhydride is mainly discussed. The characteristics of HBP and the morphologies of cured system are determined by nuclear magnetic resonance spectroscopy (NMR), gel permeation chromatography (GPC) and scanning electron microscope (SEM). The impact strength of cured system is detected and Fourier transform infrared (FTIR) measurements were used to pursue the curing process. The investigation shows that HBP can improve the toughness by forming copolymer networks between epoxy resins, HBP and anhydride. Moreover, when the molecular weight of HBP is 1342g/mol the toughening effect is the best, and the changes of toughness are small with the increase of molecular weight of HBP to 3500 g/mol.

  15. Negatively Charged Hyperbranched Polyglycerol Grafted Membranes for Osmotic Power Generation from Municipal Wastewater

    KAUST Repository

    Li, Xue

    2015-11-18

    Osmotic power holds great promise as a clean, sustainable and largely unexploited energy resource. Recent membrane development for pressure-retarded osmosis (PRO) is making the osmotic power generation more and more realistic. However, severe performance declines have been observed because the porous layer of PRO membranes is fouled by the feed stream. To overcome it, a negatively charged antifouling PRO hollow fiber membrane has been designed and studied in this work. An antifouling polymer, derived from hyperbranched polyglycerol and functionalized by α-lipoic acid and succinic anhydride, was synthesized and grafted onto the polydopamine (PDA) modified poly(ether sulfone) (PES) hollow fiber membranes. In comparison to unmodified membranes, the charged hyperbranched polyglycerol (CHPG) grafted membrane is much less affected by organic deposition, such as bovine serum albumin (BSA) adsorption, and highly resistant to microbial growths, demonstrated by E. coli adhesion and S. aureus attachment. CHPG-g-TFC was also examined in PRO tests using a concentrated wastewater as the feed. Comparing to the plain PES-TFC and non-charged HPG-g-TFC, the newly developed membrane exhibits not only the smallest decline in water flux but also the highest recovery rate. When using 0.81 M NaCl and wastewater as the feed pair in PRO tests at 15 bar, the average power density remains at 5.6 W/m2 in comparison to an average value of 3.6 W/m2 for unmodified membranes after four PRO runs. In summary, osmotic power generation may be sustained by properly designing and anchoring the functional polymers to PRO membranes.

  16. High performance hyperbranched polymers for improved processing and mechanical properties in thermoset composites

    Science.gov (United States)

    Marsh, Timothy

    Hyperbranched polymers, specifically hyperbranched poly(arylene ether ketone imide)s (HBPAEKI), are here studied as blend additives in thermoset composites to improve processing and ultimate performance properties of the composite. Monomer synthesis for HBPAEKI was further advanced in this work leading to higher yields, fewer reactions, and shorter production times. A five step synthetic method with an overall yield of 12% was reduced to a three step process with an overall yield of 38%. Polymer was synthesized under varying conditions and end group chemistry for use in thermoset blends. NMR characterization allowed for the assignment of chemical shifts in monomer and cataloguing of shifts in polymer for use in future work to characterize degree of branching. Cure kinetics of blends of HBPAEKI are explored through the use of differential scanning calorimetry (DSC) and chemorheology using small angle oscillatory shear. In a phenylethynyl terminated imide oligomer (PETI) thermoset resin, reactive phenylethynyl endcapped PAEKI (PEPAEKI) was found to retard cure while non reactive alkyl endcapped PAEKI was found to accelerate cure in DGEBA/DAH epoxy systems. Minimal effect was seen on early stage blend viscosity. Composite properties tested focused on the effect on bulk fracture and interfacial shear strength. No significant effect was seen in fracture toughness by SENB. XPS was used to verify that PEPAEKI was surface active to DGEBA/DDS epoxy/air interfaces to the complete exclusion of the epoxy at the surface. Evidence was also seen consistent with surface activity in alkyl endcapped PAEKI in DGEBA/DAH systems, although the contrast is much lower. Effect of alkyl endcapped HBPAEKI on interfacial shear strength was examined through the use of t-peel and single fiber fracture (SFF) techniques. In some systems, t-peel indicates a clear improvement in peel force, proportional to the blend concentration. In SFF, interfacial shear strength was found to be equal or slightly

  17. Synthesis of hyperbranched polypeptide and PEO block copolymer by consecutive thiol-yne chemistry.

    Science.gov (United States)

    Chang, Xiao; Dong, Chang-Ming

    2013-09-09

    Hyperbranched poly(ε-benzyloxycarbonyl-L-lysine) (HPlys) with multiple alkyne peripheries was synthesized through the click polycondensation of an AB2 type Plys macromonomer with α-thiol and ω-alkyne terminal groups (thiol is the A unit, and each π bond in alkyne is the B unit), and the resulting HPlys was further conjugated with thiol-termined poly(ethylene oxide) (PEO) to generate HPlys-b-PEO block copolymer by consecutive thiol-yne chemistry. Their molecular structures and physical properties were characterized in detail by FT-IR, (1)H NMR, gel permeation chromatography, differential scanning calorimetry, wide-angle X-ray diffraction, and polarized optical microscopy. HPlys and HPlys-b-PEO mainly assumed an α-helix conformation similar to the linear precursors, while the liquid crystalline phase transition of Plys segment disappeared within HPlys and HPlys-b-PEO. HPlys-b-PEO self-assembled into nearly spherical micelles in aqueous solution, while it gave a 5-fold lower critical aggregation concentration (8.9 × 10(-3) mg/mL) than a linear counterpart (4.5 × 10(-2) mg/mL), demonstrating a dendritic topology effect. Compared with a linear counterpart, HPlys-b-PEO gave a higher drug-loading capacity and efficiency for the anticancer drug doxorubicin (DOX) and a slower drug-release rate with an improved burst-release profile, enabling them useful for drug delivery systems. Importantly, this work provides a versatile strategy for the synthesis of hyperbranched polypeptides and related block copolymers by utilizing thiol-yne chemistry.

  18. Multi-responsive Hyperbranched Star Copolymer: Synthesis, Self-assembly and Controlled Release%多重响应性超支化星形聚合物的合成与组装以及控制释放研究

    Institute of Scientific and Technical Information of China (English)

    张文建; 范溦; 李敏; 洪春雁; 潘才元

    2012-01-01

    含二硫键的自引发单体与2-(2-甲氧基乙氧基)乙基甲基丙烯酸酯(MEO2MA)进行自缩合乙烯基共聚合得到超支化PMEO2MA(H-PMEO2MA).以它作大分子引发剂,引发二甲氨基乙基甲基丙烯酸酯(DMAEMA)进行原子转移自由基聚合,合成了具有温度、pH以及氧化还原多重响应性的超支化星形聚合物H-PMEO2MA-star-PDMAEMA.证明了H-PMEO2MA有低临界溶液温度(LCST);研究了PDMAEMA链段的长度和溶液的pH值对超支化星形聚合物的LCST的影响.当H-PMEO2MA-star-PDMAEMA水溶液温度从2℃升高至室温,H-PMEO2MA变成疏水性而发生聚集,形成以H-PMEO2MA为核,PDMAEMA为壳的胶束.在胶束形成过程中,将尼罗红装载到这种聚合物胶束中,形成释药系统,研究了pH、氧化还原响应性释药性能.%Multi-responsive(temperature,pH and redox) hyperbranched star polymers,poly(2-(2-methoxyethoxy)ethyl methacrylate)-star-poly(dimethylaminoethyl methacrylate)(H-PMEO2MA-star-PDMAEMA) have been successfully synthesized by self-condensing vinyl polymerization of disulfide-based inimer and MEO2MA first,and subsequently atom transfer radical polymerization of DMAEMA with H-PMEO2MA as macroinitiator.The Mn and Mw/Mn of the H-PMEO2MA were 8300 g/mol and 2.61,respectively.H-PMEO2MA-star-PDMAEMAs with different molecular weights were obtained by adjusting the polymerization time.The molecular weight of the hyperbranched star copolymer increased but the polydispersity index(PDI) decreased with increasing polymerization time.Since the PDI of the PDMAEMA formed by ATRP is low,with the molecular weight increase of the PDMAEMA,the relative amount of H-PMEO2MA in the hyperbranched star copolymers becomes less;as a result,the influence of the core H-PMEO2MA’s PDI on the hyperbranched star copolymers decreases.UV/Vis TU-1901 spectrophotometer was used to investigate the lower critical solution temperature(LCST) of the resultant polymer

  19. Polymeric bicontinuous microemulsions

    DEFF Research Database (Denmark)

    Bates, F.S.; Maurer, W.W.; Lipic, P.M.

    1997-01-01

    High molecular weight block copolymers can be viewed as macromolecular surfactants when blended with thermodynamically incompatible homopolymers. This Letter describes the formation of polymeric bicontinuous microemulsions in nurtures containing a model diblock copolymer and two homopolymers...

  20. Controlled Synthesis of Uniform Cobalt Phosphide Hyperbranched Nanocrystals Using Tri- n -octylphosphine Oxide as a Phosphorus Source

    KAUST Repository

    Zhang, Haitao

    2011-01-12

    A new method to produce hyperbranched Co 2P nanocrystals that are uniform in size, shape, and symmetry was developed. In this reaction tri-n-octylphosphine oxide (TOPO) was used as both a solvent and a phosphorus source. The reaction exhibits a novel monomer-saturation-dependent tunability between Co metal nanoparticle (NP) and Co 2P NP products. The morphology of Co 2P can be controlled from sheaflike structures to hexagonal symmetric structures by varying the concentration of the surfactant. This unique product differs significantly from other reported hyperbranched nanocrystals in that the highly anisotropic shapes can be stabilized as the majority shape (>84%). This is the first known use of TOPO as a reagent as well as a coordinating background solvent in NP synthesis. © 2011 American Chemical Society.

  1. Chelating polymeric membranes

    KAUST Repository

    Peinemann, Klaus-Viktor

    2015-01-22

    The present application offers a solution to the current problems associated with recovery and recycling of precious metals from scrap material, discard articles, and other items comprising one or more precious metals. The solution is premised on a microporous chelating polymeric membrane. Embodiments include, but are not limited to, microporous chelating polymeric membranes, device comprising the membranes, and methods of using and making the same.

  2. Highly efficient hybrid photovoltaics based on hyperbranched three-dimensional TiO2 electron transporting materials

    KAUST Repository

    Mahmood, Khalid

    2015-03-23

    A 3D hyperbranched TiO2 electron transporting material is demonstrated, which exhibits superior carrier transport and lifetime, as well as excellent infiltration, leading to highly efficient mesostructured hybrid solar cells, such as lead-halide perovskites (15.5%) and dye-sensitized solar cells (11.2%). © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Experimental and theoretical studies of scaling of sizes and intrinsic viscosity of hyperbranched chains in good solvents

    Science.gov (United States)

    Li, Lianwei; Lu, Yuyuan; An, Lijia; Wu, Chi

    2013-03-01

    Using a set of hyperbranched polystyrenes with different overall molar masses but a uniform subchain length or a similar overall molar mass but different subchain lengths, we studied their sizes and hydrodynamic behaviors in toluene (a good solvent) at T = 25 °C by combining experimental (laser light scattering (LLS) and viscometry) and theoretical methods based on a partially permeable sphere model. Our results show that both the average radii of gyration (⟨Rg⟩) and hydrodynamic radius (⟨Rh⟩) are scaled to the weight-average molar mass (Mw) as ⟨Rg⟩ ˜ ⟨Rh⟩ ˜ MwγMw,sφ, with γ = 0.47 ± 0.01 and φ = 0.10 ± 0.01; and their intrinsic viscosity ([η]) quantitatively follow the Mark-Houwink-Sakurada (MHS) equation as [η] = KηMwνMw,sμ with Kη = 2.26 × 10-5, ν = 0.39 ± 0.01, and μ = 0.31 ± 0.01, revealing that these model chains with long subchains are indeed fractal objects. Further, our theoretical and experimental results broadly agree with each other besides a slight deviation from the MHS equation for short subchains, similar to dendrimers, presumably due to the multi-body hydrodynamic interaction. Moreover, we also find that the average viscometric radius (⟨Rη⟩) determined from intrinsic viscosity is slightly smaller than ⟨Rh⟩ measured in dynamic LLS and their ratio (⟨Rη⟩/⟨Rh⟩) roughly remains 0.95 ± 0.05, reflecting that linear polymer chains are more draining with a smaller ⟨Rh⟩ than their hyperbranched counterparts for a given intrinsic viscosity. Our current study of the "defect-free" hyperbranched polymer chains offers a standard model for further theoretical investigation of hydrodynamic behaviors of hyperbranched polymers and other complicated architectures, in a remaining unexploited research field of polymer science.

  4. Effect of Hyperbranched Poly(amine-ester) Grafted Nano-SiO2 on Reinforcement and Toughness of PVC

    Institute of Scientific and Technical Information of China (English)

    LI Jie; ZHAO Hui; SUN Rui-min; LUO Yun-jun

    2008-01-01

    Nano-SiO2 was modified using silane coupling agent (KH-550) and hyperbranched poly(amine-ester) respectively, and Poly(vinyl chloride) (PVC)/modified nano-SiO2 composites were made by melt-blending. The composites' structures andmechanical properties were characterized by transmission electron microscopy(TEM), sanning electronic microscopy(SEM) and electronic universal testing machine. The results show that nano-SiO2 grafted by hyperbranched poly (amine-ester) increases obviously in dispersion in PVC matrix, and mechanical properties of PVC are effectively improved. Moreover, it was found that mechanical properties of PVC/nano-SiO2 composites reach the best when weight percent of nano-SiO2 in PVC matrix is 1%. Compared with crude PVC, the tensile strength of hyperbranched poly (amine-ester) grafted nano-SiO2/PVC composite increases by 24.68% and its break elongation, flexural strength and impact strength increase by 15.73%, 4.07% and 1841.84%, respectively. Moreover, the processing of the composites is improved.

  5. Hyperbranched-polyol-tethered poly (amic acid) electrospun nanofiber membrane with ultrahigh adsorption capacity for boron removal

    Science.gov (United States)

    Wang, Zhe; Wu, Zhongyu; Zhang, Yufeng; Meng, Jianqiang

    2017-04-01

    The development of efficient adsorbents with high sorption capacity remains as a challenge for the removal of micropollutants occurred globally in water resources. In this work, poly (amic acid) (PAA) electrospun nanofiber membranes grafted with hyperbranched polyols were synthesized and used for boron removal. The PAA nanofiber was reacted with hyperbranched polyethylenimine (HPEI) and further with glycidol to introduce the vicinal hydroxyl groups. The chemical composition and surface characteristics of the obtained PAA-g-PG membranes were evaluated by FESEM, FTIR, XPS and water contact angles (WCA) measurements. The boron adsorption thermodynamics and kinetics were investigated systematically. The results showed that the PAA nanofiber spun from concentration of 15% had uniform morphology and narrow diameter distribution. The PAA-g-PG nanofiber membrane had a maximum boron uptake of 5.68 mmol/g and could adsorb 0.82 mmol/g boron from a 5 mg/L solution in 15 min. Both the high surface area of nanofibers and the hyperbranched structure should contribute to the high boron uptake and high adsorption rate. The nanofiber membrane obeyed the Langmuir adsorption model and the pseudo-first-order kinetic model. The regeneration efficiency of the nanofiber membrane remained 93.9% after 10 cycled uses, indicating good regenerability of the membrane.

  6. Plasma polymerization by Softplasma

    DEFF Research Database (Denmark)

    Jiang, J.; Wu, Zhenning; Benter, Maike

    2008-01-01

    In the late 19th century, the first depositions - known today as plasma polymers, were reported. In the last century, more and more research has been put into plasma polymers. Many different deposition systems have been developed. [1, 2] Shi F. F. broadly classified them into internal electrode......, external electrode, and electrodeless microwave or high frequency reactors. [3] Softplasma™ is an internal electrode plasma setup powered by low frequenc~ gower supply. It was developed in late 90s for surface treatment of silicone rubber. [ ]- 5] It is a low pressure, low electron density, 3D homogenous...... plasma. In this study, we are presenting the surface modification"pf polymers by plasma polymerization using Softplasma™. Softplasma™ can be used for two major types of polymerization: polymerization of vinyl monomers, where plasma acts as initiator; chemical vapour deposition, where plasma acts...

  7. POLYMERIC SURFACTANT STRUCTURE

    Institute of Scientific and Technical Information of China (English)

    P.M. Saville; J.W. White

    2001-01-01

    Polymeric surfactants are amongst the most widespread of all polymers. In nature, proteins and polysaccharides cause self organization as a result of this surfactancy; in industry, polymeric surfactants play key roles in the food, explosives and surface coatings sectors. The generation of useful nano- and micro-structures in films and emulsions as a result of polymer amphiphilicity and the application of mechanical stress is discussed. The use of X-ray and neutron small angle scattering and reflectivity to measure these structures and their dynamic properties will be described. New results on linear and dendritic polymer surfactants are presented.

  8. Single-crystalline hyperbranched nanostructure of iron hydroxyl phosphate Fe5(PO4)4(OH)3·2H2O for highly selective capture of phosphopeptides.

    Science.gov (United States)

    Chen, Qun; Wei, Chengzhen; Zhang, Yizhou; Pang, Huan; Lu, Qingyi; Gao, Feng

    2014-01-17

    Single-crystalline hyperbranched nanostructures of iron hydroxyl phosphate Fe5(PO4)4(OH)3·2H2O (giniite) with orthorhombic phase were synthesized through a simple route. They have a well-defined dendrite fractal structure with a pronounced trunk and highly ordered branches. The toxicity test shows that the hyperbranched nanostructures have good biocompatibility and low toxicity level, which makes them have application potentials in life science. The study herein demonstrated that the obtained hyperbranched giniite nanostructures show highly selective capture of phosphopeptides and could be used as a kind of promising nanomaterial for the specific capture of phosphopeptides from complex tryptic digests with the detection of MALDI-TOF mass spectrometry.

  9. Polymerized and functionalized triglycerides

    Science.gov (United States)

    Plant oils are useful sustainable raw materials for the development of new chemical products. As part of our research emphasis in sustainability and green polymer chemistry, we have explored a new method for polymerizing epoxidized triglycerides with the use of fluorosulfonic acid. Depending on the ...

  10. Waterborne Polymeric Films.

    Science.gov (United States)

    1981-02-01

    Skydrol 500B is a fire resistant hydraulic fluid available from Monsanto and which is primarily tricresyl phosphate. In most cases, the above table...Makromol. Chem. 1979, 82 149.- 23. Ger. Offen 2,804,609; (8/9/79). Bayer AG. 24. Odian, G. "Principles of Polymerization; "McGraw-Hill Book Co.: New York

  11. Molecular Mobility in Hyperbranched Polymers and Their Interaction with an Epoxy Matrix

    Directory of Open Access Journals (Sweden)

    Frida Román

    2016-03-01

    Full Text Available The molecular mobility related to the glass transition and secondary relaxations in a hyperbranched polyethyleneimine, HBPEI, and its relaxation behaviour when incorporated into an epoxy resin matrix are investigated by dielectric relaxation spectroscopy (DRS and dynamic mechanical analysis (DMA. Three systems are analysed: HBPEI, epoxy and an epoxy/HBPEI mixture, denoted ELP. The DRS behaviour is monitored in the ELP system in three stages: prior to curing, during curing, and in the fully cured system. In the stage prior to curing, DRS measurements show three dipolar relaxations: γ, β and α, for all systems (HBPEI, epoxy and ELP. The α-relaxation for the ELP system deviates significantly from that for HBPEI, but superposes on that for the epoxy resin. The fully cured thermoset displays both β- and α-relaxations. In DMA measurements, both α- and β-relaxations are observed in all systems and in both the uncured and fully cured systems, similar to the behaviour identified by DRS.

  12. Thermally stable hyperbranched polyether-based polymer electrolyte for lithium-ion batteries

    Energy Technology Data Exchange (ETDEWEB)

    Wu Feng; Feng Ting; Wu Chuan; Bai Ying; Chen Junzheng [School of Chemical Engineering and Environment, Beijing Institute of Technology, Beijing 10081 (China); Ye Lin, E-mail: chuanwu@bit.edu.c [School of Materials Science and Engineering, Beijing Institute of Technology, Beijing 10081 (China)

    2010-01-27

    A thermally stable polymer matrix, comprising hyperbranched polyether PHEMO (poly(3-{l_brace}2-[2-(2-hydroxyethoxy) ethoxy] ethoxy{r_brace}methyl-3'-methyloxetane)) and PVDF-HFP (poly(vinylidene fluoride-hexafluoropropylene)), has been successfully prepared for applications in lithium-ion batteries. This type of polymer electrolyte has been made by adding different amounts of lithium bis(oxalate)borate (LiBOB) to the polymer matrix. Its thermal and structural properties were measured using differential scanning calorimetry and x-ray diffraction. Experimental results show that the polymer electrolyte system possesses good thermal stability, with a decomposition temperature above 420 {sup 0}C. The ionic conductivity of the polymer electrolyte system is dependent on the lithium salt content, reaching a maximum of 1.1 x 10{sup -5} S cm{sup -1} at 30 {sup 0}C and 2.3 x 10{sup -4} S cm{sup -1} at 80 {sup 0}C when doped with 10 wt% LiBOB.

  13. Composite Electrolyte Membranes from Partially Fluorinated Polymer and Hyperbranched, Sulfonated Polysulfone

    Directory of Open Access Journals (Sweden)

    Surya Subianto

    2013-12-01

    Full Text Available Macromolecular modification of poly(vinylidene fluoride-co-hexafluoropropylene (PVDF was done with various proportions of sulfonic acid terminated, hyperbranched polysulfone (HPSU with a view to prepare ion conducting membranes. The PVDF-co-HFP was first chemically modified by dehydrofluorination and chlorosulfonation in order to make the membrane more hydrophilic as well as to introduce unsaturation, which would allow crosslinking of the PVDF-co-HFP matrix to improve the stability of the membrane. The modified samples were characterized for ion exchange capacity, morphology, and performance. The HPSU modified S-PVDF membrane shows good stability and ionic conductivity of 5.1 mS cm−1 at 80 °C and 100% RH for blends containing 20% HPSU, which is higher than the literature values for equivalent blend membranes using Nafion. SEM analysis of the blend membranes containing 15% or more HPSU shows the presence of spherical domains with a size range of 300–800 nm within the membranes, which are believed to be the HPSU-rich area.

  14. Waterborne carboxyl-terminated hyperbranched oligomer polyester ligand: Synthesis, characterization and chelation with chromium(III)

    Science.gov (United States)

    Yao, Qi; Li, Chenying; Huang, Henghui; Chen, Hualin; Liu, Bailing

    2017-09-01

    A series of carboxyl-terminated hyperbranched oligomer polyester (HBP) with different degree of branching (DB) and number average molar mass (Mbarn) have been prepared. The molecular structure, degree of branching, molecular mass and its distribution of HBP were investigated by FTIR, 1H NMR, and GPC, respectively. And the coordination number, stability constant and degree of dissociation (α) between HBP and chromium(Ⅲ) were measured via continuous variation method (Job's plot). Experimental results show that the coordination capability between HBP and chromium(Ⅲ) affected by both DB and molecular mass, and the latter plays a decisive role. Moreover HBP outperforms low molecular weight of organic acids (citric acid, acetic acid) and linear polyacrylic acid with similar molecular mass. The coordination number and stability constants of HBP-3 (Mbarn = 1713 Da, Mbarw /Mbarn (PDI) = 1.11 and DB = 0.72) can reach 4 and 6.55e+008, which demonstrated it can be selected as a good ligand to coordination with chromium(Ⅲ). Therefore HBP can be used as chrome auxiliary in chrome tanning to improve the absorption of chromium.

  15. A Highly Photostable Hyperbranched Polyglycerol-Based NIR Fluorescence Nanoplatform for Mitochondria-Specific Cell Imaging.

    Science.gov (United States)

    Dong, Chunhong; Liu, Zhongyun; Liu, Junqing; Wu, Changzhu; Neumann, Falko; Wang, Hanjie; Schäfer-Korting, Monika; Kleuser, Burkhard; Chang, Jin; Li, Wenzhong; Ma, Nan; Haag, Rainer

    2016-09-01

    Considering the critical role of mitochondria in the life and death of cells, non-invasive long-term tracking of mitochondria has attracted considerable interest. However, a high-performance mitochondria-specific labeling probe with high photostability is still lacking. Herein a highly photostable hyperbranched polyglycerol (hPG)-based near-infrared (NIR) quantum dots (QDs) nanoplatform is reported for mitochondria-specific cell imaging. Comprising NIR Zn-Cu-In-S/ZnS QDs as extremely photostable fluorescent labels and alkyl chain (C12 )/triphenylphosphonium (TPP)-functionalized hPG derivatives as protective shell, the tailored QDs@hPG-C12 /TPP nanoprobe with a hydrodynamic diameter of about 65 nm exhibits NIR fluorescence, excellent biocompatibility, good stability, and mitochondria-targeted ability. Cell uptake experiments demonstrate that QDs@hPG-C12 /TPP displays a significantly enhanced uptake in HeLa cells compared to nontargeted QDs@hPG-C12 . Further co-localization study indicates that the probe selectively targets mitochondria. Importantly, compared with commercial deep-red mitochondria dyes, QDs@hPG-C12 /TPP possesses superior photostability under continuous laser irradiation, indicating great potential for long-term mitochondria labeling and tracking. Moreover, drug-loaded QDs@hPG-C12 /TPP display an enhanced tumor cell killing efficacy compared to nontargeted drugs. This work could open the door to the construction of organelle-targeted multifunctional nanoplatforms for precise diagnosis and high-efficient tumor therapy.

  16. Adsorption behaviors of Hg(II) on chitosan functionalized by amino-terminated hyperbranched polyamidoamine polymers.

    Science.gov (United States)

    Ma, Fang; Qu, Rongjun; Sun, Changmei; Wang, Chunhua; Ji, Chunnuan; Zhang, Ying; Yin, Ping

    2009-12-30

    The adsorption behaviors of Hg(II) on adsorbents, chitosan functionalized by generation 1.0-3.0 of amino-terminated hyperbranched polyamidoamine polymers (denoted as CTS-1.0, CTS-2.0 and CTS-3.0, respectively), were studied. The optimum pH corresponding to the maximum adsorption capacities was found to be 5.0 for the three adsorbents. The experimental equilibrium data of Hg(II) on the three adsorbents were fitted to the Freundlich and the Langmuir models, and it is found that the Langmuir isotherm was the best fitting model to describe the equilibrium adsorption. The kinetics data indicated that the adsorption process of Hg(II) ions on CTS-1.0, CTS-2.0 and CTS-3.0 were governed by the film diffusion and followed pseudo-second-order rate model. Thermodynamic analysis and FTIR analysis revealed that the adsorption behaviors of Hg(II) ions on the three adsorbents could be considered as spontaneous, endothermic and chemical sorption process, resulting in their higher adsorption capacities at higher temperature.

  17. Hyperbranched polysiloxane functionalized graphene oxide for dicyclopentadiene bisphenol dicyanate ester nanocomposites with high performance

    Directory of Open Access Journals (Sweden)

    H. X. Yan

    2014-06-01

    Full Text Available We report an efficient and novel method to functionalize graphene oxide (GO with hyperbranched polysiloxane and successfully compound them with dicyclopentadiene bisphenol dicyanate ester (DCPDCE to prepare nanocomposites. X-ray photoelectron spectroscopy (XPS and Fourier-transform infrared spectra (FT-IR were employed to examine the surface functionalization of GO. The effects of functionalized GO on the curing reaction, mechanical, dielectric and thermal properties of DCPDCE resin were investigated systematically. Results of DSC show that the addition of modified GO can facilitate the curing reaction of DCPDCE and decrease the curing temperature of DCPDCE. Compared with pure DCPDCE resin, the impact and flexural strengths of the nanocomposite materials are improved markedly with up to 66 and 50% increasing magnitude, respectively. Meanwhile, the modified GO/DCPDCE systems exhibit lower dielectric constant and loss than pure DCPDCE resin over the testing frequency from 10 to 60 MHz. In addition, the thermal stability and moisture resistance of modified GO/DCPDCE nanocomposties are also superior to that of pure DCPDCE resin.

  18. Development of novel electrically conductive scaffold based on hyperbranched polyester and polythiophene for tissue engineering applications.

    Science.gov (United States)

    Jaymand, Mehdi; Sarvari, Raana; Abbaszadeh, Parisa; Massoumi, Bakhshali; Eskandani, Morteza; Beygi-Khosrowshahi, Younes

    2016-11-01

    A novel electrically conductive scaffold containing hyperbranched aliphatic polyester (HAP), polythiophene (PTh), and poly(ε-caprolactone) (PCL) for regenerative medicine application was succesfully fabricated via electrospinning technique. For this purpose, the HAP (G4; fourth generation) was synthesized via melt polycondensation reaction from tris(methylol)propane and 2,2-bis(methylol)propionic acid (bis-MPA). Afterward, the synthesized HAP was functionalized with 2-thiopheneacetic acid in the presence of N,N-dicyclohexyl carbodiimide, and N-hydroxysuccinimide as coupling agent and catalyst, respectively, to afford a thiophene-functionalized G4 macromonomer. This macromonomer was subsequently used in chemical oxidation copolymerization with thiophene monomer to produce a star-shaped PTh with G4 core (G4-PTh). The solution of the G4-PTh, and PCL was electrospun to produce uniform, conductive, and biocompatible nanofibers. The conductivity, hydrophilicity, and mechanical properties of these nanofibers were investigated. The biocompatibility of the electrospun nanofibers were evaluated by assessing the adhesion and proliferation of mouse osteoblast MC3T3-E1 cell line and in vitro degradability to demonstrate their potential uses as a tissue engineering scaffold. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 2673-2684, 2016.

  19. Rational Design of Hyperbranched Nanowire Systems for Tunable Superomniphobic Surfaces Enabled by Atomic Layer Deposition

    Energy Technology Data Exchange (ETDEWEB)

    Bielinski, Ashley R.; Boban, Mathew; He, Yang; Kazyak, Eric; Lee, Duck Hyun; Wang, Chongmin; Tuteja, Anish; Dasgupta, Neil P.

    2017-01-24

    A method for tunable control of geometry in hyperbranched ZnO nanowire (NW) systems is reported, which enables the rational design and fabrication of superomniphobic surfaces. Branched NWs with tunable density and orientation were grown via a sequential hydrothermal process, in which atomic layer deposition (ALD) was used for NW seeding, disruption of epitaxy, and selective blocking of NW nucleation. This approach allows for the rational design and optimization of three-level hierarchical structures, in which the geometric parameters of each level of hierarchy can be individually controlled. We demonstrate the coupled relationships between geometry and contact angle for a variety of liquids, which is supported by mathematical models of structural superomniphobicity. The highest performing superomniphobic surface was designed with three levels of hierarchy and achieved the following advancing/receding contact angles, water: 172°/170°, hexadecane: 166°/156°, octane: 162°/145°, and heptane: 160°/130°. Low surface tension liquids were shown to bounce off the surface from a height of 7 cm without breaking through and wetting. This approach demonstrates the power of ALD as an enabling technique for hierarchical materials by design, spanning the macro, micro, and nano length scales.

  20. Bisphenol-A epoxy resin reinforced and toughened by hyperbranched epoxy resin

    Institute of Scientific and Technical Information of China (English)

    ZHANG Daohong; JIA Demin; HUANG Xianbo

    2007-01-01

    The study on toughening and reinforcing of bisphenol-A epoxy resin is one of important developmental direction in the field.This paper reports a one-pot synthesis of aromatic polyester hyperbranched epoxy resin HTDE-2,an effect of HTDE-2 content on the mechanical and thermal performance of the bisphenol-A (E51)/HTDE-2 hybrid resin in detail.Fourier transform infrared (FT-IR) spectrometer,scanning electronic microscopy (SEM),differential scanning calorimetry (DSC),thermogravimetric analysis (TGA),dynamic mechanical thermal analysis (DMA) and molecular simulation technology are used to study the structure of HTDE-2,performance and toughening and reinforcing mechanism of the HTDE-2/E51 hybrid resin.It has been shown that the content of HTDE-2 has an important effect on the performance of the hybrid resin,and the performance of the HTDE-2/E51 blends has maximum with the increase in HTDE-2 content.The impact strength and fracture toughness of the hybrid resin with 9 wt-% HTDE-2 are almost 3.088 and 1.749 times of E51 performance respectively,furthermore,the tensile and flexural strength can also be enhanced about 20.7% and 14.2%,respectively.The glass transition temperature and thermal degradation temperature,however,are found to decrease to some extent.

  1. Reversible Self-Assembly of Backbone-Thermoresponsive Long Chain Hyperbranched Poly(N-Isopropyl Acrylamide

    Directory of Open Access Journals (Sweden)

    Ting-Ting Liu

    2016-01-01

    Full Text Available In this paper, we mainly described the reversible self-assembly of a backbone-thermoresponsive, long-chain, hyperbranched poly(N-isopropyl acrylamide (LCHBPNIPAM in aqueous solution. Here, we revealed a reversible self-assembly behavior of LCHBPNIPAM aqueous solution derived from temperature. By controlling the temperature of LCHBPNIPAM aqueous solution, we tune the morphology of the LCHBPNIPAM self-assemblies. When the solution temperature increased from the room temperature to the lower critical solution temperature of PNIPAM segments, LCHBPNIPAM self-assembled from multi-compartment vesicles into solid micelles. The morphology of LCHBPNIPAM self-assemblies changed from solid micelles to multi-compartment vesicles again when the temperature decreased back to the room temperature. The size presented, at first, an increase, and then a decrease, tendency in the heating-cooling process. The above thermally-triggered self-assembly behavior of LCHBPNIPAM aqueous solution was investigated by dynamic/static light scattering, transmission electron microscopy, atomic force microscopy, fluorescence spectroscopy, 1H nuclear magnetic resonance in D2O, and attenuated total reflectance Fourier transform infrared spectroscopy. These results indicated that LCHBPNIPAM aqueous solution presents a reversible self-assembly process. The controlled release behaviors of doxorubicin from the vesicles and micelles formed by LCHBPNIPAM further proved the feasibility of these self-assemblies as the stimulus-responsive drug delivery system.

  2. Adsorption of Pb(II) from aqueous solution by silica-gel supported hyperbranched polyamidoamine dendrimers.

    Science.gov (United States)

    Niu, Yuzhong; Qu, Rongjun; Sun, Changmei; Wang, Chunhua; Chen, Hou; Ji, Chunnuan; Zhang, Ying; Shao, Xia; Bu, Fanling

    2013-01-15

    The adsorption properties of silica-gel supported hyperbranched polyamidoamine dendrimers (SiO(2)-G0-SiO(2)-G4.0) have been investigated by batch method. The effect of pH of the solution, contact time, initial Pb(II) ion concentration, temperature and coexisting metal ions have been demonstrated. The results indicated that the optimum pH value was 5. Adsorption kinetics was found to follow the pseudo-second-order model and controlled by film diffusion. The adsorption isotherms were fitted by Langmuir, Freundlich and Dubinin-Radushkevich (D-R) isotherm models. Langmuir isotherm model was found to be more suitable to describe the equilibrium data, suggesting the uptake of Pb(II) ions by monolayer adsorption. From D-R isotherm model, the calculated mean free energy E demonstrated the adsorption processes occurred by chemical ion-exchange mechanism. FTIR analysis revealed that amine groups were mainly responsible for the adsorption of Pb(II) by amino-terminated adsorbents, while CO of ester groups also participated in the adsorption process of ester-terminated ones. The adsorbents can selectively adsorb Pb(II) from binary ion systems in the presence of Mn(II), Cu(II), Co(II), and Ni(II). Based on the results, it is concluded that SiO(2)-G0-SiO(2)-G4.0 had great potential for the removal of Pb(II) from aqueous solution.

  3. The surface characteristics of hyperbranched polyamide modified corncob and its adsorption property for Cr(VI)

    Science.gov (United States)

    Lin, Hai; Han, Shaoke; Dong, Yingbo; He, Yinhai

    2017-08-01

    A low-cost anion adsorbent for Cr(VI) effectively removing was synthesized by hyperbranched polyamide modified corncob (HPMC). Samples were characterized by Brunauer-Emmett-Teller (BET) surface area analysis, field-emission scanning electron microscopy (FE-SEM) with energy-dispersive X-ray spectroscopy, Fourier transform infrared (FTIR) and zeta potential analysis. Kinetics, isotherms and thermodynamics studies of HPMC for Cr(VI) adsorption were investigated in batch static experiments, in the temperature range of 25-45 °C, pH = 2.0. Results showed that the adsorption was rapid and stable, with the uptake capacity higher than 80% after 30 min. Adsorption behavior and rate-controlling mechanisms were analyzed using three kinetic models (pseudo-first order, pseudo-second order, intra-particle kinetic model). Kinetic studies showed that the adsorption of HPMC to Cr(VI) relied the pseudo-second-order model, and controlled both by the intra-particle diffusion and film diffusion. Equilibrium data was tested by Langmuir and Freundlich adsorption isotherm models. Langmuir model was more suitable to indicate a homogeneous distribution of active sites on HPMC and monolayer adsorption. The maximum adsorption capacity from the Langmuir model, qmax, was 131.6 mg/g at pH 2.0 and 45 °C for HPMC. Thermodynamic parameters revealed spontaneous and endothermic nature of the Cr(VI) adsorption onto HPMC.

  4. Capillary electrophoresis using core-based hyperbranched polyethyleneimine (CHPEI) static-coated capillaries.

    Science.gov (United States)

    Boonyakong, Cheerapa; Tucker, Sheryl A

    2009-10-01

    With unique 3-D architecture, the application of core-based hyperbranched polyethyleneimine (CHPEI), as a capillary coating in capillary electrophoresis, is demonstrated by manipulation of the electroosmotic mobility (EOF). CHPEI coatings (CHPEI5, M(w) approximately 5000 and CHPEI25, M(w) approximately 25,000) were physically adsorbed onto the inner surface of bare fused-silica capillary (BFS) via electrostatic interaction of the oppositely charged molecules by rinsing the capillaries with different CHPEI aqueous solutions. The EOF values of the coated capillaries were measured over the pH range of 4.0-9.0. At higher pH (pH >6) the coated capillary surface possesses excess negative charges, which causes the reversal of the EOF. The magnitudes of the EOF obtained from the coated capillaries were three-fold lower than that of BFS capillary. Desirable reproducibility of the EOF with % RSD (n = 5) capillaries were successfully utilized to separate phenolic compounds, B vitamins, as well as basic drugs and related compounds with reasonable analysis time (capillary and capillary).

  5. New core-shell hyperbranched chitosan-based nanoparticles as optical sensor for ammonia detection.

    Science.gov (United States)

    El-Sherbiny, Ibrahim M; Hefnawy, Amr; Salih, Ehab

    2016-05-01

    In this paper, preparation of new core-shell amino-terminated hyperbranched chitosan nanoparticles (HBCs-NH2) NPs is described. The synthesized nanoparticles were characterized using ninhydrin assay, FTIR, TGA, and FESEM. The newly prepared (HBCs-NH2) NPs were then used as a platform for facile and controlled synthesis of silver nanoparticles (AgNPs) which was confirmed using FTIR, UV-vis spectrometry, X-ray diffraction, SEM and HRTEM. Formation of the AgNPs was also noted upon changing the color of (HBCs-NH2) NPs suspension from colorless into yellow as well as through the appearance of surface plasmon resonance (SPR) peak at 400 nm. HRTEM showed a uniform and spherical morphology of the resulting HBCs-NH2 NPs with average size 400 nm, and the AgNPs were formed mainly on their surface with average size of 20-50 nm. The newly developed (HBCs-NH2) NPs-AgNPs showed a great potential as optical sensor for efficient detection of the ammonia concentration in solutions based on the change in the SPR.

  6. Isolation and characterization of a hyperbranched proteoglycan from Ganoderma lucidum for anti-diabetes.

    Science.gov (United States)

    Pan, Deng; Wang, Linqiang; Chen, Congheng; Hu, Bingwen; Zhou, Ping

    2015-03-01

    Presently, an efficient protein tyrosine phosphatase 1B (PTP1B) inhibitor, named FYGL-n, was isolated from Ganoderma Lucidum and characterized for its structure and bioactivity. Structure and chain conformation of FYGL-n based on both chemical and spectroscopic analysis showed that FYGL-n was a hyperbranched heteropolysaccharide bonded with protein via both serine and threonine residues by O-type glycoside, and showed a sphere observed by AFM. Specifically, monosaccharide composition indicated that FYGL-n consisted of D-arabinose, D-galactose, L-rhamnose and D-glucose in a mole ratio of 0.08:0.21:0.24:0.47, with a molecular mass of 72.9 kDa. The analysis of amino acids in FYGL-n indicated that there were 16 common amino acids, among which aspartic acid, glycine, serine, alanine, glutamic acid and threonine were the dominant components. Also it was demonstrated that FYGL-n could inhibit the PTP1B activity on a competitive mechanism in vitro.

