稳定自由基存在下嵌段共聚物的合成及表征

SYNTHESIS AND CHARACTERIZATION OF BLOCK COPOLYMERS BY STABLE FREE-RADICAL POLYMERIZATION

合成了一系列不同分子量 ,分子链末端带有稳定自由基 (2 ,2 ,6 ,6 -四甲基 - 1-哌啶氧化物 ,TEMPO)的聚苯乙烯大分子引发剂 ,分别引发甲基丙烯酸丁酯 (BMA)、甲基丙烯酸乙酯 (EMA)、甲基丙烯酸甲酯(MMA)、甲基丙烯酸辛酯 (OMA)、醋酸乙烯酯 (VAc)、二甲基丙烯酰胺 (DMA)、丙烯酸二甲胺基乙酯(DAEA)等 7种极性单体形成两嵌段共聚物。聚苯乙烯 -聚甲基丙烯酸酯嵌段共聚物的分子量可控 ,分子量分布较窄 ,单体转化率较高。醋酸乙烯酯和丙烯酸二甲胺基乙酯在相同条件下的嵌段共聚难以达到高转化率。嵌段共聚物经 GPC和 1H-

Controlled polystyrenes with different molecular weight were synthesized starting from benzoyl peroxide and TEMPO (2,2,6,6 tetramethylpiperidinyl l oxy). The polystyrene homopolymers served as macroinitiators for the block copolymerizations of disparate vinyl monomer butyl methacrylate(BMA), ethyl methacrylate(EMA), methylmethacrylate(MMA), octyl methacrylate(OMA), vinyl acetate(VAc), N,N dimethylacrylamide(DMA), and 2 (dimethylamino)ethyl acrylate(DAEA). Polystyrene polymethacrylate diblock copolymers with well defined structures as well as controlled and narrow molar mass distribution were obtained from the lower mass polystyrene macroinitiator. Contrary to methacrylates, VAc and DAEA were reluctant in the polymerization initiated by polystyrene macroinitiator. Block copolymer formation was confirmed by 1H NMR and GPC measurements. The high field methyl resonances of the TEMPO moiety show some upfield or downfield shifts for attachment to the copolymer moiety when compared to attachment to the styryl moiety.