Controlled synthesis of sulfonated block copolymers having thermoresponsive property by RAFT polymerization of vinyl sulfonate esters
Controlled synthesis of sulfonated block copolymers having thermoresponsive property by RAFT polymerization of vinyl sulfonate esters
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DOI：
10.1016/j.polymer.2012.06.043
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发表时间：
2012-08
期刊：
影响因子：
4.6
通讯作者：
H. Mori;Yosuke Saito;E. Takahashi;Kazuhiro Nakabayashi;A. Onuma;M. Morishima
中科院分区：
文献类型：
--
作者：
H. Mori;Yosuke Saito;E. Takahashi;Kazuhiro Nakabayashi;A. Onuma;M. Morishima
采用可逆加成-断裂链转移（RAFT）聚合方法，对乙烯基磺酸的保护形态乙烯基磺酸酯衍生物甲基乙烯磺酸（MES）、乙基乙烯磺酸（EES）、2,2,2-三氟乙基乙烯磺酸（TFES）和2,2,2-三氯乙基乙烯磺酸（TCLES）进行了聚合。采用合适的黄药型链转移剂（CTA）对所有单体进行聚合，得到了分子量分布相对较窄、分子量预先确定的聚合物。发现EES和TCLES的RAFT聚合在合适的条件下以受控的方式进行，形成窄多分散产物，分子量由单体/链转移剂比例控制，分子量随转化呈线性增加。在2-丁酮回流过程中，LiBr对聚（EES）乙基的脱保护过程顺利进行，得到水溶性聚乙烯基磺酸锂。用叔丁二氧化钾对聚乙烯基磺酸钾进行脱保护，得到了聚乙烯基磺酸钾。采用聚（EES）宏观cta对n -异丙基丙烯酰胺进行RAFT聚合，然后进行脱保护，合成了含聚（乙烯基磺酸锂）段的热敏嵌段共聚物。研究了嵌段共聚物在水溶液中的热诱导相分离行为和组装结构。
Four vinyl sulfonate ester derivatives, methyl ethenesulfonate (MES), ethyl ethenesulfonate (EES), 2,2,2-trifluoroethyl ethenesulfonate (TFES), and 2,2,2-trichloroethyl ethenesulfonate (TCLES), which are protected forms of vinyl sulfonic acids, were polymerized by reversible addition-fragmentation chain transfer (RAFT) polymerization. Polymers having relatively narrow molecular weight distributions and pre-determined molecular weights were obtained by the polymerization of all monomers using a suitable xanthate-type chain transfer agent (CTA). The RAFT polymerizations of EES and TCLES were found to proceed in controlled fashions under suitable conditions, as confirmed by the formation of narrow polydispersity products, molecular weights controlled by the monomer/chain transfer agent ratio, and linear increases in molecular weight with conversion. Deprotection of the ethyl group of poly(EES) by LiBr in refluxing 2-butanone proceeded smoothly to give water-soluble poly(lithium vinyl sulfonate). Poly(potassium vinyl sulfonate) was also obtained by the deprotection of poly(TCLES) using potassium tert-butoxide. The syntheses of thermoresponsive block copolymers involving poly(lithium vinyl sulfonate) segments were conducted by RAFT polymerization of N-isopropylacrylamide using poly(EES) macro-CTA, followed by deprotection. The thermally-induced phase separation behavior and assembled structures of the block copolymers were also studied in aqueous solution.