  7. Photoluminescent hyperbranched poly(amido amine) containing β-cyclodextrin as a nonviral gene delivery vector.

    Science.gov (United States)

    Chen, Yan; Zhou, Linzhu; Pang, Yan; Huang, Wei; Qiu, Feng; Jiang, Xulin; Zhu, Xinyuan; Yan, Deyue; Chen, Qun

    2011-06-15

    Hyperbranched poly(amido amine)s (HPAAs) containing different amounts of β-cyclodextrin (β-CD) (HPAA-CDs) were synthesized in one-pot by Michael addition copolymerization of N,N'-methylene bisacrylamide, 1-(2-aminoethyl)piperazine, and mono-6-deoxy-6-ethylenediamino-β-CD. In comparison to pure HPAA, the fluorescence intensity of HPAA-CDs was enhanced significantly while the cytotoxicity became lower. Ascribed to plenty of amino groups and strong photoluminescence, HPAA-CDs could be used as nonviral gene delivery vectors, and the corresponding gene transfection was evaluated. The experimental results indicated that HPAA-CDs condensed the plasmid DNA very well. By utilizing the fluorescent properties of HPAA-CDs, the cellular uptake and gene transfection processes were tracked by flow cytometry and confocal laser scanning microscopy without any fluorescent labeling. The transfection efficiencies of HPAA-CDs were similar to that of pure HPAA. In addition, the inner cavities of β-CDs in HPAA-CDs could be used to encapsulate drugs through host--guest interaction. Therefore, the HPAA-CDs may have potential application in the combination of gene therapy and chemotherapy.

  8. Design of amino terminated hyperbranched polymer modified SBA-15 as adsorbent for dyes

    Science.gov (United States)

    Tao, Jin; Xiong, Jiaqing; Jiao, Chenlu; Chen, Yuyue; Lin, Hong

    2015-06-01

    The aim of the present work is to investigate the potential of amino terminated hyperbranched polymer (HBP) modified mesoporous silica SBA-15 (HBP-SBA) as adsorbent for the removal of cationic and anionic dyes from aqueous media. The HBP-SBA adsorbent can be facilely synthesized through two steps: carboxyl functionalization of SBA-15 (obtaining CA-SBA) via one-pot co-condensation, and further graft of HBP onto CA-SBA. As an intermediate, CA-SBA contains abundant carboxyl groups with an uniform distribution, which not only form efficiently the chemical bond with amino group by grafting HBP, but also contribute to adsorption by providing active adsorption sites. The results demonstrate HBP-SBA adsorbent that contains nanonetwork with substantial adsorption sites is successfully fabricated, showing high adsorption capacity and quick adsorption rate for dyes. Compared with SBA-15 and CA-SBA, HBP-SBA gets better adsorption property, and the maximum adsorption capacities are 399.5 mg/g for cationic dye and 609.7 mg/g for anionic dye, respectively.

  9. Surface and thermomechanical characterization of polyurethane networks based on poly(dimethylsiloxane and hyperbranched polyester

    Directory of Open Access Journals (Sweden)

    M. V. Pergal

    2013-10-01

    Full Text Available Two series of polyurethane (PU networks based on Boltorn® hyperbranched polyester (HBP and hydroxyethoxy propyl terminated poly(dimethylsiloxane (EO-PDMS or hydroxy propyl terminated poly(dimethylsiloxane (HPPDMS, were synthesized. The effect of the type of soft PDMS segment on the properties of PUs was investigated by Fourier transform infrared spectroscopy (FTIR, contact angle measurements, surface free energy determination, X-ray photoelectron spectroscopy (XPS, scanning electron microscopy (SEM, atomic force microscopy (AFM, dynamic mechanical thermal analysis (DMTA and differential scanning calorimetry (DSC. The surface characterization of PUs showed existence of slightly amphiphilic character and it revealed that PUs based on HP-PDMS have lower surface free energy, more hydrophobic surface and better waterproof performances than PUs based on EO-PDMS. PUs based on HPPDMS had higher crosslinking density than PUs based on EO-PDMS. DSC and DMTA results revealed that these newlysynthesized PUs exhibit the glass transition temperatures of the soft and hard segments. DMTA, SEM and AFM results confirmed existence of microphase separated morphology. The results obtained in this work indicate that PU networks based on HBP and PDMS have improved surface and thermomechanical properties.

  10. Hydrophobic acrylic hard coating by surface segregation of hyper-branched polymers

    Science.gov (United States)

    Haraguchi, Masayuki; Hirai, Tomoyasu; Ozawa, Masaaki; Miyaji, Katsuaki; Tanaka, Keiji

    2013-02-01

    The ability of hyperbranched polymers (HBPs) to preferentially segregate to the surface of its matrix owing to its unique structure makes it a good candidate as a surface modifier. One particular challenge in its application as an efficient surface modifier, however, is its possible elimination from the surface due to the lack of attachments between a HBP (modifier) and its host material (polymer matrix). Here, we present a novel approach to efficiently prevent the removal of HBPs from the surface of its host material by directly reacting a HBP containing fluoroalkyl segments (F-HBP) to a multi-functional acrylate monomer prior to curing. We also have characterized surface structure and wettability of the acrylic hard coating material by X-ray photoelectron spectroscopic and contact angle measurements, respectively. The results show that since F-HBP was segregated at the surface, the surface became hydrophobic and more stable. Thus, we claim that our approach results in the formation of a water-repellent acrylic hard coating material.

  11. Temperature-Responsive Biocompatible Copolymers Incorporating Hyperbranched Polyglycerols for Adjustable Functionality

    Directory of Open Access Journals (Sweden)

    Alan J. House

    2011-08-01

    Full Text Available Temperature-triggered copolymers are proposed for a number of bio-applications but there is no ideal material platform, especially for injectable drug delivery. Options are needed for degradable biomaterials that not only respond to temperature but also easily accommodate linkage of active molecules. A first step toward realizing this goal is the design and synthesis of the novel materials reported herein. A multifunctional macromer, methacrylated hyperbranched polyglycerol (HPG-MA with an average of one acrylate unit per copolymer, was synthesized and copolymerized with N-isopropylacrylamide (NIPAAm, hydroxyethyl methacrylate-polylactide (HEMAPLA and acrylic acid (AAc. The potential to fully exploit the copolymers by modification of the multiple HPG hydroxyl groups will not be discussed here. Instead, this report focuses on the thermoresponsive, biocompatible, and degradation properties of the material. Poly(NIPAAm-co-HEMAPLA-co-AAc-co-HPG-MA displayed increasing lower critical solution temperatures (LCST as the HPG content increased over a range of macromer ratios. For the copolymer with the maximum HPG incorporation (17%, the LCST was ~30 °C. In addition, this sample showed no toxicity when human uterine fibroid cells were co-cultured with the copolymer for up to 72 h. This copolymer lost approximately 92% of its mass after 17 hours at 37 °C. Thus, the reported biomaterials offer attractive properties for the design of drug delivery systems where orthogonally triggered mechanisms of therapeutic release in relatively short time periods would be attractive.

  12. Non-isothermal crystallization kinetics of polypropylene and hyperbranched polyester blends☆

    Institute of Scientific and Technical Information of China (English)

    Qingchun Fan; Feihong Duan; Huaibing Guo; Tian Wu

    2015-01-01

    Polypropylene (PP) with different contents of the second generation hyperbranched polyester (HBP) is prepared by melt blending method. The non-isothermal crystallization kinetics of PP and PP/HBP blends is investigated under differential scanning calorimetry (DSC). The Mo equation is used to analyze the DSC data. The results show that the Mo theory is suitable for crystal ization kinetics of the blends. Fast cooling rate is not good for crys-tallizing and nucleating. The values of half crystal ization time (t1/2), crystal ization enthalpy (ΔHc) and temper-ature range (ΔT) of PP/HBP blends decrease when HBP is added. The required cooling rate of PP is higher than that of PP/HBP blends in order to reach the same relative crystal inity. Crystallization rate increases with the ad-dition of HBP. The crystallization rate reaches a maximum when the content of HBP is 5%. In addition, the activa-tion energies of PP and PP/HBP blends are calculated by Kissinger equation, revealing that the content of HBP has a little effect on the crystallization activation energy.

  13. Modified Hyperbranched Polyglycerol as Dispersant for Size Control and Stabilization of Gold Nanoparticles in Hydrocarbons

    Science.gov (United States)

    Shen, Yanyu; He, Guijin; Guo, Yongsheng; Xie, Hujun; Fang, Wenjun

    2017-09-01

    Hyperbranched polyglycerol (HPG) is modified with dodecanethiol (DS) via the "thiol-ene" click reaction to obtain an amphiphilic product DSHPG. The molecular structures of DSHPG samples are characterized by NMR, FTIR, and GPC, and the thermal behaviors are characterized by DSC and TGA. Gold nanoparticles (Au NPs) are prepared with DSHPG as the stabilizer and surface-modification reagent. The size of Au NPs can be tuned by changing the molecular weight of HPG. It is observed that the HPG molecular weights of 1123, 3826, and 55,075 lead to the NP diameters of 4.1 nm for Au@DSHPG-1, 9.7 nm for Au@DSHPG-2, and 15.1 nm for Au@DSHPG-3, respectively. The morphology and size of Au NPs are characterized by TEM and DLS. Especially, the dispersion abilities of Au NPs in different pure solvents and co-solvent mixtures are investigated. The long alkyl chains on DSHPG give the ability of Au NPs to be well dispersed in nonpolar solvents. Hydrocarbon-based nanofluids can be obtained from the hydrophobic Au NPs dispersed into a series of hydrocarbons. The dispersion stability for Au NPs in hydrocarbons is monitored by UV-Vis spectroscopy, and the relative concentration of Au NPs is observed to still maintain over 80% after 3600 h.

  14. Quantum dots-hyperbranched polyether hybrid nanospheres towards delivery and real-time detection of nitric oxide

    DEFF Research Database (Denmark)

    Liu, Shuiping; Gu, Tianxun; Fu, Jiajia;

    2014-01-01

    In this work, novel hybrid nanosphere vehicles were synthesized for nitric oxide (NO) donating and real-time detection. The hybrid nanosphere vehicles consist of cadmium selenide quantum dots (CdSe QDs) as NO fluorescent probes, and the modified hyperbranched polyether (mHP)-based diazeniumdiolat...... mechanism. The low cell-toxicity of QDs-mHP-NO nanospheres was verified by means of MTT assay on L929 cells viability. The QDs-mHP-NO nanospheres provide perspectives for designing a new class of biocompatible NO donating and imaging systems....

  15. SYNTHESIS AND CHARACTERIZATION OF HYPERBRANCHED POLY(ESTER-AMIDE)S BASED ON GALLIC ACID AND DL-2-AMINOBUTYRIC ACID

    Institute of Scientific and Technical Information of China (English)

    Ya-li Su; Xiu-ru Li; Yue-jin Tong; Yue-sheng Li

    2004-01-01

    A novel AB3-type monomer was prepared from gallic acid and DL-2-aminobutyric acid, and used for the synthesis of the biocompatible hyperbranched poly(ester-amide)s by self-polycondensation. The polymers were characterized via FTIR and NMR spectroscopy and thermal analysis, and the average degree of branching of the polymers was estimated to be 0.75.The polymers with abundant acetyl end groups were found to be amorphous with lower intrinsic viscosity, better thermal stability and excellent solubility.

  16. Leukocyte-Mimicking Stem Cell Delivery via In situ Coating of Cells with a Bioactive Hyperbranched Polyglycerol (HPG)

    Science.gov (United States)

    Jeong, Jae Hyun; Schmidt, John J.; Kohman, Richie E.; Zill, Andrew T.; DeVolder, Ross J.; Smith, Cartney E.; Lai, Mei-Hsiu; Shkumatov, Artem; Jensen, Tor W.; Schook, Lawrence G.; Zimmerman, Steven C.; Kong, Hyunjoon

    2013-01-01

    Since stem cells emerged as a new generation of medicine, there are increasing efforts to deliver the stem cells to a target tissue via intravascular injection. However, the therapeutic stem cells lack a capacity to detect and adhere to the target tissue. Therefore, this study presents synthesis of a bioactive hyper-branched polyglycerol (HPG) which can non-invasively associate with stem cells and further guide them to target sites, such as inflamed endothelium. The overall process is analogous to the way in which leukocytes are mobilized to the injured endothelium. PMID:23590123

  17. Leukocyte-mimicking stem cell delivery via in situ coating of cells with a bioactive hyperbranched polyglycerol.

    Science.gov (United States)

    Jeong, Jae Hyun; Schmidt, John J; Kohman, Richie E; Zill, Andrew T; DeVolder, Ross J; Smith, Cartney E; Lai, Mei-Hsiu; Shkumatov, Artem; Jensen, Tor W; Schook, Lawrence G; Zimmerman, Steven C; Kong, Hyunjoon

    2013-06-19

    Since stem cells emerged as a new generation of medicine, there are increasing efforts to deliver stem cells to a target tissue via intravascular injection. However, the therapeutic stem cells lack the capacity to detect and adhere to the target tissue. Therefore, this study presents synthesis of a bioactive hyperbranched polyglycerol (HPG) that can noninvasively associate with stem cells and further guide them to target sites, such as inflamed endothelium. The overall process is analogous to the way in which leukocytes are mobilized to the injured endothelium.

  18. Photovoltaics: Highly Efficient Hybrid Photovoltaics Based on Hyperbranched Three-Dimensional TiO 2 Electron Transporting Materials (Adv. Mater. 18/2015)

    KAUST Repository

    Mahmood, Khalid

    2015-05-01

    Solution-processed hybrid photovoltaics are a potentially disruptive third-generation solar cell technology. On page 2859, A. Amassian and co-workers demonstrate that an electrospun hyperbranched electron-transporting material is capable of achieving highly efficient hybrid solar cells across different platforms, including lead-halide perovskites (15.5%) and dye-sensitized solar cells (11.2%).

  19. Synthesis of Aromatic Hyperbranched Polyesters and Modification of Their End-groups%全芳型超支化聚酯的合成及端基改性

    Institute of Scientific and Technical Information of China (English)

    唐黎明

    2001-01-01

    Soluble aromatic hyperbranched polyesters with controlled viscosities have been preparedby melt polycondensation of sililated 5-acetoxyisophathalic acid with sililated p-tert-butyl benzoic acidin various molar ratios. By further reaction with thionyl chloride and propargyl alcohol successively,the endgroups of the crude polyester were transferred into ethynylic groups in 78. 2% yield as calculat-ed by 1H NMR spectra.

  20. Calculation of the (liquid + liquid) equilibrium of solutions of hyperbranched polymers with the lattice-cluster theory combined with an association model

    Energy Technology Data Exchange (ETDEWEB)

    Zeiner, T. [Technical University of Dortmund, Lehrstuhl fuer Fluidverfahrenstechnik, Emil-Figge Str. 70, 44227 Dortmund (Germany); Browarzik, C. [Technical University of Berlin, Institut fuer Prozess- und Verfahrenstechnik (TK7), Fachgebiet Thermodynamik und thermische Verfahrenstechnik, Strasse des 17, Juni 135, 10623 Berlin (Germany); Browarzik, D., E-mail: dieter.browarzik@chemie.uni-halle.de [Martin-Luther University Halle-Wittenberg, Institut fuer Chemie/Physikalische Chemie, 06099 Halle (Germany); Enders, S. [Technical University of Berlin, Institut fuer Prozess- und Verfahrenstechnik (TK7), Fachgebiet Thermodynamik und thermische Verfahrenstechnik, Strasse des 17, Juni 135, 10623 Berlin (Germany)

    2011-12-15

    Highlights: > The (liquid + liquid) equilibrium of hyperbranched polyester solutions is calculated. > The solvents are n-alkanes, propan-1-ol, and butan-1-ol. > The lattice-cluster theory is combined with a chemical association model. > The solvent molecules are assumed to be linear chains of segments. > The calculations agree reasonably well with the experimental data. - Abstract: The (liquid + liquid) equilibrium of solutions of hyperbranched polyesters is calculated with the lattice-cluster theory (LCT) combined with a chemical association model. The considered solvents are n-alkanes as well as propan-1-ol and butan-1-ol. The structure of the solvents is also considered in the framework of the LCT, assuming the solvent molecules as linear chains of several segments. For polymer solutions with the non-associating n-alkanes only the self association of the hyperbranched polymer molecules has to be considered by the chemical association lattice model (CALM). For the solutions of the type alcohol + hyperbranched polymer additionally the cross association is taken into account by a modified version of the extended chemical association lattice model (ECALM). The association effects are proved to influence strongly the phase equilibrium. Calculating the cloud-point curve and the critical point the polydispersity of the polymer samples is neglected. There is a reasonable agreement of the calculated curves with the experimental data taken from the literature.

  1. Bioreducible unimolecular micelles based on amphiphilic multiarm hyperbranched copolymers for triggered drug release

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    A novel type of bioreducible amphiphilic multiarm hyperbranched copolymer (H40-star-PLA-SS-PEG) based on Boltorn H40 core,poly(L-lactide) (PLA) inner-shell,and poly(ethylene glycol) (PEG) outer-shell with disulfide-linkages between the hydrophobic and hydrophilic moieties was developed as unimolecular micelles for controlled drug release triggered by reduction.The obtained H40-star-PLA-SS-PEG was characterized in detail by nuclear magnetic resonance (NMR),Fourier transform infrared (FTIR),gel permeation chromatography (GPC),differential scanning calorimeter (DSC),and thermal gravimetric analysis (TGA).Transmission electron microscopy (TEM) and dynamic light scattering (DLS) analyses suggested that H40-star-PLA-SS-PEG formed stable unimolecular micelles in aqueous solution with an average diameter of 19 nm.Interestingly,these micelles aggregated into large particles rapidly in response to 10 mM dithiothreitol (DTT),most likely due to shedding of the hydrophilic PEG outer-shell through reductive cleavage of the disulfide bonds.As a hydrophobic anticancer model drug,doxorubicin (DOX) was encapsulated into these reductive unimolecular micelles.In vitro release studies revealed that under the reduction-stimulus,the detachment of PEG outer-shell in DOX-loaded micelles resulted in a rapid drug release.Flow cytometry and confocal laser scanning microscopy (CLSM) measurements indicated that these DOX-loaded micelles were easily internalized by living cells.Methyl tetrazolium (MTT) assay demonstrated a markedly enhanced drug efficacy of DOX-loaded H40-star-PLA-SS-PEG micelles as compared to free DOX.All of these results show that these bioreducible unimolecular micelles are promising carriers for the triggered intracellular delivery of hydrophobic anticancer drugs.

  2. 188Re-LABELED HYPERBRANCHED POLYSULFONAMINE AS A ROBUST TOOL FOR TARGETED CANCER DIAGNOSIS AND RADIOIMMUNOTHERAPY

    Institute of Scientific and Technical Information of China (English)

    Nan Li; Yue Jin; Li-zhe Xue; Pei-yong Li; De-yue Yan; Xin-yuan Zhu

    2013-01-01

    Hyperbranched polysulfonamine (HPSA) is a promising biomaterial due to its highly branched spherical architecture and efficient intracellular translocation.To realize the functionalization of HPSA,both N-succinimidyl 3-(2-pyridyldithio) propionate (SPDP) for tethering the human-mouse chimeric monoclonal antibody CH12 and N-hydroxy succinimidyl S-acetylmercaptoacetyltriglycinate (NHS-MAG3) for labeling 188Re were sequentially grafted onto the primary amine terminals of HPSA via covalent linkages,attaining the SPDP-HPSA-MAG3 intermediate.In order to reserve the structural integrity of CH12,the fragment crystallizable (Fc) region was also processed by oxidation of oligosaccharide moieties with sodium periodate and then reacted with N-(κ-maleimidoundecanoic acid) hydrazide (KMUH).After chelating 188Re with MAG3 group,the SPDP was reduced to PDP and connected onto the maleinimide group at the Fc region.As a result,both the epidermal growth factor receptor vIII (EGFRvIII) targeted monoclonal antibody CH12 and the radionuclide 188Re were conjugated to the HPSA-based vehicles,forming the 188Re-labeled and CH12-tethered HPSA (CH12-HPSA-188Re).The molecular weight and in vitro stability of CH12-HPSA-l88Re were evaluated by gel electrophoresis and paper chromatography.On one hand,the CH12-HPSA-188Re could specifically bind to the EGFRvIII-positive human hepatocarcinoma cells in vitro.On the other hand,it could also target at the tumor tissue of nude mice in vivo.Hence,the CH12-HPSA-188Re could effectively target at the human hepatocarcinoma and facilitate the tumor detection and targeted radioimmunotherapy.

  3. Influences of hyperbranched poly(amide-ester) on the properties of poly(butylene succinate)

    Energy Technology Data Exchange (ETDEWEB)

    Run, Mingtao, E-mail: lhbx@hbu.cn [Key Laboratory of Chemical Biology of Hebei Province, College of Chemistry and Environmental Science, Hebei University, Baoding 071002 (China); Wang, Jian; Yao, Meng; Guo, Lijie; Wang, Hai-jun [Key Laboratory of Chemical Biology of Hebei Province, College of Chemistry and Environmental Science, Hebei University, Baoding 071002 (China); Ba, Xinwu, E-mail: baxw@hbu.cn [Key Laboratory of Chemical Biology of Hebei Province, College of Chemistry and Environmental Science, Hebei University, Baoding 071002 (China)

    2013-05-15

    The polymer blends of hyperbranched poly(amide-ester) and poly(butylene succinate) (HBP/PBS) were prepared by melt-blending method. The molecular interaction within the blends, phase morphology, crystal morphology, mechanical, rheological and dynamic mechanical properties were investigated by using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), tensile machine, polarized optical microscopy, rotational rheometer and dynamic mechanical analyzer (DMA), respectively. The results suggest that PBS and HBP have a certain compatibility at amorphous state. A certain number of H-bonding was detected between PBS and HBP phases and it influences the material properties. HBP not only serves partially as a nucleating agent for the crystallization of PBS but also plays a role of plasticizer for the rheology of PBS. The glass transition temperatures of the blends slightly decrease with increasing HBP content. The proper amount of HBP (4–6%) has a reinforcement effect on the PBS matrix at glassy state. However, the blend with 10%HBP content has an improved impact strength mainly due to the plasticization effect or H-bonding effect of HBP on PBS matrix. The storage modulus is increased with increasing HBP contents, and the loss modulus is much smaller than the storage modulus in each blend at glassy state. At rubbery state the storage modulus of different samples is independent of HBP content. The complex viscosity of the melt decreases with increasing HBP content; however, the blend with 10%HBP is a special sample because of its abnormal larger complex viscosity at low shear frequencies. In addition, the melt’s elasticity behavior increases slightly with increasing HBP content. - Highlights: ► H-bonding was detected between PBS and HBP phases by FTIR. ► HBP serves partly as a nucleating agent for the crystallization of PBS. ► HBP plays a role of plasticizer for PBS. ► The blend with 10%HBP has abnormal larger complex viscosity.

  4. Synthesis and Characterization of the Hyperbranched Polyester%超支化聚酯的合成与表征

    Institute of Scientific and Technical Information of China (English)

    曹胜光; 翁家宝

    2001-01-01

    The one-step synthesis of a hyperbranched polyester based upon 3,5-dihydroxy benzoic acid and 3,5-dihydroxy toluene has succeeded in getting hybranched polyester. This kind of hyperbranched polymer has showed to exhibit the properties of low viscosity and high solubility.%以3,5二羟基甲苯和3,5二羟基苯甲酸为原料,采用“一锅煮”的方法合成了超支化聚酯.通过不同的原料配比来控制超支化的向外的链扩展,每个分子形成大约2,4,8个酯结构的超支化臂.该超支化聚合物具有一定刚性的二维结构,不会产生分子链的缠结,而且显示出低粘度、低熔点和良好的溶解性等特点.

  5. Research Progress in Hyperbranched/Star Polymer Electrolyte%超支化/星形聚合物电解质的研究进展

    Institute of Scientific and Technical Information of China (English)

    任士通; 贺丽娟; 常贺飞; 党小飞; 张辽云; 李化毅

    2012-01-01

    Compared with liquid electrolyte, polymer electrolyte has widely attracted researchers' attention, and has the potential to replace organic liquid electrolyte because of the advantages such as easy processing, flexible design, light weight, safety and non-toxicity. Hyperbranched/star polymer with amorphousness, low glass transition temperature and unique topology has been studied as solid polymer electrolyte. In this review, research progress in hyperbranched/star polymer electrolyte is presented. Special interests are focused on the hyperbranched/star polymer-based electrolytes, hyperbranched/star polymer blend-based electrolyte. Besides, the application of hyperbranched/star polymer based single ion electrolyte for lithium ion battery is also prospected.%与液体电解质相比较,聚合物电解质以其易加工、设计灵活、质量轻、安全无毒的特点而受到人们的广泛关注,具有取代液态电解质的潜在应用价值,而超支化/星形聚合物以其无定形、低玻璃化转变温度、支化结构等特点可被用于固态电解质。本文综述了超支化/星形聚合物电解质材料的研究进展,重点介绍了超支化/星形聚合物基电解质和超支化/星形聚合物共混基电解质,并对超支化/星形聚合物单一离子导体在锂离子电池方面的应用前景作了概述。

  6. Living olefin polymerization processes

    Science.gov (United States)

    Schrock, Richard R.; Baumann, Robert

    1999-01-01

    Processes for the living polymerization of olefin monomers with terminal carbon-carbon double bonds are disclosed. The processes employ initiators that include a metal atom and a ligand having two group 15 atoms and a group 16 atom or three group 15 atoms. The ligand is bonded to the metal atom through two anionic or covalent bonds and a dative bond. The initiators are particularly stable under reaction conditions in the absence of olefin monomer. The processes provide polymers having low polydispersities, especially block copolymers having low polydispersities. It is an additional advantage of these processes that, during block copolymer synthesis, a relatively small amount of homopolymer is formed.

  7. Phosphazene-promoted anionic polymerization

    KAUST Repository

    Zhao, Junpeng

    2014-01-01

    In the recent surge of metal-free polymerization techniques, phosphazene bases have shown their remarkable potential as organic promoters/catalysts for the anionic polymerization of various types of monomers. By complexation with the counterion (e.g. proton or lithium cation), phosphazene base significantly improve the nucleophilicity of the initiator/chain-end resulting in rapid and usually controlled anionic/quasi-anionic polymerization. In this review, we will introduce the general mechanism, i.e. in situ activation (of initiating sites) and polymerization, and summarize the applications of such a mechanism on macromolecular engineering toward functionalized polymers, block copolymers and complex macromolecular architectures.

  8. Preparation of redox-degradable and tumor-targeted smart drug vehicle based on hyperbranched polyamidoamine%还原降解、肿瘤靶向的智能型超支化聚酰胺药物载体制备研究

    Institute of Scientific and Technical Information of China (English)

    王杨; 顾准; 徐琼

    2016-01-01

    Starting from the design of an ideal drug carrier,smart redox-degradable and tumor-targeted polymeric nanocarrier was fabricated by introducing functional monomers and using Michael addition polymerization and material surface modification. Firstly, redox-degradable hyperbranched polyamidoamine (DHPAA) was prepared by Michael addition polymerization taking N,N'-bis (acryloyl) cystamine and 1-(2-aminoethyl) piperazine as functional monomer. On this basis,graft copolymerization of polyethylene glycol and conjugation of folic acid were conducted on DHPAA to obtain stable and tumor-targeted smart hyperbranched polyamidoamine (FA-DHPAP). The structure and performance of polymer DHPAA were characterized by FTIR, NMR, DLS, Zeta potentiometer, Raman spectrometer and GPC. The structure and performance of polymer FA-DHPAP were characterized by NMR, DLS, Zeta potentiometer and TEM. The biocompatibility of the polymer DHPAA and FA-DHPAP as drug carrier was further confirmed by cytotoxicity test. The results showed that the smart hyperbranched polyamidoamine (FA-DHPAP) is environment-responsive and has good biocompatibility,thus it has great potential to be used as drug carrier for the tumor therapy.%从理想药物载体的设计角度出发,通过引入功能性单体,采用迈克尔加成聚合法以及材料表面改性的方法构建还原降解、肿瘤靶向的智能型聚合物纳米载体。首先,以N,N'-双(丙烯酰)胱胺和1-(2-胺乙基)哌嗪为单体聚合得到可还原降解的超支化聚酰胺胺(DHPAA)。在此基础上,通过接枝聚乙二醇和偶联叶酸得到稳定的、肿瘤靶向的智能型超支化聚酰胺胺(FA-DHPAP)。使用红外光谱、核磁共振、动态光散射(DLS)、Zeta电位仪、拉曼光谱和凝胶渗透色谱(GPC)对聚合物DHPAA结构和性能进行表征;使用核磁共振、动态光散射(DLS)、Zeta电位仪和透射电镜(TEM)对聚合物FA-DHPAP的结构和性能进行表征。通过细胞毒性实验对聚合

  9. Gratings in polymeric waveguides

    Science.gov (United States)

    Mishakov, G.; Sokolov, V.; Kocabas, A.; Aydinli, A.

    2007-04-01

    Laser-induced formation of polymer Bragg grating filters for Dense Wavelength Division Multiplexing (DWDM) applications is discussed. Acrylate monomers halogenated with both fluorine and chlorine, which possess absorption losses less than 0.25 dB/cm and wide choice of refractive indices (from 1.3 to 1.5) in the 1.5 μm telecom wavelength region were used. The monomers are highly intermixable thus permitting to adjust the refractive index of the composition within +/-0.0001. Moreover they are photocurable under UV exposure and exhibit high contrast in polymerization. These properties make halogenated acrylates very promising for fabricating polymeric waveguides and photonic circuits. Single-mode polymer waveguides were fabricated on silicon wafers using resistless contact lithography. Submicron index gratings have been written in polymer waveguides using holographic exposure with He-Cd laser beam (325 nm) through a phase mask. Both uniform and apodized gratings have been fabricated. The gratings are stable and are not erased by uniform UV exposure. The waveguide gratings possess narrowband reflection spectra in the 1.5 μm wavelength region of 0.4 nm width, nearly rectangular shape of the stopband and reflectivity R > 99%. The fabricated Bragg grating filters can be used for multiplexing/demultiplexing optical signals in high-speed DWDM optical fiber networks.

  10. Dethreading of a Photoactive Azobenzene-Containing Molecular Axle from a Crown Ether Ring: A Computational Investigation.

    Science.gov (United States)

    Tabacchi, Gloria; Silvi, Serena; Venturi, Margherita; Credi, Alberto; Fois, Ettore

    2016-06-17

    Pseudorotaxanes formed by a dibenzo[24]crown-8 ring (R) and a dialkylammonium axle bearing either two E- or two Z-azobenzene units (EE-A or ZZ-A) revealed useful for the construction of light-powered molecular machines and motors, as they provide the opportunity of photocontrolling self-assembly/disassembly processes. The potential energies profiles for the dethreading of these complexes have been investigated by adopting a combination of first-principles molecular dynamics, metadynamics and quantum-chemical geometry optimization approaches. While the dethreading of the EE-A axle is associated with a monotonic energy increase, for that of the ZZ-A axle a transition state and an intermediate structure, in which the components are still threaded together, are found. The rate determining step for the dethreading of the ZZ axle has a higher energy barrier than that of the EE axle, in agreement with the experimental kinetic data. Moreover, the results suggest that the elliptic shape of the ring cavity is important for discriminating between the E and Z terminal azobenzene during dethreading.

  11. Effects of block copolymer self-assembly on optical anisotropy in azobenzene-containing PS-b-PMMA films

    Science.gov (United States)

    Orofino, A. B.; Camezzana, M. F.; Galante, M. J.; Oyanguren, P. A.; Zucchi, I. A.

    2012-03-01

    Polystyrene-b-polymethylmethacrylate (PS-b-PMMA) was selected as the host for 4-(4-nitrophenylazo)aniline (Disperse Orange 3, DO3) based on a previous study of DO3/PMMA and DO3/PS binary blends. Selective location of DO3 into the PMMA block of the copolymer was expected during self-assembly of the block copolymer since a preferential interaction of DO3 with PMMA has been demonstrated. However, surface segregation of DO3 was found during the thermal annealing used to nanostructure the copolymer. To avoid this, a thermoplastic polymer (Azo-TP) was synthesized from the bulk reaction of DO3 and diglycidyl ether of bisphenol A (DGEBA). The choice of DGEBA as a co-reactant was an attempt to encourage the selective location of azo groups in the PMMA phase of PS-b-PMMA. An inspection of solutions of Azo-TP in PS and PMMA, corroborates the preferential affinity of Azo-TP for PMMA. The Azo-TP could be satisfactorily dissolved in PS-b-PMMA. We have investigated the growth and decay processes of the optically induced birefringence in films of PS-b-PMMA containing 12 wt% Azo-TP. The resulting materials showed a good photoinduced time response, high maximum birefringence and an elevated fraction of remnant anisotropy.

  12. Photoswitching of azobenzene-containing self-assembled monolayers as a tool for control over silicon surface electronic properties

    Science.gov (United States)

    Malyar, Ivan V.; Titov, Evgenii; Lomadze, Nino; Saalfrank, Peter; Santer, Svetlana

    2017-03-01

    We report on photoinduced remote control of work function and surface potential of a silicon surface modified with a photosensitive self-assembled monolayer consisting of chemisorbed azobenzene molecules (4-nitroazobenzene). It was found that the attachment of the organic monolayer increases the work function by hundreds of meV due to the increase in the electron affinity of silicon substrates. The change in the work function on UV light illumination is more pronounced for the azobenzene jacketed silicon substrate (ca. 250 meV) in comparison to 50 meV for the unmodified surface. Moreover, the photoisomerization of azobenzene results in complex kinetics of the work function change: immediate decrease due to light-driven processes in the silicon surface followed by slower recovery to the initial state due to azobenzene isomerization. This behavior could be of interest for electronic devices where the reaction on irradiation should be more pronounced at small time scales but the overall surface potential should stay constant over time independent of the irradiation conditions.

  13. Collaborative Research: Polymeric Multiferroics

    Energy Technology Data Exchange (ETDEWEB)

    Ren, Shenqiang [Temple Univ., Philadelphia, PA (United States). College of Engineering

    2017-04-20

    The goal of this project is to investigate room temperature magnetism and magnetoelectric coupling of polymeric multiferroics. A new family of molecular charge-transfer crystals has been emerged as a fascinating opportunity for the development of all-organic electrics and spintronics due to its weak hyperfine interaction and low spin-orbit coupling; nevertheless, direct observations of room temperature magnetic spin ordering have yet to be accomplished in organic charge-transfer solids. Furthermore, room temperature magnetoelectric coupling effect hitherto known multiferroics, is anticipated in organic donor-acceptor complexes because of magnetic field effects on charge-transfer dipoles, yet this is also unexplored. The PI seeks to fundamental understanding of the control of organic crystals to demonstrate and explore room temperature multiferroicity. The experimental results have been verified through the theoretical modeling.

  14. Application of hyperbranched rolling circle amplification for direct detection of mycobacterium tuberculosis in clinical sputum specimens.

    Directory of Open Access Journals (Sweden)

    Yang Liu

    Full Text Available BACKGROUND: Global tuberculosis (TB control is encumbered by the lack of a rapid and simple detection method for diagnosis, especially in low-resource areas. An isothermal amplification method, hyperbranched rolling circle amplification (HRCA, was optimized to detect Mycobacterium tuberculosis (Mtb in clinical sputum specimens. METHODS: A clinical validation study was performed to assess the diagnostic accuracy of HRCA. In order to analyze the detection limit of HRCA under optimal conditions, the method was initially used to detect purified H37Rv strain DNA and culture suspensions. Next, three strains of Mycobacterium tuberculosis complex (MTC and eight strains of non-tuberculosis mycobacterium (NTM were analyzed in order to evaluate specificity. Sputum specimens from 136 patients with diagnosed pulmonary TB, 38 lung cancer patients, and 34 healthy donors were tested by HRCA to validate the clinical application of HRCA for the rapid detection of Mtb. RESULTS: The detection limit of HRCA for purified H37Rv DNA and culture suspensions was 740 aM and 200cfu/ml, respectively. The results of all MTC strains were positive in contrast to the NTM specimens which were all negative. The detection sensitivity for the 136 sputum specimens from TB patients was 77.2% (105/136, which was slightly lower than that of quantitative real-time PCR(79.4%, 108/136 and culture (80.9%,110/136. The sensitivity of all three methods was statistically higher than smear microscopy (44.9%, 61/136. The overall specificity of HRCA was 98.6% (71/72 which was similar to that of quantitative real-time PCR (qRT-PCR and smear/culture methods (100%, 72/72. CONCLUSIONS: Use of the HRCA assay for detection of Mtb within clinical sputum specimens was demonstrated to be highly sensitive and specific. Moreover, the performance of HRCA is simple and cost-effective compared with qRT-PCR and is less time consuming than culture. Therefore, HRCA is a promising TB diagnostic tool that can be

  15. Polymer nanostructures synthesized by controlled living polymerization for tumor-targeted drug delivery.

    Science.gov (United States)

    Wang, Christine E; Stayton, Patrick S; Pun, Suzie H; Convertine, Anthony J

    2015-12-10

    The development of drug delivery systems based on well-defined polymer nanostructures could lead to significant improvements in the treatment of cancer. The design of these therapeutic nanosystems must account for numerous systemic and circulation obstacles as well as the specific pathophysiology of the tumor. Nanoparticle size and surface charge must also be carefully selected in order to maintain long circulation times, allow tumor penetration, and avoid clearance by the reticuloendothelial system (RES). Targeting ligands such as vitamins, peptides, and antibodies can improve the accumulation of nanoparticle-based therapies in tumor tissue but must be optimized to allow for intratumoral penetration. In this review, we will highlight factors influencing the design of nanoparticle therapies as well as the development of modern controlled "living" polymerization techniques (e.g. ATRP, RAFT, ROMP) that are leading to the creation of sophisticated new polymer architectures with discrete spatially-defined functional modules. These innovative materials (e.g. star polymers, polymer brushes, macrocyclic polymers, and hyperbranched polymers) combine many of the desirable properties of traditional nanoparticle therapies while substantially reducing or eliminating the need for complex formulations.

  16. Highly Active New a-Diimine Nickel Catalyst for Polymerization of Ethylene

    Institute of Scientific and Technical Information of China (English)

    YUAN Jian-chao; LIU Yu-feng; MEI Tong-jian; WANG Xue-hu

    2011-01-01

    A new a-diimine ligand 1a,bis[N,N'-(4-tert-butyl-2,6-dimethylphenyl)imino]-2,3-butanediylidene and its corresponding Ni(II)complex 2a,{bis[N,N'-(4-tert-butyi-2,6-dimethylphenyi)imino]-2,3-butanediylidene}dibromonickel were successfully synthesized,and characterized by 1H NMR,13C NMR,Fourier transform infrared spectroscope(FTIR),elemental analysis and X-ray photoelectron spectroscopy(XPS).a-Diimine ligand 1b,bis[N,N'-(2,6-dimethylphenyl)imino]-2,3-butanediylidene and its corresponding Ni(Ⅱ)complex 2b,{bis[N,N'-(2,6-dimethylphenyl)imino]-2,3-butanediylidene}dibromonickel were also synthesized and characterized for comparison.The pre-catalyst 2a with sterically bulky,electron-donating group tert-butyl,activated by diethylaluminum chloride (DEAC)and tested in the polymerization of ethylene,was very highly active[2.01 × 107g PE/(mol Ni.h·0.1 MPa)]and led to a very highly branched polyethylene(ca.35-103 branches/1000 C).The state of the polyethylene obtained varied from plastic,elastomer polymers to the oil-like hyperbranched polymers.

