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Amphiphilic Copolymers (amphiphilic + copolymer)
Selected AbstractsOxidation of Allylic Alcohols, Amines, and Sulfides Mediated by Assembled Triphase Catalyst of Phosphotungstate and Non-cross-linked Amphiphilic Copolymer.CHEMINFORM, Issue 35 2004Yoichi M. A. Yamada Abstract For Abstract see ChemInform Abstract in Full Text. [source] Temperature-Responsive Water-Soluble Copolymers Based on 2-Hydroxyethyl Acrylate and Butyl AcrylateMACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 9 2007Grigoriy A. Mun Abstract Amphiphilic copolymers have been synthesised by free radical copolymerisation of 2-hydroxyethyl acrylate with butyl acrylate, the reactivity ratios of which indicate practically equal reactivity. The copolymers containing less than 30 mol-% of BA were soluble in water and exhibited a LCST in aqueous solutions. It was found that the interaction between these copolymers and poly(acrylic acid) in aqueous solutions resulted in the formation of interpolymer complexes stabilised by hydrogen bonds and hydrophobic interactions. This interaction was significantly affected by solution pH and led to modification of the temperature-responsive behaviour of the copolymers. [source] Blood cell separation using crosslinkable copolymers containing N,N -dimethylacrylamidePOLYMERS FOR ADVANCED TECHNOLOGIES, Issue 4 2007Shizue Hayashi Natori Abstract Amphiphilic copolymers using hydrophilic N,N -dimethylacrylamide (DMA), hydrophobic methyl methacrylate (MMA) and a crosslinkable monomer, 3-methacryloyloxypropyl trimethoxysilane (MTSi), were synthesized and evaluated as coating materials for leukocyte removal filters for whole blood. When filters composed of non-woven fabrics were coated with crosslinked synthesized copolymers, the elution ratios of the copolymers to water were adequately low because of the crosslinking with trimethoxysilane groups of MTSi units in the copolymers. Filters coated with crosslinked poly(DMA- co -MTSi) having a 0.96 mole fraction of DMA units showed a 0.35,±,0.44% platelet permeation ratio and a logarithmic reduction of 4.0,±,0.68 for leukocytes. On the other hand, an increase in the content of MMA units in the DMA-containing copolymers improved the permeation ratio of the platelets dramatically. Filters coated with crosslinked poly(DMA- co -MMA- co -MTSi) containing a 0.39 mole fraction of MMA units and a 0.58 mole fraction of DMA units showed an 86,±,3.0% platelet permeation ratio and a logarithmic reduction of 2.1,±,1.2 for leukocytes. This indicates that an adequate content of hydrophobic monomer units, such as MMA units, is necessary for effective platelet permeation. Copyright © 2007 John Wiley & Sons, Ltd. [source] Copolymerization of vinyl acetate with 1-octene and ethylene by cobalt-mediated radical polymerizationJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 12 2007Rayna Bryaskova Abstract The cobalt-mediated radical polymerization of vinyl acetate was extended to copolymerization with 1-alkenes (ethylene or 1-octene). In agreement with the low amount of 1-alkene that could be incorporated into the copolymer, a gradient structure was predictable, but a rather low polydispersity was observed. A poly(vinyl acetate)- b -poly(octene) copolymer was also successfully synthesized, leading to a poly (vinyl alcohol)- b -poly(octene) amphiphilic copolymer upon the methanolysis of the poly (vinyl acetate) block. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 2532,2542, 2007 [source] Multiple morphologies from a novel diblock copolymer containing dendronized polymethacrylate and linear poly(ethylene oxide)JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 11 2005Cai-Xia Cheng Abstract A novel amphiphilic diblock copolymer, consisting of dendronized polymethacrylate- b -poly(ethylene oxide), was synthesized via atom transfer radical polymerization; from it, micellelike aggregates of various morphologies, prepared under near-equilibrium conditions, were studied with transmission electron microscopy and scanning electron microscopy. The effects of various factors on the aggregate morphologies of the amphiphilic copolymer, such as the water content, the copolymer concentration, and the type of common solvent, were investigated systematically. The unique architecture of the block copolymer led to morphological variety and peculiarities such as dendritic and shuttle-shaped aggregates, which could be attributed to the effective packing of the bulky side chains, that is, another driving force for the aggregates. