~(13)C-NMR研究稀土催化聚戊二烯-1,3的末端链结构

用~(13)C-NMR方法研究了稀土催化聚戊二烯-1,3的末端链结构及聚合温度对聚合物微观结构的影响。结果指出,聚合物的末端活性增长链是以头-尾或尾-头加成生成的anti-和syn-四种 π-烯丙基。聚合温度降低时,顺-1,4含量增加,这可解释为由于 anti-和 syn-异构化的作用。同时解释了反-1,2结构形成的过程。

STUDY ON TERMINAL CHAIN STRUCTURE OF POLYPENTADIENE PREPARED FROM RARE EARTH CATALYST WITH C-13 NMR

The terminal structures of poly-l,3-pemadiene chains obtained by rare earth catalyst have been investigated with C-13 NMR method and effect of polymerization temperature on micros-tructure of the polymer has been studied. According to the experimental results it was supposed that the terminal active growing chain of the polymer would be anti- and syn-π-allyl formed in the "head-tail" and "tail-head" addition of the monomer. Therefore, there are four configurations of π-allylic terminal in the stereoregular polymerization of 1,3-pentadiene. When the polymerization temperature was reduced, the content of cis-poly-1,3-pentadiene increased. It is explained by the isomerization between the anti- and syn-pπ-allyl. The process forming trans-1,2 unit in the polymer was described.