  17. Evaluation of Polymeric Nanomedicines Targeted to PSMA: Effect of Ligand on Targeting Efficiency.

    Science.gov (United States)

    Fuchs, Adrian V; Tse, Brian W C; Pearce, Amanda K; Yeh, Mei-Chun; Fletcher, Nicholas L; Huang, Steve S; Heston, Warren D; Whittaker, Andrew K; Russell, Pamela J; Thurecht, Kristofer J

    2015-10-12

    Targeted nanomedicines offer a strategy for greatly enhancing accumulation of a therapeutic within a specific tissue in animals. In this study, we report on the comparative targeting efficiency toward prostate-specific membrane antigen (PSMA) of a number of different ligands that are covalently attached by the same chemistry to a polymeric nanocarrier. The targeting ligands included a small molecule (glutamate urea), a peptide ligand, and a monoclonal antibody (J591). A hyperbranched polymer (HBP) was utilized as the nanocarrier and contained a fluorophore for tracking/analysis, whereas the pendant functional chain-ends provided a handle for ligand conjugation. Targeting efficiency of each ligand was assessed in vitro using flow cytometry and confocal microscopy to compare degree of binding and internalization of the HBPs by human prostate cancer (PCa) cell lines with different PSMA expression status (PC3-PIP (PSMA+) and PC3-FLU (PSMA-). The peptide ligand was further investigated in vivo, in which BALB/c nude mice bearing subcutaneous PC3-PIP and PC3-FLU PCa tumors were injected intravenously with the HBP-peptide conjugate and assessed by fluorescence imaging. Enhanced accumulation in the tumor tissue of PC3-PIP compared to PC3-FLU highlighted the applicability of this system as a future imaging and therapeutic delivery vehicle.

  18. Fabrication of magnetic water-soluble hyperbranched polyol functionalized graphene oxide for high-efficiency water remediation

    Science.gov (United States)

    Hu, Lihua; Li, Yan; Zhang, Xuefei; Wang, Yaoguang; Cui, Limei; Wei, Qin; Ma, Hongmin; Yan, Liangguo; Du, Bin

    2016-06-01

    Magnetic water-soluble hyperbranched polyol functionalized graphene oxide nanocomposite (MWHPO-GO) was successfully prepared and applied to water remediation in this paper. MWHPO-GO was characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), magnetization curve, zeta potential, scanning electron microscope (SEM) and transmission electron microscope (TEM) analyses. MWHPO-GO exhibited excellent adsorption performance for the removal of synthetic dyes (methylene blue (MB) and methyl violet (MV)) and heavy metal (Pb(II)). Moreover, MWHPO-GO could be simply recovered from water with magnetic separation. The pseudo-second order equation and the Langmuir model exhibited good correlation with the adsorption kinetic and isotherm data, respectively, for these three pollutants. The thermodynamic results (ΔG water remediation.

  19. Performance of an in situ formed bioactive hydrogel dressing from a PEG-based hyperbranched multifunctional copolymer.

    Science.gov (United States)

    Dong, Yixiao; Hassan, Waqar U; Kennedy, Robert; Greiser, Udo; Pandit, Abhay; Garcia, Yolanda; Wang, Wenxin

    2014-05-01

    Hydrogel dressings have been widely used for wound management due to their ability to maintain a hydrated wound environment, restore the skin's physical barrier and facilitate regular dressing replacement. However, the therapeutic functions of standard hydrogel dressings are restricted. In this study, an injectable hybrid hydrogel dressing system was prepared from a polyethylene glycol (PEG)-based thermoresponsive hyperbranched multiacrylate functional copolymer and thiol-modified hyaluronic acid in combination with adipose-derived stem cells (ADSCs). The cell viability, proliferation and metabolic activity of the encapsulated ADSCs were studied in vitro, and a rat dorsal full-thickness wound model was used to evaluate this bioactive hydrogel dressing in vivo. It was found that long-term cell viability could be achieved for both in vitro (21days) and in vivo (14days) studies. With ADSCs, this hydrogel system prevented wound contraction and enhanced angiogenesis, showing the potential of this system as a bioactive hydrogel dressing for wound healing.

  20. Water- and organo-dispersible gold nanoparticles supported by using ammonium salts of hyperbranched polystyrene: preparation and catalysis.

    Science.gov (United States)

    Gao, Lei; Nishikata, Takashi; Kojima, Keisuke; Chikama, Katsumi; Nagashima, Hideo

    2013-12-01

    Gold nanoparticles (1 nm in size) stabilized by ammonium salts of hyperbranched polystyrene are prepared. Selection of the R groups provides access to both water- and organo-dispersible gold nanoparticles. The resulting gold nanoparticles are subjected to studies on catalysis in solution, which include reduction of 4-nitrophenol with sodium borohydride, aerobic oxidation of alcohols, and homocoupling of phenylboronic acid. In the reduction of 4-nitrophenol, the catalytic activity is clearly dependent on the size of the gold nanoparticles. For the aerobic oxidation of alcohols, two types of biphasic oxidation are achieved: one is the catalyst dispersing in the aqueous phase, whereas the other is in the organic phase. The catalysts are reusable more than four times without loss of the catalytic activity. Selective synthesis of biphenyl is achieved by the homocoupling of phenylboronic acid catalyzed by organo-dispersible gold nanoparticles.

  1. Influence of end groups in hyperbranched polyesters used as modifiers in the characteristics of epoxy thermosets cured by adipic dihydrazide

    Directory of Open Access Journals (Sweden)

    A. Serra

    2013-07-01

    Full Text Available Mixtures of diglycidylether of bisphenol A (DGEBA resin and different ratios of aliphatic-aromatic hyperbranched polyester (HBP were cured by a latent curing agent, adipic dihydrazide (AH. The HBPs prepared have hydroxyl groups or 10-undecenoyl or allyl groups as chain ends. The curing mixtures were investigated by differential scanning calorimetry (DSC to study the curing process and to evaluate the kinetic parameters of the different formulations. These studies suggest that HBPs decrease the curing rate of epoxy/AH in the case of vinyl terminated HPB, whereas OH terminated HBP accelerates the first stages and delays the lasts. The thermosets obtained showed an improvement in microhardness and impact strength without any reduction of the Tg and thermal parameters. Microparticle phase separation was observed with the undecenoyl HBP derivatives or when a 10% of allyl HBP derivative was in the formulation.

  2. Hyperbranched poly(NIPAM) polymers modified with antibiotics for the reduction of bacterial burden in infected human tissue engineered skin.

    Science.gov (United States)

    Shepherd, Joanna; Sarker, Prodip; Rimmer, Stephen; Swanson, Linda; MacNeil, Sheila; Douglas, Ian

    2011-01-01

    The escalating global incidence of bacterial infection, particularly in chronic wounds, is a problem that requires significant improvements to existing therapies. We have developed hyperbranched poly(NIPAM) polymers functionalized with the antibiotics Vancomycin and Polymyxin-B that are sensitive to the presence of bacteria in solution. Binding of bacteria to the polymers causes a conformational change, resulting in collapse of the polymers and the formation of insoluble polymer/bacteria complexes. We have applied these novel polymers to our tissue engineered human skin model of a burn wound infected with Pseudomonas aeruginosa and Staphylococcus aureus. When the polymers were removed from the infected skin, either in a polymer gel solution or in the form of hydrogel membranes, they removed bound bacteria, thus reducing the bacterial load in the infected skin model. These bacteria-binding polymers have many potential uses, including coatings for wound dressings.

  3. Thermosetting resin modified by hyperbranched polymer%超支化聚合物改性热固性树脂

    Institute of Scientific and Technical Information of China (English)

    王思明; 王晓洁; 刘锋; 李建

    2014-01-01

    介绍了超支化聚合物(HBP)的结构和特性,综述了其在改性热固性树脂[如环氧树脂(EP)、不饱和聚酯树脂、乙烯基树脂及酚醛树脂(PF)等]方面的应用。最后对HBP改性热固性树脂的发展方向进行了展望。%The structure and character of hyperbranched polymer(HBP)were introduced,the its applications were summarized in modified thermosetting resin[such as epoxy resin(EP),unsaturated polyester resin,vinyl resin and phenolic resin(PF)]. Finally,the development direction of HBP modified thermosetting resin was expected.

  4. Miktoarms hyperbranched polymer brushes:One-step fast synthesis by parallel click chemistry and hierarchical self-assembly

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Spherical molecular brushes with amphiphilic heteroarms were facilely synthesized by grafting the arms of hydrophobic 2-azidoethyle palmitate and hydrophilic monoazide-terminated poly(ethylene glycol) onto the core of alkyne-modified hyperbranched polyglycerol (HPG) with high molecular weight (Mn=122 kDa) via one-pot parallel click chemistry.The parallel click grafting strategy was demonstrated to be highly efficient (~100%),very fast (~ 2 h) and well controllable to the amphilicity of molecular brushes.Through adjusting the feeding ratio of hydrophobic and hydrophilic arms,a series of brushes with different arm ratios were readily obtained.The resulting miktoarms hyperbranched polymer brushes (HPG-g-C16/PEG350) were characterized by hydrogen-nuclear magnetic resonance (1H NMR),Fourier transform infrared (FT-IR) spectroscopy,gel permeation chromatography (GPC),and differential scanning calorimetry (DSC) measurements.The spherical molecular brushes showed high molecular weights up to 230 kDa,and thus could be visualized by atomic force microscopy (AFM).AFM and dynamic laser light scattering (DLS) were employed to investigate the self-assembly properties of amphiphilic molecular brushes with closed proportion of hydrophobic and hydrophilic arms.The brushes could self-assemble hierarchically into spherical micelles,and network-like fibre structures,and again spherical micelles by addition of n-hexane into the dichloromethane or chloroform solution of brushes.In addition,this kind of miktoarms polymer brush also showed the ability of dye loading via host-guest encapsulation,which promises the potential application of spherical molecular brushes in supramolecular chemistry.

  5. Effect and origin of the structure of hyperbranched polysiloxane on the surface and integrated performances of grafted Kevlar fibers

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Hongrui; Yuan, Li [Jiangsu Key Laboratory of Advanced Functional Polymer Design and Application, Department of Materials Science and Engineering, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123 (China); Liang, Guozheng, E-mail: lgzheng@suda.edu.cn [Jiangsu Key Laboratory of Advanced Functional Polymer Design and Application, Department of Materials Science and Engineering, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123 (China); National Engineering Laboratory for Modern Silk, Suzhou 215123 (China); Gu, Aijuan, E-mail: ajgu@suda.edu.cn [Jiangsu Key Laboratory of Advanced Functional Polymer Design and Application, Department of Materials Science and Engineering, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123 (China)

    2014-11-30

    Highlights: • Four new hyperbranched polysiloxanes (HPSis) with various structures were prepared. • HPSis have different molecular weights and contents of active groups. • Four grafted Kevlar fibers (HPSi-g-KFs) were facilely prepared with different HPSis. • The structure and properties of HPSi-g-KF depend on the structure of HPSi. • The origin behind greatly improved integrated properties of HPSi-g-KF is discussed. - Abstract: Four hyperbranched polysiloxanes (HPSis) with different molecular weights and concentration ratios of double bonds to epoxy groups (1:6.5–1:0.7) were synthesized and characterized. Each HPSi was facilely grafted onto surfaces of Kevlar fibers (KFs) to develop novel modified fibers (HPSi-g-KFs). The structures and integrated properties of HPSi-g-KFs as well as the origin behind were systematically investigated. Results show that HPSi-g-KFs have much rougher surface morphologies, and their surface free energies are as high as about 1.7 times that of KFs, showing greatly improved wettability. Besides, HPSi-g-KFs have excellent UV resistance after 168 h UV irradiation, the retentions of tenacity, energy to break, modulus and break extension are as high as 92, 86, 95 and 96%, respectively, while those of KFs are 66–85%. In addition, compared with KFs, HPSi-g-KFs have higher tensile tenacity and energy to break with similar modulus and break extension, much better thermal stability and flame retardancy. The nature of HPSi has different influence on different property of fibers, the HPSi with smaller molecular weight and more epoxy groups is beneficial to prepare HPSi-g-KFs with better wettability, while that with larger molecular weight and more double bonds tends to prepare HPSi-g-KF with better flame retardancy and UV resistance.

  6. Organometallic Polymeric Conductors

    Science.gov (United States)

    Youngs, Wiley J.

    1997-01-01

    For aerospace applications, the use of polymers can result in tremendous weight savings over metals. Suitable polymeric materials for some applications like EMI shielding, spacecraft grounding, and charge dissipation must combine high electrical conductivity with long-term environmental stability, good processability, and good mechanical properties. Recently, other investigators have reported hybrid films made from an electrically conductive polymer combined with insulating polymers. In all of these instances, the films were prepared by infiltrating an insulating polymer with a precursor for a conductive polymer (either polypyrrole or polythiophene), and oxidatively polymerizing the precursor in situ. The resulting composite films have good electrical conductivity, while overcoming the brittleness inherent in most conductive polymers. Many aerospace applications require a combination of properties. Thus, hybrid films made from polyimides or other engineering resins are of primary interest, but only if conductivities on the same order as those obtained with a polystyrene base could be obtained. Hence, a series of experiments was performed to optimize the conductivity of polyimide-based composite films. The polyimide base chosen for this study was Kapton. 3-MethylThiophene (3MT) was used for the conductive phase. Three processing variables were identified for producing these composite films, namely time, temperature, and oxidant concentration for the in situ oxidation. Statistically designed experiments were used to examine the effects of these variables and synergistic/interactive effects among variables on the electrical conductivity and mechanical strength of the films. Multiple linear regression analysis of the tensile data revealed that temperature and time have the greatest effect on maximum stress. The response surface of maximum stress vs. temperature and time (for oxidant concentration at 1.2 M) is shown. Conductivity of the composite films was measured for

  7. High temperature structural, polymeric foams from high internal emulsion polymerization

    Energy Technology Data Exchange (ETDEWEB)

    Hoisington, M.A.; Duke, J.R.; Apen, P.G.

    1996-02-01

    In 1982, a high internal phase emulsion (HIPE) polymerization process to manufacture microcellular, polymeric foam systems was patented by Unilever. This patent discloses a polymerization process that occurs in a water-in-oil emulsion in which the water represents at least 76% of the emulsion by volume. The oil phase consists of vinyl monomers such as styrene and acrylates that are crosslinked by divinyl monomers during polymerization. After polymerization and drying to remove the water phase, the result is a crosslinked polymer foam with an open cell microstructure that is homogeneous throughout in terms of morphology, density, and mechanical properties. Since 1982, numerous patents have examined various HIPE polymerized foam processing techniques and applications that include absorbents for body fluids, cleaning materials, and ion exchange systems. All the published HIPE polymerized foams have concentrated on materials for low temperature applications. Copolymerization of styrene with maleic anhydride and N-substituted maleimides to produce heat resistant thermoplastics has been studied extensively. These investigations have shown that styrene will free radically copolymerize with N-substituted maleimides to create an alternating thermoplastic copolymer with a Tg of approximately 200{degrees}C. However, there are many difficulties in attempting the maleimide styrene copolymerization in a HIPE such as lower polymerization temperatures, maleimide solubility difficulties in both styrene and water, and difficulty obtaining a stable HIPE with a styrene/maleimide oil phase. This work describes the preparation of copolymer foams from N-ethylmaleimide and Bis(3-ethyl-5-methyl-4-maleimide-phenyl)methane with styrene based monomers and crosslinking agents.

  8. Comparison of Properties among Dendritic and Hyperbranched Poly(ether ether ketone)s and Linear Poly(ether ketone)s.

    Science.gov (United States)

    Morikawa, Atsushi

    2016-02-16

    Poly(ether ether ketone) dendrimers and hyperbranched polymers were prepared from 3,5-dimethoxy-4'-(4-fluorobenzoyl)diphenyl ether and 3,5-dihydroxy-4'-(4-fluorobenzoyl)diphenyl ether through aromatic nucleophilic substitution reactions. 1-(tert-Butyldimethylsiloxy)-3,5-bis(4-fluorobenzoyl)benzene was polycondensed with bisphenols, followed by cleavage of the protective group to form linear poly(ether ketone)s having the same hydroxyl groups in the side chains as the chain ends of the dendrimer and hyperbranched polymers. Their properties, such as solubilities, reduced viscosities, and thermal properties, were compared with one another. Similar comparisons were also carried out among the corresponding methoxy group polymers, and the size of the molecules was shown to affect the properties.

  9. Modified Thermoresponsive Hyperbranched Polymers for Improved Viscosity and Enhanced Lubricity of Engine Oils

    Energy Technology Data Exchange (ETDEWEB)

    Cosimbescu, Lelia [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Robinson, Joshua W. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Bays, John Timothy [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Qu, Jun [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); West, Brian [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2016-09-30

    The manuscript captures the chronological succession of the molecular design progression through multiple architectures and topologies of the polymeric viscosity index improvers and their rheology bench test performance. Tribology testing was also performed on selected analogs and their friction and wear was evaluated. Finally, a top performing polymer was selected for engine testing, scaled-up, and its rheological performance in a complete formulation was assessed. The engine performance of the viscosity index improver was examined against an industry-established baseline.

  10. SYNTHESIS OF A HYPERBRANCHED POLY(AROYLARYLENE) CONTAINING TRIAZOLE AND FLUORENE FUNCTIONALITIES BY CLICK CHEMISTRY AND METAL-FREE, REGIOSELECTIVE POLYCYCLOTRIMERIZATION

    Institute of Scientific and Technical Information of China (English)

    An-jun Qin; Cathy,K. W. Jim; Jacky,W. Y. Lam; Jing-zhi Sun; Ben Zhong Tang

    2009-01-01

    A new bis(aroylacetylene) containing tfiazole and fluorene moieties is synthesized by click chemistry.Polycyclotrimerization of the monomer is catalyzed by piperidine in refluxed dioxane,furnishing a regioregular poly(aroylarylene) in a satisfactory yield.The hyperbranched structure of the polymer is characterized spectroscopically with satisfactory results.The polymer enjoys no metal detriment and is soluble in common organic solvents such as tetrahydrofuran (THF), chloroform, dichloromethane (DCM), and N,N-dimethylformamide (DMF).

  11. Thermal curing of an epoxy-anhydride system modified with hyperbranched poly(ethylene imine)s with different terminal groups

    OpenAIRE

    Morancho Llena, José María; Fernández Francos, Xavier; Acebo Gorostiza, Cristina; Ramis Juan, Xavier; Salla Tarragó, José María; Serra Albet, Àngels

    2017-01-01

    New hyperbranched polymers (HBP) have been synthesized by reaction of a poly(ethylene imine) with phenyl and t-butyl isocyanates. These HBPs have been characterized by 1H-NMR (nuclear magnetic resonance of hydrogen) and Fourier transform infrared spectroscopy. Their influence on the curing and properties of epoxy-anhydride thermosets has been studied by different techniques: differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and thermogravimetry (TG). The ...

  12. Electroactivity in Polymeric Materials

    CERN Document Server

    2012-01-01

    Electroactivity in Polymeric Materials provides an in-depth view of the theory of electroactivity and explores exactly how and why various electroactive phenomena occur. The book explains the theory behind electroactive bending (including ion-polymer-metal-composites –IPMCs), dielectric elastomers, electroactive contraction, and electroactive contraction-expansion cycles.  The book also balances theory with applications – how electroactivity can be used – drawing inspiration from the manmade mechanical world and the natural world around us.  This book captures: A complete introduction to electroactive materials including examples and recent developments The theory and applications of numerous topics like electroactive bending of dielectric elastomers and electroactive contraction and expansion New topics, such as biomimetic applications and energy harvesting This is a must-read within the electroactive community, particularly for professionals and graduate students who are interested in the ...

  13. Kinetics of silica polymerization

    Energy Technology Data Exchange (ETDEWEB)

    Weres, O.; Yee, A.; Tsao, L.

    1980-05-01

    The polymerization of silicic acid in geothermal brine-like aqueous solutions to produce amorphous silica in colloidal form has been studied experimentally and theoretically. A large amount of high quality experimental data has been generated over the temperature rang 23 to 100{sup 0}C. Wide ranges of dissolved silica concentration, pH, and sodium chloride concentration were covered. The catalytic effects of fluoride and the reaction inhibiting effects of aluminum and boron were studied also. Two basic processes have been separately studied: the formation of new colloidal particles by the homogeneous nucleation process and the deposition of dissolved silica on pre-existing colloidal particles. A rigorous theory of the formation of colloidal particles of amorphous silica by homogeneous nucleation was developed. This theory employs the Lothe-Pound formalism, and is embodied in the computer code SILNUC which quantitatively models the homogeneous nucleation and growth of colloidal silica particles in more than enough detail for practical application. The theory and code were extensively used in planning the experimental work and analyzing the data produced. The code is now complete and running in its final form. It is capable of reproducing most of the experimental results to within experimental error. It is also capable of extrapolation to experimentally inaccessible conditions, i.e., high temperatures, rapidly varying temperature and pH, etc.

  14. Polymerization of anionic wormlike micelles.

    Science.gov (United States)

    Zhu, Zhiyuan; González, Yamaira I; Xu, Hangxun; Kaler, Eric W; Liu, Shiyong

    2006-01-31

    Polymerizable anionic wormlike micelles are obtained upon mixing the hydrotropic salt p-toluidine hydrochloride (PTHC) with the reactive anionic surfactant sodium 4-(8-methacryloyloxyoctyl)oxybenzene sulfonate (MOBS). Polymerization captures the cross-sectional radius of the micelles (approximately 2 nm), induces micellar growth, and leads to the formation of a stable single-phase dispersion of wormlike micellar polymers. The unpolymerized and polymerized micelles were characterized using static and dynamic laser light scattering, small-angle neutron scattering, 1H NMR, and stopped-flow light scattering. Stopped-flow light scattering was also used to measure the average lifetime of the unpolymerized wormlike micelles. A comparison of the average lifetime of unpolymerized wormlike micelles with the surfactant monomer propagation rate was used to elucidate the mechanism of polymerization. There is a significant correlation between the ratio of the average lifetime to the monomer propagation rate and the average aggregation number of the polymerized wormlike micelles.

  15. Nanocomposites Derived from Carbon Nanofibers and a Hyperbranched Poly(Ether-Ketone): In Situ Polymerization, Chain-End Modification, and Properties (Preprint)

    Science.gov (United States)

    2007-05-01

    benzothiazole , dodecyl ester and amine endgroups. For example, the dodecyl-terminated nanocomposite displayed an excellent solubility in chloroform and a much...converted to benzothiazole , dodecyl ester and amine endgroups. For example, the dodecyl-terminated nanocomposite displayed an excellent solubility in... Benzothiazole -terminated (HBP-PEK)-g-VGCNF (4): Into a 250 mL resin flask equipped with a high torque mechanical stirrer, and nitrogen inlet and outlet

  16. Metastable tetragonal Cu2Se hyperbranched structures: large-scale preparation and tunable electrical and optical response regulated by phase conversion.

    Science.gov (United States)

    Zhu, Jinbao; Li, Qiuyang; Bai, Liangfei; Sun, Yongfu; Zhou, Min; Xie, Yi

    2012-10-08

    Despite the promising applications of copper selenide nanoparticles, an in-depth elucidation of the inherent properties of tetragonal Cu(2)Se (β-Cu(2)Se) has not been performed because of the lack of a facile synthesis on the nanoscale and an energy-intensive strategy is usually employed. In this work, a facile wet-chemical strategy, employing HCOOH as reducing agent, has been developed to access single-crystalline metastable β-Cu(2)Se hyperbranched architectures for the first time. The process avoids hazardous chemistry and high temperatures, and thus opens up a facile approach to the large-scale low-cost preparation of metastable β-Cu(2)Se hyperbranched architectures. A possible growth mechanism to explain the formation of the β-Cu(2)Se dendritic morphology has been proposed based on time-dependent shape evolution. Further investigations revealed that the metastable β-Cu(2)Se can convert into the thermodynamically more stable cubic α-Cu(2-x)Se maintaining the dendritic morphology. An increase in electrical conductivity and a tunable optical response were observed under ambient conditions. This behavior can be explained by the oxidation of the surface of the β-Cu(2)Se hyperbranched structures, ultimately leading to solid-state phase conversion from β-Cu(2)Se into superionic conductor α-Cu(1.8)Se, which has potential applications in energy-related devices and sensors.

  17. OX26 modified hyperbranched polyglycerol-conjugated poly(lactic-co-glycolic acid) nanoparticles: synthesis, characterization and evaluation of its brain delivery ability.

    Science.gov (United States)

    Bao, Hanmei; Jin, Xu; Li, Ling; Lv, Feng; Liu, Tianjun

    2012-08-01

    A novel nanoparticles-based brain drug delivery system made of hyperbranched polyglycerol-conjugated poly(lactic-co-glycolic acid) which was surface functionalized with transferrin antibody (OX26) was prepared. Hyperbranched polyglycerol-conjugated poly(lactic-co-glycolic acid) was synthesized, characterized and applied to prepare nanoparticles by means of double emulsion solvent evaporation technique. Transmission electron micrograph and dynamic light scattering showed that nanoparticles had a round and regular shape with a mean diameter of 170 ± 20 nm. Surface chemical composition was detected by X-ray photoelectron spectroscopy. Endomorphins, as a model drug, was encapsulated in the nanoparticles. In vitro drug release study showed that endomorphins was released continuously for 72 h. Cellular uptake study showed that the uptake of nanoparticles by the brain microvascular endothelial cells was both time- and concentration-dependant. Further uptake inhibition study indicated that the uptake of nanoparticles was via a caveolae-mediated endocytic pathway. In vivo endomorphins brain delivery ability was evaluated based upon the rat model of chronic constriction injury of sciatic nerve. OX26 modified nanoparticles had achieved better analgesic effects, compared with other groups. Thus, OX26 modified hyperbranched polyglycerol-conjugated poly(lactic-co-glycolic acid) nanoparticles may be a promising brain drug delivery carrier.

  18. Surface glycosylation of polymeric membranes

    Institute of Scientific and Technical Information of China (English)

    DAI ZhengWei; WAN LingShu; XU ZhiKang

    2008-01-01

    Surface glycosylation of polymeric membranes has been inspired by the structure of natural biomembranes. It refers to that glycosyl groups are introduced onto the membrane surface by various strategies, which combine the separation function of the membrane with the biological function of the saccharides in one system. In this review, progress in the surface glycosylation of polymeric membranes is highlighted in two aspects, i.e. the glycosylation methods and the potential applications of the surface-glycosylated membranes.

  19. AQUEOUS STABLE FREE RADICAL POLYMERIZATION PROCESSES

    Institute of Scientific and Technical Information of China (English)

    Andrea R. Szkurhan; Michael K. Georges

    2004-01-01

    An overview of aqueous polymerizations, which include emulsion, miniemulsion and suspension polymerizations,under stable free radical polymerization (SFRP) conditions is presented. The success of miniemulsion and suspension SFRP polymerizations is contrasted with the difficulties associated with obtaining a stable emulsion polymerization. A recently developed unique microprecipitation technique is referenced as a means of making submicron sized particles that can be used to achieve a stable emulsion SFRP process.

  20. Polymeric materials for neovascularization

    Science.gov (United States)

    DeVolder, Ross John

    Revascularization therapies have emerged as a promising strategy to treat various acute and chronic wounds, cardiovascular diseases, and tissue defects. It is common to either administer proangiogenic growth factors, such as vascular endothelial growth factor (VEGF), or transplant cells that endogenously express multiple proangiogenic factors. Additionally, these strategies utilize a wide variety of polymeric systems, including hydrogels and biodegradable plastics, to deliver proangiogenic factors in a sophisticated manner to maintain a sustained proangiogenic environment. Despite some impressive results in rebuilding vascular networks, it is still a challenging task to engineer mature and functional neovessels in target tissues, because of the increasing complexities involved with neovascularization applications. To resolve these challenges, this work aims to design a wide variety of proangiogenic biomaterial systems with tunable properties used for neovascularization therapies. This thesis describes the design of several biomaterial systems used for the delivery of proangiogenic factors in neovascularization therapies, including: an electrospun/electrosprayed biodegradable plastic patch used for directional blood vessel growth (Chapter 2), an alginate-g-pyrrole hydrogel system that biochemically stimulates cellular endogenous proangiogenic factor expression (Chapter 3), an enzyme-catalyzed alginate-g-pyrrole hydrogel system for VEGF delivery (Chapter 4), an enzyme-activated alginate-g-pyrrole hydrogel system with systematically controllable electrical and mechanical properties (Chapter 5), and an alginate-g-pyrrole hydrogel that enables the decoupled control of electrical conductivity and mechanical rigidity and is use to electrically stimulate cellular endogenous proangiogenic factor expression (Chapter 6). Overall, the biomaterial systems developed in this thesis will be broadly useful for improving the quality of a wide array of molecular and cellular based

  1. Stereospecific olefin polymerization catalysts

    Science.gov (United States)

    Bercaw, John E.; Herzog, Timothy A.

    1998-01-01

    A metallocene catalyst system for the polymerization of .alpha.-olefins to yield stereospecific polymers including syndiotactic, and isotactic polymers. The catalyst system includes a metal and a ligand of the formula ##STR1## wherein: R.sup.1, R.sup.2, and R.sup.3 are independently selected from the group consisting of hydrogen, C.sub.1 to C.sub.10 alkyl, 5 to 7 membered cycloalkyl, which in turn may have from 1 to 3 C.sub.1 to C.sub.10 alkyls as a substituent, C.sub.6 to C.sub.15 aryl or arylalkyl in which two adjacent radicals may together stand for cyclic groups having 4 to 15 carbon atoms which in turn may be substituted, or Si(R.sup.8).sub.3 where R.sup.8 is selected from the group consisting of C.sub.1 to C.sub.10 alkyl, C.sub.6 to C.sub.15 aryl or C.sub.3 to C.sub.10 cycloalkyl; R.sup.4 and R.sup.6 are substituents both having van der Waals radii larger than the van der Waals radii of groups R.sup.1 and R.sup.3 ; R.sup.5 is a substituent having a van der Waals radius less than about the van der Waals radius of a methyl group; E.sup.1, E.sup.2 are independently selected from the group consisting of Si(R.sup.9).sub.2, Si(R.sup.9).sub.2 --Si(R.sup.9).sub.2, Ge(R.sup.9).sub.2, Sn(R.sup.9).sub.2, C(R.sup.9).sub.2, C(R.sup.9).sub.2 --C(R.sup.9).sub.2, where R.sup.9 is C.sub.1 to C.sub.10 alkyl, C.sub.6 to C.sub.15 aryl or C.sub.3 to C.sub.10 cycloalkyl; and the ligand may have C.sub.S or C.sub.1 -symmetry. Preferred metals are selected from the group consisting of group III, group IV, group V or lanthanide group elements. The catalysts are used to prepare stereoregular polymers including polypropylene from .alpha.-olefin monomers.

  2. Mechanically controlled radical polymerization initiated by ultrasound

    Science.gov (United States)

    Mohapatra, Hemakesh; Kleiman, Maya; Esser-Kahn, Aaron Palmer

    2017-02-01

    In polymer chemistry, mechanical energy degrades polymeric chains. In contrast, in nature, mechanical energy is often used to create new polymers. This mechanically stimulated growth is a key component of the robustness of biological materials. A synthetic system in which mechanical force initiates polymerization will provide similar robustness in polymeric materials. Here we show a polymerization of acrylate monomers initiated and controlled by mechanical energy provided by ultrasonic agitation. The activator for an atom-transfer radical polymerization is generated using piezochemical reduction of a Cu(II) precursor complex, which thus converts a mechanical activation of piezoelectric particles to the synthesis of a new material. This polymerization reaction has some characteristics of controlled radical polymerization, such as narrow molecular-weight distribution and linear dependence of the polymeric chain length on the time of mechanical activation. This new method of controlled radical polymerization complements the existing methods to synthesize commercially useful well-defined polymers.

  3. 超支化水煤浆分散剂的合成与性能研究%Synthesis of hyperbranched dispersant from coal water slurry and its chemical properties

    Institute of Scientific and Technical Information of China (English)

    张光华; 韩文静; 强轶; 刘龙; 尚婷; 赵方

    2012-01-01

    In this article, we have introduced a new type of disper-sant we have gained from the high-concentrated coal water slurry (CWS). To be exact, we have synthesized lower-generation hyper-branched molecular skeletons from the methanol solvent out of raw materials of dehydroabietylamine, methyl acrylate, and ethylenedi-amine through the divergent analysis. The actual products we have developed can be stated as follows: firstly, we have synthesized 0.5 generation hyperbranched organic molecules via Michael addition reaction with dehydroabietylamine as the principal acrylate raw material . Secondly, we have synthesized the 1.0 generation hyperbranched organic molecules through amidation condensation reaction by taking 0.5 generation hyperbranched molecule and ethylenediamine as the o- riginal materials. And, finally, the lower generation hyperbranched molecular skeleton can further be found to result in 1.0 generation hyperbranched organic molecules. The new-type dispersant of rosin hyperbranched from the coal water slurry has been synthetically made by using skeleton as initiator by making it react with the chloroactic acid. And, after that, we have applied infrared spectroscope and hydrogen nuclear magnetic resonance spectroscope to characterization of the 0.5 generation and 1.0 generation organic molecules and rosin hyperbranched dispersants. Moreover, we have done the slurry performance test with Shenfu coal for their viscosity, Zeta potential and static stability of the slurry. The results of our investigation indicate that the rosin hyperbranched dispersant has ability in reducing the viscosity of the coal slurry for this purpose at lower dosages. When the slurry concentration is lowered to 67% , and the dosage of the rosin hyperbranched dispersant was 0.4% ( quantity fraction) of the slurry, its viscosity tends to be only at 980 mPa · s. This shows that the rosin hyperbranched dispersant helps to improve the behavior of coal water slurry, enhance the static

  4. Supramolecular Polymeric Materials Containing Cyclodextrins.

    Science.gov (United States)

    Nakahata, Masaki; Takashima, Yoshinori; Harada, Akira

    2017-01-01

    Smart design of polymeric materials may lead to intelligent materials exhibiting unique functional properties. Looking at nature, living systems use specific and reversible intermolecular interactions in realizing complex functions. Hence reversible bonds based on selective molecular recognition can impart artificial materials with unique functional properties. This review mainly focuses on supramolecular polymeric materials based on cyclodextrin-based host-guest interactions. Polymeric materials using molecular recognition at polymer main chain, side chain, and termini are described. Polymers carrying host and guest residues exhibit unique properties such as: 1) formation of macroscopic self-assembly of polymer gels carrying host and guest residues; 2) stimuli-responsive self-healing properties due to the reversible nature of host-guest interactions; and 3) macroscopic motion of artificial muscle cross-linked by host-guest interaction controlled by external stimuli. An overview of recent developments in this new frontier between materials science and life science is given.

  5. Surface glycosylation of polymeric membranes

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Surface glycosylation of polymeric membranes has been inspired by the structure of natural biomem-branes. It refers to that glycosyl groups are introduced onto the membrane surface by various strate-gies, which combine the separation function of the membrane with the biological function of the sac-charides in one system. In this review, progress in the surface glycosylation of polymeric membranes is highlighted in two aspects, i.e. the glycosylation methods and the potential applications of the sur-face-glycosylated membranes.

  6. On-demand photoinitiated polymerization

    Science.gov (United States)

    Boydston, Andrew J; Grubbs, Robert H; Daeffler, Chris; Momcilovic, Nebojsa

    2013-12-10

    Compositions and methods for adjustable lenses are provided. In some embodiments, the lenses contain a lens matrix material, a masking compound, and a prepolymer. The lens matrix material provides structure to the lens. The masking compound is capable of blocking polymerization or crosslinking of the prepolymer, until photoisomerization of the compound is triggered, and the compound is converted from a first isomer to a second isomer having a different absorption profile. The prepolymer is a composition that can undergo a polymerization or crosslinking reaction upon photoinitiation to alter one or more of the properties of the lenses.

  7. Functionalization and Polymerization on the CNT Surfaces

    KAUST Repository

    Albuerne, Julio

    2013-07-01

    In this review we focus on the current status of using carbon nanotube (CNT) as a filler for polymer nanocomposites. Starting with the historical background of CNT, its distinct properties and the surface functionalization of the nanotube, the three different surface polymerization techniques, namely grafting "from", "to" and "through/in between" were discussed. Wider focus has been given on "grafting from" surface initiated polymerizations, including atom transfer radical polymerization (ATRP), reversible addition fragmentation chain-transfer (RAFT) Polymerization, nitroxide mediated polymerization (NMP), ring opening polymerization (ROP) and other miscellaneous polymerization methods. The grafting "to" and "through / in between" also discussed and compared with grafting from polymerization. The merits and shortcomings of all three grafting methods were discussed and the bottleneck issue in grafting from method has been highlighted. Furthermore the current and potential future industrial applications were deliberated. Finally the toxicity issue of CNTs in the final product has been reviewed with the limited available literature knowledge. © 2013 Bentham Science Publishers.

  8. The absorption of polymeric composites

    Science.gov (United States)

    Řídký, R.; Popovič, M.; Rolc, S.; Drdlová, M.; Krátký, J.

    2016-06-01

    An absorption capacity of soft, viscoelastic materials at high strain rates is important for wide range of practical applications. Nowadays there are many variants of numerical models suitable for this kind of analysis. The main difficulty is in selection of the most realistic numerical model and a correct setup of many unknown material constants. Cooperation between theoretical simulations and real testing is next crucial point in the investigation process. Standard open source material database offer material properties valid for strain rates less than 250 s-1. There are experiments suitable for analysis of material properties with strain rates close to 2000 s-1. The high strain-rate characteristics of a specific porous blast energy absorbing material measured by modified Split Hopkinson Pressure Bar apparatus is presented in this study. Testing these low impedance materials using a metallic split Hopkinson pressure bar setup results in poor signal to noise ratios due to impedance mismatching. These difficulties are overcome by using polymeric Hopkinson bars. Conventional Hopkinson bar analysis cannot be used on the polymeric bars due to the viscoelastic nature of the bar material. One of the possible solution leads to complex and frequency depended Young modulus of testing bars material. This testing technique was applied to materials composed of porous glass/ceramic filler and polymeric binder, with density of 125 - 300 kg/m3 and particle size in range of 50 µm - 2 mm. The achieved material model was verified in practical application of sandwich structure includes polymeric composites under a blast test.

  9. The Viscosity of Polymeric Fluids.

    Science.gov (United States)

    Perrin, J. E.; Martin, G. C.

    1983-01-01

    To illustrate the behavior of polymeric fluids and in what respects they differ from Newtonian liquids, an experiment was developed to account for the shear-rate dependence of non-Newtonian fluids. Background information, procedures, and results are provided for the experiment. Useful in transport processes, fluid mechanics, or physical chemistry…

  10. Biodegradable polymeric prodrugs of naltrexone

    NARCIS (Netherlands)

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

    1991-01-01

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

  11. Buckling of polymerized monomolecular films

    Science.gov (United States)

    Bourdieu, L.; Daillant, J.; Chatenay, D.; Braslau, A.; Colson, D.

    1994-03-01

    The buckling of a two-dimensional polymer network at the air-water interface has been evidenced by grazing incidence x-ray scattering. A comprehensive description of the inhomogeneous octadecyltrichlorosilane polymerized film was obtained by atomic force microscopy and x-ray scattering measurements. The buckling occurs with a characteristic wavelength ~=10 μm.

  12. Novel polymeric materials from triglycerides

    Science.gov (United States)

    Triglycerides are good platforms for new polymeric products that can substitute for petroleum-based materials. As part of our research emphasis in sustainability and green polymer chemistry, we have explored a number of reactions in efforts to produce a wide range of value-added products. In this ...

  13. A label-free and high sensitive aptamer biosensor based on hyperbranched polyester microspheres for thrombin detection.

    Science.gov (United States)

    Sun, Chong; Han, Qiaorong; Wang, Daoying; Xu, Weimin; Wang, Weijuan; Zhao, Wenbo; Zhou, Min

    2014-11-19

    In this paper, we have synthesized hyperbranched polyester microspheres with carboxylic acid functional groups (HBPE-CA) and developed a label-free electrochemical aptamer biosensor using thrombin-binding aptamer (TBA) as receptor for the measurement of thrombin in whole blood. The indium tin oxide (ITO) electrode surface modified with HBPE-CA microspheres was grafted with TBA, which has excellent binding affinity and selectivity for thrombin. Binding of the thrombin at the modified ITO electrode surface greatly restrained access of electrons for a redox probe of [Fe(CN)6](3-/4-). Moreover, the aptamer biosensor could be used for detection of thrombin in whole blood, a wide detection range (10fM-100nM) and a detection limit on the order of 0.90fM were demonstrated. Control experiments were also carried out by using bull serum albumin (BSA) and lysozyme in the absence of thrombin. The good stability and repeatability of this aptamer biosensor were also proved. We expect that this demonstration will lead to the development of highly sensitive label-free sensors based on aptamer with lower cost than current technology. The integration of the technologies, which include anticoagulant, sensor and nanoscience, will bring significant input to high-performance biosensors relevant to diagnostics and therapy of interest for human health.

