Now showing 1 - 4 of 4
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    Amphiphilic polystyrene-graft-poly(N,N-dimethylamino-2-ethyl methacrylate) hydrogels synthesized via room temperature ATRP: Studies on swelling behaviour and dye sorption
    (01-05-2008)
    Vivek, A. V.
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    The swelling behavior and dye sorption of polystyrene-graft-poly(N,N-dimethylamino-2-ethyl methacrylate (pseudo-hydrogel) have been investigated. The grafting of N,N-dimethylamino-2-ethyl methacrylate (DMAEMA) onto the molecular surface of polystyrene through the "grafting from" approach is performed at room temperature ATRP, resulting in pseudo-hydrogels. The swelling behavior of these hydrogel at different pH and by varying the chain length of DMAEMA was carried out. The effect of altering pH and the temperature towards the swelling is also studied. The dimensional change, caused by the stimulus behavior of the hydrogel, at varying pH is also investigated. The stimulus responsive graft copolymer was studied for the adsorption of common dyes like green torquoise blue, magenta red, rhodamine, crystal violet, congo red, methylene blue, under static condition at room temperature. The graft copolymers are observed to possess a high affinity for basic, acid, and reactive dyes. © 2008 Elsevier Ltd. All rights reserved.
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    Polymer brushes via ATRP: Role of activator and deactivator in the surface-initiated ATRP of styrene on planar substrates
    (14-03-2002)
    Jeyaprakash, J. D.
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    Samuel, S.
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    Rühe, Jürgen
    The role of activator and deactivator species in the surface-initiated atom-transfer radical polymerization of styrene using CuBr/CuBr2/pentamethyldiethylenetriamine as a model system is described. The influence of initially added deactivator with respect to the degree of controlling the layer growth and thickness is studied. Variation of the activator concentration results in changes of the kinetics as well as brush thicknesses consistent with the well-known rate laws of ATRP.
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    Synthesis of silver nanoparticles using a novel graft copolymer and enhanced particle stability via a "polymer brush effect"
    (02-05-2008)
    Vivek, A. V.
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    Pradipta, S. M.
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    Polymer-encapsulated silver nanoparticles were synthesized and sterically stabilized by a new core-shell type system consisting of poly(S-alt-MA)-graft- PMMA copolymer that acts as a scaffold for the synthesis of size confined nanoparticles. The graft copolymer is synthesized via ambient temperature ATRP using the CuBr/PMDETA catalytic system at ambient temperature. The graft copolymer is hypothesized to function as a scaffold with the anhydride part interacting strongly with the silver ions, while the PMMA graft functions as a polymer brush that stabilizes the dispersion and prevents the particle aggregation due to a 'polymer brush effect'. UV absorption and TEM studies confirm that the synthesized silver composite particles have a core-shell structure. © 2008 WILEY-VCH Verlag GmbH & Co. KGaA.
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    Publication
    Grafting of methacrylates and styrene on to polystyrene backbone via a "grafting from" ATRP process at ambient temperature
    (01-09-2007)
    Vivek, A. V.
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    Well defined graft copolymers are prepared by "grafting from" atom transfer radical polymerization (ATRP) at room temperature (30°C). The experiments were aimed at grafting methacrylates and styrene at latent initiating sites of polystyrene. For this purpose, the benzylic hydrogen in polystyrene was subjected to allylic bromination with Af-bromosuccinimide and azobisisobutrylnitirle to generate tertiary bromide ATRP initiating sites (Br-C-PS). The use of Br-C-PS with lesser mol % of bromide initiating groups results in better control and successful graft copolymerization. This was used to synthesize a series of new graft copolymers such as PS-g-PBnMA, PS-g-PBMA, PS-g-GMA, and PS-g-(PMMA-b-PtBA) catalyzed by CuBr/PMDETA system, in bulk, at room temperature. The polymers are characterized by GPC, NMR, FTIR, TEM, and TGA. Graft copolymerization followed by block polymerization enabled the synthesis of highly branched polymer brush, in which the grafting density can be adjusted by appropriate choice of bromide concentration in the polystyrene. © 2007 Wiley Periodicals, Inc.