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Well-defined Polymers (well-defined + polymer)
Selected AbstractsNovel well-defined glycopolymers synthesized via the reversible addition fragmentation chain transfer process in aqueous mediaJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 2 2009Zhicheng Deng Abstract We describe here the direct synthesis of novel gluconamidoalkyl methacrylamides by reacting D -gluconolactone with aminoalkyl methacrylamides. The glycomonomers were then successfully polymerized via the reversible addition-fragmentation chain transfer process (RAFT) using 4-cyanopentanoic acid dithiobenzoate (CTP) as chain transfer agent and 4,4,-azobis(4-cyanovaleric acid) (ACVA) as the initiator in aqueous media. Well-defined polymers were obtained as revealed by gel permeation chromatography. Diblock copolymers were then synthesized by the macro-CTA approach. The cationic glycopolymers were subsequently used in the formation of nanostructures via the complexation with plasmid DNA. As noted by dynamic light scattering, monodisperse nanoparticles were obtained via the electrostatic interaction of the cationic glycopolymer with DNA. The sizes of the nanoparticles formed were found to be stable and independent of pH. In vitro cell viability studies of the glycopolymers were carried out using HELA cell lines. The RAFT synthesized glycopolymers and cationic glyco-copolymers revealed to be nontoxic. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 614,627, 2009 [source] Grafting polymer chains bearing an N -succinimidyl activated ester end-group onto primary amine-coated silica particles and application of a simple, one-step approach via nitroxide-mediated controlled/living free-radical polymerizationJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 1 2010Julien Parvole Abstract In a first part, the alkoxyamine initiator derived from BlocBuilder® based on the nitroxide SG1 and bearing an N -succinimidyl ester function was used to synthesize a variety of well-defined polymers with the activated ester group at the ,-end. The grafting of those polymer chains onto primary-amine functionalized Stöber silica particles was performed in soft conditions at room temperature and was studied as a function of the polymer chain length, the type of solvent, and the concentrations of both polymer and amine. Polymer grafting densities were mainly in the 0.1,0.2 chain nm,2 range. To increase the grafting density in simple experimental conditions, a direct one-step method was then proposed: the primary-amine modified silica, the N -succinimidyl ester functionalized alkoxyamine, and the monomer were all introduced into the reaction medium at once. This technique allowed grafting and chain growth to take place simultaneously at the polymerization temperature (i.e., 120 °C for styrene), in a single step, and produced hybrid particles with very high grafting density, up to 0.9 chain nm,2, and long polymer chains. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 173,185, 2010 [source] Recent advances in the synthesis of well-defined glycopolymersJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 11 2007Sebastian G. Spain Abstract Glycopolymers are receiving increasing interest due to their application in areas, such as glycomics, medicine, biotechnology, sensors, and separation science. Consequently, new methods for their synthesis are constantly being developed, with an increasing emphasis on the preparation of well-defined polymers and on the production of complex macromolecular architectures such as stars. This review covers recent developments in the synthesis of glycopolymers, with a particular emphasis on (i) the use of controlled radical polymerization to prepare well-defined glycopolymers from unprotected monomers and (ii) postpolymerization modification strategies using reactive polymer precursors (including "click" reactions). Recent work on the production of glycosylated polypeptides, which are under investigation as mimics of naturally occurring glycoproteins, is also included. The authors offer some suggestions as to future developments and remaining challenges in this topical area of polymer chemistry. © 2007 Wiley Periodicals, Inc. J Polym Sci PartA: Polym Chem45: 2059,2072, 2007 [source] Rapid Synthesis and MALDI-ToF Characterization of Poly(ethylene oxide) Multiarm Star PolymersMACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 1 2010Maria Doycheva Abstract Multiarm PEO star polymers with a purely aliphatic polyether structure have been synthesized using hyperbranched polyglycerol (PG) with different molecular weights as a multifunctional initiator. Different degrees of deprotonation of the initiator were studied with respect to molecular weight control. The results show that the degree of deprotonation is a crucial parameter for the synthesis of well-defined polymers with controlled molecular weights. Partial deprotonation of the PG hydroxyl groups (5,8%) was proven to represent an optimum for the synthesis of star polymers with molecular masses close to the theoretical values. Molecular weights of the stars ranged between 9,000 and 30,000,g,·,mol,1. MALDI-ToF spectra confirmed that the PEO arms in the star polymers possess homogeneous lengths. [source] Controlled Radical Polymerization of Vaporized Vinyl Monomers on Solid Surfaces under UV IrradiationMACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 4 2004Mikio Yasutake Abstract Summary: In order to prepare well-defined polymers on solid surfaces in the gas phase, a gas phase-assisted surface polymerization (GASP) of vinyl monomers was carried out on solid surfaces pre-coated with a photoiniferter, 2-cyanoprop-2-yl N,N,-dimethyldithiocarbamate, under UV irradiation. The GASP of methyl methacrylate (MMA) resulted in the formation of polymer on the surfaces and showed a proportional relationship between and polymer yield. Consecutive copolymerization of MMA and styrene led to the formation of a block copolymer, which was confirmed by a selective solvent fractionation method. These results demonstrate that controlled radical polymerization of vaporized monomer occurred on the solid surfaces. Expected mechanism of GASP under UV irradiation. [source] Synthesis of block copolymers by combination of ATRP and photoiniferter processesPOLYMER INTERNATIONAL, Issue 10 2008Yasemin Yuksel Durmaz Abstract BACKGROUND: Block copolymers of monomers polymerizing by different mechanisms can be prepared by the transformation approach. A wide range of combinations of different polymerization modes has been reported in the literature. In this work, the transformation approach was further extended to the preparation of block copolymers by combining atom transfer radical polymerization (ATRP) and photoiniferter processes. RESULTS: Photoactive morpholine-4-dithiocarbamate-terminated polystyrene (MDC-PS-MDC) was prepared by the reaction of dibrominated polystyrene, obtained by ATRP, with morpholine-4-dithiocarbamate sodium salt in dimethylformamide. The structure of MDC-PS-MDC was confirmed by 1H NMR and UV-visible spectral analysis. The ability of MDC-PS-MDC to act as a photoiniferter for the block copolymerization of methyl acrylate was examined. The polymerization shows a ,living' character at up to 25% conversion and produces well-defined polymers with molecular weights close to those predicted from theory and relatively narrow polydispersities (Mw/Mn , 1.40). CONCLUSION: It is demonstrated that the end groups of polymers obtained by ATRP can be converted into morpholino-4-dithiocarbamate groups which act as photoiniferters. In this way, the desired mechanistic transformation between two controlled free radical polymerization methods can be achieved. Copyright © 2008 Society of Chemical Industry [source] | ||||||||||