  14. Vegetable-Oil-Based Hyperbranched Polyester-Styrene Copolymer Containing Silver Nanoparticle as Antimicrobial and Corrosion-Resistant Coating Materials

    Directory of Open Access Journals (Sweden)

    Manawwer Alam

    2013-01-01

    Full Text Available Pongamia oil (PO was converted to Pongamia oil hydroxyl (POH via epoxidation process. The esterification of POH with linolenic acid was carried out to form hyperbranched polyester (HBPE, and further styrenation was performed at the conjugated double bond in the chain of linolenic acid. After styrenation, silver nanoparticle was added in different weight percentages (0.1–0.4 wt%. The structural elucidation of POH, HBPE, and HBPE-St was carried out by FT-IR, 1H-NMR, and 13C-NMR spectroscopic techniques. Physicochemical and physicomechanical analyses were performed by standard method. Thermal behavior of the HBPE-St was analyzed by using thermogravimetric analysis (TGA and differential scanning calorimetry (DSC. The coatings of HBPE-St were prepared on mild steel strips. The anticorrosive behavior of HBPE-St resin-based coatings in acid, saline, and tap water was evaluated, and the molecular weight of HBPE-St was determined by gel permeation chromatography (GPC. The antibacterial activities of the HBPE-St copolymers were tested in vitro against bacteria and fungi by disc diffusion method. The HBPE-St copolymers exhibited good antibacterial activities and can be used as antimicrobial and corrosion-resistant coating materials.

  15. Active site formation mechanism of carbon-based oxygen reduction catalysts derived from a hyperbranched iron phthalocyanine polymer

    Science.gov (United States)

    Hiraike, Yusuke; Saito, Makoto; Niwa, Hideharu; Kobayashi, Masaki; Harada, Yoshihisa; Oshima, Masaharu; Kim, Jaehong; Nabae, Yuta; Kakimoto, Masa-aki

    2015-04-01

    Carbon-based cathode catalysts derived from a hyperbranched iron phthalocyanine polymer (HB-FePc) were characterized, and their active-site formation mechanism was studied by synchrotron-based spectroscopy. The properties of the HB-FePc catalyst are compared with those of a catalyst with high oxygen reduction reaction (ORR) activity synthesized from a mixture of iron phthalocyanine and phenolic resin (FePc/PhRs). Electrochemical measurements demonstrate that the HB-FePc catalyst does not lose its ORR activity up to 900°C, whereas that of the FePc/PhRs catalyst decreases above 700°C. Hard X-ray photoemission spectra reveal that the HB-FePc catalysts retain more nitrogen components than the FePc/PhRs catalysts between pyrolysis temperatures of 600°C and 800°C. This is because the linked structure of the HB-FePc precursor has high thermostability against nitrogen desorption. Consequently, effective doping of active nitrogen species into the sp 2 carbon network of the HB-FePc catalysts may occur up to 900°C.

  16. Active site formation mechanism of carbon-based oxygen reduction catalysts derived from a hyperbranched iron phthalocyanine polymer.

    Science.gov (United States)

    Hiraike, Yusuke; Saito, Makoto; Niwa, Hideharu; Kobayashi, Masaki; Harada, Yoshihisa; Oshima, Masaharu; Kim, Jaehong; Nabae, Yuta; Kakimoto, Masa-Aki

    2015-01-01

    Carbon-based cathode catalysts derived from a hyperbranched iron phthalocyanine polymer (HB-FePc) were characterized, and their active-site formation mechanism was studied by synchrotron-based spectroscopy. The properties of the HB-FePc catalyst are compared with those of a catalyst with high oxygen reduction reaction (ORR) activity synthesized from a mixture of iron phthalocyanine and phenolic resin (FePc/PhRs). Electrochemical measurements demonstrate that the HB-FePc catalyst does not lose its ORR activity up to 900°C, whereas that of the FePc/PhRs catalyst decreases above 700°C. Hard X-ray photoemission spectra reveal that the HB-FePc catalysts retain more nitrogen components than the FePc/PhRs catalysts between pyrolysis temperatures of 600°C and 800°C. This is because the linked structure of the HB-FePc precursor has high thermostability against nitrogen desorption. Consequently, effective doping of active nitrogen species into the sp (2) carbon network of the HB-FePc catalysts may occur up to 900°C.

  17. Effect of the microstructure of a hyperbranched polymer and nanoclay loading on the morphology and properties of novel polyurethane nanocomposites.

    Science.gov (United States)

    Maji, Pradip K; Guchhait, Prasanta K; Bhowmick, Anil K

    2009-02-01

    Novel polyurethane nanocomposites based on toluene diisocyanate, poly(propylene glycol), various hyperbranched polymers (HBPs), and layered silicate were synthesized with the aim of determining the effect of the layered silicate loading and the functionality of HBP on the structure and properties of polyurethane nanocomposites. The microstructure of the nanocomposites was investigated by X-ray diffraction analysis and high-resolution transmission electron microscopy. It was found that exfoliated morphology and good dispersion were obtained up to 8 phr clay loading for all of the nanocomposites. approximately 100% increment in tensile strength, approximately 2-fold increase in the lap shear strength, approximately 200% increment in the peel strength, and 120% increment in the storage modulus along with a dramatic improvement in thermal stability were observed with the addition of 8 phr clay, over the pristine polyurethane. The higher the level of functionality of the HBP, the higher is the property enhancement. These properties were correlated with the state of dispersion of the clay platelets in the polyurethane matrix, the structure of the matrix, and clay-polymer interaction.

  18. Cure Kinetics of DGEBA with Hyperbranched Poly(3-hydroxyphenyl) Phosphate as Curing Agent Studied by Non-isothermal DSC

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The cure kinetics of diglycidyl ether of bisphenol A(DGEBA) with hyperbranched poly(3-hydroxyphenyl) phosphate(HHPP) as the curing agent was investigated by means of non-isothermal differential scanning calorimetry(DSC) at various heating rates. The results were compared with the corresponding results by using 1,3-dihydroxybenzene(DHB) as a model compound. The results show that HHPP can enhance the cure reaction of DGEBA, resulting in the decrease of the peak temperature of the curing curve as well as the decrease of the activation energy because of the flexible -P-O- groups in the backbone of HHPP. However, both the activation energy of the cured polymer and the peak temperature of the curing curve are increased with DHB as a curing agent. The cure kinetics of the DGEBA/HHPP system was calculated by using the isoconversional method given by Málek. It was found that the two-parameter autocatalytic model(esták-Berggren equation) is the most adequate one to describe the cure kinetics of the studied system at various heating rates. The obtained non-isothermal DSC curves from the experimental data show the results being accordant with those theoretically calculated.

  19. Electrochemiluminescence biosensor for ultrasensitive determination of ochratoxin A in corn samples based on aptamer and hyperbranched rolling circle amplification.

    Science.gov (United States)

    Yang, Linlin; Zhang, Ying; Li, Ruibao; Lin, Cuiying; Guo, Longhua; Qiu, Bin; Lin, Zhenyu; Chen, Guonan

    2015-08-15

    Determination of ochratoxin A (OTA) is highly important for food safety control. In this study, a signal-on electrochemiluminescence (ECL) biosensor which combined the characteristics of high efficiency of hyperbranched rolling circle amplification (HRCA) and high selectivity of aptamer was developed for OTA determination. The capture probe DNA (CDNA) was firstly immobilized on the gold electrode surface through Au-S interaction, then the OTA aptamer was modified on the electrode surface through hybridization with CDNA. Since OTA can competitively bind with the aptamer due to their high affinity, which would induce the releasing of aptamer from the electrode surface. Subsequently, the free CDNA on the electrode surface can hybridize with the padlock probe and induce HRCA reaction subsequently. Thus, the HRCA products which contained large amount of double-stranded DNA (dsDNA) fragments can be accumulated on the electrode surface. Since Ru(phen)3(2+) can intercalate into the groove of dsDNA and acts as ECL indicator, high ECL intensity can be detected from the electrode surface. The enhanced ECL intensity has a linear relationship with OTA in the range of 0.05-500 pg/mL with a correlation coefficient of 0.9957, and the limit of detection (LOD) was 0.02 pg/mL. The developed biosensor has been applied to determine OTA concentration in the corn samples with satisfied results.

  20. Effect and origin of the structure of hyperbranched polysiloxane on the surface and integrated performances of grafted Kevlar fibers

    Science.gov (United States)

    Zhang, Hongrui; Yuan, Li; Liang, Guozheng; Gu, Aijuan

    2014-11-01

    Four hyperbranched polysiloxanes (HPSis) with different molecular weights and concentration ratios of double bonds to epoxy groups (1:6.5-1:0.7) were synthesized and characterized. Each HPSi was facilely grafted onto surfaces of Kevlar fibers (KFs) to develop novel modified fibers (HPSi-g-KFs). The structures and integrated properties of HPSi-g-KFs as well as the origin behind were systematically investigated. Results show that HPSi-g-KFs have much rougher surface morphologies, and their surface free energies are as high as about 1.7 times that of KFs, showing greatly improved wettability. Besides, HPSi-g-KFs have excellent UV resistance after 168 h UV irradiation, the retentions of tenacity, energy to break, modulus and break extension are as high as 92, 86, 95 and 96%, respectively, while those of KFs are 66-85%. In addition, compared with KFs, HPSi-g-KFs have higher tensile tenacity and energy to break with similar modulus and break extension, much better thermal stability and flame retardancy. The nature of HPSi has different influence on different property of fibers, the HPSi with smaller molecular weight and more epoxy groups is beneficial to prepare HPSi-g-KFs with better wettability, while that with larger molecular weight and more double bonds tends to prepare HPSi-g-KF with better flame retardancy and UV resistance.

  1. Hyperbranched poly(glycidol)/poly(ethylene oxide) crosslinked hydrogel for tissue engineering scaffold using e-beams.

    Science.gov (United States)

    Haryanto; Singh, Deepti; Huh, Pil Ho; Kim, Seong Cheol

    2016-01-01

    A microporous hydrogel scaffold was developed from hyperbranched poly(glycidol) (HPG) and poly(ethylene oxide) (PEO) using electron beam (e-beam) induced cross-linking for tissue engineering applications. In this study, HPG was synthesized from glycidol using trimethylol propane as a core initiator and cross-linked hydrogels were made using 0, 10, 20, and 30% HPG with respect to PEO. The effects of %-HPG on the swelling ratio, cross-linking density, mechanical properties, morphology, degradation, and cytotoxicity of the hydrogel scaffolds were then investigated. Increasing the HPG content increased the pore size of the hydrogel scaffold, as well as the porosity, elongation at break, degree of degradation and swelling ratio. In contrast, the presence of HPG decreased the cross-linking density of the hydrogel. There was no significant difference in compressive modulus and tensile strength of all compositions. The pore size of hydrogel scaffolds could be easily tailored by controlling the content of HPG in the polymer blend. Evaluation of the cytotoxicity demonstrated that HPG/PEO hydrogel scaffold has potential for use as a matrix for cellular attachment and proliferation. These results indicate that cross-linked HPG/PEO hydrogel can function as a potential material for tissue engineering scaffolds. Moreover, a facile method to prepare hydrogel microporous scaffolds for tissue engineering by e-beam irradiation was developed.

  2. Quantum dots-hyperbranched polyether hybrid nanospheres towards delivery and real-time detection of nitric oxide

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Shuiping; Gu, Tianxun; Fu, Jiajia [Key Laboratory of Eco-Textiles, Ministry of Education (Jiangnan University), Wuxi 214122 (China); College of Textile and Clothing, Jiangnan University, Wuxi 214122 (China); Li, Xiaoqiang, E-mail: leecaiwei@163.com [Key Laboratory of Eco-Textiles, Ministry of Education (Jiangnan University), Wuxi 214122 (China); College of Textile and Clothing, Jiangnan University, Wuxi 214122 (China); Technical University of Denmark, DTU Food, Søltofts plads, B227, 2800 Kgs. Lyngby (Denmark); Chronakis, Ioannis S. [Technical University of Denmark, DTU Food, Søltofts plads, B227, 2800 Kgs. Lyngby (Denmark); Ge, Mingqiao [Key Laboratory of Eco-Textiles, Ministry of Education (Jiangnan University), Wuxi 214122 (China); College of Textile and Clothing, Jiangnan University, Wuxi 214122 (China)

    2014-12-01

    In this work, novel hybrid nanosphere vehicles were synthesized for nitric oxide (NO) donating and real-time detection. The hybrid nanosphere vehicles consist of cadmium selenide quantum dots (CdSe QDs) as NO fluorescent probes, and the modified hyperbranched polyether (mHP)-based diazeniumdiolates as NO donors, respectively. The nanospheres have spherical outline with dimension of ∼ 127 nm. The data of systematic characterization demonstrated that the mHP-based hybrid nanosphere vehicles (QDs-mHP-NO) can release and real-time detect NO with the low limit of 25 nM, based on fluorescence quenching mechanism. The low cell-toxicity of QDs-mHP-NO nanospheres was verified by means of MTT assay on L929 cells viability. The QDs-mHP-NO nanospheres provide perspectives for designing a new class of biocompatible NO donating and imaging systems. - Highlights: • QDs-mHP-NO fluorescent probe was prepared. • The QDs-mHP-NO probe is capable of releasing NO. • The QDs-mHP-NO probe can quantitatively detecting the release of NO in real time. • The low cell-toxicity of QDs-mHP-NO nanospheres was verified.

  3. Facile synthesis of titania/hyperbranched polyglycidol nanohybrids with controllable morphologies: from solid spheres, capsules to tubes

    Energy Technology Data Exchange (ETDEWEB)

    Li Haiqing; Zhang Lin; Jo, Jung Kyu; Ha, Chang-Sik; Shchipunov, Yury A.; Kim, Il, E-mail: ilkim@pusan.ac.kr [Pusan National University, WCU Center for Synthetic Polymer Bioconjugate Hybrid Materials, Department of Polymer Science and Engineering (Korea, Republic of)

    2011-05-15

    Titania/Hyperbranched polyglycidol (HBP) nanohybrids with tunable morphologies have been synthesized via a sol-gel process at ambient temperature. One-shot addition of varied amounts of titanium precursor tetraisopropoxide (TTIP) yields spherical titania/HBP solid particles with tunable size, while a controlled addition of TTIP results in spherical titania/HBP capsules. The average outer and inner diameters of the resultant capsules are also controllable according to the amount of TTIP via an Oswald ripening process. In addition, the modality of additional water supplied in the reaction systems can tune the morphologies of the resulting titania/HBP particles from nanocapsules to nanotubes owing to the accelerated hydrolysis rate of TTIP. The tunability in morphologies of the titania/HBP nanostructures ranging from solid spheres, capsules to tubes could be attributed to the self-assembly of a large amount of titania/HBP aggregates in a rapid, controlled and anisotropic manner, respectively. Surprisingly, by means of HBP contained in the resulting titania/HBP nanostructures, the gold nanoparticles are in situ generated and encapsulated into titania/HBP matrix in the absence of additional reducing agent. The as-prepared gold nanoparticles functionalized titania/HBP hybrids exhibit excellent catalytic function toward the reduction of 4-nitrophenol. This strategy demonstrates a typical example for functionalizing the titania/HBP hybrids targeted to specific applications.

  4. A New Epoxy-Based Layered Silicate Nanocomposite Using a Hyperbranched Polymer: Study of the Curing Reaction and Nanostructure Development

    Directory of Open Access Journals (Sweden)

    Pilar Cortés

    2014-03-01

    Full Text Available Polymer layered silicate (PLS nanocomposites have been prepared with diglycidyl ether of bisphenol-A (DGEBA epoxy resin as the matrix and organically modified montmorillonite (MMT as the clay nanofiller. Resin-clay mixtures with different clay contents (zero, two, five and 10 wt% were cured, both isothermally and non-isothermally, using a poly(ethyleneimine hyperbranched polymer (HBP, the cure kinetics being monitored by differential scanning calorimetry (DSC. The nanostructure of the cured nanocomposites was characterized by small angle X-ray scattering (SAXS and transmission electron microscopy (TEM, and their mechanical properties were determined by dynamic mechanical analysis (DMA and impact testing. The results are compared with an earlier study of the structure and properties of the same DGEBA-MMT system cured with a polyoxypropylene diamine, Jeffamine. There are very few examples of the use of HBP as a curing agent in epoxy PLS nanocomposites; here, it is found to enhance significantly the degree of exfoliation of these nanocomposites compared with those cured with Jeffamine, with a corresponding enhancement in the impact energy for nanocomposites with the low clay content of 2 wt%. These changes are attributed to the different cure kinetics with the HBP, in which the intra-gallery homopolymerization reaction is accelerated, such that it occurs before the bulk cross-linking reaction.

  5. Change in size, morphology and stability of DNA polyplexes with hyperbranched poly(ethyleneimines) containing bulky maltose units.

    Science.gov (United States)

    Rumschöttel, Jens; Kosmella, Sabine; Prietzel, Claudia; Appelhans, Dietmar; Koetz, Joachim

    2016-02-01

    Polyplexes between Salmon DNA and non-modified hyperbranched poly(ethyleneimines) of varying molar mass, i.e., PEI(5 k) with 5000 g/mol and PEI(25 k) with 25,000 g/mol, and modified PEI(5 k) with maltose units (PEI-Mal) were investigated in dependence on the molar N/P ratio by using dynamic light scattering (DLS), zeta potential measurements, micro differential scanning calorimetry (μ-DSC), scanning-transmission electron microscopy (STEM), and cryo-scanning electron microscopy (cryo-SEM). A reloading of the polyplexes can be observed by adding the unmodified PEI samples of different molar mass. In excess of PEI a morphological transition from core-shell particles (at N/P 8) to loosely packed onion-like polyplexes (at N/P 40) is observed. The shift of the DSC melting peak from 88 °C to 76 °C indicates a destabilization of the DNA double helix due to the complexation with the unmodified PEI. Experiments with the maltose-modified PEI show a reloading already at a lower N/P ratio. Due to the presence of the sugar units in the periphery of the polycation electrostatic interactions between DNA become weaker, but cooperative H-bonding forces are reinforced. The resulting less-toxic, more compact polyplexes in excess of the PEI-Mal with two melting points and well distributed DNA segments are of special interest for extended gene delivery experiments.

  6. Polymeric amines and biomedical uses thereof

    NARCIS (Netherlands)

    Broekhuis, Antonius; Zhang, Youchum; Picchioni, Francesco; Roks, Antonius

    2010-01-01

    The invention relates to the field of polymers and biomedical applications thereof. In particular, it relates to the use of polymeric amines derived from alternating polyketones.Provided is the use of a polymeric amine for modulating or supporting cellular behavior, said polymeric amine being an alt

  7. THE POLYMERIZATION OF AROMATIC AND HETEROCYCLIC DINITRILES

    Institute of Scientific and Technical Information of China (English)

    HUANG Zhitang

    1988-01-01

    This review is a concise survey about the works in our laboratory on the polymerization of aromatic and heterocyclic dinitriles, including the polymerization kinetics and mechanism, synthesis of heterocyclic dinitriles, the structure of polymers, and the correlation between the structures of dinitriles and polymerization rates and thermal performances of polymers.

  8. Glycine Polymerization on Oxide Minerals

    Science.gov (United States)

    Kitadai, Norio; Oonishi, Hiroyuki; Umemoto, Koichiro; Usui, Tomohiro; Fukushi, Keisuke; Nakashima, Satoru

    2016-07-01

    It has long been suggested that mineral surfaces played an important role in peptide bond formation on the primitive Earth. However, it remains unclear which mineral species was key to the prebiotic processes. This is because great discrepancies exist among the reported catalytic efficiencies of minerals for amino acid polymerizations, owing to mutually different experimental conditions. This study examined polymerization of glycine (Gly) on nine oxide minerals (amorphous silica, quartz, α-alumina and γ-alumina, anatase, rutile, hematite, magnetite, and forsterite) using identical preparation, heating, and analytical procedures. Results showed that a rutile surface is the most effective site for Gly polymerization in terms of both amounts and lengths of Gly polymers synthesized. The catalytic efficiency decreased as rutile > anatase > γ-alumina > forsterite > α- alumina > magnetite > hematite > quartz > amorphous silica. Based on reported molecular-level information for adsorption of Gly on these minerals, polymerization activation was inferred to have arisen from deprotonation of the NH3 + group of adsorbed Gly to the nucleophilic NH2 group, and from withdrawal of electron density from the carboxyl carbon to the surface metal ions. The orientation of adsorbed Gly on minerals is also a factor influencing the Gly reactivity. The examination of Gly-mineral interactions under identical experimental conditions has enabled the direct comparison of various minerals' catalytic efficiencies and has made discussion of polymerization mechanisms and their relative influences possible Further systematic investigations using the approach reported herein (which are expected to be fruitful) combined with future microscopic surface analyses will elucidate the role of minerals in the process of abiotic peptide bond formation.

  9. SCATTERING FROM RAMIFIED POLYMERIC SYSTEMS

    Directory of Open Access Journals (Sweden)

    M.Benhamou

    2004-01-01

    Full Text Available Here, of great interest to us is a quantitative study of the scattering properties from ramified polymeric systems of arbitrary topology. We consider three types of systems, namely ramified polymers in solution, ramified polymer blends, or ternary mixtures made of two ramified polymers of different chemical nature immersed in a good solvent. To achieve the goal of the study, use is made of the Random Phase Approximation. First we determine the exact expression of the form factor of an ideal ramified polymer of any topology, from which we extract the exact expression of its gyration radius. Using the classical Zimm's formulae and the exact form factor, we determine all scattering properties of these three types of ramified polymeric systems. The main conclusion is that ramification of the chains induces drastic changes of the scattering properties.

  10. Magnetic properties of polymerized diphenyloctatetrayne

    Energy Technology Data Exchange (ETDEWEB)

    Beristain, Miriam F.; Jimenez-Solomon, Maria F.; Ortega, Alejandra; Escudero, Roberto [Instituto de Investigaciones en Materiales, Universidad Nacional Autonoma de Mexico, Apartado Postal 70-360, Ciudad Universitaria, Mexico DF 04510 (Mexico); Munoz, Eduardo [Instituto de Fisica, Universidad Nacional Autonoma de Mexico, Apartado Postal 20-364, Ciudad Universitaria, Mexico DF 01000 (Mexico); Maekawa, Yasunari; Koshikawa, Hiroshi [High Performance Polymer Group, Quantum Beam Science Directorate, Japan Atomic Energy Agency, 1233 Watanuki, Takasaki, Gunma 370-1292 (Japan); Ogawa, Takeshi, E-mail: ogawa@unam.mx [Instituto de Investigaciones en Materiales, Universidad Nacional Autonoma de Mexico, Apartado Postal 70-360, Ciudad Universitaria, Mexico DF 04510 (Mexico)

    2012-10-15

    A new type of metal-free ferromagnetic carbon material was obtained by thermal polymerization and electron beam irradiation of diphenyloctatetrayne (DPOT). The isothermal magnetic measurements showed hysteresis loops indicating weak but intrinsic ferromagnetism with Curie temperatures of around 600 K. Electron spin resonance spectroscopy showed that the material contained stable free radicals in the range of 10{sup 17}-10{sup 20} radicals g{sup -1} depending on the polymerization process. The ferromagnetism should be due to high radical concentration although no correlation was observed between them. It was shown that an amorphous ferromagnetic carbon could be obtained from a simple crystalline solid by heating at moderate temperatures. Highlights: Black-Right-Pointing-Pointer Diphenyloctatetrayne as a precursor for carbon with high radical concentration. Black-Right-Pointing-Pointer The carbon material consists of sp{sup 2} configuration. Black-Right-Pointing-Pointer A weak intrinsic metal-free ferromagnetism was observed for the carbon products.

  11. Polymeric Microspheres for Medical Applications

    Directory of Open Access Journals (Sweden)

    Ketie Saralidze

    2010-06-01

    Full Text Available Synthetic polymeric microspheres find application in a wide range of medical applications. Among other applications, microspheres are being used as bulking agents, embolic- or drug-delivery particles. The exact composition of the spheres varies with the application and therefore a large array of materials has been used to produce microspheres. In this review, the relation between microsphere synthesis and application is discussed for a number of microspheres that are used for different treatment strategies.

  12. A label-free and high sensitive aptamer biosensor based on hyperbranched polyester microspheres for thrombin detection

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Chong [Jiangsu Key Laboratory of Biofunctional Materials, Biomedical Functional Materials Collaborative Innovation Center, College of Chemistry and Materials Science, Nanjing Normal University, Nanjing 210023 (China); Institute of Agricultural Products Processing, Jiangsu Academy of Agricultural Sciences, Nanjing 210014 (China); Han, Qiaorong [Jiangsu Key Laboratory of Biofunctional Materials, Biomedical Functional Materials Collaborative Innovation Center, College of Chemistry and Materials Science, Nanjing Normal University, Nanjing 210023 (China); Wang, Daoying; Xu, Weimin [Institute of Agricultural Products Processing, Jiangsu Academy of Agricultural Sciences, Nanjing 210014 (China); Wang, Weijuan [Jiangsu Key Laboratory of Biofunctional Materials, Biomedical Functional Materials Collaborative Innovation Center, College of Chemistry and Materials Science, Nanjing Normal University, Nanjing 210023 (China); Zhao, Wenbo, E-mail: zhaowenbo@njnu.edu.cn [Jiangsu Key Laboratory of Biofunctional Materials, Biomedical Functional Materials Collaborative Innovation Center, College of Chemistry and Materials Science, Nanjing Normal University, Nanjing 210023 (China); Zhou, Min, E-mail: zhouminnju@126.com [Department of Vascular Surgery, the Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing 210008 (China)

    2014-11-19

    Highlights: • A label-free thrombin aptamer biosensor applied in whole blood has been developed. • The aptamer biosensor showed a wide detection range and a low detection limit. • The antibiofouling idea utilized for biosensor is significant for diagnostics. - Abstract: In this paper, we have synthesized hyperbranched polyester microspheres with carboxylic acid functional groups (HBPE-CA) and developed a label-free electrochemical aptamer biosensor using thrombin-binding aptamer (TBA) as receptor for the measurement of thrombin in whole blood. The indium tin oxide (ITO) electrode surface modified with HBPE-CA microspheres was grafted with TBA, which has excellent binding affinity and selectivity for thrombin. Binding of the thrombin at the modified ITO electrode surface greatly restrained access of electrons for a redox probe of [Fe(CN){sub 6}]{sup 3−/4−}. Moreover, the aptamer biosensor could be used for detection of thrombin in whole blood, a wide detection range (10 fM–100 nM) and a detection limit on the order of 0.90 fM were demonstrated. Control experiments were also carried out by using bull serum albumin (BSA) and lysozyme in the absence of thrombin. The good stability and repeatability of this aptamer biosensor were also proved. We expect that this demonstration will lead to the development of highly sensitive label-free sensors based on aptamer with lower cost than current technology. The integration of the technologies, which include anticoagulant, sensor and nanoscience, will bring significant input to high-performance biosensors relevant to diagnostics and therapy of interest for human health.

  13. Development of hyperbranched polymers with non-covalent interactions for extraction and determination of aflatoxins in cereal samples.

    Science.gov (United States)

    Liu, Xiaoyan; Li, Huihui; Xu, Zhigang; Peng, Jialin; Zhu, Shuqiang; Zhang, Haixia

    2013-10-01

    A novel approach for assembling homogeneous hyperbranched polymers based on non-covalent interactions with aflatoxins was developed; the polymers were used to evaluate the extraction of aflatoxins B1, B2, G1 and G2 (AFB1, AFB2, AFG1 and AFG2) in simulant solutions. The results showed that the extraction efficiencies of three kinds of synthesized polymers for the investigated analytes were not statistically different; as a consequence, one of the representative polymers (polymer I) was used as the solid-phase extraction (SPE) sorbent to evaluate the influences of various parameters, such as desorption conditions, pH, ionic strength, concentration of methanol in sample solutions, and the mass of the sorbent on the extraction efficiency. In addition, the extraction efficiencies for these aflatoxins were compared between the investigated polymer and the traditional sorbent C18. The results showed that the investigated polymer had superior extraction efficiencies. Subsequently, the proposed polymer for the SPE packing material was employed to enrich and analyze four aflatoxins in the cereal powder samples. The limits of detection (LODs) at a signal-to-noise (S/N) ratio of 3 were in the range of 0.012-0.120 ng g(-1) for four aflatoxins, and the limits of quantification (LOQs) calculated at S/N=10 were from 0.04 to 0.40 ng g(-1) for four aflatoxins. The recoveries of four aflatoxins from cereal powder samples were in the range of 82.7-103% with relative standard deviations (RSDs) lower than 10%. The results demonstrate the suitability of the SPE approach for the analysis of trace aflatoxins in cereal powder samples.

  14. Cold preservation with hyperbranched polyglycerol-based solution improves kidney functional recovery with less injury at reperfusion in rats

    Science.gov (United States)

    Li, Shadan; Liu, Bin; Guan, Qiunong; Chafeeva, Irina; Brooks, Donald E; Nguan, Christopher YC; Kizhakkedathu, Jayachandran N; Du, Caigan

    2017-01-01

    Minimizing donor organ injury during cold preservation (including cold perfusion and storage) is the first step to prevent transplant failure. We recently reported the advantages of hyperbranched polyglycerol (HPG) as a novel substitute for hydroxyethyl starch in UW solution for both cold heart preservation and cold kidney perfusion. This study evaluated the functional recovery of the kidney at reperfusion after cold preservation with HPG solution. The impact of HPG solution compared to conventional UW and HTK solutions on tissue weight and cell survival at 4°C was examined using rat kidney tissues and cultured human umbilical vein endothelial cells (HUVECs), respectively. The kidney protection by HPG solution was tested in a rat model of cold kidney ischemia-reperfusion injury, and was evaluated by histology and kidney function. Here, we showed that preservation with HPG solution prevented cell death in cultured HUVECs and edema formation in kidney tissues at 4°C similar to UW solution, whereas HTK solution was less effective. In rat model of cold ischemia-reperfusion injury, the kidneys perfused and subsequently stored 1-hour with cold HPG solution showed less leukocyte infiltration, less tubular damage and better kidney function (lower levels of serum creatinine and blood urea nitrogen) at 48 h of reperfusion than those treated with UW or HTK solution. In conclusion, our data show the superiority of HPG solution to UW or HTK solution in the cold perfusion and storage of rat kidneys, suggesting that the HPG solution may be a promising candidate for improved donor kidney preservation prior to transplantation. PMID:28337272

  15. Ultrasound-Mediated Polymeric Micelle Drug Delivery.

    Science.gov (United States)

    Xia, Hesheng; Zhao, Yue; Tong, Rui

    2016-01-01

    The synthesis of multi-functional nanocarriers and the design of new stimuli-responsive means are equally important for drug delivery. Ultrasound can be used as a remote, non-invasive and controllable trigger for the stimuli-responsive release of nanocarriers. Polymeric micelles are one kind of potential drug nanocarrier. By combining ultrasound and polymeric micelles, a new modality (i.e., ultrasound-mediated polymeric micelle drug delivery) has been developed and has recently received increasing attention. A major challenge remaining in developing ultrasound-responsive polymeric micelles is the improvement of the sensitivity or responsiveness of polymeric micelles to ultrasound. This chapter reviews the recent advance in this field. In order to understand the interaction mechanism between ultrasound stimulus and polymeric micelles, ultrasound effects, such as thermal effect, cavitation effect, ultrasound sonochemistry (including ultrasonic degradation, ultrasound-initiated polymerization, ultrasonic in-situ polymerization and ultrasound site-specific degradation), as well as basic micellar knowledge are introduced. Ultrasound-mediated polymeric micelle drug delivery has been classified into two main streams based on the different interaction mechanism between ultrasound and polymeric micelles; one is based on the ultrasound-induced physical disruption of the micelle and reversible release of payload. The other is based on micellar ultrasound mechanochemical disruption and irreversible release of payload.

  16. Cationic Copolymerization of 3,3-Bis(hydroxymethyl)oxetane and Glycidol: Biocompatible Hyperbranched Polyether Polyols with High Content of Primary Hydroxyl Groups.

    Science.gov (United States)

    Christ, Eva-Maria; Hobernik, Dominika; Bros, Matthias; Wagner, Manfred; Frey, Holger

    2015-10-12

    The cationic ring-opening copolymerization of 3,3-bis(hydroxymethyl)oxetane (BHMO) with glycidol using different comonomer ratios (BHMO content from 25 to 90%) and BF3OEt2 as an initiator has been studied. Apparent molecular weights of the resulting hyperbranched polyether copolymers ranged from 1400 to 3300 g mol(-1) (PDI: 1.21-1.48; method: SEC, linear PEG standards). Incorporation of both comonomers is evidenced by MALDI-TOF mass spectroscopy. All hyperbranched polyether polyols with high content of primary hydroxyl groups portray good solubility in water, which correlates with an increasing content of glycerol units. Detailed NMR characterization was employed to elucidate the copolymer microstructures. Kinetic studies via FTIR demonstrated a weak gradient-type character of the copolymers. MTT assays of the copolymers (up to 100 μg mL(-1)) on HEK and fibroblast cell lines (3T3, L929, WEHI) as well as viability tests on the fibroblast cells were carried out to assess the biocompatibility of the materials, confirming excellent biocompatibility. Transfection efficiency characterization by flow cytometry and confocal laser microscopy demonstrated cellular uptake of the copolymers. Antiadhesive properties of the materials on surfaces were assessed by adhesion assays with fibroblast cells.

  17. Study on Modification of Hyperbranched Polyester Boltorn H20%超支化聚酯Boltorn H20的改性研究

    Institute of Scientific and Technical Information of China (English)

    王芳; 贾晓辉; 武亚新; 廖云

    2015-01-01

    The hyperbranched polyester Boltorn H20 contains a lot of hydroxyl groups,the reflux condensation method was adopted,some hydroxyl groups of H20 was modified with maleic anhydride,thereby some carboxyl groups were introduced in the H20. The effect of different solvents and modified hydroxyl number on the reaction time were discussed. Reac-tion end point was determined with FTIR,NMR spectroscopy confirmed that Boltorn H20 was successfully modified with maleic anhydride, this may be usefull for further study of hyperbranched polyester application on waterborne coatings.%超支化聚酯Boltorn H20分子末端含有很多羟基,采用回流冷凝法,用顺丁烯二酸酐将H20部分端羟基进行改性,从而在H20分子上引入了端羧基。主要讨论了溶剂和改性不同端羟基数目对反应的影响,反应终点采用红外光谱来确定。核磁共振谱图证实了Boltorn H20被成功改性,这为进一步研究超支化聚酯在水性涂料中的应用奠定了基础。

  18. Achieving high performance electric field induced strain: a rational design of hyperbranched aromatic polyamide functionalized graphene-polyurethane dielectric elastomer composites.

    Science.gov (United States)

    Chen, Tian; Qiu, Jinhao; Zhu, Kongjun; Li, Jinhuan; Wang, Jingwen; Li, Shuqin; Wang, Xiaoliang

    2015-03-26

    Dielectric elastomers have great potentials as flexible actuators in micro-electromechanical systems (MEMS) due to their large deformation, light weight, mechanical compliancy, and low cost. The low dielectric constant of these elastomers requires a rather high voltage electric field, which has greatly limited their applications. In this work, a diaphragm-type flexible microactuator comprising a hyperbranched aromatic polyamide functionalized graphene (HAPFG) filler embedded into the polyurethane (PU) dielectric elastomer matrix is described. The rational designed HAPFG sheets exhibits uniform dispersion in PU matrix and strong adhesion with the matrix by hydrogen-bond coupling. Consequently, the HAPFG-PU composites possess high dielectric performance and low loss modulus. The effect of hyperbranched aromatic polyamide functionalized graphene on high voltage electric field induced strain was experimentally investigated using the Fotonic sensor. The high electric field response of the composite was discussed by applying different kinds of alternating-current field. In addition, a comparison of the breakdown strength between the HAPFG-PU composite and the pure PU was carried out.

  19. Hyperbranched polyglycerol/graphene oxide nanocomposite reinforced hollow fiber solid/liquid phase microextraction for measurement of ibuprofen and naproxen in hair and waste water samples.

    Science.gov (United States)

    Rezaeifar, Zohreh; Es'haghi, Zarrin; Rounaghi, Gholam Hossein; Chamsaz, Mahmoud

    2016-09-01

    A new design of hyperbranched polyglycerol/graphene oxide nanocomposite reinforced hollow fiber solid/liquid phase microextraction (HBP/GO -HF-SLPME) coupled with high performance liquid chromatography used for extraction and determination of ibuprofen and naproxen in hair and waste water samples. The graphene oxide first synthesized from graphite powders by using modified Hummers approach. The surface of graphene oxide was modified using hyperbranched polyglycerol, through direct polycondensation with thionyl chloride. The ready nanocomposite later wetted by a few microliter of an organic solvent (1-octanol), and then applied to extract the target analytes in direct immersion sampling mode.After the extraction process, the analytes were desorbed with methanol, and then detected via high performance liquid chromatography (HPLC). The experimental setup is very simple and highly affordable. The main factors influencing extraction such as; feed pH, extraction time, aqueous feed volume, agitation speed, the amount of functionalized graphene oxide and the desorption conditions have been examined in detail. Under the optimized experimental conditions, linearity was observed in the range of 5-30,000ngmL(-1) for ibuprofen and 2-10,000ngmL(-1) for naproxen with correlation coefficients of 0.9968 and 0.9925, respectively. The limits of detection were 2.95ngmL(-1) for ibuprofen and 1.51ngmL(-1) for naproxen. The relative standard deviations (RSDs) were found to be less than 5% (n=5).

  20. Fabrication of glucose biosensor for whole blood based on Au/hyperbranched polyester nanoparticles multilayers by antibiofouling and self-assembly technique

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Chong [Jiangsu Key Laboratory of Biofunctional Materials, College of Chemistry and Materials Science, Nanjing Normal University, Nanjing 210023 (China); Key Laboratory for Soft Chemistry and Functional Materials of Ministry of Education, School of Chemical Engineering, Nanjing University of Science and Technology, Nanjing 210094 (China); Chen, Xiaohan; Han, Qiaorong [Jiangsu Key Laboratory of Biofunctional Materials, College of Chemistry and Materials Science, Nanjing Normal University, Nanjing 210023 (China); Zhou, Min [Department of Vascular Surgery, the Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing 210008 (China); Mao, Chun, E-mail: maochun127@yahoo.cn [Jiangsu Key Laboratory of Biofunctional Materials, College of Chemistry and Materials Science, Nanjing Normal University, Nanjing 210023 (China); Zhu, Qinshu [Jiangsu Key Laboratory of Biofunctional Materials, College of Chemistry and Materials Science, Nanjing Normal University, Nanjing 210023 (China); Shen, Jian, E-mail: jshen@njnu.edu.cn [Jiangsu Key Laboratory of Biofunctional Materials, College of Chemistry and Materials Science, Nanjing Normal University, Nanjing 210023 (China)

    2013-05-07

    Highlight: •A novel method for detection of glucose in whole blood has been developed. •The method based on antibiofouling and self-assembly technology was investigated. •The antibiofouling technique utilized for sensor is significant for diagnostics. -- Abstract: Acknowledging the benefits of hyperbranched polymers and their nanoparticles, herein we report the design and synthesis of sulfonic acid group functionalized hydroxyl-terminated hyperbranched polyester (H30-SO{sub 3}H) nanoparticles and their biomedical application. The H30-SO{sub 3}H nanoparticles were characterized by transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy and proton nuclear magnetic resonance spectroscopy ({sup 1}H NMR). The good hemocompatibility of H30-SO{sub 3}H nanoparticles was also investigated by coagulation tests, complement activation and platelet activation. The novel glucose biosensor was fabricated by immobilizing the positively charged Au nanoparticles, H30-SO{sub 3}H nanoparticles and glucose oxidase (GOx) onto the surface of glassy carbon electrode (GCE). It can be applied in whole blood directly, which was based on the good hemocompatibility and antibiofouling property of H30-SO{sub 3}H nanoparticles. The biosensor had good electrocatalytic activity toward glucose with a wide linear range (0.2–20 mM), a low detection limit 1.2 × 10{sup −5} M in whole blood and good anti-interference property. The development of materials science will offer a novel platform for application to substance detection in whole blood.