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2291,2297, 2005 [source] Synthesis and Self-Assembly of Novel Amphiphilic Six-Armed Star Copolymers TP[PDMAEMA -b- PSt]6MACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 6 2009Kang Tao Abstract A triphenylene (TP)-based hexafunctional initiator was prepared and used in successive ATRP of DMAEMA and St. Well-defined six-armed star block copolymers TP[PDMAEMA -b- PSt]6 bearing hydrophilic backbones inside and hydrophobic blocks outside were successfully synthesized. The self-assembly behaviors of the novel amphiphilic copolymer were further investigated. Co-existing spherical and bowl-shaped aggregates were observed from their neutral aqueous solution, while large spherical structures with different dimensions were obtained from their diluted HCl and CF3COOH aqueous solution, respectively. Dynamic light scattering in different aqueous solutions were conducted to give further confirmation. The possible mechanism of the morphology formation was proposed. [source] Synthesis of Poly(glycidyl methacrylate)- block -Poly(pentafluorostyrene) by RAFT: Precursor to Novel Amphiphilic Poly(glyceryl methacrylate)- block -Poly(pentafluorostyrene)MACROMOLECULAR RAPID COMMUNICATIONS, Issue 23 2008Chakravarthy S. Gudipati Abstract Poly(glycidyl methacrylate) (PGMA) was synthesized by the RAFT method in the presence of 2-cyanoprop-2-yl dithiobenzoate (CPDB) chain transfer agent using different [GMA]/[CPDB] molar ratios. The living radical polymerization resulted in controlled molecular weights and narrow polydispersity indices (PDI) of ,1.1. The polymerization of pentafluorostyrene (PFS) with PGMA as the macro-RAFT agent yielded narrow PDIs of ,1.2 at 60,°C and ,1.5 at 80,°C. The epoxy groups of the PGMA block were hydrolyzed to obtain novel amphiphilic copolymer, poly(glyceryl methacrylate)- block -poly(pentafluorostyrene) [PGMA(OH)- b -PPFS]. The PGMA epoxy group hydrolysis was confirmed by 1H NMR and FTIR spectroscopy. DSC investigation revealed that the PGMA- b -PPFS polymer was amorphous while the PGMA(OH)- b -PPFS displayed a high degree of crystallinity. [source] Characterization of pegylated copolymeric micelles and in vivo pharmacokinetics and biodistribution studiesJOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 1 2006Wen-Jen Lin Abstract The aim of this study was to evaluate the influence of pegylated copolymeric micelle carrier on the biodistribution of drug in rats. The copolymers were synthesized via a modified ring-opening copolymerization of lactone monomers (,-caprolactone, ,-valerolactone, L -lactide) and poly(ethylene glycol) (PEG10,000 and PEG4000). The molecular weights and the polydispersities of synthesized copolymers were in the range of 15,000,31,000 g/mol and 1.7,2.7, respectively. All of the pegylated amphiphilic copolymers were micelles formed with low CMC values in the range of 10,7,10,8M. The drug-loaded micelles were prepared via a dialysis method. The average particle size of micelles was around 150,200 nm. The cytotoxicity in terms of cell viability after treated with PCL,PEG, PVL,PEG, and PLA,PEG micelles was insignificant. PCL,PEG and PVL,PEG micelles without branch side chain in structures had higher drug loading than PLA,PEG micelles. In vitro release profiles indicated the release of indomethacin from these micelles exhibited a sustained release behavior. The similar phenomenon was also observed in vivo in rats. The pegylated copolymeric micelles not only decreased drug uptake by the liver and kidney, but also prolonged drug retention in the blood. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006 [source] Synthesis and self-assembly of well-defined cyclodextrin-centered amphiphilic A14B7 multimiktoarm star copolymers based on poly(,-caprolactone) and poly(acrylic acid)JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 14 2010Peng-Fei Gou Abstract Novel amphiphilic A14B7 multimiktoarm star copolymers composed of 14 poly(,-caprolactone) (PCL) arms and 7 poly(acrylic acid) (PAA) arms with ,-cyclodextrin (,-CD) as core moiety were synthesized by the combination of controlled ring-opening polymerization (CROP) and atom transfer radical polymerization (ATRP). 14-Arm star PCL homopolymers (CDSi-SPCL) were first synthesized by the CROP of CL using per-6-(tert -butyldimethylsilyl)-,-CD as the multifunctional initiator in the presence of Sn(Oct)2 at 125 °C. Subsequently, the hydroxyl end groups of CDSi-SPCL were blocked by acetyl chloride. After desilylation of the tert -butyldimethylsilyl ether groups from the ,-CD core, 7 ATRP initiating sites were introduced by treating with 2-bromoisobutyryl bromide, which further initiated ATRP of tert -butyl acrylate (tBA) to prepare well-defined A14B7 multimiktoarm star copolymers [CDS(PCL-PtBA)]. Their molecular structures and physical properties were in detail characterized by 1H NMR, SEC-MALLS, and DSC. The selective hydrolysis of tert -butyl ester groups of the PtBA block gave the amphiphilic A14B7 multimiktoarm star copolymers [CDS(PCL-PAA)]. These amphiphilic copolymers could self-assemble into multimorphological