异戊二烯阳离子聚合物链结构EI

用ＡｌＣｌ３、ＴｉＣｌ４、ＢＦ３ＯＥｔ２和ＣＦ３ＳＯ３Ｈ在不同溶剂中引发异戊二烯阳离子聚合反应，结果表明，反应条件对聚合物结构有很大影响。ＡｌＣｌ３引发的聚合反应生成不溶性交联产物和可溶聚合物两部分，后者又包含了环状和线型链（主要是１，４和３，４结构单元）两种主要链节，由ＣＦ３ＳＯ３Ｈ引发的聚合反应只生成可溶性聚合物，聚合物链全部由环状结构组成。ＴｉＣｌ４和ＢＦ３ＯＥｔ２引发的聚合反应受反应介质影响较大，在正己烷中有交联产物生成，可溶性聚合物链包含环状结构和线型链，当用极性的二氯甲烷或用甲苯作反应介质时，交联反应得到完全的抑制，且聚合物链的环状结构分数显著增加。

CHAIN STRUCTURE OF ISOPRENE CATIONIC POLYMER

The cationic polymerizations of isoprene initiated by AlCl 3, TiCl 4, BF 3OEt 2 and CF 3SO 3H were carried out in various solvent. The polymer structrue is mainly determined by reaction conditions. The polymerization initiated by AlCl 3 produces both insoluble (crosslinked) and soluble polymers, and the latter contains cyclic and linear (1,4 and 3,4 units) segments. In contrast, the CF 3SO 3H induced polymerization generates only soluble polymer consisting of completely cyclized structure. On the other hand, TiCl 4 and BF 3OEt 2 based polymerizations are heavily influenced by reaction medium. The polymerization in n hexane produces insoluble crosslinked products and soluble polymers made of cyclic and linear structures, and only soluble polymers of highly cyclized structure are formed in methylene chlorides and in toluene.