  1. Construction of amphiphilic copolymer nanoparticles based on hyperbranched poly (amine-ester) and 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine as drug carriers for cancer therapy.

    Science.gov (United States)

    Wu, Yan; Jiao, Fang; Han, Siyuan; Fan, Tengfei; Liu, Ying; Li, Wei; Hu, Liming; Zhao, Yuliang; Chen, Chunying

    2011-12-01

    Novel amphiphilic copolymer nanoparticles (HPAE-co-PLA-DPPE) composed of hyperbranched poly (amine-ester), polylactide and 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine (DPPE) segments were designed and synthesized that provided high encapsulation efficiency. These nanoparticles (NPs) were used to encapsulate an antitumor model drug, doxorubicin (DOX). The resulting NPs exhibited high encapsulation efficiency to DOX under an appropriate condition. In vitro release experiments revealed that the release of DOX from NPs was faster at pH 4.5 than that at pH 7.4 or pH 6.0. Confocal microscopy observation indicated that the DOX-loaded NPs can enter cells and localize in lysosomes that can be released quickly into the cytoplasm. The DOX-loaded NPs showed comparable anticancer efficacy with the free drug both in vivo and in vitro. These results demonstrate a feasible application of the hyperbranched copolymer, HPAE-co-PLA-DPPE, as a promising nanocarrier for intracellular delivery of antitumor drugs. In this paper, the development of novel amphiphilic copolymer nanoparticles is discussed with the goal of establishing high encapsulation efficiency for chemotherapy drugs. Copyright © 2011 Elsevier Inc. All rights reserved.

  2. Polymerization rate and mechanism of ultrasonically initiated emulsion polymerization of n-butyl acrylate.

    Science.gov (United States)

    Xia, Hesheng; Wang, Qi; Liao, Yongqin; Xu, Xi; Baxter, Steven M; Slone, Robert V; Wu, Shuguang; Swift, Graham; Westmoreland, David G

    2002-07-01

    The factors affecting the induction period and polymerization rate in ultrasonically initiated emulsion polymerization of n-butyl acrylate (BA) were investigated. The induction period takes only an instant in ultrasonically initiated emulsion polymerization of BA without any added initiator by enhancing the N2 flow rate. Increasing temperature, power output and SDS concentration, decreasing the monomer concentration results in further decreasing induction period and enhanced polymerization rate. Under optimized reaction conditions the conversion of BA reaches 92% in 11 min. The polymerization rate can be controlled by varying reaction parameters. The apparatus of ultrasonically initiated semi-continuous and continuous emulsion polymerization were set up and the feasibility was first studied. Based on the experimental results, a free radical polymerization mechanism for ultrasonically initiated emulsion polymerization was proposed, including the sources of the radicals, the process of radical formation, the locus of polymerization and the polymerization process. Compared with conventional emulsion polymerization, where the radicals come from thermal decomposition of a chemical initiator, ultrasonically initiated emulsion polymerization has attractive features such as no need for a chemical initiator, lower reaction temperature, faster polymerization rate, and higher molecular weight of the polymer prepared.

  3. Dynamic Monte Carlo simulation of chain growth polymerization and its concentration effect

    Institute of Scientific and Technical Information of China (English)

    LüWenqi

    2005-01-01

    [1]He, J., Zhang, H., Chen, J. et al., Monte Carlo simulation of kinetics and chain length distributions in living free-radical polymerization, Macromolecules, 1997, 30: 8010-8018.[2]Li, L., He, J., Yang, Y., Monte Carlo simulation on living radical polymerization with RAFT process, Chem. J. Chinese Univ. (in Chinese), 2000, 21(7): 1146-1148.[3]Ling, J., Shen, Z., Chen W., Algorithm and application of Monte Carlo simulation for multi-dispersive copolymerization system, Science in China, Series B, 2002, 45(3): 243-250.[4]Butte, A., Storti, G., Morbidelli, M., Evaluation of the chain length distribution in free-radical polymerization, 1. Bulk polymerization, Macromol. Theory Simul., 2002, 11: 22-36.[5]Smith, G. B., Russell, G. T., Heuts, J. P. A., Termination in dilute-solution free-radical polymerization: A composite model, Macromol. Theory Simul., 2003, 12: 299-314.[6]Zetterlund, P. B., Yamazoe, H., Yamada, B., Free radical bulk po- lymerization of styrene: Simulation of molecular weight distribu- tions to high conversion using experimentally obtained rate coef- ficients, Macromol. Theory Simul., 2003, 12: 379-385.[7]Binder, K., Paul, W., Monte Carlo simulations of polymer dy- namics: Recent advances, J. Polym. Sci., Polym. Phys. Ed., 1997, 35(1): 1-31.[8]Rouault, Y., Milchev, A., Monte Carlo study of living polymers with the bond-fluctuation method, Phys. Rev. E, 1995, 51(6): 5905-5910.[9]Jo, W. H., Lee, J. W., Lee, M. S. et al., Effect of interchange reactions on the molecular weight distribution of poly(ethylene terephthalate): A Monte Carlo simulation, J. Polym. Sci., Polym. Phys. Ed., 1996, 34: 725-729.[10]Jang, S. S., Ha, W. S., Jo, W. H. et al., Monte Carlo simulation of copolymerization by ester interchange reaction in miscible polyester blends, J. Polym. Sci., Polym. Phys. Ed., 1998, 36: 1637-1645.[11]Lee, Y. U., Jang, S. S., Jo, W. H., Off-lattice Monte Carlo simulation of hyperbranched polymers, 1. Polycondensation of AB2 type monomers, Macromol. Theory

  4. Nanoporous Polymeric Grating-Based Biosensors

    KAUST Repository

    Gao, Tieyu

    2012-05-02

    We demonstrate the utilization of an interferometrically created nanoporous polymeric gratings as a platform for biosensing applications. Aminopropyltriethoxysilane (APTES)-functionalized nanoporous polymeric gratings was fabricated by combining holographic interference patterning and APTES-functionalization of pre-polymer syrup. The successful detection of multiple biomolecules indicates that the biofunctionalized nanoporous polymeric gratings can act as biosensing platforms which are label-free, inexpensive, and applicable as high-throughput assays. Copyright © 2010 by ASME.

  5. PHOTOSENSITIVITY OF CERIC ION INITIATED ACRYLAMIDE POLYMERIZATION

    Institute of Scientific and Technical Information of China (English)

    DONG Jianhua; QIU Kunyuan; FENG Xinde

    1992-01-01

    Polymerization of acrylamide initiated by ceric ammonium nitrate alone has been studied in aqueous medium. The effects of UV light irradiation on the initial rates of polymerization, the activation energy and on the polymer molecular weights have been investigated. Compared with that in the dark, the rate of polymerization under UV light was accelerated to eleven times higher, and the overall activation energy was lowered markedly.

  6. Directional Growth of Polymeric Nanowires

    Science.gov (United States)

    Thapa, Prem; Flanders, Bret

    2009-03-01

    This work establishes an innovative electrochemical approach to the template free growth of conducting polypyrrole and polythiophene wires. These polymeric wires exhibit a knobby structure, but persistent growth in a given direction up to 30 μm in length. A long-range component of the applied voltage signal defines the growth-path. Moreover, the presence of this component enables the growth of amorphous nanowires with wire-like geometries. Such wires are employed in a non-invasive methodology for attaining strong mechanical attachments to live cells. This capability is of potential use in the electro-mechanical probing of cell physiological processes.

  7. Marketing NASA Langley Polymeric Materials

    Science.gov (United States)

    Flynn, Diane M.

    1995-01-01

    A marketing tool was created to expand the knowledge of LaRC developed polymeric materials, in order to facilitate the technology transfer process and increase technology commercialization awareness among a non-technical audience. The created brochure features four materials, LaRC-CP, LaRC-RP46, LaRC-SI, and LaRC-IA, and highlights their competitive strengths in potential commercial applications. Excellent opportunities exist in the $40 million per year microelectronics market and the $6 billion adhesives market. It is hoped that the created brochure will generate inquiries regarding the use of the above materials in markets such as these.

  8. Charge transport in polymeric transistors

    Directory of Open Access Journals (Sweden)

    Alberto Salleo

    2007-03-01

    Full Text Available Polymeric semiconductors have attracted much attention because of their possible use as active materials in printed electronics. Thin-film transistors (TFTs are a convenient tool for studying charge-transport physics in conjugated polymers. Two families of materials are reviewed here: fluorene copolymers and polythiophenes. Because charge transport is highly anisotropic in molecular conductors, the electrical properties of conjugated polymers are strongly dependent on microstructure. Molecular weight, polydispersity, and regioregularity all affect morphology and charge-transport in these materials. Charge transport models based on microstructure are instrumental in identifying the electrical bottlenecks in these materials.

  9. High Vacuum Techniques for Anionic Polymerization

    KAUST Repository

    Ratkanthwar, Kedar

    2015-09-01

    Anionic polymerization high vacuum techniques (HVTs) are the most suitable for the preparation of polymer samples with well-defined complex macromolecular architectures. Though HVTs require glassblowing skill for designing and making polymerization reactor, it is the best way to avoid any termination of living polymers during the number of steps for the synthesis of polymers with complex structure. In this chapter, we describe the different polymerization reactors and HVTs for the purification of monomers, solvents, and other reagents for anionic polymerization as well as few model reactions for the synthesis of polymers with simple to complex structure.

  10. Effect of Polymerization Condition on Particle Size Distribution in St/BA/MAA Emulsion Polymerization Process

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    A series of St/BA/MAA emulsion polymerizations was carried out. By using PCS (photon correlation spectroscopy), the particle size distribution(PSD) of the whole St/BA/MAA emulsion polymerization process was gotten easily and quickly. The effect of polymerization condition on PSD in St/BA/MAA emulsion process was discussed.

  11. Twin screw extruders as polymerization reactors for a free radical homo polymerization

    NARCIS (Netherlands)

    Ganzeveld, K.J.; Janssen, L.P.B.M.

    1993-01-01

    The bulk polymerization of n-butylmethacrylate was investigated in a counter-rotating twin screw extruder. It appeared that the gel effect, occurring with bulk polymerizations, affected the polymerization progress very strongly. Due to this effect the conversion of the reaction is independent of the

  12. Electrochemical Polymerization of Methylene Green

    Institute of Scientific and Technical Information of China (English)

    ZHU,Hong-Ping; MU,Shao-Lin

    2001-01-01

    The electrochemical polymerization of methylene green has been carried out using cyclic voltammetry. The electrolytic so lution consisted of 4 × 10-3 mol/L methylene green, 0.1 mol/L NaNO3 and 1 × 10-2 mol/L sodium tetraborate with pH 11.0. The temperature for polymerization is controlled at 60℃. The scan potential is set between -0.2 and 1.2 V (vs. Ag/AgCl with saturated KCl solution). There are an anodic peak and a cathodic peak on the cyclic voltammogram of poly(methylene green) at pH≤3.8. Both peak potentials shift towards nega tive potentials with increasing pH value, and their peak cur rents decrease with increasing pH value. Poly(methylene green) has a good electrochemical activity and stability in aqueous solutions with pH ≤ 3.8. The UV-Visible spectrum and FTIR spectrum of poly (methylene green) are different from those of methylene green.

  13. Schlenk Techniques for Anionic Polymerization

    KAUST Repository

    Ratkanthwar, Kedar

    2015-09-01

    Anionic polymerization-high vacuum techniques (HVTs) are doubtlessly the most prominent and reliable experimental tools to prepare polymer samples with well-defined and, in many cases, complex macromolecular architectures. Due to the high demands for time and skilled technical personnel, HVTs are currently used in only a few research laboratories worldwide. Instead, most researchers in this filed are attracted to more facile Schlenk techniques. The basic principle of this technique followed in all laboratories is substantially the same, i.e. the use of alternate vacuum and inert gas atmosphere in glass apparatus for the purification/charging of monomer, solvents, additives, and for the manipulation of air-sensitive compounds such as alkyl metal initiators, organometallic or organic catalysts. However, it is executed quite differently in each research group in terms of the structure of Schlenk apparatus (manifolds, connections, purification/storage flasks, reactors, etc.), the use of small supplementary devices (soft tubing, cannulas, stopcocks, etc.) and experimental procedures. The operational methods are partly purpose-oriented while also featured by a high flexibility, which makes it impossible to describe in detail each specific one. In this chapter we will briefly exemplify the application of Schlenk techniques for anionic polymerization by describing the performance of a few experiments from our own work.

  14. POLYMERIC NANOPARTICLES FROM SUPERCRITICAL CO2 MICROEMULSION POLYMERIZATION

    Institute of Scientific and Technical Information of China (English)

    Wei-jun Ye; Jason S. Keiper; Joseph M. DeSimone

    2006-01-01

    Herein, we reported the microemulsion polymerization in supercritical carbon dioxide. With the aid of an anionic phosphate fluorosurfactant (bis-[2-(F-hexyl)ethyl]phosphate sodium), water-soluble/CO2-insoluble acryloxyethyltrimethyl ammonium chloride monomer and N,N'-methylene-bisacrylamide cross-linker were solubilized into CO2 continuous phase via the formation of water-in-CO2 (w/c) microemulsion water pools. Initiated by a CO2-soluble initiator, 2,2'-azo-bisisobutyronitrile (AIBN), cross-linked poly(acryloxyethyltrimethyl ammonium chloride) particles were produced and stabilized in these w/c internal water pools. Nano-sized particles with sizes less than 20 nm in diameter and narrow particle size distributions were obtained.

  15. Inflation and Instability of a Polymeric Membrane

    DEFF Research Database (Denmark)

    Hassager, Ole; Kristensen, Susanne Brogaard; Larsen, Johannes Ruben

    1999-01-01

    We consider an axisymmetric polymeric membrane inflated by a uniform pressure difference acting across the membrane. The polymeric material is described by an arbitrary combination of a viscoelastic and a purely viscous component to the stress. Some viscoelastic materials described by a Mooney...

  16. Inflation and Instability of a Polymeric Membrane

    DEFF Research Database (Denmark)

    Neergaard, Jesper; Hassager, Ole

    1999-01-01

    We consider an axisymmetric polymeric membrane inflated by a uniform pressure difference acting across the membrane. The polymeric materialis described by an arbitrary combination of a viscoelastic and a purely viscous component to the stress. Some viscoelastic materials described by a Mooney...

  17. Photoacoustic analysis of dental resin polymerization

    Science.gov (United States)

    Coloiano, E. C. R.; Rocha, R.; Martin, A. A.; da Silva, M. D.; Acosta-Avalos, D.; Barja, P. R.

    2005-06-01

    In this work, we use the photoacoustic technique to monitor the curing process of diverse dental materials, as the resins chemically activated (RCA). The results obtained reveal that the composition of a determined RCA significantly alters its activation kinetics. Photoacoustic data also show that temperature is a significant parameter in the activation kinetics of resins. The photoacoustic technique was also applied to evaluate the polymerization kinetics of photoactivated resins. Such resins are photoactivated by incidence of continuous light from a photodiode. This leads to the polymerization of the resin, modifying its thermal properties and, consequently, the level of the photoacoustic signal. Measurements show that the polymerization of the resin changes the photoacoustic signal amplitude, indicating that photoacoustic measurements can be utilized to monitor the polymerization kinetic and the degree of polymerization of photoactivated dental resins.

  18. Fluid Effects in Polymers and Polymeric Composites

    CERN Document Server

    Weitsman, Y Jack

    2012-01-01

    Fluid Effects in Polymers and Polymeric Composites, written by the late Dr. Y. Jack Weitsman, addresses the wide range of parameters that affect the interaction of fluids with polymers and polymeric composites. The book aims at broadening the scope of available data, mostly limited up to this time to weight-gain recordings of fluid ingress into polymers and composites, to the practical circumstances of fluctuating exposure. Various forms of experimental data are given, in conjunction with theoretical models derived from basic scientific principles, and correlated with severity of exposure conditions and interpreted by means of rationally based theoretical models. The practical implications of the effects of fluids are discussed. The issue of fluid effects on polymers and polymeric composites is of concern to engineers and scientists active in aerospace and naval structures, as an increasing portion of these structures are made of polymeric composites and employ polymeric adhesives as a joining device. While...

  19. Modeling liquid crystal polymeric devices

    Science.gov (United States)

    Gimenez Pinto, Vianney Karina

    The main focus of this work is the theoretical and numerical study of materials that combine liquid crystal and polymer. Liquid crystal elastomers are polymeric materials that exhibit both the ordered properties of the liquid crystals and the elastic properties of rubbers. Changing the order of the liquid crystal molecules within the polymer network can induce shape change. These materials are very valuable for applications such as actuators, sensors, artificial muscles, haptic displays, etc. In this work we apply finite element elastodynamics simulations to study the temperature induced shape deformation in nematic elastomers with complex director microstructure. In another topic, we propose a novel numerical method to model the director dynamics and microstructural evolution of three dimensional nematic and cholesteric liquid crystals. Numerical studies presented in this work are in agreement with experimental observations and provide insight into the design of application devices.

  20. MESO—STRUCTURED POLYMERIC HYDROGELS

    Institute of Scientific and Technical Information of China (English)

    Zhen-zhongYang; Jian-huaRong; DanLi

    2003-01-01

    Meso-structured(opal and inverse opal) polymeric hydrogels of varied morphology and composition were prepared by using two methods:post-modification of the template-synthesized structured polymers and templatepolymerization of functional monomers.A polyacrylic acid based inverse opal hydrogel was chosen to demonstrate its fast pH response by changing color,which is important in designing tunable photonic crystals.Template effects of the hydrogels on controlling structure of the template-synthesized inorganic materials were discussed.The catalytic effect of acid groups in the templates was emphasized for a preferential formation of TiO2 in the region containing acid groups,which allowed duplicating inorganic colloidal crystals from colloidal crystal hydrogels (or macroporous products from macroporous hydrogels) via one step duplication.

  1. MESO-STRUCTURED POLYMERIC HYDROGELS

    Institute of Scientific and Technical Information of China (English)

    Zhen-zhong Yang; Jian-hua Rong; Dan Li

    2003-01-01

    Meso-structured (opal and inverse opal) polymeric hydrogels of varied morphology and composition were prepared by using two methods: post-modification of the template-synthesized structured polymers and templatepolymerization of functional monomers. A polyacrylic acid based inverse opal hydrogel was chosen to demonstrate its fast pH response by changing color, which is important in designing tunable photonic crystals. Template effects of the hydrogels on controlling structure of the template-synthesized inorganic materials were discussed. The catalytic effect of acid groups inthe templates was emphasized for a preferential formation of TiO2 in the region containing acid groups, which allowed duplicating inorganic colloidal crystals from colloidal crystal hydrogels (or macroporous products from macroporous hydrogels) via one step duplication.

  2. Pressure induced polymerization of Formates

    Science.gov (United States)

    Tschauner, Oliver

    2004-03-01

    The discovery of pressure induced polymerization of CO2 inspired us to search for C-O based chain structures forming at high pressure. We used salts of carboxylic acids as starting materials and exposed them to pressures between 10 and 30 GPa. Upon heating to temperatures above 1800 K we observed deprotonation and significant changes in the Raman shifts of C-O streching modes. Structure analysis based on powder diffraction patterns collected at sector 16 of the APS showed formation of extended C-O chain structures with the cations of the salts residing in the interchain spaces. These new high pressure polymers are interesting by their mechanical strength and provide basic molecular patterns of organic metallic conductors.

  3. Environment-Responsive Polymeric Hydrogels

    Institute of Scientific and Technical Information of China (English)

    Zhn X. X.; M. Nichifor; Lin H.Y.; D. Avoce

    2004-01-01

    Some polymers may respond by changing their physico-chemical perperties when the environmental conditions such as pH, temperature and ionic strength are varied. For example,thermosensentive polymers can exhibit a sharp change in solubility in a solvent such as water at a certain temperature known as the lower critical solution temperature (LCST). The responsiveness of the polymeric materials has important technological implications since they can be employed for various applications. The responsiveness of such polymers can be varied by means of copolymerization, chemical modification of the polymer, or the addition of reagents into the solutions. It is interesting and important to tune predictably the responsiveness of the polymers for the different applications. The sensitivity towards the external environment can be modulated by the relative hydrophilicity of the copolymers, hence the chemical structure and composition of the comonomers used.

  4. Hemocompatibility of polymeric nanostructured surfaces.

    Science.gov (United States)

    Leszczak, Victoria; Smith, Barbara S; Popat, Ketul C

    2013-01-01

    Tissue integration is an important property when inducing transplant tolerance, however, the hemocompatibility of the biomaterial surface also plays an important role in the ultimate success of the implant. Therefore, in order to induce transplant tolerance, it is critical to understand the interaction of blood components with the material surfaces. In this study, we have investigated the adsorption of key blood serum proteins, in vitro adhesion and activation of platelets and clotting kinetics of whole blood on flat polycaprolactone (PCL) surfaces, nanowire (NW) surfaces and nanofiber (NF) surfaces. Previous studies have shown that polymeric nanostructured surfaces improve cell adhesion, proliferation and viability; however it is unclear how these polymeric nanostructured surfaces interact with the blood and its components. Protein adsorption results indicate that while there were no significant differences in total albumin (ALB) adsorption on PCL, NW and NF surfaces, NW surfaces had higher total fibrinogen (FIB) and immunoglobulin-G (IgG) adsorption compared to NF and PCL surfaces. In contrast, NF surfaces had higher surface FIB and IgG adsorption compared to PCL and NW surfaces. Platelet adhesion and viability studies show more adhesion and clustering of platelets on the NF surfaces as compared to PCL and NW surfaces. Platelet activation studies reveal that NW surfaces have the highest percentage of unactivated platelets, whereas NF surfaces have the highest percentage of fully activated platelets. Whole blood clotting results indicate that NW surfaces maintain an increased amount of free hemoglobin during the clotting process compared to PCL and NF surface, indicating less clotting and slower rate of clotting on their surfaces.

  5. Polymeric materials from renewable resources

    Science.gov (United States)

    Frollini, Elisabete; Rodrigues, Bruno V. M.; da Silva, Cristina G.; Castro, Daniele O.; Ramires, Elaine C.; de Oliveira, Fernando; Santos, Rachel P. O.

    2016-05-01

    The goals of our studies have been the use of renewable raw materials in the preparation of polymeric materials with diversified properties. In this context, lignosulfonate, which is produced in large scale around the world, but not widely used in the production of polymeric materials, was used to replace phenol and polyols in the preparation of phenolic- (Ligno-PH) and polyurethane-type (Ligno-PU) polymers, respectively. These polymers were used to prepare composites reinforced with sisal lignocellulosic fibers. The use of lignosulfonate in the formulation of both types of polymers was beneficial, because in general composites with improved properties, specially impact strength, were obtained. Composites were also prepared from the so called "biopolyethylene" (HDPE), curaua lignocellulosic fiber, and castor oil (CO). All composites HDBPE/CO/Fiber exhibited higher impact strength, when compared to those of the corresponding HDBPE/Fiber. These results, combined with others (eg SEM images of the fractured surfaces) indicated that, in addition to acting as a plasticizer, this oil may have acted as a compatibilizer of the hydrophilic fiber with the hydrophobic polymer. The set of results indicated that (i) mats with nano (diameter ≤ 100nm) and/or ultrafine (submicron scale) fibers were produced, (ii) hybrid fibers were produced (bio-based mats composites), (iii) cellulosic pulp (CP) and/or lignin (Lig) can be combined with PET matrices to control properties such as stiffness and hydrophilicity of the respective mats. Materials with diversified properties were prepared from high content of renewable raw materials, thus fulfilling the proposed targets.

  6. Polymeric materials from renewable resources

    Energy Technology Data Exchange (ETDEWEB)

    Frollini, Elisabete; Rodrigues, Bruno V. M.; Silva, Cristina G. da; Castro, Daniele O.; Ramires, Elaine C.; Oliveira, Fernando de; Santos, Rachel P. O. [Macromolecular Materials and Lignocellulosic Fibers Group, Center for Research on Science and Technology of BioResources, Institute of Chemistry of São Carlos, University of São Paulo, CP 780, 13560-970 São Carlos, São Paulo (Brazil)

    2016-05-18

    The goals of our studies have been the use of renewable raw materials in the preparation of polymeric materials with diversified properties. In this context, lignosulfonate, which is produced in large scale around the world, but not widely used in the production of polymeric materials, was used to replace phenol and polyols in the preparation of phenolic- (Ligno-PH) and polyurethane-type (Ligno-PU) polymers, respectively. These polymers were used to prepare composites reinforced with sisal lignocellulosic fibers. The use of lignosulfonate in the formulation of both types of polymers was beneficial, because in general composites with improved properties, specially impact strength, were obtained. Composites were also prepared from the so called “biopolyethylene” (HDPE), curaua lignocellulosic fiber, and castor oil (CO). All composites HDBPE/CO/Fiber exhibited higher impact strength, when compared to those of the corresponding HDBPE/Fiber. These results, combined with others (eg SEM images of the fractured surfaces) indicated that, in addition to acting as a plasticizer, this oil may have acted as a compatibilizer of the hydrophilic fiber with the hydrophobic polymer. The set of results indicated that (i) mats with nano (diameter ≤ 100nm) and/or ultrafine (submicron scale) fibers were produced, (ii) hybrid fibers were produced (bio-based mats composites), (iii) cellulosic pulp (CP) and/or lignin (Lig) can be combined with PET matrices to control properties such as stiffness and hydrophilicity of the respective mats. Materials with diversified properties were prepared from high content of renewable raw materials, thus fulfilling the proposed targets.

  7. Preparation and characterization of multi stimuli-responsive photoluminescent nanocomposites of graphene quantum dots with hyperbranched polyethylenimine derivatives

    Science.gov (United States)

    Liu, Xing; Liu, Hua-Ji; Cheng, Fa; Chen, Yu

    2014-06-01

    Oxidized graphene sheets (OGS) were treated with a hyperbranched polyethylenimine (PEI) under hydrothermal conditions to generate nanocomposites of graphene quantum dots (GQDs) functionalized with PEI (GQD-PEIs). The influence of the reaction temperature and the PEI/OGS feed ratio on the photoluminescence properties of the GQD-PEIs was studied. The obtained GQD-PEIs were characterized by TEM, dynamic light scattering, elemental analysis, FTIR, zeta potential measurements and 1H NMR spectroscopy, from which their structural information was inferred. Subsequently, isobutyric amide (IBAm) groups were attached to the GQD-PEIs through the amidation reaction of isobutyric anhydride with the PEI moieties, which resulted in GQD-PEI-IBAm nanocomposites. GQD-PEI-IBAm was not only thermoresponsive, but also responded to other stimuli, including inorganic salts, pH, and loaded organic guests. The cloud point temperature (Tcp) of aqueous solutions of GQD-PEI-IBAm could be modulated through changing the number of IBAm units in GQD-PEI-IBAm, by varying the type and concentration of the inorganic salts and loaded organic guests, or by varying the pH. All the obtained GQD-PEI-IBAm nanocomposites were photoluminescent, and their maximum emission wavelengths were not influenced by outside stimuli. Their emission intensities were influenced a little or negligibly by pH, traditional salting-out anions (Cl- and SO42-), and the relatively polar aspirin guest. However, the traditional salting-in I- anion and the more hydrophobic 1-pyrenebutyric acid (PBA) guest could effectively quench their fluorescence. 2D NOESY 1H NMR spectra verified that GQD-PEI-IBAm accommodated the relatively polar aspirin guest using the PEI-IBAm shell, but adsorbed the relatively hydrophobic PBA guest through the nanographene core. The release rate of the guest encapsulated by the thermoresponsive GQD is different below and above Tcp.Oxidized graphene sheets (OGS) were treated with a hyperbranched

  8. Spin-assembled nanolayer of a hyperbranched polymer on the anode in organic light-emitting diodes: the mechanism of hole injection and electron blocking.

    Science.gov (United States)

    Lee, Tae-Woo; Park, Jong-Jin; Kwon, Young; Hayakawa, Teruaki; Choi, Tae-Lim; Park, Jong Hyeok; Das, Rupasree Ragini; Kakimoto, Masa-aki

    2008-11-04

    We introduced a spin-assembled nanolayer of hyperbranched poly(ether sulfone) with sulfonic acid terminal on top of an indium-tin oxide anode in organic light-emitting diodes. This results in great improvement in luminous efficiency, better than that of devices using a commercially available conducting polymer composition as a hole-injection layer. The effect of the nanolayer was investigated by impedance spectroscopy, photovoltaic measurement for built-in-potential, and transient electroluminescence. We concluded that the high luminous efficiency resulted from the efficient electron-blocking by the nanolayer and hole-injection assisted by the accumulation of electrons at the interface. This result implies that, for an efficient hole-injection layer, the electron-blocking capability should be incorporated in addition to the hole-injection and -transport capability.

  9. Rational design of hyperbranched 3D heteroarrays of SrS/CdS: synthesis, characterization and evaluation of photocatalytic properties for efficient hydrogen generation and organic dye degradation.

    Science.gov (United States)

    Khan, Ziyauddin; Chetia, Tridip Ranjan; Qureshi, Mohammad

    2012-06-07

    Hyperbranched 3D SrS/CdS nanostructures were synthesized using a one pot hydrothermal method. Transmission Electron Microscopy (TEM) and Field Emission-Scanning Electron Microscopy (FE-SEM) analysis showed the formation of flower-like structure and the crystalline phase was confirmed by powder X-ray diffraction. The prepared 3D SrS/CdS exhibited improved photocatalytic activity for water splitting leading to H(2) generation (AQY 10%) and nearly complete degradation of methyl orange (MO) dye. The dye degradation followed first order kinetics and the apparent reaction rate constant (k(app)) was 0.136 min(-1). The present 3D SrS/CdS structure promise to be efficient photocatalysts due to (i) the facile intersystem charge transfer resulting from their band alignment (ii) enhanced specific surface area and (iii) crystallinity.

  10. Facile preparation of highly luminescent CdTe quantum dots within hyperbranched poly(amidoamine)s and their application in bio-imaging.

    Science.gov (United States)

    Shi, Yunfeng; Liu, Lin; Pang, Huan; Zhou, Hongli; Zhang, Guanqing; Ou, Yangyan; Zhang, Xiaoyin; Du, Jimin; Xiao, Wangchuan

    2014-03-13

    A new strategy for facile preparation of highly luminescent CdTe quantum dots (QDs) within amine-terminated hyperbranched poly(amidoamine)s (HPAMAM) was proposed in this paper. CdTe precursors were first prepared by adding NaHTe to aqueous Cd2+ chelated by 3-mercaptopropionic sodium (MPA-Na), and then HPAMAM was introduced to stabilize the CdTe precursors. After microwave irradiation, highly fluorescent and stable CdTe QDs stabilized by MPA-Na and HPAMAM were obtained. The CdTe QDs showed a high quantum yield (QY) up to 58%. By preparing CdTe QDs within HPAMAM, the biocompatibility properties of HPAMAM and the optical, electrical properties of CdTe QDs can be combined, endowing the CdTe QDs with biocompatibility. The resulting CdTe QDs can be directly used in biomedical fields, and their potential application in bio-imaging was investigated.

  11. 超支化聚酯季铵盐的合成与表征%Synthesis and characterization of quaternary ammonium salt of hyperbranched polyester

    Institute of Scientific and Technical Information of China (English)

    杜英英; 陈倩兰; 邢彦军; 戴瑾瑾

    2011-01-01

    In the presence of alkaline catalyst sodium hydroxide, quaternary ammonium salt of hyperbranched polyester (GTA-H20) was prepared by the modification of hyperbranched polyester Boltorn H20 with glycidyltrimethylammonium chloride (GTA).The influences of reaction conditions on the yield of product were studied.The results showed that under the conditions of n(H20):n(GTA)=1 :16, n(NaOH)/n(H20-OH)=0.5, 50 ℃ of reaction temperature and 24 h of reaction time, the product 61.11 % of yield was obtained.The element analysis indicated that the substitution degree of GTA was 22.32%, and the structure of the product was characterized by iH NMH,FT-IR and 13C NMR.%在氢氧化钠催化条件下,利用缩水甘油三甲基氯化铵(GTA)对端羟基超支化聚酯Boltom H20进行季铵化改性,得到了超支化聚酯季铵盐GTA-H20,研究了反应条件对产率的影晌,结果表明:当n(H20):n(GTA)=1:16,n(NaOH)/n(H20-OH)=0.5,50℃反应24h,产率为61.11%.元素分析结果表明:此时GTA的取代度为22.32%,并用(1)H NMR、FF-IR和(13)C NMR谱图对GTA-H20进行了表征.

  12. pH-responsive unimolecular micelles self-assembled from amphiphilic hyperbranched block copolymer for efficient intracellular release of poorly water-soluble anticancer drugs.

    Science.gov (United States)

    Tabatabaei Rezaei, Seyed Jamal; Abandansari, Hamid Sadeghi; Nabid, Mohammad Reza; Niknejad, Hassan

    2014-07-01

    Novel unimolecular micelles from amphiphilic hyperbranched block copolymer H40-poly(ε-caprolactone)-b-poly(acrylic acid)-b'-methoxy poly(ethylene glycol)/poly(ethylene glycol)-folate (i.e., H40-PCL-b-PAA-b'-MPEG/PEG-FA (HCAE-FA)) as new multifunctional nanocarriers to pH-induced accelerated release and tumor-targeted delivery of poorly water-soluble anticancer drugs were developed. The hydrophobic core of the unimolecular micelle was hyperbranched polyester (H40-poly(ε-caprolactone) (H40-PCL)). The inner hydrophilic layer was composed of PAA segments, while the outer hydrophilic shell was composed of PEG segments. This copolymer formed unimolecular micelles in the aqueous solution with a mean particle size of 33 nm, as determined by dynamic light scattering (DLS) and transmission electron microscopy (TEM). To study the feasibility of micelles as a potential nanocarrier for targeted drug delivery, we encapsulated a hydrophobic anticancer drug, paclitaxel (PTX), in the hydrophobic core, and the loading content was determined by UV-vis analysis to be 10.35 wt.%. In vitro release studies demonstrated that the drug-loaded delivery system is relatively stable at physiologic conditions but susceptible to acidic environments which would trigger the release of encapsulated drugs. Flow cytometry and fluorescent microscope studies revealed that the cellular binding of the FA-conjugated micelles against HeLa cells was higher than that of the neat micelles (without FA). The in vitro cytotoxicity studies showed that the PTX transported by these micelles was higher than that by the commercial PTX formulation Tarvexol®. All of these results show that these unique unimolecular micelles may offer a very promising approach for targeted cancer therapy. Copyright © 2014 Elsevier Inc. All rights reserved.

  13. Synthesis of Novel Hyperbranched Polybenzo-Bisthiazole Amide with Donor–Acceptor (D-A Architecture, High Fluorescent Quantum Yield and Large Stokes Shift

    Directory of Open Access Journals (Sweden)

    Xiaobing Hu

    2017-07-01

    Full Text Available Two novel highly fluorescent hyperbranched polybenzobisthiazole amides with a donor–acceptor architecture and large Stokes shift were rationally designed and synthesized. The chemical structures of the prepared hyperbranched polymers were characterized using Fourier Transform Infrared Spectroscopy (FTIR analysis, Hydrogen Nuclear Magnetic Resonance (1H-NMR analysis, and Gel Permeation Chromatography (GPC analysis. These two polymers were soluble in dimethyl sulfoxide (DMSO and N,N-dimethylformamide (DMF, and their DMSO and DMF solutions emitted strong green light (517–537 nm with high quantum yields (QYs and large Stokes shifts. Their relative fluorescence QYs in the DMSO solution were calculated as 77.75% and 81.14% with the Stokes shifts of 137 nm (0.86 eV and 149 nm (0.92 eV for HP–COOH and HP–NH2, respectively, using quinine sulfate as the standard. In the DMF solution, the QYs of HP–COOH and HP–NH2 were calculated as 104.65% and 118.72%, with the Stokes shifts of 128 nm (0.79 eV and 147 nm (0.87 eV, respectively. Their films mainly emitted strong blue light with the maximum emission wavelengths of 436 nm and 480 nm for HP–COOH and HP–NH2, respectively. The Stokes shifts for HP–COOH and HP–NH2 films were 131 nm (0.42 eV and 179 nm (0.86 eV, respectively. They are promising candidates for luminescent solar concentrators and blue light emitting materials.

  14. Hyperbranched polyester: single route synthesis, characterization and evaluation as impact modifier of an epoxy resin; Poliester hiperramificado: sintese por uma rota simples, caracterizacao e avaliacao como modificador de impacto de uma resina epoxi

    Energy Technology Data Exchange (ETDEWEB)

    Miranda, B.H.S.; Sousa, A.R., E-mail: rangel@deii.cefetmg.br [Centro Federal de Educacao Tecnologica de Minas Gerais (DEMAT/CEFET-MG), Belo Horizonte (Brazil). Departamento de Engenharia de Materiais; Alves, A.P.P.; Silva, G.G. [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte (Brazil). Departamento de Quimica. Lab. de Materiais Polimericos Multicomponentes

    2015-07-01

    Two hyperbranched polyesters were obtained using glycerol and adipic acid as monomers, they were characterized through nuclear magnetic resonance ({sup 13}C NMR) to branching degree determination, size exclusion chromatography to molar mass obtention and thermogravimetric analysis (TGA) to evaluate the thermal stability. The polyesters synthesized were added to epoxy resin, at 10% by weight, to evaluate the implication on mechanical properties, impact and stress strain, and thermal (glassy transition temperature - Tg). We observed that rising the synthesis time from 6 to 15,5 hours the degree of branching, molar mass and thermal stability of the polyester increased. The addition of hyperbranched polyesters did not change the mechanical properties of epoxy resin significantly, but the Tg was reduced. (author)

  15. Study of hyperbranched star polycarboxylate superplasticizer and its application in sulphoaluminate cement%超支化星型聚羧酸减水剂的合成及其在硫铝酸盐水泥中的应用

    Institute of Scientific and Technical Information of China (English)

    寿崇琦; 徐磊; 蒋大庆; 刘冰; 许林

    2011-01-01

    A novel hyperbranched star polycarboxylic superplasticizer (HPC) was synthesized by ATRP from bromo-terminated hyperbranched poly (amine-ester) , acrylic acid,monomethoxy-capped polyethylene glycol allyl and characterized by FTIR spectra and 1HNMR. The dispersing effectiveness of HPC in sulphoaluminate cement was assessed by flow of paste. The amount of superplasticizers adsorbed on sulphoaluminate cement was tested and the result showed the novel hyperbranched star polycarboxylic superplasticizer could be significantly adsorbed on the surface of cement particles. The compressive strength tests showed that the hyperbranched star polycarboxylic superplasticizer has good mechanical properties in sulphoaluminate cement.%以溴端基超支化聚(胺-酯)、丙烯酸、烯丙基聚乙二醇甲基醚为原料,采用活性聚合法(ATRP)制备了一种超支化星型聚羧酸系减水剂,并采用红外、核磁对产品进行了表征.水泥净浆流动性实验表明,该种减水剂在硫铝酸盐水泥中具有较好的分散性;表观吸附量的测试验证了该种减水剂可以有效地吸附在硫铝酸盐水泥颗粒表面;抗压强度等的测试表明,该种减水剂应用于硫铝酸盐水泥中具有较好的力学性能.

  16. Programming magnetic anisotropy in polymeric microactuators.

    Science.gov (United States)

    Kim, Jiyun; Chung, Su Eun; Choi, Sung-Eun; Lee, Howon; Kim, Junhoi; Kwon, Sunghoon

    2011-10-01

    Polymeric microcomponents are widely used in microelectromechanical systems (MEMS) and lab-on-a-chip devices, but they suffer from the lack of complex motion, effective addressability and precise shape control. To address these needs, we fabricated polymeric nanocomposite microactuators driven by programmable heterogeneous magnetic anisotropy. Spatially modulated photopatterning was applied in a shape-independent manner to microactuator components by successive confinement of self-assembled magnetic nanoparticles in a fixed polymer matrix. By freely programming the rotational axis of each component, we demonstrate that the polymeric microactuators can undergo predesigned, complex two- and three-dimensional motion.

