Cyclopolymerization Behavior of Bis(dimethylvinylsilyl)methane
Cyclopolymerization Behavior of Bis(dimethylvinylsilyl)methane
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双(二甲基乙烯基甲硅烷基)甲烷的环聚行为
DOI：
10.1295/polymj.30.790
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发表时间：
1998
期刊：
影响因子：
--
通讯作者：
M. Takaki
中科院分区：
文献类型：
--
作者：
Y. Suga;J. Oku;M. Takaki
研究了双（二甲基乙烯基硅基）甲烷（BVSM）在己烷中的阴离子环化聚合，得到了以六元环为重复环单元的聚合物。在不存在N，N，N′，N′-四甲基乙二胺（TMEDA）的情况下，BVSM与正丁基锂（n-BuLi）聚合的低聚合物产率归因于交联反应和增长末端在−10°C下的缔合以及氢化锂在40°C下从增长末端的消除。用n-BuLi/TMEDA进行聚合时，虽然不经常，但伴随着由两个硅原子插入的亚甲基质子的提取，其形成非活性阴离子。这种抽象是由六元环中的增长端引起的。在0.5 mol l-1的高单体浓度下，即使在TMEDA存在下，交联反应也不可忽略。作为引发剂，n-，s-，t-BuLi进行了检查，只有s-BuLi/TMEDA被发现引起质子从插入两个硅原子的亚甲基提取。用BuLi的亲核性和位阻效应解释了引发剂的作用。评价了三种胺对聚合反应的影响。其中TMEDA最适合于BVSM的环化聚合。
Anionic cyclopolymerization of bis(dimethylvinylsilyl)methane (BVSM) in hexane, which affords a polymer having six-membered rings as repeating cyclic units, is investigated. Low polymer yields in the polymerization of BVSM with n-butyllithium (n-BuLi) in the absence of N,N,N′,N′-tetramethylethylenediamine (TMEDA) are attributed to cross-linking reactions and association of the propagating ends at −10°C and elimination of lithium hydride from the propagating end at 40°C. Polymerization with n-BuLi/TMEDA is accompanied, though not frequently, by the abstraction of the methylene proton interposed by two silicon atoms, which forms an inactive anion. This abstraction is caused by the propagating end in the six-membered ring. At high monomer concentration, 0.5 mol l−1, cross-linking reaction is not negligible even in the presence of TMEDA. As initiators, n-, s-, t-BuLi are examined, and only s-BuLi/TMEDA is found to cause the proton abstraction from the methylene interposed by two silicon atoms. The effects of the initiator are explained by the nucleophilicity of BuLi and the steric hindrance in the abstraction. The effects of three amines on the polymerization are evaluated. TMEDA is the most suitable for the cyclopolymerization of BVSM among them.