A Ruthenium-Catalyzed Hydrosilane-Induced Polymerization of 3-Alkyl-3-hydroxymethyloxetane Derivatives: Facile Access to Functionalized Polyoxetanes by Virtue of Organosilyl Groups
作者:Nari-aki Harada、Jushiro Yasuhara、Yukihiro Motoyama、Osamu Fujimura、Tetsuro Tsuji、Takeshi Takahashi、Yoshiaki Takahashi、Hideo Nagashima
DOI:10.1246/bcsj.20100155
日期:2011.1.15
Ring-opening polymerization of 3-alkyl-3-alkoxymethyl- or 3-alkyl-3-siloxymethyloxetanes is catalyzed by a triruthenium cluster, [Ru3μ3-(η2,η3,η5-C12H8)}(CO)7], in the presence of trialkylsilanes, providing a novel accessible method for functionalized polyoxetanes of Mn = 103–105. Oxetanes having alkoxy-, fluoroalkoxy-, triethyleneglycoloxy-, and trialkylsiloxy functions undergo polymerization and copolymerization. Consumption rates of two monomers in the copolymerization of 3-benzyloxymethyl- and 3-trimethylsiloxymethyl-3-alkyloxetanes are almost the same, indicating formation of random copolymers. The organosilyl group in the polymer and copolymers with siloxymethyl side chains is converted to CH2OH or CH2OCOR groups by hydrolysis or silyl/acyl exchange. These protocols give the way to access polymers or copolymers bearing OH and OCOR side chains. A ruthenium-catalyzed reaction of 3-ethyl-3-hydroxymethyloxetane with trialkylsilanes results in dehydrogenative silylation to give 3-ethyl-3-siloxymethyloxetane, which is followed by ring-opening polymerization. Combination of tandem dehydrogenative silylation/ring-opening polymerization/the silyl/acyl exchange realizes one-pot synthesis of polymers with CH2OCOR side chains from 3-ethyl-3-hydroxymethyloxetane. DSC analyses of the formed polymers provided Tg and Tm data, which are a good example showing that the polymer properties are controlled by appropriate selection of functional groups at the side chain.
三价铑簇[Ru3μ3-(η2,η3,η5-C12H8)}(CO)7]可以在三烷基硅烷的存在下催化3-烷基-3-烷氧甲基或3-烷基-3-硅氧甲基环状醚的环开聚合反应,提供了一种新型的制备功能化聚醚(Mn=103–105)的方法。3-烷氧基、3-氟烷氧基、3-三乙二醇氧基和3-三烷基硅氧基醚基环醚可以进行聚合和共聚反应。消耗速率:在3-苄氧甲基和3-三甲基硅氧甲基-3-烷氧基环醚共聚反应中两种单体的消耗速率几乎相同,表明形成了无规共聚物。在具有硅氧甲基侧链的聚合物和共聚物中的有机硅基团可以被转换成CH2OH或CH2OCOR基团,通过水解或硅/酰交换反应。这些反应方法提供了一种合成带OH或OCOR侧链的聚合物或共聚物的方法。由铑催化的3-乙基-3-羟甲基环醚与三烷基硅烷的反应得到3-乙基-3-硅氧甲基环醚,再进行环开聚合反应。通过脱氢硅烷化/环开聚合/硅/酰交换的串联反应,可以实现从3-乙基-3-羟甲基环醚的一锅法合成带CH2OCOR侧链的聚合物。通过DSC分析得到的玻璃化转变温度和熔点数据说明只要合理地选择好侧链上的功能基团,就可以精确地控制聚合物材料的其他性质。