aggregates in aqueous solution, which were characterized by dynamic light scattering (DLS), transmission electron microscopy (TEM) and atomic force microscopy (AFM). © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2961,2974, 2010 [source] Determination of block size in poly(ethylene oxide)- b -polystyrene block copolymers by matrix-assisted laser desorption/ionization time-of-flight mass spectrometryJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 13 2009Marion Girod Abstract Characterization of block size in poly(ethylene oxide)- b -poly(styrene) (PEO- b -PS) block copolymers could be achieved by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) after scission of the macromolecules into their constituent blocks. The performed hydrolytic cleavage was demonstrated to specifically occur on the targeted ester function in the junction group, yielding two homopolymers consisting of the constitutive initial blocks. This approach allows the use of well-established MALDI protocols for a complete copolymer characterization while circumventing difficulties inherent to amphiphilic macromolecule ionization. Although the labile end-group in PS homopolymer was modified by the MALDI process, PS block size could be determined from MS data since polymer chains were shown to remain intact during ionization. This methodology has been validated for a PEO- b -PS sample series, with two PEO of number average molecular weight (Mn) of 2000 and 5000 g mol,1 and Mn(PS) ranging from 4000 to 21,000 g mol,1. Weight average molecular weight (Mw), and thus polydispersity index, could also be reached for each segment and were consistent with values obtained by size exclusion chromatography. This approach is particularly valuable in the case of amphiphilic copolymers for which Mn values as determined by liquid state nuclear magnetic resonance might be affected by micelle formation. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 3380,3390, 2009 [source] Interfacial living radical copolymerization of oil- and water-soluble comonomers to form composite polymer capsulesJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 1 2006Mir Mukkaram Ali Abstract The suspension copolymerization of methyl methacrylate with hydroxy-functional poly(ethylene glycol) monomethacrylate (PEGMA) by atom transfer radical polymerization (ATRP) yielded soluble, controlled-molecular-weight amphiphilic copolymers (weight-average molecular weight/number-average molecular weight <1.3). Despite extensive partitioning of PEGMA into the water phase, copolymers containing up to 24 mol % PEGMA were formed in the oil phase, from comonomer feeds containing 30 mol % PEGMA. Conversions by suspension polymerization were comparable to those obtained by solution polymerization, at over 70%. Suspension copolymers with high PEGMA contents contained high-molecular-weight polymer formed by uncontrolled polymerization, unless poly(vinyl pyrrolidone) was added to displace the growing polymer from the interface. The addition of diethylene glycol dimethacrylate gave capsules at 17 mol % PEGMA with ATRP, whereas conventional free-radical polymerization required 24 mol % PEGMA to form capsules. The lower PEGMA level required for capsule formation with ATRP was attributed to the lower rates of propagation and crosslinking and to improved incorporation of PEGMA into the final gels. Suspension ATRP with 24 mol % PEGMA in the feed gave two-layer capsule walls consisting of an inner layer visible by transmission electron microscopy and an outer layer visible by both transmission electron microscopy and environmental scanning electron microscopy, which indicated a compositional gradient across the capsule wall. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 156,171, 2006 [source] Synthesis of new amphiphilic diblock copolymers containing poly(ethylene oxide) and poly(,-olefin)JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 20 2002Yingying Lu Abstract This article discusses an effective route to prepare amphiphilic diblock copolymers containing a poly(ethylene oxide) block and a polyolefin block that includes semicrystalline thermoplastics, such as polyethylene and syndiotactic polystyrene (s-PS), and elastomers, such as poly(ethylene- co -1-octene) and poly(ethylene- co -styrene) random copolymers. The broad choice of polyolefin blocks provides the amphiphilic copolymers with a wide range of thermal properties from high melting temperature ,270 °C to low glass-transition temperature ,,60 °C. The chemistry involves two reaction steps, including the preparation of a borane group-terminated polyolefin by the combination of a metallocene catalyst and a borane chain-transfer agent as well as the interconversion of a borane terminal group to an anionic (O,K+) terminal group for the subsequent ring-opening polymerization of ethylene oxide. The overall reaction process resembles a transformation from the metallocene polymerization of ,-olefins to the ring-opening polymerization of ethylene oxide. The well-defined reaction mechanisms in both steps provide the diblock copolymer with controlled molecular structure in terms of composition, molecular weight, moderate molecular weight distribution (Mw/Mn < 2.5), and absence of homopolymer. