连锁聚合机理与单体结构和活性种匹配关系的讨论

Discussing About Matching of Mechanism of Chain Polymerization with Monomer Structure and Reactive Species

在连锁聚合中,聚合机理与单体结构和活性种有关,明确选择单体的标准。分析乙烯基单体取代基吸电子、供电子诱导效应和共轭效应与单体阴离子聚合、阳离子聚合和自由基聚合相关性:氯乙烯只能自由基聚合,而异丁烯仅能阳离子聚合;单体具有吸电子效应的基团,容易进行阴离子聚合;单体具有供电子效应的基团易阳离子聚合;单体具有共轭效应的基团,可以进行三种聚合。归纳用Q值、σ值、pKa和聚合热半定量考察单体活性的知识体系,剖析影响选择单体各因素的交叉作用这一难点;理解单体与引发剂的匹配进行连锁聚合。

The mechanism of chain polymerization may be understood easily by monomer structure and reactive species, which is cleanly the criteria of the choosing monomers. For vinyl monomer, induction effect of electron withdrawing substituent, electron supplying substituent and conjugation effect have the correlation of anionic polymerization, cationic polymerization and radical polymerization. Radical polymerization of vinyl chloride can be in contrast to cationic polymerization of isobutylene, while the anionic polymerization of monomer with electron withdrawing substituent can be in contrast to cationic polymerization of monomer with electron supplying substituent. Monomer with conjugation effect substituent might be easily polymerized by the above three kinds of method. Monomer reactive can be semi-quantitatively characterized by Q value, a value, pKa and polymerization heat, which is summarized, therefore monomers are easily chosen by solving the crossing influence of factors. During chain polymerization monomer has to match initiator.