endo-双环戊二烯阳离子聚合及聚合物链结构

Cationic Polymerization of endo-Dicyclopentadiene and Microstructure of the Polymers

使用不同阳离子引发剂和引发体系在甲苯、正己烷和二氯甲烷中引发endo-双环戊二烯(DCPD)聚合,得到了低分子量的DCPD聚合物(PDCPD),采用IR和~1H NMR对PDCPD链结构进行了表征.结果表明,DCPD分子的降冰片烯(NB)双键和环戊烯(CP)双键均参与了聚合反应并根据不同链增长机理产生四种链结构单元:通过NB双键的链增长反应可生成直接加成结构单元Ⅱ和重排结构单元Ⅱ,通过CP双键的链增长反应生成直接加成结构单元Ⅲ和跨环重排单元Ⅳ.正己烷和甲苯中所合成的PDCPD包含全部四种结构单元,并呈现,Ⅰ【Ⅱ和Ⅲ【Ⅳ的规律,而采用二氯甲烷作反应介质所合成的PDCPD仅含重排结构单元Ⅱ和Ⅳ.

Cationic polymerizations of endo - dicyclopentadiene (DCPD) were initiated by different initiating systems in toluene, n - hexane and methylene chloride and the polymers (PDCPD) of low molecular weight were obtained. The microstructure of PDCPD was determined by IR and *H NMR methods. The results show that both norbornenic (NB) and cyclopentenic (CP) double bonds are involved in the polymerization. The propagation on the NB double bondgenerates structural unit I by direct addition and unit II by carbocation rearrangement, respectively. Similarly, the propagation on the CP double bond produces structural unit III by direct addition and unit IV by transannular rearrangement, respectively. The chain of PDCPD synthesized in toluene and n - hexane consists of all four structural units and shows the content order I < II and III < IV, while the chain of polymers prepared in methylene chloride is composed of only two rearranged segments II and IV.