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3416,3425, 2002 [source] Synthesis and Thermosensitive Properties of Poly[(N -vinylamide)- co -(vinyl acetate)]s and Their Hydrogels,MACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 7 2003Kazuya Yamamoto Abstract Free radical copolymerization of water-soluble N -vinylamides such as N -vinylacetamide (NVA) and N -vinylformamide (NVF) with hydrophobic vinyl acetate (VAc) gave amphiphilic copolymers. The monomer reactivity ratios were determined as r1,=,5.8 and r2,=,0.68 (M1,=,NVA, M2,=,VAc) and r1,=,6.2 and r2,=,0.37 (M1,=,NVF, M2,=,VAc), respectively. The growing radical of the terminals of N -vinylamides propagates more favorably for N -vinylamide monomers than for VAc monomer, resulting in the possible formation of blocky copolymers. It is found that aqueous solutions of these amphiphilic copolymers exhibited a lower critical solution temperature (LCST), depending on their chemical composition, followed by coacervate formation above the LCST. Furthermore, thermosensitive hydrogels could be prepared by the free radical copolymerization of N -vinylamide and VAc in the presence of the crosslinker butylenebis(N -vinylacetamide) (Bis-NVA). The swelling ratios of these hydrogels decreased with an immediate increase in temperature from 20 to 80,°C, and then reversibly increased with decreasing temperature. These hydrogels showed the same thermosensitive properties as linear copolymers of NVF and VAc. Relationship between LCST and vinyl acetate content in poly(N -vinylamide- co -VAc)s. [source] Novel Amphiphilic Degradable Poly(, -caprolactone)- graft -poly(4-vinyl pyridine), Poly(, -caprolactone)- graft -poly(dimethylaminoethyl methacrylate) and Water-Soluble DerivativesMACROMOLECULAR RAPID COMMUNICATIONS, Issue 9 2008Benjamin Nottelet Abstract New amphiphilic graft copolymers that have a poly(, -caprolactone) (PCL) biodegradable hydrophobic backbone and poly(4-vinylpyridine) (P4VP) or poly(2-(N,N- dimethylamino)ethyl methacrylate) (PDMAEMA) hydrophilic side chains have been prepared by anionic polymerization of the corresponding 4VP and DMAEMA monomers using a PCL-based macropolycarbanion as initiator. The water solubility of these amphiphilic copolymers is improved by quaternization, which leads to fully water-soluble cationic copolymers that give micellar aggregates in deionized water with diameters ranging from 65 to 125 nm. In addition, to improve the hydrophilicity of PCL- g -P4VP, grafting of poly(ethylene glycol) (PEG) segments has been carried out to give a water-soluble double grafted PCL- g -(P4VP;PEG) terpolymer. [source] Synthesis of poly(fluorinated styrene)- block -poly(ethylene oxide) amphiphilic copolymers via atom transfer radical polymerization: potential application as paper coating materialsPOLYMER INTERNATIONAL, Issue 8 2009Khalid A Ibrahim Abstract BACKGROUND: The surface of a substrate which comprises a fibrous material is brought into contact with a type of amphiphilic block copolymer which comprises hydrophilic/hydrophobic polymeric blocks. These amphiphilic copolymers have been synthesized by atom transfer radical polymerization (ATRP) technique. The atom transfer radical polymerization of poly(2,3,4,5,6-pentafluorostyrene)- block -poly(ethylene oxide) (PFS- b -PEO) copolymers (di- and triblock structures) with various ranges of PEO molecular weights was initiated by a PEO chloro-telechelic macroinitiator. The polymerization, carried out in bulk and catalysed by copper(I) chloride in the presence of 2,2,-bipyridine ligand, led to A,B,A amphiphilic triblock and A,B amphiphilic diblock structures. RESULTS: With most of the macroinitiators, the living nature of the polymerizations led to block copolymers with narrow molecular weight distributions (1.09 < Mw/Mn < 1.33) and well-controlled molecular structures. These block copolymers turned out to be water-soluble through adjustment of the PEO block content (>90 wt%). Of all the block copolymers synthesized, PFS- b -PEO(10k)- b -PFS containing 10 wt% PFS was found to retard water absorption considerably. CONCLUSION: The printability of paper treated with the copolymers was evaluated with contact angle measurements and felt pen tests. The adsorption of such copolymers at the solid/liquid interface is relevant to the wetting and spreading of liquids on hydrophobic/hydrophilic surfaces. Copyright © 2009 Society of Chemical Industry [source] | ||||||||||