聚苯乙烯-b-聚硅氧烷-b-聚苯乙烯三嵌段共聚物的合成及表征

采用乙烯基封端的聚 (二甲基硅氧烷 )与溴化氢反应制得末端含有C Br的双官能聚 (二甲基硅氧烷 ) ,以此聚 (二甲基硅氧烷 )大分子为引发剂 ,CuCl为催化剂 ,4 ,4′ 二 (5 壬基 ) 2 ,2′ 联吡啶为配体 ,通过原子转移自由基聚合法 ,制得分子量和结构可控的聚苯乙烯 b 聚硅氧烷 b 聚苯乙烯 (PSt b PDMS b PSt)共聚物 .

SYNTHESIS AND CHARACTERIZATION OF PSt-b-PDMS-b-PSt TRIBLOCK COPOLYMERS

The atom transfer radical polymerization (ATRP) of styrene from poly(dimethylsiloxane)(PDMS) macroinitiators was described. Commercially available difunctional PDMS containing vinylsilyl terminal species was reacted with hydrogen bromide resulting in the PDMS macroinitiators containing alkyl bromide end groups. The ATRP of styrene was then conducted at 130℃ using the PDMS containing alkyl bromide end groups as initiators,cuprous chloride (CuCl) as catalyst and 4,4′ di(5 nonyl) 2,2′ bipydine (dNbpy) as ligand to produce block copolymers.Using this technique,copolymers consisting of a PDMS center block and polystyrene terminal blocks were synthesized.Analysis of the copolymers by gel permeation chromatography (GPC) showed that the molecular weight increased linearly with the conversion of monomer,and the polydispersity decreased with the progress of polymerization.The molecular weight increased from 6400 to 17890 and the polydispersity ranged from 1 38～1 26,demonstrating that the reaction was controlled and the polystyrene blocks had low polydispersities typical of radical polymerization by an atom transfer process.IR and 1H NMR analyses of the PDMS macroinitiators and the copolymers showed that the PDMS macroinitiators containing alkyl bromide end groups were formed,and the copolymers consisted of polystyrene and PDMS.A DSC analysis confirmed the results. T g in 100℃ and 120℃ were attributed to polystyrene blocks and PDMS blocks respectively,indicating the copolymer consisted of polystyrene and PDMS,the triblock copolymers polystyrene b polysiloxane b polystyrene (PSt b PDMS b PSt) were formed.All these results also demonstrated the effectiveness of ATRP to synthesize a variety of inorganic/organic polymer hybrids.