  17. Polymeric nanoparticles: the future of nanomedicine.

    Science.gov (United States)

    Banik, Brittany L; Fattahi, Pouria; Brown, Justin L

    2016-01-01

    Polymeric nanoparticles (NPs) are one of the most studied organic strategies for nanomedicine. Intense interest lies in the potential of polymeric NPs to revolutionize modern medicine. To determine the ideal nanosystem for more effective and distinctly targeted delivery of therapeutic applications, particle size, morphology, material choice, and processing techniques are all research areas of interest. Utilizations of polymeric NPs include drug delivery techniques such as conjugation and entrapment of drugs, prodrugs, stimuli-responsive systems, imaging modalities, and theranostics. Cancer, neurodegenerative disorders, and cardiovascular diseases are fields impacted by NP technologies that push scientific boundaries to the leading edge of transformative advances for nanomedicine.

  18. SYNTHESIS AND POLYMERIZATION OF BISPHENYLENE ORTHOCARBONATE

    Institute of Scientific and Technical Information of China (English)

    PAN Caiyuan; ZHAO Yulong; William J. Bailey

    1988-01-01

    Bisphenylene orthocarbonate (Ⅱ) was synthesized by the reaction of dicopper catecholate with carbon tetrachloride, and underwent cationic ring-opening polymerization with the introduction of phenyl group into the main ehain. The obtained polymer with ester and ether group was verified by IR and 1H NMR spectra.Based on the analysis of the polymer structures, the polymerization mechanism was proposed. Its Tm and Tg are 254℃ and 160℃ respectively. No decomposition of the polymer was observed below 320℃. The volume expansion property of the monomer during polymerization was studied by measuring the density difference between I and its polymer at various temperatures.

  19. Performance of epoxy resin-anhydride pouring materials modified with hyperbranched polyester%超支化聚酯改性环氧-酸酐浇注树脂及性能研究

    Institute of Scientific and Technical Information of China (English)

    井丰喜; 石兆从; 张道洪

    2016-01-01

    The epoxy pouring resin was prepared by using the hydroxyl-terminated hyperbranched polyester, epoxy resin, methyl tetrahydrophthalic anhydride and silica powder as the main materials. The effects of hyperbranched polyester as the addictive on the viscosity, settleability, heat-resistance, mechanical and electrical properties of the cured pouring resin were in detail studied. The results showed that hyperbranched polyester not only increased the heat-resistance, mechanical and electrical properties of the cured pouring resin, but also effectively dispersed the silica powder into the pouring resin and improved the evenness of the mixing system.%采用端羟基超支化聚酯、环氧树脂、甲基四氢苯酐和活性硅微粉为主要材料制备了高性能环氧浇注树脂。研究了超支化聚酯对体系黏度、沉降性、耐温指数、机械性能和电性能的影响及其规律。结果表明,超支化聚酯可有效分散硅微粉,提高混合体系的均匀度,提高浇筑树脂的耐热性、机械强度和电性能。

  20. Characterization of Polymeric Nanofiltration Membranes

    Directory of Open Access Journals (Sweden)

    Simoncic, B.

    2007-11-01

    Full Text Available As membrane processes are increasingly used in industrial applications, there is a growing interest in methods of membrane characterization. Traditional membrane characteristics, such as cut-off value and pore size distribution, are being supplemented by membrane surface characteristics, such as charge density or zeta potential and hydrophobicity. This study, therefore, characterizes the three different polymeric membranes used (NFT-50, DL and DK. The molecular mass cut-off (MMCO value was determined using a set of reference solutes within the molecular range 150-600 Da, whereas streaming potential measurements enabled quantification of the surface charge characteristics. Hydrophobicity was studied using contact angle measurements. The results indicated that even though all three membranes had very similar layer compositions which consisted of poly(piperazneamide, as top layers they showed different values of measured quantitive. The NFT-50 membrane had the lowest MMCO value and the most hydrophilic membrane surface, followed by DK and DL. Membrane fouling as measured by flux reduction was determined by streaming potential measurements and accompanied by a positive change in zeta potential.

  1. Polymerization as a Model Chain Reaction

    Science.gov (United States)

    Morton, Maurice

    1973-01-01

    Describes the features of the free radical, anionic, and cationic mechanisms of chain addition polymerization. Indicates that the nature of chain reactions can be best taught through the study of macromolecules. (CC)

  2. Deformation and flow of polymeric materials

    CERN Document Server

    Münstedt, Helmut

    2014-01-01

    This book describes the properties of single polymer molecules and polymeric materials and the methods how to characterize them. Molar masses, molar mass distributions and branching structure are discussed in detail. These properties are decisive for a deeper understanding of structure/properties relationships of polymeric materials. This book therefore describes and discusses them in detail. The mechanical behavior as a function of time and temperature is a key subject of the book. The authors present it on the basis of many original results they have obtained in their long research careers. They present the temperature dependence of mechanical properties of various polymeric materials in a wide temperature range: from cryogenic temperatures to the melt. Besides an extensive data collection on the transitions of various different polymeric materials, they also carefully present the physical explanations of the observed phenomena. Glass transition and melting temperatures are discussed, particularly, with the...

  3. Isothermal Titration Calorimetry of Chiral Polymeric Nanoparticles.

    Science.gov (United States)

    Werber, Liora; Preiss, Laura C; Landfester, Katharina; Muñoz-Espí, Rafael; Mastai, Yitzhak

    2015-09-01

    Chiral polymeric nanoparticles are of prime importance, mainly due to their enantioselective potential, for many applications such as catalysis and chiral separation in chromatography. In this article we report on the preparation of chiral polymeric nanoparticles by miniemulsion polymerization. In addition, we describe the use of isothermal titration calorimetry (ITC) to measure the chiral interactions and the energetics of the adsorption of enantiomers from aqueous solutions onto chiral polymeric nanoparticles. The characterization of chirality in nano-systems is a very challenging task; here, we demonstrate that ITC can be used to accurately determine the thermodynamic parameters associated with the chiral interactions of nanoparticles. The use of ITC to measure the energetics of chiral interactions and recognition at the surfaces of chiral nanoparticles can be applied to other nanoscale chiral systems and can provide further insight into the chiral discrimination processes of nanomaterials. © 2015 Wiley Periodicals, Inc.

  4. Reverse-osmosis membranes by plasma polymerization

    Science.gov (United States)

    Hollahan, J. R.; Wydeven, T.

    1972-01-01

    Thin allyl amine polymer films were developed using plasma polymerization. Resulting dry composite membranes effectively reject sodium chloride during reverse osmosis. Films are 98% sodium chloride rejective, and 46% urea rejective.

  5. Polymeric lithography editor: Editing lithographic errors with nanoporous polymeric probes.

    Science.gov (United States)

    Rajasekaran, Pradeep Ramiah; Zhou, Chuanhong; Dasari, Mallika; Voss, Kay-Obbe; Trautmann, Christina; Kohli, Punit

    2017-06-01

    A new lithographic editing system with an ability to erase and rectify errors in microscale with real-time optical feedback is demonstrated. The erasing probe is a conically shaped hydrogel (tip size, ca. 500 nm) template-synthesized from track-etched conical glass wafers. The "nanosponge" hydrogel probe "erases" patterns by hydrating and absorbing molecules into a porous hydrogel matrix via diffusion analogous to a wet sponge. The presence of an interfacial liquid water layer between the hydrogel tip and the substrate during erasing enables frictionless, uninterrupted translation of the eraser on the substrate. The erasing capacity of the hydrogel is extremely high because of the large free volume of the hydrogel matrix. The fast frictionless translocation and interfacial hydration resulted in an extremely high erasing rate (~785 μm(2)/s), which is two to three orders of magnitude higher in comparison with the atomic force microscopy-based erasing (~0.1 μm(2)/s) experiments. The high precision and accuracy of the polymeric lithography editor (PLE) system stemmed from coupling piezoelectric actuators to an inverted optical microscope. Subsequently after erasing the patterns using agarose erasers, a polydimethylsiloxane probe fabricated from the same conical track-etched template was used to precisely redeposit molecules of interest at the erased spots. PLE also provides a continuous optical feedback throughout the entire molecular editing process-writing, erasing, and rewriting. To demonstrate its potential in device fabrication, we used PLE to electrochemically erase metallic copper thin film, forming an interdigitated array of microelectrodes for the fabrication of a functional microphotodetector device. High-throughput dot and line erasing, writing with the conical "wet nanosponge," and continuous optical feedback make PLE complementary to the existing catalog of nanolithographic/microlithographic and three-dimensional printing techniques. This new PLE

  6. Inflation and Failure of Polymeric Membranes

    DEFF Research Database (Denmark)

    Hassager, Ole; Neergaard, Jesper

    2000-01-01

    We consider the inflation of an axisymmetric polymeric membrane.Some membranes composed of viscoelastic materialsdescribed by a Mooney-Rivlin model show a monotone increasingpressure during inflation. These materialsdevelop a homogeneous membrane thickness in agreement with the Considere-Pearson ......We consider the inflation of an axisymmetric polymeric membrane.Some membranes composed of viscoelastic materialsdescribed by a Mooney-Rivlin model show a monotone increasingpressure during inflation. These materialsdevelop a homogeneous membrane thickness in agreement with the Considere...

  7. Thermo-inelastic Response of Polymeric Solids

    Science.gov (United States)

    2014-08-11

    Public Release; Distribution Unlimited Final Report: Thermo -inelastic Response of Polymeric Solids The views, opinions and/or findings contained in this...in non peer-reviewed journals: Final Report: Thermo -inelastic Response of Polymeric Solids Report Title We the study the impact response of a large...none) Challenges and opportunities in the modeling of thermo -viscoelastic materials, Society of Experimental Mechanics, Greenville, North, Carolina

  8. Nucleotide Selectivity in Abiotic RNA Polymerization Reactions

    Science.gov (United States)

    Coari, Kristin M.; Martin, Rebecca C.; Jain, Kopal; McGown, Linda B.

    2017-09-01

    In order to establish an RNA world on early Earth, the nucleotides must form polymers through chemical rather than biochemical reactions. The polymerization products must be long enough to perform catalytic functions, including self-replication, and to preserve genetic information. These functions depend not only on the length of the polymers, but also on their sequences. To date, studies of abiotic RNA polymerization generally have focused on routes to polymerization of a single nucleotide and lengths of the homopolymer products. Less work has been done the selectivity of the reaction toward incorporation of some nucleotides over others in nucleotide mixtures. Such information is an essential step toward understanding the chemical evolution of RNA. To address this question, in the present work RNA polymerization reactions were performed in the presence of montmorillonite clay catalyst. The nucleotides included the monophosphates of adenosine, cytosine, guanosine, uridine and inosine. Experiments included reactions of mixtures of an imidazole-activated nucleotide (ImpX) with one or more unactivated nucleotides (XMP), of two or more ImpX, and of XMP that were activated in situ in the polymerization reaction itself. The reaction products were analyzed using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) to identify the lengths and nucleotide compositions of the polymerization products. The results show that the extent of polymerization, the degree of heteropolymerization vs. homopolymerization, and the composition of the polymeric products all vary among the different nucleotides and depend upon which nucleotides and how many different nucleotides are present in the mixture.

  9. Post polymerization cure shape memory polymers

    Science.gov (United States)

    Wilson, Thomas S; Hearon, Michael Keith; Bearinger, Jane P

    2014-11-11

    This invention relates to chemical polymer compositions, methods of synthesis, and fabrication methods for devices regarding polymers capable of displaying shape memory behavior (SMPs) and which can first be polymerized to a linear or branched polymeric structure, having thermoplastic properties, subsequently processed into a device through processes typical of polymer melts, solutions, and dispersions and then crossed linked to a shape memory thermoset polymer retaining the processed shape.

  10. Volumetric polymerization shrinkage of contemporary composite resins

    Directory of Open Access Journals (Sweden)

    Halim Nagem Filho

    2007-10-01

    Full Text Available The polymerization shrinkage of composite resins may affect negatively the clinical outcome of the restoration. Extensive research has been carried out to develop new formulations of composite resins in order to provide good handling characteristics and some dimensional stability during polymerization. The purpose of this study was to analyze, in vitro, the magnitude of the volumetric polymerization shrinkage of 7 contemporary composite resins (Definite, Suprafill, SureFil, Filtek Z250, Fill Magic, Alert, and Solitaire to determine whether there are differences among these materials. The tests were conducted with precision of 0.1 mg. The volumetric shrinkage was measured by hydrostatic weighing before and after polymerization and calculated by known mathematical equations. One-way ANOVA (a or = 0.05 was used to determine statistically significant differences in volumetric shrinkage among the tested composite resins. Suprafill (1.87±0.01 and Definite (1.89±0.01 shrank significantly less than the other composite resins. SureFil (2.01±0.06, Filtek Z250 (1.99±0.03, and Fill Magic (2.02±0.02 presented intermediate levels of polymerization shrinkage. Alert and Solitaire presented the highest degree of polymerization shrinkage. Knowing the polymerization shrinkage rates of the commercially available composite resins, the dentist would be able to choose between using composite resins with lower polymerization shrinkage rates or adopting technical or operational procedures to minimize the adverse effects deriving from resin contraction during light-activation.

  11. Post polymerization cure shape memory polymers

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, Thomas S.; Hearon, II, Michael Keith; Bearinger, Jane P.

    2017-01-10

    This invention relates to chemical polymer compositions, methods of synthesis, and fabrication methods for devices regarding polymers capable of displaying shape memory behavior (SMPs) and which can first be polymerized to a linear or branched polymeric structure, having thermoplastic properties, subsequently processed into a device through processes typical of polymer melts, solutions, and dispersions and then crossed linked to a shape memory thermoset polymer retaining the processed shape.

  12. Nucleotide Selectivity in Abiotic RNA Polymerization Reactions

    Science.gov (United States)

    Coari, Kristin M.; Martin, Rebecca C.; Jain, Kopal; McGown, Linda B.

    2017-02-01

    In order to establish an RNA world on early Earth, the nucleotides must form polymers through chemical rather than biochemical reactions. The polymerization products must be long enough to perform catalytic functions, including self-replication, and to preserve genetic information. These functions depend not only on the length of the polymers, but also on their sequences. To date, studies of abiotic RNA polymerization generally have focused on routes to polymerization of a single nucleotide and lengths of the homopolymer products. Less work has been done the selectivity of the reaction toward incorporation of some nucleotides over others in nucleotide mixtures. Such information is an essential step toward understanding the chemical evolution of RNA. To address this question, in the present work RNA polymerization reactions were performed in the presence of montmorillonite clay catalyst. The nucleotides included the monophosphates of adenosine, cytosine, guanosine, uridine and inosine. Experiments included reactions of mixtures of an imidazole-activated nucleotide (ImpX) with one or more unactivated nucleotides (XMP), of two or more ImpX, and of XMP that were activated in situ in the polymerization reaction itself. The reaction products were analyzed using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) to identify the lengths and nucleotide compositions of the polymerization products. The results show that the extent of polymerization, the degree of heteropolymerization vs. homopolymerization, and the composition of the polymeric products all vary among the different nucleotides and depend upon which nucleotides and how many different nucleotides are present in the mixture.

  13. Polymeric micellar drug carriers with fluorescent properties

    OpenAIRE

    Abreu, Ana Sofia Lemos Machado; Sá, Arsénio Vasconcelos; Oliveira, Manuel; Moura, I; Machado, A.V.

    2015-01-01

    Self-assembling polymeric surfactants, based on amphiphilic block copolymers into nanosized aggregates in aqueous solution, are of great interest in the biomedical fields as one class of promising carrier systems, for drug delivery, gene therapy and diagnostic biosensors.[1] The incorporation of fluorescent probes into polymeric micelles has been fulfilled either by physically encapsulation or chemically attachment of fluorophores. [2] These micelle-based fluorescent probes not only facili...

  14. Post polymerization cure shape memory polymers

    Science.gov (United States)

    Wilson, Thomas S.; Hearon, II, Michael Keith; Bearinger, Jane P.

    2017-01-10

    This invention relates to chemical polymer compositions, methods of synthesis, and fabrication methods for devices regarding polymers capable of displaying shape memory behavior (SMPs) and which can first be polymerized to a linear or branched polymeric structure, having thermoplastic properties, subsequently processed into a device through processes typical of polymer melts, solutions, and dispersions and then crossed linked to a shape memory thermoset polymer retaining the processed shape.

  15. Polymeric micelles for acyclovir drug delivery.

    Science.gov (United States)

    Sawdon, Alicia J; Peng, Ching-An

    2014-10-01

    Polymeric prodrug micelles for delivery of acyclovir (ACV) were synthesized. First, ACV was used directly to initiate ring-opening polymerization of ɛ-caprolactone to form ACV-polycaprolactone (ACV-PCL). Through conjugation of hydrophobic ACV-PCL with hydrophilic methoxy poly(ethylene glycol) (MPEG) or chitosan, polymeric micelles for drug delivery were formed. (1)H NMR, FTIR, and gel permeation chromatography were employed to show successful conjugation of MPEG or chitosan to hydrophobic ACV-PCL. Through dynamic light scattering, zeta potential analysis, transmission electron microscopy, and critical micelle concentration (CMC), the synthesized ACV-tagged polymeric micelles were characterized. It was found that the average size of the polymeric micelles was under 200nm and the CMCs of ACV-PCL-MPEG and ACV-PCL-chitosan were 2.0mgL(-1) and 6.6mgL(-1), respectively. The drug release kinetics of ACV was investigated and cytotoxicity assay demonstrates that ACV-tagged polymeric micelles were non-toxic.

  16. The tempered polymerization of human neuroserpin.

    Directory of Open Access Journals (Sweden)

    Rosina Noto

    Full Text Available Neuroserpin, a member of the serpin protein superfamily, is an inhibitor of proteolytic activity that is involved in pathologies such as ischemia, Alzheimer's disease, and Familial Encephalopathy with Neuroserpin Inclusion Bodies (FENIB. The latter belongs to a class of conformational diseases, known as serpinopathies, which are related to the aberrant polymerization of serpin mutants. Neuroserpin is known to polymerize, even in its wild type form, under thermal stress. Here, we study the mechanism of neuroserpin polymerization over a wide range of temperatures by different techniques. Our experiments show how the onset of polymerization is dependent on the formation of an intermediate monomeric conformer, which then associates with a native monomer to yield a dimeric species. After the formation of small polymers, the aggregation proceeds via monomer addition as well as polymer-polymer association. No further secondary mechanism takes place up to very high temperatures, thus resulting in the formation of neuroserpin linear polymeric chains. Most interesting, the overall aggregation is tuned by the co-occurrence of monomer inactivation (i.e. the formation of latent neuroserpin and by a mechanism of fragmentation. The polymerization kinetics exhibit a unique modulation of the average mass and size of polymers, which might suggest synchronization among the different processes involved. Thus, fragmentation would control and temper the aggregation process, instead of enhancing it, as typically observed (e.g. for amyloid fibrillation.

  17. Molecular Arrangement in Self-Assembled Azobenzene-Containing Thiol Monolayers at the Individual Domain Level Studied through Polarized Near-Field Raman Spectroscopy

    Directory of Open Access Journals (Sweden)

    Razvigor Ossikovski

    2011-02-01

    Full Text Available 6-[4-(phenylazophenoxy]hexane-1-thiol self-assembled monolayers deposited on a gold surface form domain-like structures possessing a high degree of order with virtually all the molecules being identically oriented with respect to the surface plane. We show that, by using polarized near-field Raman spectroscopy, it is possible to derive the Raman scattering tensor of the ordered layer and consequently, the in-plane molecular orientation at the individual domain level. More generally, this study extends the application domain of the near-field Raman scattering selection rules from crystals to ordered organic structures.

  18. Orientation control of photo-immobilized antibodies on the surface of azobenzene-containing polymers by the introduction of functional groups.

    Science.gov (United States)

    Mouri, Makoto; Ikawa, Taiji; Narita, Mamiko; Hoshino, Fumihiko; Watanabe, Osamu

    2010-06-11

    In our photo-induced immobilization technique for an antibody (IgG) using azopolymers, the introduction of COOH and NMe(2) into the azopolymers, which can introduce surface charges, strongly affected the immobilization properties such as the efficiency of immobilization and the activity of the immobilized IgG (i.e., the orientation of the immobilized IgG). The introduction of COOH promoted a more active orientation of the immobilized IgG. The orientation was determined during the adsorption process onto the azopolymer surface in solution before photo-immobilization, and was maintained during the photo-immobilization. The surface charge of the azopolymer appears to be an important factor for IgG orientation, which involves electrostatic interactions between its Fab and the azopolymer surface.

  19. Photoswitchable cluster glycosides as tools to probe carbohydrate-protein interactions: synthesis and lectin-binding studies of azobenzene containing multivalent sugar ligands.

    Science.gov (United States)

    Srinivas, Oruganti; Mitra, Nivedita; Surolia, Avadhesha; Jayaraman, Narayanaswamy

    2005-09-01

    Synthetic cluster glycosides have often been used to unravel mechanisms of carbohydrate-protein interactions. Although synthetic cluster glycosides are constituted on scaffolds to achieve high avidities in lectin binding, there have been no known attempts to modulate the orientations of the sugar clusters with the aid of a functional scaffold onto which the sugar units are linked. Herein, we describe synthesis, physical, and lectin-binding studies of a series of alpha-D-mannopyranoside and beta-D-galactopyranosyl-(1-->4)-beta-D-glucopyranoside glycoclusters that are attached to a photoswitchable azobenzenoid core. These glycoclusters were synthesized by the amidation of amine-tethered glycopyranosides with azobenzene carbonyl chlorides. From kinetic studies, the cis forms of the azobenzene-glycopyranoside derivative were found to be more stable in aqueous solutions than in organic solvents. Molecular modeling studies were performed to estimate the relative geometries of the photoswitchable glycoclusters in the trans- and cis-isomeric forms. Isothermal titration calorimetry (ITC) was employed to assess the binding of these glycoclusters to lectins peanut agglutinin (PNA) and concanavalin A (Con A). Although binding affinities were enhanced several orders higher as the valency of the sugar was increased, a biphasic-binding profile in ITC plots was observed during few glycoclusters lectin-binding processes. The biphasic-binding profile indicates a "cooperativity" in the binding process. An important outcome of this study is that in addition to inherent clustering of the sugar units as a molecular feature, an induced clustering emanates because of the isomerization of the trans form of the azobenzene scaffold to the cis-isomeric form.

  20. Genotoxic evaluation of polymeric nanoparticles

    Directory of Open Access Journals (Sweden)

    Tamara Iglesias Alonso

    2015-06-01

    Full Text Available An important strategy for optimizing the therapeutic efficacy of many conventional drugs is the development of polymeric nanoparticles (NPs, as it may expand their activities, reduce their toxicity, increase their bioactivity and improve biodistribution. The main objective of this study was to evaluate the genotoxicity of 8 different poly (anhydride NPs designed for the oral administration of therapeutic compounds by using the comet assay in combination with the enzyme formamidopypiridine DNA-glycosylase (FPG. Furthermore, the mitogen capacity of the NPs was evaluated by the proliferation assay. All NPs were tested at four concentrations (0, 0.5, 1 and 2 mg/mL in Caco-2 cells after 3 hours of treatment while selected NPs were also tested after 24 h. The comet assay was performed immediately after the treatment and cell proliferation was assessed by counting the treated cells after their incubation at 37 °C for 48h. Cells treated with 1 µM of the photosensitizer Ro 19-8022 plus 5 min of light, as well as cells treated with 100 µM H2O2 were included as positive controls in all the experiments. All NPs studied did not result in any increase in the frequency of strand breaks or alkali-labile sites in Caco-2 cells but they induced a slight concentration-dependent increase in net FPG sensitive sites (oxidized and/or alkylated bases. Furthermore, treated cells did not show changes in levels of proliferation in comparison with the negative control.

  1. Polymerization in emulsion microdroplet reactors

    Science.gov (United States)

    Carroll, Nick J.

    The goal of this research project is to utilize emulsion droplets as chemical reactors for execution of complex polymerization chemistries to develop unique and functional particle materials. Emulsions are dispersions of immiscible fluids where one fluid usually exists in the form of drops. Not surprisingly, if a liquid-to-solid chemical reaction proceeds to completion within these drops, the resultant solid particles will possess the shape and relative size distribution of the drops. The two immiscible liquid phases required for emulsion polymerization provide unique and complex chemical and physical environments suitable for the engineering of novel materials. The development of novel non-ionic fluorosurfactants allows fluorocarbon oils to be used as the continuous phase in a water-free emulsion. Such emulsions enable the encapsulation of almost any hydrocarbon compound in droplets that may be used as separate compartments for water-sensitive syntheses. Here, we exemplify the promise of this approach by suspension polymerization of polyurethanes (PU), in which the liquid precursor is emulsified into droplets that are then converted 1:1 into polymer particles. The stability of the droplets against coalescence upon removal of the continuous phase by evaporation confirms the formation of solid PU particles. These results prove that the water-free environment of fluorocarbon based emulsions enables high conversion. We produce monodisperse, cross-linked, and fluorescently labeled PU-latexes with controllable mesh size through microfluidic emulsification in a simple one-step process. A novel method for the fabrication of monodisperse mesoporous silica particles is presented. It is based on the formation of well-defined equally sized emulsion droplets using a microfluidic approach. The droplets contain the silica precursor/surfactant solution and are suspended in hexadecane as the continuous oil phase. The solvent is then expelled from the droplets, leading to

  2. Polymeric lithography editor: Editing lithographic errors with nanoporous polymeric probes

    Science.gov (United States)

    Rajasekaran, Pradeep Ramiah; Zhou, Chuanhong; Dasari, Mallika; Voss, Kay-Obbe; Trautmann, Christina; Kohli, Punit

    2017-01-01

    A new lithographic editing system with an ability to erase and rectify errors in microscale with real-time optical feedback is demonstrated. The erasing probe is a conically shaped hydrogel (tip size, ca. 500 nm) template-synthesized from track-etched conical glass wafers. The “nanosponge” hydrogel probe “erases” patterns by hydrating and absorbing molecules into a porous hydrogel matrix via diffusion analogous to a wet sponge. The presence of an interfacial liquid water layer between the hydrogel tip and the substrate during erasing enables frictionless, uninterrupted translation of the eraser on the substrate. The erasing capacity of the hydrogel is extremely high because of the large free volume of the hydrogel matrix. The fast frictionless translocation and interfacial hydration resulted in an extremely high erasing rate (~785 μm2/s), which is two to three orders of magnitude higher in comparison with the atomic force microscopy–based erasing (~0.1 μm2/s) experiments. The high precision and accuracy of the polymeric lithography editor (PLE) system stemmed from coupling piezoelectric actuators to an inverted optical microscope. Subsequently after erasing the patterns using agarose erasers, a polydimethylsiloxane probe fabricated from the same conical track-etched template was used to precisely redeposit molecules of interest at the erased spots. PLE also provides a continuous optical feedback throughout the entire molecular editing process—writing, erasing, and rewriting. To demonstrate its potential in device fabrication, we used PLE to electrochemically erase metallic copper thin film, forming an interdigitated array of microelectrodes for the fabrication of a functional microphotodetector device. High-throughput dot and line erasing, writing with the conical “wet nanosponge,” and continuous optical feedback make PLE complementary to the existing catalog of nanolithographic/microlithographic and three-dimensional printing techniques. This new

  3. Survey and research on precision polymerization polymeric materials; Seimitsu jugo kobunshi zairyo ni kansuru chosa kenkyu

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-03-01

    Survey and research on the precision control of primary structure of polymeric materials and the precision evaluation technology have been conducted to develop advanced polymeric materials. It is proposed that the three basic processes of polymer synthesis, i.e., addition, condensation, and biomimesis, in forming the precision polymerization skeleton are to be covered through a centralized joint research effort with participation of industry, academia, and the government institute and under the leadership of researchers from academic institutions as the team leaders. For the study of technology trends, international conferences held in UK, Germany, and Hawaii are introduced, and domestic meetings, i.e., Annual Polymer Congress and Polymer Conference, are summarized. In addition, Precision Polymerization Forum and International Workshop on Precision Polymerization were held. The basic studies include a quantum-chemical elucidation of the elementary process in polymerization reaction, time-resolved analysis of polymerization process and polymer properties, synthesis of polymers with controlled microstructures by coordination polymerization using metal complexes, synthesis of polymer with controlled microstructures by precision polycondensation, molecular recognition in catalyst-reaction site, and synthesis of imprinting polymers. 246 refs., 117 figs., 14 tabs.

  4. Fire-Retardant Polymeric Additives

    Science.gov (United States)

    Williams, Martha K.; Smith, Trent M.

    2011-01-01

    component forms polybenzoxazole (PBO) in a reaction that absorbs heat from its surroundings. PBO under thermal stress cross-links, forming a protective char layer, which thermally insulates the polymer. Thus, the formation of the char layer further assists to extinguish the fire by preventing vaporization of the polymeric fuel.

  5. Mixing in polymeric microfluidic devices.

    Energy Technology Data Exchange (ETDEWEB)

    Schunk, Peter Randall; Sun, Amy Cha-Tien; Davis, Robert H. (University of Colorado at Boulder, Boulder, CO); Brotherton, Christopher M. (University of Colorado at Boulder, Boulder, CO)

    2006-04-01

    This SAND report describes progress made during a Sandia National Laboratories sponsored graduate fellowship. The fellowship was funded through an LDRD proposal. The goal of this project is development and characterization of mixing strategies for polymeric microfluidic devices. The mixing strategies under investigation include electroosmotic flow focusing, hydrodynamic focusing, physical constrictions and porous polymer monoliths. For electroosmotic flow focusing, simulations were performed to determine the effect of electroosmotic flow in a microchannel with heterogeneous surface potential. The heterogeneous surface potential caused recirculations to form within the microchannel. These recirculations could then be used to restrict two mixing streams and reduce the characteristic diffusion length. Maximum mixing occurred when the ratio of the mixing region surface potential to the average channel surface potential was made large in magnitude and negative in sign, and when the ratio of the characteristic convection time to the characteristic diffusion time was minimized. Based on these results, experiments were performed to evaluate the manipulation of surface potential using living-radical photopolymerization. The material chosen to manipulate typically exhibits a negative surface potential. Using living-radical surface grafting, a positive surface potential was produced using 2-(Dimethylamino)ethyl methacrylate and a neutral surface was produced using a poly(ethylene glycol) surface graft. Simulations investigating hydrodynamic focusing were also performed. For this technique, mixing is enhanced by using a tertiary fluid stream to constrict the two mixing streams and reduce the characteristic diffusion length. Maximum mixing occurred when the ratio of the tertiary flow stream flow-rate to the mixing streams flow-rate was maximized. Also, like the electroosmotic focusing mixer, mixing was also maximized when the ratio of the characteristic convection time to the

  6. Delivery of antibiotics with polymeric particles.

    Science.gov (United States)

    Xiong, Meng-Hua; Bao, Yan; Yang, Xian-Zhu; Zhu, Yan-Hua; Wang, Jun

    2014-11-30

    Despite the wide use of antibiotics, bacterial infection is still one of the leading causes of hospitalization and mortality. The clinical failure of antibiotic therapy is linked with low bioavailability, poor penetration to bacterial infection sites, and the side effects of antibiotics, as well as the antibiotic resistance properties of bacteria. Antibiotics encapsulated in nanoparticles or microparticles made up of a biodegradable polymer have shown great potential in replacing the administration of antibiotics in their "free" form. Polymeric particles provide protection to antibiotics against environmental deactivation and alter antibiotic pharmacokinetics and biodistribution. Polymeric particles can overcome tissue and cellular barriers and deliver antibiotics into very dense tissues and inaccessible target cells. Polymeric particles can be modified to target or respond to particular tissues, cells, and even bacteria, and thereby facilitate the selective concentration or release of the antibiotic at infection sites, respectively. Thus, the delivery of antibiotics with polymeric particles augments the level of the bioactive drug at the site of infection while reducing the dosage and the dosing frequency. The end results are improved therapeutic effects as well as decreased "pill burden" and drug side effects in patients. The main objective of this review is to analyze recent advances and current perspectives in the use of polymeric antibiotic delivery systems in the treatment of bacterial infection.

  7. Probing the interaction of ferrocene containing hyperbranched poly-ester with model plasma protein: Effect on the interaction mechanism and conformational change

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, Fengjuan, E-mail: xfj66@126.com; Gu, Muqing; Liang, Ye; Li, Lanlan; Yu, Xiaolei; Wu, Xiangfeng

    2014-05-01

    Interaction mechanism and conformational change of model plasma protein-bovine serum albumin (BSA) induced by ferrocenyl-functionalized hyperbranched polyester (HBPE-Fc) were investigated using cyclicvoltammetry (CV), differential pulsed voltammetry (DPV), fluorescence, UV–vis absorption spectrometry and circular dichroism (CD). Some complicated interactions occurred between BSA and HBPE-Fc and the new redox centers appeared in the BSA/HBPE-Fc complex that changed and hindered the electron transfer of Fe/Fe{sup 2+}. Fluorescence quenching data showed that the fluorescence of BSA was statically quenched by HBPE-Fc, which implied that ground state complex formed between BSA and HBPE-Fc. van der Waals force and hydrogen bond played major roles in the interaction of HBPE-Fc with BSA. The binding constant Ka for HBPE-Fc–protein interaction is in the order of 10{sup 6} at room temperature indicates that there is a strong interaction between HBPE-Fc and BSA. Synchronous, three-dimensional fluorescence and CD studies indicated that the interaction of BSA with HBPE-Fc induced conformational changes in BSA with overall decrease in the α-helical structure and increase in β-pleated sheet structure. The molecular model of the interaction between HBPE-Fc and BSA was also presented according to the results in this study. - Highlights: • A novel ferrocenyl-functionalized hyperbranched polymer (HBPE-Fc) with potential anticancer effects. • New redox centers appear in the BSA/HBPE-Fc complex that changed and hindered the electron transfer of Fe/Fe{sup 2+}. • BSA fluorescence was statically quenched by HBPE-Fc. • BSA/HBPE-Fc ground state complex was mainly formed by the hydrogen bonds and van der Waals force. • HBPE-Fc induced conformational changes in BSA with overall decrease in the α-helical structure and increase in β-pleated sheet structure. • The molecular model of the interaction was presented according to the results in this study.

  8. Development of radioisotope labeled polymeric carriers

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Seung Jin; Jeong, Jea Min; Hwang, Hyun Jeong [Ewha Womans University, Seoul (Korea)

    2000-04-01

    This research was performed with the aim of developing polymeric radioisotope or drug carriers for obtaining efficient diagnostic therapeutic efficacy. As polymers, polyethylene oxides, polylactides, polycaprolactone were chosen to prepare the devices including micelle system, microemulsion, nanospheres. In addition, anticancer drug loaded polylactide microparticulates were fabricated as a regional chemotherapeutics for the treatment of cancer. Technetium or radioactive iodine was labeled to the polymeric carriers via ligands such as DTPA and HPP, respectively. Labeling efficiency was above 90% and stable enough up to 24 hours. Moreover, injected polymer carriers demonstrated higher blood maintenance and bone uptake than Tin colloid, a control. These results suggested that radioisotope carrying polymeric particulate are promising tools for diagnosing blood vessels or bones. Besides, anticancer drug loaded particulates demonstrated appropriate maintenance of therapeutic concentration and localization. Therefore it was proposed that this therapeutic system may be potential as a cancer therapy modality. 20 refs., 24 figs.,5 tabs. (Author)

  9. Medical prototyping using two photon polymerization

    Directory of Open Access Journals (Sweden)

    Roger J Narayan

    2010-12-01

    Full Text Available Two photon polymerization involves nearly simultaneous absorption of ultrashort laser pulses for selective curing of photosensitive material. This process has recently been used to create small-scale medical devices out of several classes of photosensitive materials, such as acrylate-based polymers, organically-modified ceramic materials, zirconium sol-gels, and titanium-containing hybrid materials. In this review, the use of two photon polymerization for fabrication of several types of small-scale medical devices, including microneedles, artificial tissues, microfluidic devices, pumps, sensors, and valves, from computer models is described. Necessary steps in the development of two photon polymerization as a commercially viable medical device manufacturing method are also considered.

  10. Self-Healing of biocompatible polymeric nanocomposities

    Science.gov (United States)

    Espino, Omar; Chipara, Dorina

    2014-03-01

    Polymers are vulnerable to damage in form of cracks deep within the structure, where detection is difficult and repair is near to impossible. These cracks lead to mechanical degradation of the polymer. A method has been created to solve this problem named polymeric self healing. Self healing capabilities implies the dispersion within the polymeric matrix of microcapsules filled with a monomer and of catalyst. Poly urea-formaldehyde microcapsules used in this method are filled with dicyclopentadiene that is liberated after being ruptured by the crack propagation in the material. Polymerization is assisted by a catalyst FGGC that ignites the self healing process. Nanocomposites, such as titanium oxide, will be used as an integration of these polymers that will be tested by rupturing mechanically slowly. In order to prove the self healing process, Raman spectroscopy, FTIR, and SEM are used.

  11. Removal of radioactive contaminants by polymeric microspheres.

    Science.gov (United States)

    Osmanlioglu, Ahmet Erdal

    2016-11-01

    Radionuclide removal from radioactive liquid waste by adsorption on polymeric microspheres is the latest application of polymers in waste management. Polymeric microspheres have significant immobilization capacity for ionic substances. A laboratory study was carried out by using poly(N-isopropylacrylamide) for encapsulation of radionuclide in the liquid radioactive waste. There are numbers of advantages to use an encapsulation technology in radioactive waste management. Results show that polymerization step of radionuclide increases integrity of solidified waste form. Test results showed that adding the appropriate polymer into the liquid waste at an appropriate pH and temperature level, radionuclide was encapsulated into polymer. This technology may provide barriers between hazardous radioactive ions and the environment. By this method, solidification techniques became easier and safer in nuclear waste management. By using polymer microspheres as dust form, contamination risks were decreased in the nuclear industry and radioactive waste operations.

  12. SYNTHESIS AND POLYMERIZATION OF OLIGO (OXYETHYLENE) MACROMONOMER

    Institute of Scientific and Technical Information of China (English)

    ZHANG Shengshui; LIU Qingguo; YANG Leiling; FARRINGTON; Gregory C.

    1993-01-01

    This paper reports the synthesis of methoxyoligo (oxyethylene) methacrylate (MEOn , n is the repeating unit number of (CH2CH2O) in the macromonomer),and its polymerization in different solvents. MEOn is prepared through such two independent reactions as (1) anionic polymerization of oxirane initiated by potassium alkoxide and (2) end-capping of methoxy oligo(oxyethylene) by methacrylic group. The n value can be conveniently controlled over the range of 5~30 by varying the molar ratio of oxirane to initiator and the molecular weight distribution of MEOn be narrowed by increasing reaction time only in step (1). MEOn thus obtained shows a rapid polymerization in water and benzene respectively, and both give water-soluble polymers as long as suitable conditions are used.

