Synthesis of block copolymers by nitroxyl‐controlled radical polymerization

Abstract

The homopolymerization of methyl methacrylate (MMA) in the presence of 2,2,6,6-tetramethyl-l-piperidinyloxy (TEMPO) is described and compared to the TEMPO-mediated polymerization of styrene. Furthermore, the formation of block copolymers between MMA and styrene from polystyrene chains with TEMPO fragments as end groups is examined. The degree ofblock formation is estimated by GPC analyses. ESRexperiments are performed on the polystyrene chains to study the scission behavior of the TEMPO fragments.

Styrene-vinylferrocene random and block copolymers by TEMPO-mediated radical polymerization

“…on conversion can be seen for all polymerizations; (b) the actually obtained molecular weight is lower than the theoretical molecular weight. With increasing fraction of vinylferrocene this difference increases; (c) the maximum conversion decreases with increasing fraction of Vfc; (d) polydispersity increases with conversion, except for the homopolymerization of styrene; (e) the polydispersity increases with increasing fraction of Vfc, as also observed for copolymerization of other comonomers such as MMA [8][9][10] or acrylonitrile (AN) 6,7) with styrene in TEMPO-mediated polymerizations.…”

“…Various systems have been used, the most common at present being the 2,2,6,6-tetramethyl-1-piperidinyl-1-oxy (TEMPO) 1,2) radical as well as the atom-transfer polymerization technique (ATRP) [3][4][5] . TEMPO has been successfully employed to copolymerize styrene with a variety of monomers, such as acrylonitrile 6,7) , butyl-and methyl methacrylates [8][9][10] , N-cyclohexylmaleimide 11) , N-vinylcarbazole 12) , styrene derivatives 13) and vinylpyridine 14) to obtain random copolymers with narrow polydispersity. Yet it appears that controlled polymerization of monomers other than styrene and styrene derivatives with TEMPO is not feasible.…”

Synthesis, characterization, and glass transition temperature of poly(styrene‐b‐butyl methacrylate) block copolymers by stable free radical polymerization

“…6 This idea has special interest on the synthesis of block copolymers, because the control of morphology in block copolymers has became important in the design of new physical properties through a structure-property relationship. 7,8 The synthesis of styrene-b-methyl methacrylate, p(S-b-MMA), 9 styrene-b-2-dimethylamino ethyl methacrylate, p(S-b-DAMA), 10 styrene-bstyrene-co-butyl methacrylate, p(S-b-S-BMA), 11 and styrene-b-butyl methacrylate, p(S-b-BMA) 12 have been reported. In all the cases polystyrene-TEMPO end capped has been used as the macroinitiator.…”

Síntese de copolímeros em bloco com propriedades líquido cristalinas

“…Os copolímeros em bloco de monômeros ordinários obtidos via radicais livres mediados por nitróxidos estáveis têm sido anunciados na literatura desde 1994 [39][40][41][42][43][44][45][46][47][48][49][50] . A obtenção de um copolímero em bloco LC contendo um segmento amorfo e um segmento LC empregando essa técnica de polimerização foi um trabalho pioneiro do IMA.…”

“…A potencialidade de síntese de copolímeros em bloco LC empregando o mecanismo de polimerização via radicais livres por transferência atômica catalisada por cobre foi também investigada [33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49][50][51] . Essa técnica começou a ser mundialmente explorada para obtenção de copolímeros em bloco não-LC, a partir de 1995, na polimerização de monômeros estirênicos e acrílicos com bom controle estrutural.…”