  13. DESIGN, SYNETHESIS, DYE-LOADING AND HOST-GUEST COLORING APPLICATION OF AMPHIPHILIC HYPERBRANCHED POLY (QUATERNARY AMMONIUM SALT) S%两亲性全季铵盐超支化聚合物的设计与合成及主-客体超分子着色应用研究

    Institute of Scientific and Technical Information of China (English)

    唐爱金; 韩金; 翁祝林; 高超

    2013-01-01

    A novel AB2-type monomer with one azide group and two alkyne groups and two quaternary ammonium salt units was synthesized via highly efficient thiol-yne click chemistry and Menschutkin reaction. The synthetic protocol includes three steps; (1) 4-oxo-4-( prop-2-ynyloxy ) butanoic acid 1 reacts with 3-( dimethylamino) -1-propanethiol via thiol-yne click chemistry to obtain intermediate 2 containing one carboxyl group and two dimethyamino groups with high yield ( ~97. 5% ) , (2) esterification between carboxyl group of 2 and 2-azidoethanol to afford intermediate 3,(3) fast click-like Menschutkin quaterization of the two dimethylamino groups of 3 with propargyl bromide to give the final AB2-type monomer 4 possessing one azide group,two alkyne groups and two quaternary ammonium salt units. The monomer structure was confirmed by NMR,FT-IR and MS. The subsequent click polymerization of 4 gave rise to quaternary ammonium salt-type hyperbranched polymers. End-capping the polymers with azide-terminated alkyl long chains resulted in amphiphilic hyperbranched polymers ( AHPs ) with hydrophilic quaternary ammonium salt core and hydrophobic alkyl shell. The AHPs were characterized by H-NMR,FTIR, and gel permeation chromatography ( GPC ) measurements. The AHPs have number-average molecular weights ( Mn ) of 3800 ~ 5300 and narrow polydispersity index (PDI,1. 17 ~ 1. 27) . The host-guest dye-encapsulation property of AHPs was investigated using congo red ( CR ) , methyl orange ( MO ) , methyl violet ( MV ) , methyl blue ( MB ) , eosin Y ( EY ) , iluorescein sodium (FS) and rose Bengal (RB) as guests with UV-Vis spectrometer. The AHPs exhibited high capabilities to load water-soluble dyes due to their polarity difference between core and shell, and the dye-transfer percentage from water to chloroform phase reached 93% ~99% for MO,MV,FS,and EY,and 71% ~ 76% for RB and CR. The average numbers of dye molecules trapped per macromolecule achieved 0. 5 ~ 0. 6 for MO

  14. Thrombin interaction with fibrin polymerization sites.

    Science.gov (United States)

    Hsieh, K

    1997-05-15

    Thrombin is central to hemostasis, and postclotting fibrinolysis and wound healing. During clotting, thrombin transforms plasma fibrinogen into polymerizing fibrin, which selectively adsorbs the enzyme into the clot. This protects thrombin from heparin-antithrombin inactivation, thus preserving the enzyme for postclotting events. To determine how the fibrin N-terminal polymerization sites of A alpha 17-23 (GPRVVER) and B beta 15-25 (GHRPLDKKREE) and their analogs may interact with thrombin, amidolysis vs. plasma- and fibrinogen-clotting assays were used to differentiate blockade of catalytic site vs. other thrombin domains. Amidolysis studies suggest GPRVVER inhibition of thrombin catalytic site through hydrophobic interaction, and GPRVVER inhibited clotting. Neither GPRP nor VVER nor the B beta 15-25 homologs inhibited amidolysis. Contrary to heparin, acyl-DKKREE promoted plasma-clotting, but inhibited fibrinogen-clotting. In addition, acyl-DKKREE reversed the anticoagulant effect of heparin (0.1 U/ml) in plasma. The results suggest fibrin B beta 15-25 interaction with thrombin, possibly by blocking the heparin-binding site. Together with the reported fibrin A alpha 27-50 binding to thrombin, polymerizing fibrin appears to initially bind to thrombin catalytic site and exosite-1 through A alpha 17-50, and to another thrombin site through B beta 15-25. As these fibrin sites are also involved in polymerization, competition of the polymerization process with thrombin-binding could subsequently dislodge thrombin from fibrin alpha-chain. This may re-expose the catalytic site and exosite-1, thus explaining the thrombogenicity of clot-bound thrombin. The implications of these findings in polymerization mechanism and anticoagulant design are discussed.

  15. Influence of Cyclodextrin on the Styrene Polymerization

    Institute of Scientific and Technical Information of China (English)

    HU Jie; LIU Bai-ling

    2004-01-01

    Cyclodextrin (CD) are oligosaccharides consisting of 6( α ), 7( β ), 8( γ ) units of1,4-linked glucose. Due to their polar hydrophilic outer shell and relatively hydrophobic cavity, theyare able to build up host-guest complexes by inclusion of suitable hydrophobic molecules. Theformation of these complexes leads to significant changes of the solubility and reactivity of the guestmolecules, but without any chemical modification. Thus, water insoluble molecules may becomecompletely water soluble simply by mixing with an aqueous solution of native CD or CD-derivatives.Hydrogen bonds or hydrophobic interactions are responsible for the stability of the complexes and itturned out that the complexed monomers could be successfully polymerized by free radicalpolymerization in water.In our present work, using styrene as monomer, potassium peroxodisulfate as radical initiator thatreacted in water in the presence ofβ-CD but without any additional surfactant, the effect ofcyclodextrin on the polymerization was described. Additionally, the acceleration mechanism ofcyclodextrin in the polymerization was also explained based on dynamic study.Table 1 Effect of CD on the monomer reactivityIt is found that β -CD could greatly accelerate the polymerization, enhance the final conversion ofmonomer. And the more the amount of β-CD was introduced, the faster the polymerization wasobtained. From Figure 1, after 5 hours reaction at 80℃, the monomer conversion in the presence of1.0g cyclodextrin reached to 95%. However, that in absence of cyclodextrin was only 60%. And themonomer conversion was not to exceed 75% even reacted for 8 hours when no CD in reactionsystem.In order to describe the acceleration of CD in the polymerization quantitatively, based onCD and without CD. As shown in Table 1, CD produced significant effect on the monomer reactivity.The relative relativities of monomer were greatly increased with the increase of the amount of CD.

  16. Polymeric matrix materials for infrared metamaterials

    Science.gov (United States)

    Dirk, Shawn M; Rasberry, Roger D; Rahimian, Kamyar

    2014-04-22

    A polymeric matrix material exhibits low loss at optical frequencies and facilitates the fabrication of all-dielectric metamaterials. The low-loss polymeric matrix material can be synthesized by providing an unsaturated polymer, comprising double or triple bonds; partially hydrogenating the unsaturated polymer; depositing a film of the partially hydrogenated polymer and a crosslinker on a substrate; and photopatterning the film by exposing the film to ultraviolet light through a patterning mask, thereby cross-linking at least some of the remaining unsaturated groups of the partially hydrogenated polymer in the exposed portions.

  17. The flat phase of quantum polymerized membranes

    CERN Document Server

    Coquand, O

    2016-01-01

    We investigate the flat phase of quantum polymerized phantom membranes by means of a nonperturbative renormalization group approach. We first implement this formalism for general quantum polymerized membranes and derive the flow equations that encompass both quantum and thermal fluctuations. We then deduce and analyze the flow equations relevant to study the flat phase and discuss their salient features : quantum to classical crossover and, in each of these regimes, strong to weak coupling crossover. We finally illustrate these features in the context of free standing graphene physics.

  18. Mechanism and kinetics of addition polymerizations

    CERN Document Server

    Kucera, M

    1991-01-01

    This volume presents an up-to-date survey of knowledge concerning addition type polymerizations. It contains nine chapters, each of which covers a particular basic term. Whenever necessary, the phenomena are discussed from the viewpoint of both stationary and non-stationary state of radical, ionic (i.e. anionic and cationic) and coordination polymerization. Special attention has been paid to the propagation process. It provides not only a general overview but also information on important special cases (theoretical conditions of propagation, influence of external factors, controlled propagatio

  19. Producing ORMOSIL scaffolds by femtosecond laser polymerization

    Science.gov (United States)

    Matei, A.; Zamfirescu, M.; Radu, C.; Buruiana, E. C.; Buruiana, T.; Mustaciosu, C.; Petcu, I.; Radu, M.; Dinescu, M.

    2012-07-01

    Structures with different geometries and sizes were built via direct femtosecond laser writing, starting from new organic/inorganic hybrid monomers based on hybrid methacrylate containing triethoxysilane, in addition to urethane and urea groups. Multifunctional oligomer of urethane dimethacrylate type was chosen as comonomer in polymerization experiments because dimethacrylates give rise to the formation of a polymer network, having a number of favorable properties including biocompatibility and surface nanostructuring. Free standing polymeric structures were designed and created in order to be tested in fibroblast cells culture. Investigations of the cellular adhesion, proliferation, and viability of L929 mouse fibroblasts on free-standing laser processed scaffolds were performed for different scaffold designs.

  20. The pH-sensitive fusogenic 3-methyl-glutarylated hyperbranched poly(glycidol)-conjugated liposome induces antigen-specific cellular and humoral immunity.

    Science.gov (United States)

    Hebishima, Takehisa; Yuba, Eiji; Kono, Kenji; Takeshima, Shin-Nosuke; Ito, Yoshihiro; Aida, Yoko

    2012-09-01

    We examined the ability of a novel liposome, surface modified by 3-methyl-glutarylated hyperbranched poly(glycidol) (MGlu-HPG), to enhance antigen-specific immunity in vitro and in vivo and to function as a vaccine carrier. Murine bone marrow-derived dendritic cells took up ovalbumin (OVA) encapsulated in MGlu-HPG-modified liposomes more effectively than free OVA or OVA encapsulated in unmodified liposomes. Immunization of mice with OVA-containing MGlu-HPG-modified liposomes induced antigen-specific splenocyte proliferation and production of gamma interferon (IFN-γ) more strongly than did immunization with free OVA or OVA encapsulated in unmodified liposomes. The immune responses induced by OVA encapsulated in MGlu-HPG-modified liposomes were significantly suppressed by addition of anti-major histocompatibility complex (MHC) class I and class II monoclonal antibodies, indicating the involvement of antigen presentation via MHC class I and II. Furthermore, delayed-type hypersensitivity responses and OVA-specific antibodies were induced more effectively in mice immunized with OVA encapsulated by MGlu-HPG-modified liposomes than with unencapsulated OVA or OVA encapsulated in unmodified liposomes. These results suggested that MGlu-HPG-modified liposomes effectively induced both cell-mediated and humoral immune responses. Collectively, this study is the first to demonstrate the induction of both cell-mediated and humoral immune responses in vivo by MGlu-HPG-modified liposomes.

  1. Surfactant-free synthesis of hyperbranched monoclinic bismuth vanadate and its applications in photocatalysis, gas sensing, and lithium-ion batteries.

    Science.gov (United States)

    Zhao, Yu; Xie, Yi; Zhu, Xi; Yan, Si; Wang, Sunxi

    2008-01-01

    Hyperbranched monoclinic BiVO(4) (h-BiVO(4)) has been synthesized on a large scale and with good uniformity by a surfactant-free hydrothermal route. h-BiVO(4) consists of four trunks with branches distributed on opposite sides. From observation of the intermediates at an early stage of the reaction process, it can be seen that during formation h-BiVO(4) has different growth rates along the a, b, and c axes. Based on crystal structure analysis and experimental results, h-BiVO(4) shows preferential growth along the [100] direction, and subsequently, along the [010] and [001] directions. As-synthesized h-BiVO(4) exhibits excellent photocatalytic ability in the photodegradation reaction of an aqueous solution of RB under visible light. Electrochemical measurements predict that h-BiVO(4) possesses high sensitivity to formaldehyde and ethanol gases, favorable discharge capacity, and capacity retention, which indicate potential applications in the fields of sensing devices and lithium-ion batteries.

  2. Full-Color Emissive Poly(Ethylene Oxide) Electrospun Nanofibers Containing a Single Hyperbranched Conjugated Polymer for Large-Scale, Flexible Light-Emitting Sheets.

    Science.gov (United States)

    Kim, Jongho; Lee, Taek Seung

    2016-02-01

    White-light-emitting protocols based on organic materials have received much attention in the academic and industrial fields because of their potential applications in full-color displays and back-lighting units for liquid crystal displays. Here, the attempt is made to fabricate white-light-emitting, electrospun poly(ethylene oxide) (PEO) sheets containing controlled concentrations of a single light-emitting material composed of a type of hyperbranched conjugated polymer (HCP). The HCPs used here have the unique property of exhibiting a variety of fluorescence colors in the electrospun matrix that is caused by the different distances between HCP chains depending on their concentrations, leading to different degrees of intermolecular energy transfer. Therefore, the emission colors of the PEO sheets can be easily manipulated by simply varying the HCP concentrations in the PEO matrix. The resulting method for fabricating nanofibers comprising light-emitting materials in the polymer matrix has great potential for easy fabrication of cost-effective, flexible light-emitting system.

  3. NOVEL HYPERBRANCHED POLY(PHENYLENE OXIDE)S WITH PHENOLIC TERMINAL GROUPS: EFFECTS OF REACTION TIME AND CORE MOLECULES ON THE MOLECULAR WEIGHT AND POLYDISPERSITY

    Institute of Scientific and Technical Information of China (English)

    Ji-gui Zhang; Hai-qiao Wang; Xiao-yu Li

    2006-01-01

    A novel hyperbranched poly(phenylene oxide) (HPPO) with phenolic terminal groups was prepared from 4-bromo-4′,4″-dihydroxytriphenylmethane as AB2 monomer in dimethylsulfoxide (DMSO) via a modified Ullmann reaction.The molecular weight and polydispersity (PD) of the resulting polymers increased with increasing reaction time. In the presence of core molecules (bisphenol A and 1,3,5-trihydroxybenzene), which have the similar molecular backbones to the reactive monomer, the molecular weight could be controlled by varying the core-to-monomer ratio. Incorporation of a very small amount of core molecules could lead to a higher molecular weight as compared with that without the addition of core molecules. However, when the core content reached certain extent, the molecular weight would decrease with the further increase in the core content. A new similar behavior of control over the PD was also obtained. The resulting polymers were characterized by 1H-NMR, 13C-NMR, FT-IR, and GPC.

  4. Preparation, Properties and Application of Polymeric Organic-Inorganic Nanocomposites

    Institute of Scientific and Technical Information of China (English)

    任杰; 刘艳; 唐小真

    2003-01-01

    Six preparation methods for polymeric organic-inorganic nanocomposites and their respective mechanisms and features are reviewed. The extraordinary properties of polymeric organic-inorganic nanocomposites are discussed,and their potential applications are evaluated.

  5. Polymerization Initiated at the Sidewalls of Carbon Nanotubes

    Science.gov (United States)

    Tour, James M.; Hudson, Jared L.

    2011-01-01

    A process has been developed for growing polymer chains via anionic, cationic, or radical polymerization from the side walls of functionalized carbon nanotubes, which will facilitate greater dispersion in polymer matrices, and will greatly enhance reinforcement ability in polymeric material.

  6. Properties of Waterborne Polyurethane Emulsion Modified by Waterborne Hyperbranched Polyurethane%超支化水性聚氨酯共混改性聚氨酯乳液的性能研究

    Institute of Scientific and Technical Information of China (English)

    田星; 李杰; 罗运军

    2012-01-01

    A acetyl-terminated waterborne hyperbranched polyurethane (AWHBPU) was synthesized by acetic anhydride and waterborne hyperbranched polyurethane (WHBPU). The viscosity, particle size distribution and surface tension of waterborne polyurethane emulsion modified by waterborne hyperbranched polyurethane were studied. Results show that the viscosity of the modified emulsion can be reduced by AWHBPU blending, while non-Newtonian index of the emulsion modified by AWHBPU increases. The test results of particle size distribution and surface tension show that the main cause of the viscosity declining is the particle size increasing, which is induced by AWHBPU accessing to the inside of waterborne polyurethane micelle.%利用乙酸酐对自身可以水分散的超支化水性聚氨酯(WHBPU)进行封端,得到了乙酰基封端的超支化水性聚氨酯(AWHBPU).研究了超支化水性聚氨酯共混改性聚氨酯乳液的剪切黏度、粒径分布以及表面张力.实验结果表明,对WHBPU羟基的封闭可以有效降低共混聚氨酯乳液的黏度;AWHBPU共混乳液偏离牛顿流体程度明显下降;粒径和表面张力测试表明,超支化水性聚氨酯进入胶束内部引起粒径上升是引起黏度下降的重要原因.

  7. Kinetics of crosslinking in emulsion polymerization

    Energy Technology Data Exchange (ETDEWEB)

    Ghielmi, A.; Fiorentino, S.; Morbidelli, M. [Universitaetstrasse Zuerich (Switzerland)] [and others

    1996-12-31

    A mathematical model for evaluating the chain length distribution of nonlinear polymers produced in emulsions is presented. The heterogeneous emulsion polymerization process is described. The aim of the analysis is the distribution of active polymer chains and pairs of chains with a given growth time in latex particles in state.

  8. The Morphology of Emulsion Polymerized Latex Particles

    Science.gov (United States)

    Wignall, G. D.; Ramakrishnan, V. R.; Linne, M. A.; Klein, A.; Sperling, L. H.; Wai, M. P.; Gelman, R. A.; Fatica, M. G.; Hoerl, R. H.; Fisher, L. W.

    1987-11-01

    Under monomer starved feed conditions, emulsion polymerization of perdeuterated methyl methacrylate and styrene in the presence of preformed polymethylmethacrylate latexes resulted in particles with a core-shell morphology, as determined by small-angle neutron scattering (SANS) analysis for a hollow sphere. The locus of polymerization of the added deuterated monomer is therefore at the particle surface. In similar measurements a statistical copolymer of styrene and methyl methacrylate was used as seed particles for further polymerization of trideuteromethyl methacrylate. The resulting polymer latex was again shown to have a core-shell morphological structure as determined by SANS. SANS experiments were also undertaken on polystyrene latexes polymerized by equilibrium swelling methods, with deuterated polymer forming the first or second step. The experiments covered a molecular weight range of 6 x 10{sup 4} 10{sup 6} the molecular weights are consistent with the experimental errors, indicating that the deuterium labeled molecules are randomly distributed in the latex. These results led to the finding that the polymer chains were constrained in the latex particles by factors of 2 to 4 from the relaxed coil dimensions. For M < 10{sup 6} g/mol SANS gave zero angle scattering intensities much higher than expected on the basis of a random distribution of labeled molecules. Several models were examined, including the possible development of core-shell structures at lower molecular weights.

  9. Controlled Cationic Polymerization of N-Vinylcarbazol

    NARCIS (Netherlands)

    Nuyken, O.; Rieß, G.; Loontjens, J.A.

    1995-01-01

    Cationic polymerization of N-Vinylcarbazol (NVC) was initiated with 1-iodo-1-(2-methylpropyloxy)ethane in the presence of N(n-Bu)4ClO4 and without addition of this activator. Furthermore, 1-chloro-1-(2-methylpropyloxy) ethane, with and without activator has been applied as initiator for NVC. These i

  10. Planar elongation of soft polymeric networks

    DEFF Research Database (Denmark)

    Jensen, Mette Krog; Hassager, Ole; Rasmussen, Henrik K.

    2010-01-01

    A new test fixture for the filament stretch rheometer (FSR) has been developed to measure planar elongation of soft polymeric networks with application towards pressure-sensitive adhesives (PSAs). The concept of this new geometry is to elongate a tube-like sample by keeping the perimeter constant...

  11. Operating Modes Of Chemical Reactors Of Polymerization

    Directory of Open Access Journals (Sweden)

    Meruyert Berdieva

    2012-05-01

    Full Text Available In the work the issues of stable technological modes of operation of main devices of producing polysterol reactors have been researched as well as modes of stable operation of a chemical reactor have been presented, which enables to create optimum mode parameters of polymerization process, to prevent emergency situations of chemical reactor operation in industrial conditions.

  12. Proteins and Peptides in Biomimetic Polymeric Membranes

    DEFF Research Database (Denmark)

    Perez, Alfredo Gonzalez

    2013-01-01

    This chapter discusses recent advances and the main advantages of block copolymers for functional membrane protein reconstitution in biomimetic polymeric membranes. A rational approach to the reconstitution of membrane proteins in a functional form can be addressed by a more holistic view by usin...

  13. Forming of Polymeric Tubular Micro-components

    DEFF Research Database (Denmark)

    Qin, Yi; Zhao, Jie; Anyasodor, Gerald;

    2015-01-01

    This chapter is intended to provide an overview of three nontraditional shaping technologies for the forming of polymeric micro-tubes, which are hot embossing, blow molding, and cross rolling, as well as realization of a process chain and the integration of a modular machine-based manufacturing...

  14. Polymerization of different lignins by laccase

    NARCIS (Netherlands)

    Mattinen, M.L.; Suortti, T.; Gosselink, R.J.A.; Argyropoulos, D.S.; Evtuguin, D.; Suurnäkki, A.; Jong, de E.; Tamminen, T.

    2008-01-01

    In this study the oxidative polymerization of different lignins, i.e. Flax Soda lignin, Spruce EMAL, and Eucalyptus Dioxane lignin by Trametes hirsuta laccase was compared. Initially the structures of the different lignins were compared by Fourier transform infrared spectroscopy. The reactivity of l

  15. Olefin polymerization over supported chromium oxide catalysts

    NARCIS (Netherlands)

    Weckhuysen, B.M.; Schoonheydt, R.A.

    1999-01-01

    Cr/SiO2 or Phillips-type catalysts are nowadays responsible for a large fraction of all polyethylene (HDPE and LLDPE) worldwide produced. In this review, several key-properties of Cr/SiO2 catalysts will be discussed in relation to their polymerization characteristics. It will be shown how the polyol

  16. Bioactive Polymeric Materials for Tissue Repair

    Directory of Open Access Journals (Sweden)

    Diane R. Bienek

    2017-01-01

    Full Text Available Bioactive polymeric materials based on calcium phosphates have tremendous appeal for hard tissue repair because of their well-documented biocompatibility. Amorphous calcium phosphate (ACP-based ones additionally protect against unwanted demineralization and actively support regeneration of hard tissue minerals. Our group has been investigating the structure/composition/property relationships of ACP polymeric composites for the last two decades. Here, we present ACP’s dispersion in a polymer matrix and the fine-tuning of the resin affects the physicochemical, mechanical, and biological properties of ACP polymeric composites. These studies illustrate how the filler/resin interface and monomer/polymer molecular structure affect the material’s critical properties, such as ion release and mechanical strength. We also present evidence of the remineralization efficacy of ACP composites when exposed to accelerated acidic challenges representative of oral environment conditions. The utility of ACP has recently been extended to include airbrushing as a platform technology for fabrication of nanofiber scaffolds. These studies, focused on assessing the feasibility of incorporating ACP into various polymer fibers, also included the release kinetics of bioactive calcium and phosphate ions from nanofibers and evaluate the biorelevance of the polymeric ACP fiber networks. We also discuss the potential for future integration of the existing ACP scaffolds into therapeutic delivery systems used in the precision medicine field.

  17. Proteins and Peptides in Biomimetic Polymeric Membranes

    DEFF Research Database (Denmark)

    Perez, Alfredo Gonzalez

    2013-01-01

    This chapter discusses recent advances and the main advantages of block copolymers for functional membrane protein reconstitution in biomimetic polymeric membranes. A rational approach to the reconstitution of membrane proteins in a functional form can be addressed by a more holistic view by using...

  18. Vibrating polymeric microsieves: Antifouling strategies for microfiltration

    NARCIS (Netherlands)

    Gironès i Nogué, M.; Akbarsyah, Imam J.; Bolhuis-Versteeg, Lydia A.M.; Lammertink, Rob G.H.; Wessling, Matthias

    2006-01-01

    Constant flux performance in time is achieved with polyethersulfone (PES) polymeric microsieves when filtering protein solutions, skimmed milk and white beer in combination with backpulsing. Such microsieves are fabricated by phase separation micromolding (PSμM) and possess pores around 2 μm. The fi

  19. Polymerization of epoxidized triglycerides with fluorosulfonic acid

    Science.gov (United States)

    The use of triglycerides as agri-based renewable raw materials for the development of new products is highly desirable in view of uncertain future petroleum prices. A new method of polymerizing epoxidized soybean oil has been devised with the use of fluorosulfonic acid. Depending on the reaction con...

  20. Structure-properties relationships in polymeric fibres

    NARCIS (Netherlands)

    Penning, Jan Paul

    1994-01-01

    Dit proefschrift beschrijft een onderzoek naar de samenhang tussen de struktuur en de mechanische eigenschappen van polymere vezels, met als centrale vraag hoe men deze eigenschappen het best kan beschrijven op grond van de vezelstruktuur en hoe deze struktuur onstaat tijdens de diverse stappen van

  1. SYNTHESIS OF BLOCK COPOLYMER BY INTEGRATED LIVING ANIONIC POLYMERIZATION-ATOM TRANSFER RADICAL POLYMERIZATION (ATRP)

    Institute of Scientific and Technical Information of China (English)

    Bing Liu; Feng Liu; Ning Luo; Sheng-kang Ying; Qing Liu

    2000-01-01

    Alpha-trichloroacetoxy terminated polystyrene oligomer (PS-CH2CH2OCOCCl3) and poly-(styrene-b-butadiene)oligomer [P(S-b-B)-CH2CH2OCOCCl3)] were synthesized by living anionic polymeri-zation using n-butyllithium as initiator.Then the PS-CH2CH2OCOCCl3 (PS-Cl3) or P(S-b-B)-CH2CH2O-COCCl3 (PSB-Cl3) was used as the macroinitiator in the polymerization of (meth)acrylates in the presence of CuX/bpy. AB diblock and ABC triblock copolymers were prepared by the integrated living anionic polymerization (LAP)-atom transfer radical polymerization (ATRP). The structures of the PSB-Cl3 and the P(S-b-MMA) were identified by FTIR and 1H-NMR spectrum, respectively. A new way to design block copolymers (the combination of LAP and ATRP) was developed.

  2. Mechanism and Kinetics of Nitroxide-Controlled Free Radical Polymerization (ORGANIC MATERIALS CHEMISTRY-Polymeric Materials)

    OpenAIRE

    1997-01-01

    In the nitroxide-mediated free radical polymerization, the rate of polymerization is determined by the balance of the rates of thermal initiation and bialkyl termination, just like in the conventional system, while the polydispersity is determined by the dissociation-combination frequency of the polymer-nitroxyl adduct and the rate of decomposition of the adduct. These mechanisms were quantitatively confirmed by both experiments and computer simulations.

  3. 21 CFR 177.2250 - Filters, microporous polymeric.

    Science.gov (United States)

    2010-04-01

    ... as Components of Articles Intended for Repeated Use § 177.2250 Filters, microporous polymeric. Microporous polymeric filters identified in paragraph (a) of this section may be safely used, subject to the... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Filters, microporous polymeric. 177.2250 Section...

  4. Mechanism and Modeling for Polymerization of Acrylamide in Inverse Microemulsions

    Institute of Scientific and Technical Information of China (English)

    LiXiao; ZhangWeiying; YuanHuigen

    2004-01-01

    After discussion on the mechanism of polymer particle nucleation and growth in inverse microemulsion polymerization, a schematic physical model for polymerization of acrylamide in inverse microemulsions was presented. Furthermore, several key problems in mathematically modeling of inverse microemulsion polymerization were pointed out.

  5. Biocompatible Polymeric Materials Intended for Drug Delivery and Therapeutic Applications

    DEFF Research Database (Denmark)

    Hvilsted, Søren; Javakhishvili, Irakli; Bednarek, Melania

    2007-01-01

    water soluble polymers, polyethylene glycol (PEG), and poly(acrylic acid) (PAA) with good mycoadhesive properties, are all prepared by living/controlled polymerization techniques. These techniques, atom transfer radical polymerization (ATRP) and ring opening polymerization (ROP), ensure at the same time...

  6. 21 CFR 870.3650 - Pacemaker polymeric mesh bag.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Pacemaker polymeric mesh bag. 870.3650 Section 870...) MEDICAL DEVICES CARDIOVASCULAR DEVICES Cardiovascular Prosthetic Devices § 870.3650 Pacemaker polymeric mesh bag. (a) Identification. A pacemaker polymeric mesh bag is an implanted device used to hold a...

  7. Free heme and sickle hemoglobin polymerization

    Science.gov (United States)

    Uzunova, Veselina V.

    This work investigates further the mechanism of one of the most interesting of the protein self-assembly systems---the polymerization of sickle hemoglobin and the role of free heme in it. Polymerization of sickle hemoglobin is the primary event in the pathology of a chronic hemolytic condition called sickle cell anemia with complex pathogenesis, unexplained variability and symptomatic treatment. Auto-oxidation develops in hemoglobin solutions exposed to room temperature and causes release of ferriheme. The composition of such solutions is investigated by mass spectrometry. Heme dimers whose amount corresponds to the initial amounts of heme released from the protein are followed. Differences in the dimer peak height are established for hemoglobin variants A, S and C and depending on the exposure duration. The effects of free heme on polymerization kinetics are studied. Growth rates and two characteristic parameters of nucleation are measured for stored Hb S. After dialysis of polymerizing solutions, no spherulites are detected at moderately high supersaturation and prolonged exposure times. The addition of 0.16-0.26 mM amounts of heme to dialyzed solutions leads to restoration of polymerization. The measured kinetic parameters have higher values compared to the ones before dialysis. The amount of heme in non-dialyzed aged solution is characterized using spectrophotometry. Three methods are used: difference in absorbance of dialyzed and non-dialyzed solutions, characteristic absorbance of heme-albumin complex and absorbance of non-dialyzed solutions with added potassium cyanide. The various approaches suggest the presence of 0.12 to 0.18 mM of free ferriheme in such solutions. Open questions are whether the same amounts of free heme are present in vivo and whether the same mechanism operates intracellulary. If the answer to those questions is positive, then removal of free heme from erythrocytes can influence their readiness to sickle.

  8. NATO Advanced Study Institute on Ring-opening Metathesis Polymerization of Olefins and Polymerization of Alkynes

    CERN Document Server

    1998-01-01

    The first NATO Advanced Study Institute on Olefin Metathesis and Polymerization Catalysts was held on September 10-22, 1989 in Akcay, Turkey. Based on the fundamental research of RRSchrock, RGrubbs and K.B.Wagener in the field of ring opening metathesis polymerization (ROMP), acyclic diene metathesis (ADMET) and alkyne polymerization, these areas gained growing interest within the last years. Therefore the second NATO-ASI held on metathesis reactions was on Ring Opening Metathesis Po­ lymerization of Olefins and Polymerization of Alkynes on September 3-16, 1995 in Akcay, Turkey. The course joined inorganic, organic and polymer chemists to exchange their knowledge in this field. This volume contains the main and short lectures held in Akcay. To include ADMET reactions better into the title of this volume we changed it into: Metathesis Polymerization of Olefins and Alkyne Polymerization. This volume is addressed to research scientists, but also to those who start to work in the area of olefin metathesis and al...

  9. Signal amplification strategies for DNA and protein detection based on polymeric nanocomposites and polymerization: A review

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Shaohong; Yuan, Liang; Hua, Xin; Xu, Lingling; Liu, Songqin, E-mail: liusq@seu.edu.cn

    2015-06-02

    Highlights: • We review the innovative advances in polymer-based signal amplification. • Conceptual connectivity between different amplified methodologies is illustrated. • Examples explain the mechanisms of polymers/polymerizations-based amplification. • Several elegant applications are summarized that illustrate underlying concept. - Abstract: Demand is increasing for ultrasensitive bioassays for disease diagnosis, environmental monitoring and other research areas. This requires novel signal amplification strategies to maximize the signal output. In this review, we focus on a series of significant signal amplification strategies based on polymeric nanocomposites and polymerization. Some common polymers are used as carriers to increase the local concentration of signal probes and/or biomolecules on their surfaces or in their interiors. Some polymers with special fluorescence and optical properties can efficiently transfer the excitation energy from a single site to the whole polymer backbone. This results in superior fluorescence signal amplification due to the resulting collective effort (integration of signal). Recent polymerization-based signal amplification strategies that employ atom transfer radical polymerization (ATRP) and photo-initiated polymerization are also summarized. Several distinctive applications of polymers in ultrasensitive bioanalysis are highlighted.

  10. THE EFFECTS OF N-2-HYDROXYETHYL-N-METHYL-P-TOLUIDINE ON METHYL METHACRYLATE RADICAL POLYMERIZATION AND ACRYLONITRILE PHOTOINDUCED POLYMERIZATION

    Institute of Scientific and Technical Information of China (English)

    QIU Kunyuan; ZHANG Zhanghua; FENG Xinde

    1992-01-01

    The effects of N-2-hydroxyethyl-N-methyl-p-toluidine (HMT) on MMA polymerization using organic peroxide as an initiator and on AN photoinduced polymerization have been investigated respectively. The kinetics of polymerization and the overall activation energy of polymerization were determined. Based on kinetics study and the end group analysis of the polymer obtained by UV spectrum method, the initiation mechanism is proposed.

  11. Functionalized polymer networks: synthesis of microporous polymers by frontal polymerization

    Indian Academy of Sciences (India)

    N S Pujari; A R Vishwakarma; T S Pathak; A M Kotha; S Ponrathnam

    2004-12-01

    A series of glycidyl methacrylate (GMA)–ethylene dimethacrylate (EGDM) copolymers of varying compositions were synthesized by free-radically triggered thermal frontal polymerization (FP) as well as by suspension polymerization (SP) using azobisisobutyronitrile [AIBN] as initiator. The two sets of copolymers were characterized by IR spectroscopy and mercury intrusion porosimetry, for determination of epoxy number and specific surface area. Frontal polymerization was more efficient, yielding greater conversions at much shorter reaction times. The self-propagating frontal polymerization also generates microporous material with narrow pore size distribution. It yields higher internal pore volume and surface area than suspension polymerization, surface morphologies are, however, inferior.

  12. Dynamic self-assembly of 'living' polymeric chains

    Science.gov (United States)

    Deng, Binghui; Shi, Yunfeng

    2017-01-01

    We report a dynamic self-assembly system of 'living' polymeric chains sustained by chemistry using reactive molecular dynamics simulations. The linear polymeric chains consist of self-assembled nanoparticles connected by metastable linker molecules. As such, the polymeric chains, once assembled, undergo spontaneous dissociation driven by thermodynamics. However, with a continuous supply of linker molecules and the stored chemical energy therein, the polymeric chains can survive and maintain a steady state averaged chain length. These dynamically self-assembled polymeric chains are analogous to biological systems that both are thermodynamically metastable, yet dynamically stable upon continuous influx of matter and energy.

  13. Complex Macromolecular Architectures by Living Cationic Polymerization

    KAUST Repository

    Alghamdi, Reem D.

    2015-05-01

    Poly (vinyl ether)-based graft polymers have been synthesized by the combination of living cationic polymerization of vinyl ethers with other living or controlled/ living polymerization techniques (anionic and ATRP). The process involves the synthesis of well-defined homopolymers (PnBVE) and co/terpolymers [PnBVE-b-PCEVE-b-PSiDEGVE (ABC type) and PSiDEGVE-b-PnBVE-b-PSiDEGVE (CAC type)] by sequential living cationic polymerization of n-butyl vinyl ether (nBVE), 2-chloroethyl vinyl ether (CEVE) and tert-butyldimethylsilyl ethylene glycol vinyl ether (SiDEGVE), using mono-functional {[n-butoxyethyl acetate (nBEA)], [1-(2-chloroethoxy) ethyl acetate (CEEA)], [1-(2-(2-(t-butyldimethylsilyloxy)ethoxy) ethoxy) ethyl acetate (SiDEGEA)]} or di-functional [1,4-cyclohexanedimethanol di(1-ethyl acetate) (cHMDEA), (VEMOA)] initiators. The living cationic polymerizations of those monomers were conducted in hexane at -20 0C using Et3Al2Cl3 (catalyst) in the presence of 1 M AcOEt base.[1] The PCEVE segments of the synthesized block terpolymers were then used to react with living macroanions (PS-DPE-Li; poly styrene diphenyl ethylene lithium) to afford graft polymers. The quantitative desilylation of PSiDEGVE segments by n-Bu4N+F- in THF at 0 °C led to graft co- and terpolymers in which the polyalcohol is the outer block. These co-/terpolymers were subsequently subjected to “grafting-from” reactions by atom transfer radical polymerization (ATRP) of styrene to afford more complex macromolecular architectures. The base assisted living cationic polymerization of vinyl ethers were also used to synthesize well-defined α-hydroxyl polyvinylether (PnBVE-OH). The resulting polymers were then modified into an ATRP macro-initiator for the synthesis of well-defined block copolymers (PnBVE-b-PS). Bifunctional PnBVE with terminal malonate groups was also synthesized and used as a precursor for more complex architectures such as H-shaped block copolymer by “grafting-from” or

  14. SYNTHESIS AND POLYMERIZATION KINETICS OF AB3 TYPE HYPERBRANCHED(AMIDE-ESTR)S%AB3型超支化聚(酰胺-酯)的合成及缩聚动力学研究

    Institute of Scientific and Technical Information of China (English)

    王素娟; 巴信武; 赵宝辉; 张书文; 侯文龙

    2004-01-01

    采用丁二酸酐、三羟甲基氨基甲烷为主要原料,在冰水浴条件下,合成AB3型单体,然后进行熔融缩聚制得超支化聚(酰胺-酯),没有出现凝胶现象.采用Fourier变换红外谱仪(FTIR)、粘度测试、端基分析等方法对其结构、特性粘数进行了表征.同时对AB3型超支化聚(酰胺-酯)的缩聚反应动力学进行了研究,得出了130℃、140℃和150℃时的缩聚反应速率常数,并进一步得出了缩聚反应活化能.实验结果证明缩聚过程为自催化过程,且为三级反应.

  15. 原子转移自由基聚合制备超支化聚合物进展%Progress in preparation of hyperbranched polymers via atom transfer radical polymerization

    Institute of Scientific and Technical Information of China (English)

    张新荔; 井新利

    2009-01-01

    介绍了原子转移自由基聚合(ATRP)制备超支化聚合物的原理以及近年来采用ATRP方法制备的各种支化/超支化聚合物,展望了ATRP的发展趋势.ATRP是目前可控,活性聚合最成功的方法之一,它以过渡金属配合物为催化剂,通过有机卤化物引发乙烯基单体的自由基聚合,合成相对分子质量可控、相对分子质量分布窄的多种聚合物.

  16. Synthesis and characterization of poly(2-ethylhexyl acrylate) prepared via atom transfer radical polymerization, reverse atom transfer radical polymerization and radical polymerization

    Indian Academy of Sciences (India)

    Dhruba Jyoti Haloi; Bishnu Prasad Koiry; Prithwiraj Mandal; Nikhil Kumar Singha

    2013-07-01

    This investigation reports a comparative study of poly(2-ethylhexyl acrylate) (PEHA) prepared via atom transfer radical polymerization (ATRP), reverse atom transfer radical polymerization (RATRP) and conventional free radical polymerization (FRP). The molecular weights and the molecular weight distributions of the polymers were measured by gel permeation chromatography (GPC) analysis. Structural characterization of the polymers was carried out by 1H NMR and MALDI-TOF-MS analyses. Thermal properties of the polymers were evaluated by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The polymerization results and the thermal properties of PEHAs prepared via ATRP, RATRP and FRP were compared.

  17. Therapeutic Strategies Based on Polymeric Microparticles

    Directory of Open Access Journals (Sweden)

    C. Vilos

    2012-01-01

    Full Text Available The development of the field of materials science, the ability to perform multidisciplinary scientific work, and the need for novel administration technologies that maximize therapeutic effects and minimize adverse reactions to readily available drugs have led to the development of delivery systems based on microencapsulation, which has taken one step closer to the target of personalized medicine. Drug delivery systems based on polymeric microparticles are generating a strong impact on preclinical and clinical drug development and have reached a broad development in different fields supporting a critical role in the near future of medical practice. This paper presents the foundations of polymeric microparticles based on their formulation, mechanisms of drug release and some of their innovative therapeutic strategies to board multiple diseases.

  18. Low-Energy Polymeric Phases of Alanates

    Science.gov (United States)

    Huan, Tran Doan; Amsler, Maximilian; Marques, Miguel A. L.; Botti, Silvana; Willand, Alexander; Goedecker, Stefan

    2013-03-01

    Low-energy structures of alanates are currently known to be described by patterns of isolated, nearly ideal tetrahedral [AlH4] anions and metal cations. We discover that the novel polymeric motif recently proposed for LiAlH4 plays a dominant role in a series of alanates, including LiAlH4, NaAlH4, KAlH4, Mg(AlH4)2, Ca(AlH4)2, and Sr(AlH4)2. In particular, most of the low-energy structures discovered for the whole series are characterized by networks of corner-sharing [AlH6] octahedra, forming wires and/or planes throughout the materials. Finally, for Mg(AlH4)2 and Sr(AlH4)2, we identify two polymeric phases to be lowest in energy at low temperatures.

  19. Polymeric membrane studied using slow positron beam

    Energy Technology Data Exchange (ETDEWEB)

    Hung, W.-S.; Lo, C.-H. [R and D Center for Membrane Technology, Chung Yuan Christian University, Chung-Li 32023, Taiwan (China); Department of Chemical Engineering, Chung Yuan Christian University, Chung-Li 32023, Taiwan (China); Cheng, M.-L. [Department of Chemistry, University of Missouri-Kansas City, Kansas City, MO 64110 (United States); Department of Chemical Engineering and Materials Science, Yuan Ze University, Chung-Li 32003, Taiwan (China); Chen Hongmin; Liu Guang; Chakka, Lakshmi [Department of Chemistry, University of Missouri-Kansas City, Kansas City, MO 64110 (United States); Nanda, D.; Tung, K.-L.; Huang, S.-H.; Lee, Kueir-Rarn; Lai, J.-Y. [R and D Center for Membrane Technology, Chung Yuan Christian University, Chung-Li 32023, Taiwan (China); Department of Chemical Engineering, Chung Yuan Christian University, Chung-Li 32023, Taiwan (China); Sun Yiming [R and D Center for Membrane Technology, Chung Yuan Christian University, Chung-Li 32023, Taiwan (China); Department of Chemical Engineering and Materials Science, Yuan Ze University, Chung-Li 32003, Taiwan (China); Yu Changcheng [R and D Center for Membrane Technology, Chung Yuan Christian University, Chung-Li 32023, Taiwan (China); Department of Physics, Chung Yuan Christian University, Chung-Li 32023, Taiwan (China); Zhang Renwu [Physical Science Department, Southern Utah University, Cedar City, UT 84720 (United States); Jean, Y.C. [R and D Center for Membrane Technology, Chung Yuan Christian University, Chung-Li 32023, Taiwan (China); Department of Chemical Engineering, Chung Yuan Christian University, Chung-Li 32023, Taiwan (China); Department of Chemistry, University of Missouri-Kansas City, Kansas City, MO 64110 (United States)], E-mail: jeany@umkc.edu

    2008-10-31

    A radioisotope slow positron beam has been built at the Chung Yuan Christian University in Taiwan for the research and development in membrane science and technology. Doppler broadening energy spectra and positron annihilation lifetime have been measured as a function of positron energy up to 30 keV in a polyamide membrane prepared by the interfacial polymerization between triethylenetetraamine (TETA) and trimesoyl chloride (TMC) on modified porous polyacrylonitrile (PAN) asymmetric membrane. The multilayer structures and free-volume depth profile for this asymmetric membrane system are obtained. Positron annihilation spectroscopy coupled with a slow beam could provide new information about size selectivity of transporting molecules and guidance for molecular designs in polymeric membranes.

  20. Polymeric Piezoelectric Transducers for Hydrophone Applications

    Directory of Open Access Journals (Sweden)

    D. K. Kharat

    2007-01-01

    Full Text Available Conventional ceramic piezoelectric materials have been used in hydrophones for sonarapplications since 1940's. In the last few years since the discovery of polymeric piezoelectrichydrophones, the technology has matured, applications have emerged in extraordinary number ofcases such as underwater navigation, biomedical applications, biomimetics, etc. Hydrophones areused underwater at high hydrostatic pressures. In the presence of hydrostatic pressures, theanisotropic piezoelectric response of ceramic materials is such that it has poor hydrophone performancecharacteristics whereas polymeric piezoelectric materials show enough hydrostatic piezoelectriccoefficients. Moreover, piezoelectric polymers have low acoustic impedance, which is only 2-6 timethat of water, whereas in piezoelectric ceramics, it is typically 11-time greater than that of water. Aclose impedance match permits efficient transduction of acoustic signals in water and tissues. Newlydeveloped hydrostatic-mode polyvinylidene flouride (PVDF hydrophones use a pressure-releasesystem to achieve improved sensitivity. Recently, voided PVDF materials have been used for makinghydrophones having higher sensitivity and figure of merit than unvoided PVDF materials.

  1. Simultaneous covalent and noncovalent hybrid polymerizations

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Zhilin; Tantakitti, Faifan; Yu, Tao; Palmer, Liam C.; Schatz, George C.; Stupp, Samuel I. (NWU)

    2016-01-28

    Covalent and supramolecular polymers are two distinct forms of soft matter, composed of long chains of covalently and noncovalently linked structural units, respectively. We report a hybrid system formed by simultaneous covalent and supramolecular polymerizations of monomers. The process yields cylindrical fibers of uniform diameter that contain covalent and supramolecular compartments, a morphology not observed when the two polymers are formed independently. The covalent polymer has a rigid aromatic imine backbone with helicoidal conformation, and its alkylated peptide side chains are structurally identical to the monomer molecules of supramolecular polymers. In the hybrid system, covalent chains grow to higher average molar mass relative to chains formed via the same polymerization in the absence of a supramolecular compartment. The supramolecular compartments can be reversibly removed and re-formed to reconstitute the hybrid structure, suggesting soft materials with novel delivery or repair functions.

  2. Enhancement of peptide immunogenicity by linear polymerization.

    Science.gov (United States)

    Borras-Cuesta, F; Fedon, Y; Petit-Camurdan, A

    1988-02-01

    The effect of linear homopolymerization on the immunogenicity of synthetic peptides was studied using either haptenic peptides (representing amino acid sequences 103-115 and 133-147 of bovine rotavirus major protein) or immunogenic peptides TD-103-115 and TD-133-147 which were constructed by co-linear synthesis of the former peptides and an amino acid sequence representing a determinant recognized by T helper cells (TD). It was found that the two haptenic peptides were rendered immunogenic by linear homopolymerization. Moreover, homopolymerization also enhanced the immunogenicity of TD-103-115 but not that of TD-133-147. In the three cases where polymerization enhanced immunogenicity, a reinforced amphipathic pattern was predicted in the neighborhood of the junction of the monomers. The possibility that polymerization might have generated a new T cell determinant is discussed.

  3. Raman Laser Polymerization of C60 Nanowhiskers

    Directory of Open Access Journals (Sweden)

    Ryoei Kato

    2012-01-01

    Full Text Available Photopolymerization of C60 nanowhiskers (C60NWs was investigated by using a Raman spectrometer in air at room temperature, since the polymerized C60NWs are expected to exhibit a high mechanical strength and a thermal stability. Short C60NWs with a mean length of 4.4 μm were synthesized by LLIP method (liquid-liquid interfacial precipitation method. The Ag(2 peak of C60NWs shifted to the lower wavenumbers with increasing the laser beam energy dose, and an energy dose more than about 1520 J/mm2 was found necessary to obtain the photopolymerized C60NWs. However, excessive energy doses at high-power densities increased the sample temperature and lead to the thermal decomposition of polymerized C60 molecules.

  4. Multi-modal magnetic resonance imaging and histology of vascular function in xenografts using macromolecular contrast agent hyperbranched polyglycerol (HPG-GdF).

    Science.gov (United States)

    Baker, Jennifer H E; McPhee, Kelly C; Moosvi, Firas; Saatchi, Katayoun; Häfeli, Urs O; Minchinton, Andrew I; Reinsberg, Stefan A

    2016-01-01

    Macromolecular gadolinium (Gd)-based contrast agents are in development as blood pool markers for MRI. HPG-GdF is a 583 kDa hyperbranched polyglycerol doubly tagged with Gd and Alexa 647 nm dye, making it both MR and histologically visible. In this study we examined the location of HPG-GdF in whole-tumor xenograft sections matched to in vivo DCE-MR images of both HPG-GdF and Gadovist. Despite its large size, we have shown that HPG-GdF extravasates from some tumor vessels and accumulates over time, but does not distribute beyond a few cell diameters from vessels. Fractional plasma volume (fPV) and apparent permeability-surface area product (aPS) parameters were derived from the MR concentration-time curves of HPG-GdF. Non-viable necrotic tumor tissue was excluded from the analysis by applying a novel bolus arrival time (BAT) algorithm to all voxels. aPS derived from HPG-GdF was the only MR parameter to identify a difference in vascular function between HCT116 and HT29 colorectal tumors. This study is the first to relate low and high molecular weight contrast agents with matched whole-tumor histological sections. These detailed comparisons identified tumor regions that appear distinct from each other using the HPG-GdF biomarkers related to perfusion and vessel leakiness, while Gadovist-imaged parameter measures in the same regions were unable to detect variation in vascular function. We have established HPG-GdF as a biocompatible multi-modal high molecular weight contrast agent with application for examining vascular function in both MR and histological modalities. Copyright © 2015 John Wiley & Sons, Ltd.

  5. Progress in Long-Chain Hyperbranched Polymers%长链超支化聚合物的合成研究进展

    Institute of Scientific and Technical Information of China (English)

    刘婷婷; 田威; 白阳; 范晓东

    2013-01-01

    长链超支化聚合物(HyperMacs)凭借其含有大量的功能端基和可调控的链结构等优点已经引起国内外科研人员越来越广泛的关注.HyperMcs除了拥有超支化聚合物固有的低粘度、溶解性好、含有大量的功能性端基的特点外,同时拥有高剪切敏感性、熔体弹性、冲击强度和零剪切粘度,因而在药物载体、能量存储及传递和纳米催化剂等方面可能拥有更为广泛的应用.本文根据HyperMacs合成方法的不同,分别从迭代法和ABx线型大分子单体法两个主要方面对其研究进展进行了总结和评述,并在此基础上展望了该类聚合物的研究方向和发展趋势.%Long-chain hyperbranched polymers (HyperMacs) with well-defined and well-adjusted linear chains between branch points have received widespread attention in the macromolecule research due to their potential applications in various fields such as drug carrier,energy storage,and delivery,nanotechnology and catalysis.In this paper,we reviewed the various synthetic strategies for HyperMacs:including iteration and ABx linear macromonomer apporaches.In addition,new research trends are expected based on the progress of this kind of polymers.

  6. Thermal Analyses of Blends of Hyperbranched Linear Low-density Polyethylene (LLDPE with High-density Polyethylene and LLDPE Prepared by Dissolving Method

    Directory of Open Access Journals (Sweden)

    Triinu POLTIMÄE

    2011-09-01

    Full Text Available Blends of high-density polyethylene (HDPE, moderate and hyper-branched LLDPEs (LLDPE and HbPE, respectively have attained widespread commercial applications, though the understanding of the mechanical and melt-flow properties of such blends has been handicapped by the absence of a consensus concerning the degrees of mixing of the components. Moreover, usually the blends are obtained by melt blending, which may not ensure the initial homogeneity of the components. In our work the mixtures were prepared by dissolving the conventional LLDPE having branching content 7.2 wt% with HbPE with comonomer content 17.8 wt% in xylene at 130 °C and stirring for 2 hours. The same procedure was applied for the blending of HDPE with HbPE. After dissolving the mixtures were cooled in liquid nitrogen and after that freeze dried in vacuum line. The ratio of components in the blends was varied. Differential scanning calorimetry has been used to investigate the miscibility and thermal behavior of the blends. For this purpose isothermal and non-isothermal treatment of prepared blends were conducted. By preliminary study the double melting peaks in non-isothermal endotherms have been observed in all the studied blends. The presence of two peaks in DSC scan can be attributed to the formation of separated crystals from both the high density/linear low density and highly branched components. However, certain limited degree of co-crystallization is detected in all the LLDPE/HbPE blends and HDPE/HbPE blend rich in HbPE component.http://dx.doi.org/10.5755/j01.ms.17.3.589

  7. Microencapsulation of Chlorocyclophosphazene by Interfacial Polymerization

    Institute of Scientific and Technical Information of China (English)

    LIU Ya-qing; ZHAO Gui-zhe

    2007-01-01

    A polyurea-chlorocyclophosphazene microcapsule flame retardant is prepared by an interfacial polymerization process using 2, 4-toluene diisocyanate (TDI) and hexanediamine as the raw materials. TG tests show that the thermal decomposition temperature of chlorocyclophosphazene in microcapsule obviously rises. The flame retardancy of HDPE/chlorocyclophosphazene in microencapsules is better than that of HDPE/chlorocyclophosphazene. Mechanical properties of HDPE/chlorocyclophosphazene microencapsule turn out to be superior to those of HDPE/chlorocyclophosphazene.

  8. Remendable Polymeric Materials Using Reversible Covalent Bonds

    Science.gov (United States)

    2008-12-01

    phenyl glycidyl ether (PGE), and N,N- dimethylformamide DMF were obtained from Sigma- Aldrich. EPON 828, a Diglycidyl ether of bisphenol-A ( DGEBA ...RT). The linear polymer was a copolymer of FA and DGEBA . Stoichiometric amounts of FA and DGEBA were mixed to form a 15 wt.% solution in DMF... DGEBA reacts via step growth polymerization with 4,4’-methylenebiscyclohexanamine PACM, an aliphatic diamine. This system was modified by

  9. On viscoelastic instability in polymeric filaments

    DEFF Research Database (Denmark)

    Rasmussen, Henrik Koblitz; Hassager, Ole

    1999-01-01

    The 3D Lagrangian Integral Method is used to simulate the effects of surface tension on the viscoelastic end-plate instability, occuring in the rapid extension of some polymeric filaments between parallel plates. It is shovn that the surface tension delays the onset of the instability. Furthermore...... it is demonstrated that surface tension plays a key role in the selection of the most unstable mode...

  10. Sono-enzymatic polymerization of catechol

    OpenAIRE

    Fernandes, Margarida M.; Basto, Carlos; Zille, Andrea; Munteanu, Florentina-Daniela; Gübitz, Georg M.; Paulo, Artur Cavaco

    2006-01-01

    "Abstracts of papers presented at the 232nd American Chemical Society National Meeting" The potential of laccase enzymes for polymerizing, crosslinking and functionalizing various compounds was studied extensively and increasing interest has been focused on the application of this enzyme as a new biocatalyst in organic synthesis.[1-6] Laccases (EC 1.10.3.2) are a class of multi-copper-containing oxidoreductase enzymes able to catalyze the transformation of various aromatic c...

  11. Single-Molecule Visualization of Living Polymerization

    Science.gov (United States)

    2014-02-18

    proposed to use a magnetic tweezers (MT) approach to visualize real-time single-polymer growth to study polymerization catalysis . Fig 1A illustrates our...on the magnetic particle to stretch the polymer. By monitoring the vertical (z) position of the particle in real time under catalysis , we can...which show very different extension lengths over the same applied force range. These different extension lengths reflect the heterogeneity in chain

  12. Homogeneous catalysts for stereoregular olefin polymerization

    Science.gov (United States)

    Marks, T.J.; Eisen, M.S.; Giardello, M.A.

    1995-10-03

    The synthesis, and use as precatalysts of chiral organozirconium complexes for olefin polymerization are disclosed, having the structure (C{sub 5}R{prime}{sub 4{minus}x}R*{sub x})A(C{sub 5}R{double_prime}{sub 4{minus}y}R{double_prime}{prime}{sub y})MQ{sub p}, where x and y represent the number of unsubstituted locations on the cyclopentadienyl ring; R{prime}, R{double_prime}, R{double_prime}{prime}, and R* represent substituted and unsubstituted alkyl groups having 1--30 carbon atoms and R* is a chiral ligand; A is a fragment containing a Group 13, 14, 15, or 16 element of the Periodic Table; M is a Group 3, 4, or 5 metal of the Periodic Table; and Q is a hydrocarbyl radical, or halogen radical, with 3{>=}p{>=}0. Related complexes may be prepared by alkylation of the corresponding dichlorides. In the presence of methylalumoxane or triarylborane cocatalysts, these complexes form ``cation-like`` species which are highly active for olefin polymerization. In combination with a Lewis acid cocatalyst, propylene or other {alpha}-olefin polymerization can be effected with very high efficiency and isospecificity. 1 fig.

  13. Preparation of polyvinylpyrrodione microspheres by dispersion polymerization

    Institute of Scientific and Technical Information of China (English)

    Linfeng ZHAI; Tiejun SHI; Hualin WANG

    2009-01-01

    The preparation of polyvinylpyrrolidone (PVP) microspheres in ethyl acetate by dispersion polymerization with N-vinylpyrrolidone (NVP) as initial monomer, poly(N-vinylpyrrolidone-co-vinyl acetate) (P (NVP-co-VAc)) as dispersant, and 2, 2'-azobisisobutyr-onitrile(AIBN) as initiator is reported. The influences of monomer concentration, dispersant concentration and initiator concentration on the size of PVP microspheres as well as the monomer conversion were studied. The structure and properties of PVP microspheres were analyzed. The results show that the prepared PVP micro-spheres have a mean diameter of 3-4 μm. With an increase in NVP concentration, the size and the molecular weight of the PVP microspheres as well as the monomer conversion all increase. With increasing P(NVP-co-VAc) concentra-tions, the PVP molecular weight and monomer conversion both increase while the size of the microspheres becomes smaller. As the concentration of AIBN increases, the microsphere size and monomer conversion increase whereas the PVP molecular weight decreases. The PVP prepared by dispersion polymerization has a crystal structure, and its molecular weight is lower compared to that prepared by solution polymerization.

  14. POLYMERIZATION OF DIFFERENT LIGNINS BY LACCASE

    Directory of Open Access Journals (Sweden)

    Maija-Liisa Mattinen

    2008-02-01

    Full Text Available In this study the oxidative polymerization of different lignins, i.e. Flax Soda lignin, Spruce EMAL, and Eucalyptus Dioxane lignin by Trametes hirsuta laccase was compared. Initially the structures of the different lignins were compared by Fourier transform infrared spectroscopy. The reactivity of laccase with the different types of lignins in the absence of mediators was examined and verified by oxygen consumption measurements. The molecular weight distributions of treated and untreated lignins were determined by two different size exclusion chromatography methods. Furthermore, the potential of matrix-assisted laser desorption/ionisation-time of flight-mass spectroscopy for determination of the absolute molecular weights of the different lignins was evaluated. The data showed that all the technical lignins could be activated and polymerized by laccase to different degrees. The efficiency as indicated by measurements of the degree of polymerization was found to increase in the order of Spruce EMAL < Eucalyptus Dioxane lignin < Flax Soda lignin. Overall, this data supplies foundations for using enzymes more efficiently in the enzymatic upgrading of lignin.

  15. Polymerization initated at sidewalls of carbon nanotubes

    Science.gov (United States)

    Tour, James M. (Inventor); Hudson, Jared L. (Inventor); Krishnamoorti, Ramanan (Inventor); Yurekli, Koray (Inventor); Mitchell, Cynthia A. (Inventor)

    2011-01-01

    The present invention is directed to aryl halide (such as aryl bromide) functionalized carbon nanotubes that can be utilized in anionic polymerization processes to form polymer-carbon nanotube materials with improved dispersion ability in polymer matrices. In this process the aryl halide is reacted with an alkyllithium species or is reacted with a metal to replace the aryl-bromine bond with an aryl-lithium or aryl-metal bond, respectively. It has further been discovered that other functionalized carbon nanotubes, after deprotonation with a deprotonation agent, can similarly be utilized in anionic polymerization processes to form polymer-carbon nanotube materials. Additionally or alternatively, a ring opening polymerization process can be performed. The resultant materials can be used by themselves due to their enhanced strength and reinforcement ability when compared to their unbound polymer analogs. Additionally, these materials can also be blended with pre-formed polymers to establish compatibility and enhanced dispersion of nanotubes in otherwise hard to disperse matrices resulting in significantly improved material properties. The resultant polymer-carbon nanotube materials can also be used in drug delivery processes due to their improved dispersion ability and biodegradability, and can also be used for scaffolding to promote cellular growth of tissue.

  16. Homogeneous catalysts for stereoregular olefin polymerization

    Science.gov (United States)

    Marks, Tobin J.; Eisen, Moris S.; Giardello, Michael A.

    1994-01-01

    The synthesis, and use as precatalysts of chiral organozirconium complexes for olefin polymerization are disclosed, having the structure (C.sub.5 R'.sub.4-x R*.sub.x) A (C.sub.5 R".sub.4-y R'".sub.y) M Q.sub.p, where x and y represent the number of unsubstituted locations on the cyclopentadienyl ring; R', R", R'", and R* represent substituted and unsubstituted alkyl groups having 1-30 carbon atoms and R* is a chiral ligand; A is a fragment containing a Group 13, 14, 15, or 16 element of the Periodic Table; M is a Group 3, 4, or 5 metal of the Periodic Table; and Q is a hydrocarbyl radical, or halogen radical, with 3.ltoreq.p.ltoreq.o. Related complexes may be prepared by alkylation of the corresponding dichorides. In the presence of methylalumoxane or triarylborane cocatalysts, these complexes form "cation-like" species which are highly active for olefin polymerization. In combination with a Lewis acid cocatalyst, propylene or other .alpha.-olefin polymerization can be effected with very high efficiency and isospecificity.

  17. Photothermal determination of thermal diffusivity and polymerization depth profiles of polymerized dental resins

    Science.gov (United States)

    Martínez-Torres, P.; Mandelis, A.; Alvarado-Gil, J. J.

    2009-12-01

    The degree and depth of curing due to photopolymerization in a commercial dental resin have been studied using photothermal radiometry. The sample consisted of a thick layer of resin on which a thin metallic gold layer was deposited, thus guaranteeing full opacity. Purely thermal-wave inverse problem techniques without the interference of optical profiles were used. Thermal depth profiles were obtained by heating the gold coating with a modulated laser beam and by performing a frequency scan. Prior to each frequency scan, photopolymerization was induced using a high power blue light emitted diode (LED). Due to the highly light dispersive nature of dental resins, the polymerization process depends strongly on optical absorption of the blue light, thereby inducing a depth dependent thermal diffusivity profile in the sample. A robust depth profilometric method for reconstructing the thermal diffusivity depth dependence on degree and depth of polymerization has been developed. The thermal diffusivity depth profile was linked to the polymerization kinetics.

  18. Synthesis of Glycopolymer Architectures by Reversible-Deactivation Radical Polymerization

    Directory of Open Access Journals (Sweden)

    Ali Ghadban

    2013-05-01

    Full Text Available This review summarizes the state of the art in the synthesis of well-defined glycopolymers by Reversible-Deactivation Radical Polymerization (RDRP from its inception in 1998 until August 2012. Glycopolymers architectures have been successfully synthesized with four major RDRP techniques: Nitroxide-mediated radical polymerization (NMP, cyanoxyl-mediated radical polymerization (CMRP, atom transfer radical polymerization (ATRP and reversible addition-fragmentation chain transfer (RAFT polymerization. Over 140 publications were analyzed and their results summarized according to the technique used and the type of monomer(s and carbohydrates involved. Particular emphasis was placed on the experimental conditions used, the structure obtained (comonomer distribution, topology, the degree of control achieved and the (potential applications sought. A list of representative examples for each polymerization process can be found in tables placed at the beginning of each section covering a particular RDRP technique.

  19. Polymerization monitoring in plasma etching systems

    Science.gov (United States)

    Kim, Jinsoo

    1999-11-01

    In plasma etching processes, the polymers used to enhance etch anisotropy and selectivity also deposit on various parts of the reaction chamber. This polymerization on reactor surface not only strongly affects the concentration of reactants in the plasma discharge, eventually changing the etching characteristics, but also can produce particulates which lower yield. This thesis explores the development of a direct in-situ polymerization monitoring sensor to minimize the drifts in plasma etching processes. In addition, polymerization dependencies on basic processing parameters and polymerization effects on etching characteristics have been explored for the first time using a direct in-situ sensor. The polymer buildup process is a strong function of parameters such as power, base pressure, and flow rate, and is also dependent on the reactor materials used, temperature, and the hydrogen/oxygen concentrations present. Experiments performed in an Applied Materials 8300 plasma etcher show a significant increase in polymerization with increased pressure and flow rates and a decrease as a function of power. These experiments provide insight into how the chamber state changes under the different processing recipes used for etching specific material layers and also suggest how the chamber seasoning process can best be carried out. The reactor surface, which serves as both a source and a sink for reactive gas species, not only strongly affects the concentration of reactants in the plasma discharge, eventually changing the etching characteristics, but also can produce particulates which lower yield. The etch rate and selectivity variations for specific silicon dioxide and silicon nitride etching recipes have been explored as a function of the polymer thickness on the reactor walls. The etch rates of nitride and polysilicon decrease dramatically with polymer thickness up to a thickness of 60nm, while the oxide etch rate remains virtually constant due to the polymerization

  20. Shape of the Polymerization Rate in the Prion Equation

    CERN Document Server

    Gabriel, Pierre

    2010-01-01

    We consider a polymerization (fragmentation) model with size-dependent parameters involved in prion proliferation. Using power laws for the different rates of this model, we recover the shape of the polymerization rate using experimental data. The technique used is inspired from an article of Zampieri et al. where the fragmentation dependency on prion strains is investigated. Our improvement is to use power laws for the rates whereas Zampieri et al. used a constant polymerization coefficient and linear fragmentation.

  1. Organosilicon Polymeric Nonlinear Optical Materials for Optical Switching and Modulation

    Science.gov (United States)

    1994-02-28

    Organosilicon Polymeric Nonlinear Optical Materials for Optical C: F49620-93-C-0039 Switching and Modulation 6. AUTHOR(S) Mr. Sandip K. Sengupta, Dr...D FINAL REPORT for Organosilicon Polymeric Nonlinear Optical Materials for Optical Switching and Modulation Prepared for: USAF, AFMC (AFOSR) Air Force...34Organosilicon Polymeric Nonlinear Optical Materials for Optical Switching and Modulation," contract number F49620-93-C-0039. The work has been performed by Dr

  2. Polymerization of Pyrrole and Thiophene on Polyethylene Adipate Electrodes

    OpenAIRE

    Erturan, Seyfettin; TORAMAN, Burcu YALVAÇ and Sena

    1998-01-01

    Polymerizations of pyrrole and thiophene on a platinum foil coated by polyethylene adipate (PEA) were carried out in acetonitrile by electrochemical methods. Different compositions of semi-conducting composite films of PEA/Polypyrrole(PPy), PEA/Polythiophene(PT) were prepared by the electrochemical polymerization of pyrrole and thiophene on PEA electrode. The polymerization was possible only for a certain thickness of the polyethylene adipate(PEA) on the platinum. Conductivities of PEA/PPy, P...

  3. Polymerization shrinkage of flowable resin-based restorative materials

    OpenAIRE

    Stavridakis, Minos M; Dietschi, Didier; Krejci, Ivo

    2005-01-01

    This study measured the linear polymerization displacement and polymerization forces induced by polymerization shrinkage of a series of flowable resin-based restorative materials. The materials tested were 22 flowable resin-based restorative materials (Admira Flow, Aelite Flow, Aeliteflow LV, Aria, Crystal Essence, Definite Flow, Dyract Flow, Filtek Flow, FloRestore, Flow-it, Flow-Line, Freedom, Glacier, OmegaFlo, PermaFlo, Photo SC, Revolution 2, Star Flow, Synergy Flow, Tetric Flow, Ultrase...

  4. Diacetylene mixed Langmuir monolayers for interfacial polymerization.

    Science.gov (United States)

    Ariza-Carmona, Luisa; Rubia-Payá, Carlos; García-Espejo, G; Martín-Romero, María T; Giner-Casares, Juan J; Camacho, Luis

    2015-05-19

    Polydiacetylene (PDA) and its derivatives are promising materials for applications in a vast number of fields, from organic electronics to biosensing. PDA is obtained through polymerization of diacetylene (DA) monomers, typically using UV irradiation. DA polymerization is a 1-4 addition reaction with both initiation and growth steps with topochemical control, leading to the "blue" polymer form as primary reaction product in bulk and at interfaces. Herein, the diacetylene monomer 10,12-pentacosadiynoic acid (DA) and the amphiphilic cationic N,N'-dioctadecylthiapentacarbocyanine (OTCC) have been used to build a mixed Langmuir monolayer. The presence of OTCC imposes a monolayer supramolecular structure instead of the typical trilayer of pure DA. Surface pressure, Brewster angle microscopy, and UV-vis reflection spectroscopy measurements, as well as computer simulations, have been used to assess in detail the supramolecular structure of the DA:OTCC Langmuir monolayer. Our experimental results indicate that the DA and OTCC molecules are sequentially arranged, with the two OTCC alkyl chains acting as spacing diacetylene units. Despite this configuration is expected to prevent photopolymerization of DA, the polymerization takes place without phase segregation, thus exclusively leading to the red polydiacetylene form. We propose a simple model for the initial formation of the "blue" or "red" PDA forms as a function of the relative orientation of the DA units. The structural insights and the proposed model concerning the supramolecular structure of the "blue" and "red" forms of the PDA are aimed at the understanding of the relation between the molecular and macroscopical features of PDAs.

  5. Durability of Polymeric Glazing and Absorber Materials

    Energy Technology Data Exchange (ETDEWEB)

    Jorgensen, G.; Terwilliger, K.; Bingham, C.; Lindquist, C.; Milbourne, M.

    2005-11-01

    The Solar Heating and Lighting Program has set the goal of reducing the cost of solar water heating systems by at least 50%. An attractive approach to such large cost reduction is to replace glass and metal parts with less-expensive, lighter-weight, more-integrated polymeric components. The key challenge with polymers is to maintain performance and assure requisite durability for extended lifetimes. We have begun evaluation of several new UV-screened polycarbonate sheet glazing constructions. This has involved interactions with several major polymer industry companies to obtain improved candidate samples. Proposed absorber materials were tested for UV resistance, and appear adequate for unglazed ICS absorbers.

  6. Novel hybrid polymeric materials for barrier coatings

    Science.gov (United States)

    Pavlacky, Erin Christine

    Polymer-clay nanocomposites, described as the inclusion of nanometer-sized layered silicates into polymeric materials, have been widely researched due to significant enhancements in material properties with the incorporation of small levels of filler (1--5 wt.%) compared to conventional micro- and macro-composites (20--30 wt.%). One of the most promising applications for polymer-clay nanocomposites is in the field of barrier coatings. The development of UV-curable polymer-clay nanocomposite barrier coatings was explored by employing a novel in situ preparation technique. Unsaturated polyesters were synthesized in the presence of organomodified clays by in situ intercalative polymerization to create highly dispersed clays in a precursor resin. The resulting clay-containing polyesters were crosslinked via UV-irradiation using donor-acceptor chemistry to create polymer-clay nanocomposites which exhibited significantly enhanced barrier properties compared to alternative clay dispersion techniques. The impact of the quaternary alkylammonium organic modifiers, used to increase compatibility between the inorganic clay and organic polymer, was studied to explore influence of the organic modifier structure on the nanocomposite material properties. By incorporating just the organic modifiers, no layered silicates, into the polyester resins, reductions in film mechanical and thermal properties were observed, a strong indicator of film plasticization. An alternative in situ preparation method was explored to further increase the dispersion of organomodified clay within the precursor polyester resins. In stark contrast to traditional in situ polymerization methods, a novel "reverse" in situ preparation method was developed, where unmodified montmorillonite clay was added during polyesterification to a reaction mixture containing the alkylammonium organic modifier. The resulting nanocomposite films exhibited reduced water vapor permeability and increased mechanical properties

  7. Polymeric materials for solar thermal applications

    CERN Document Server

    Köhl, Michael; Papillon, Philippe; Wallner, Gernot M; Saile, Sandrin

    2012-01-01

    Bridging the gap between basic science and technological applications, this is the first book devoted to polymers for solar thermal applications.Clearly divided into three major parts, the contributions are written by experts on solar thermal applications and polymer scientists alike. The first part explains the fundamentals of solar thermal energy especially for representatives of the plastics industry and researchers. Part two then goes on to provide introductory information on polymeric materials and processing for solar thermal experts. The third part combines both of these fields, dis

  8. Polymeric Cantilever Arrays for Biosensing Applications

    DEFF Research Database (Denmark)

    Calleja, M.; Tamayo, J.; Johansson, Alicia

    2003-01-01

    We report the fabrication of arrays of polymeric cantilevers for biochemistry applications. The cantilevers are fabricated in the polymer SU-8. The use of a polymer as the component material for the cantilevers provides the sensors with very high sensitivity due to convenient mechanical material...... properties. The fabrication process is based on spin coating of the photosensitive polymer and near-ultraviolet exposure. The method allows obtaining well-controlled and uniform mechanical properties of the cantilevers. The elastic constant of the cantilevers was measured, and their dynamic response...

  9. Extracellular polymeric bacterial coverages as minimal surfaces

    CERN Document Server

    Saa, A; Saa, Alberto; Teschke, Omar

    2005-01-01

    Surfaces formed by extracellular polymeric substances enclosing individual and some small communities of {\\it Acidithiobacillus ferrooxidans} on plates of hydrophobic silicon and hydrophilic mica are analyzed by means of atomic force microscopy imaging. Accurate nanoscale descriptions of such coverage surfaces are obtained. The good agreement with the predictions of a rather simple but realistic theoretical model allows us to conclude that they correspond, indeed, to minimal area surfaces enclosing a given volume associated with the encased bacteria. This is, to the best of our knowledge, the first shape characterization of the coverage formed by these biomolecules, with possible applications to the study of biofilms.

  10. Direct Laser Printing of Tailored Polymeric Microlenses.

    Science.gov (United States)

    Florian, Camilo; Piazza, Simonluca; Diaspro, Alberto; Serra, Pere; Duocastella, Martí

    2016-07-13

    We report a laser-based approach for the fast fabrication of high-optical-quality polymeric microlenses and microlens arrays with controllable geometry and size. Our strategy consists of the direct laser printing of microdroplets of a highly viscous UV prepolymer at targeted positions, followed by photocuring. We study the morphological characteristics and imaging performance of the microlenses as a function of the substrate and laser parameters and investigate optimal printing conditions and printing mechanisms. We show that the microlens size and focusing properties can be easily tuned by the laser pulse energy, with minimum volumes below 20 fL and focal lengths ranging from 7 to 50 μm.

  11. Clickable Polymeric Coating for Oriented Peptide Immobilization.

    Science.gov (United States)

    Sola, Laura; Gori, Alessandro; Cretich, Marina; Finetti, Chiara; Zilio, Caterina; Chiari, Marcella

    2016-01-01

    A new methodology for the fabrication of an high-performance peptide microarray is reported, combining the higher sensitivity of a layered Si-SiO2 substrate with the oriented immobilization of peptides using a N,N-dimethylacrylamide-based polymeric coating that contains alkyne monomers as functional groups. This clickable polymer allows the oriented attachment of azido-modified peptides via a copper-mediated azide/alkyne cycloaddition. A similar coating that does not contain the alkyne functionality has been used as comparison, to demonstrate the importance of a proper orientation for facilitating the probe recognition and interaction with the target antibody.

  12. Multiphoton polymerization using optical trap assisted nanopatterning

    Science.gov (United States)

    Leitz, Karl-Heinz; Tsai, Yu-Cheng; Flad, Florian; Schäffer, Eike; Quentin, Ulf; Alexeev, Ilya; Fardel, Romain; Arnold, Craig B.; Schmidt, Michael

    2013-06-01

    In this letter, we show the combination of multiphoton polymerization and optical trap assisted nanopatterning (OTAN) for the additive manufacturing of structures with nanometer resolution. User-defined patterns of polymer nanostructures are deposited on a glass substrate by a 3.5 μm polystyrene sphere focusing IR femtosecond laser pulses, showing minimum feature sizes of λ/10. Feature size depends on the applied laser fluence and the bead surface spacing. A finite element model describes the intensity enhancement in the microbead focus. The results presented suggest that OTAN in combination with multiphoton processing is a viable technique for additive nanomanufacturing with sub-diffraction-limited resolution.

  13. Polymeric biomaterials structure and function, v.1

    CERN Document Server

    Dumitriu, Severian

    2013-01-01

    Biomaterials have had a major impact on the practice of contemporary medicine and patient care. Growing into a major interdisciplinary effort involving chemists, biologists, engineers, and physicians, biomaterials development has enabled the creation of high-quality devices, implants, and drug carriers with greater biocompatibility and biofunctionality. The fast-paced research and increasing interest in finding new and improved biocompatible or biodegradable polymers has provided a wealth of new information, transforming this edition of Polymeric Biomaterials into a two-volume set. This volume

  14. Studies of molecular properties of polymeric materials

    Science.gov (United States)

    Harries, W. L.; Long, Sheila Ann T.; Long, Edward R., Jr.

    1990-01-01

    Aerospace environment effects (high energy electrons, thermal cycling, atomic oxygen, and aircraft fluids) on polymeric and composite materials considered for structural use in spacecraft and advanced aircraft are examined. These materials include Mylar, Ultem, and Kapton. In addition to providing information on the behavior of the materials, attempts are made to relate the measurements to the molecular processes occurring in the material. A summary and overview of the technical aspects are given along with a list of the papers that resulted from the studies. The actual papers are included in the appendices and a glossary of technical terms and definitions is included in the front matter.

  15. Polysaccharide-modified synthetic polymeric biomaterials.

    Science.gov (United States)

    Baldwin, Aaron D; Kiick, Kristi L

    2010-01-01

    This review presents an overview of polysaccharide-conjugated synthetic polymers and their use in tissue-engineered scaffolds and drug-delivery applications. This topic will be divided into four categories: (1) polymeric materials modified with non-mammalian polysaccharides such as alginate, chitin, and dextran; (2) polymers modified with mammalian polysaccharides such as hyaluronan, chondroitin sulfate, and heparin; (3) multi-polysaccharide-derivatized polymer conjugate systems; and (4) polymers containing polysaccharide-mimetic molecules. Each section will discuss relevant conjugation techniques, analysis, and the impact of these materials as micelles, particles, or hydrogels used in in-vitro and in-vivo biomaterial applications. (c) 2010 Wiley Periodicals, Inc.

  16. Charpy Impact Test on Polymeric Molded Parts

    Directory of Open Access Journals (Sweden)

    Alexandra Raicu

    2012-09-01

    Full Text Available The paper presents the Charpy impact tests on the AcrylonitrileButadiene-Styrene (ABS polymeric material parts. The Charpy impact test, also known as the Charpy V-notch test, is a standardized strain rate test which determines the amount of energy absorbed by a material during fracture. This is a typical method described in ASTM Standard D 6110. We use for testing an Instron - Dynatup equipment which have a fully integrated hardware and software package that let us capture load information at very high speed from the impact tests.

  17. Polymeric micelles as carriers of diagnostic agents.

    Science.gov (United States)

    Trubetskoy

    1999-04-01

    This review deals with diagnostic applications of polymeric micelles composed of amphiphilic block-copolymers. In aqueous solutions these polymers spontaneously form particles with diameter 20-100 nm. A variety of diagnostic moieties can be incorporated covalently or non-covalently into the particulates with high loads. Resulting particles can be used as particulate agents for diagnostic imaging using three major imaging modalities: gamma-scintigraphy, magnetic resonance imaging and computed tomography. The use of polyethyleneoxide-diacyllipid micelles loaded with chelated (111)In/Gd(3+) as well as iodine-containing amphiphilic copolymer in percutaneous lymphography and blood pool/liver imaging are discussed as specific examples.

  18. Role(s) of TMA in polymerization.

    Science.gov (United States)

    Ehm, C; Cipullo, R; Budzelaar, P H M; Busico, V

    2016-04-28

    Quenched-flow data for propene polymerization with rac-Me2Si(2-Me-4-Ph-1-indenyl)2ZrCl2/MAO support a picture where removal of MAO qualitatively changes the kinetic profile from a mainly enthalpic to a mainly entropic barrier. DFT studies suggest that a not previously recognized singly-bridged end-on coordination mode of Me6Al2 to catalytically active centers may be kinetically relevant as a resting state. In contrast, the more traditional doubly-bridged complex of Me3Al is proposed to be more relevant to chain transfer to cocatalyst.

  19. Modelling degradation of bioresorbable polymeric medical devices

    CERN Document Server

    Pan, J

    2015-01-01

    The use of bioresorbable polymers in stents, fixation devices and tissue engineering is revolutionising medicine. Both industry and academic researchers are interested in using computer modelling to replace some experiments which are costly and time consuming. This book provides readers with a comprehensive review of modelling polymers and polymeric medical devices as an alternative to practical experiments. Chapters in part one provide readers with an overview of the fundamentals of biodegradation. Part two looks at a wide range of degradation theories for bioresorbable polymers and devices.

  20. Development of Polymeric Coatings for Antifouling Applications

    Science.gov (United States)

    Toumayan, Edward Philip

    Fouling, or the deposition of unwanted material onto a surface, is a serious problem that can impair the function of submerged structures, such as marine-going vessels and underwater equipment. Water filtration membranes are particularly susceptible to fouling due to their microstructure and high water pressure operating conditions. For this reason, there has been considerable interest in developing fouling-resistant, or "antifouling" coatings for membranes, specifically coatings that mitigate fouling propensity while maintain high water flux. Polymer coatings have garnered significant interest in antifouling literature, due to their synthetic versatility and variety, and their promising resistance to a wide range of foulants. However, antifouling research has yet to establish a consistent framework for polymer coating synthesis and fouling evaluation, making it difficult or impossible to compare previously established methodologies. To this end, this work establishes a standardized methodology for synthesizing and evaluating polymer antifouling coatings. Specifically, antifouling coatings are synthesized using a grafting-from polymerization and fouling propensity is evaluated by quartz crystal microbalance with dissipation (QCM-D). Using this framework, a number of different surface functionalization strategies are compared, including grafting-to and grafting-from polymerization. A number of different surface functionalization strategies, including grafting-to and grafting-from, were investigated and the fouling performance of these films was evaluated. Primarily, sulfobetaine methacrylate, and poly(ethylene oxide) methacrylate monomers were investigated, among others. Grafting-to, while advantageous from a characterization standpoint, was ultimately limited to low grafting densities, which did not afford a significant improvement in fouling resistance. However, the higher grafting densities achievable by grafting-from did indicate improved fouling resistance. A