Stereoselective Feature in Anionic Ring-Opening Polymerization of 2-(1-Naphthyl)-2-phenyl-5,5-dimethyl-1-oxa-2,5-disilacyclopentane and Influence of Tacticity on the Thermal Property of Polymers
Stereoselective Feature in Anionic Ring-Opening Polymerization of 2-(1-Naphthyl)-2-phenyl-5,5-dimethyl-1-oxa-2,5-disilacyclopentane and Influence of Tacticity on the Thermal Property of Polymers
复制标题
2-(1-萘基)-2-苯基-5,5-二甲基-1-氧杂-2,5-二硅杂环戊烷阴离子开环聚合的立体选择性特征及立构规整对聚合物热性能的影响
DOI：
10.1021/ma991861z
复制
发表时间：
2000
期刊：
影响因子：
5.5
通讯作者：
Y. Kawakami
中科院分区：
文献类型：
--
作者：
Yuning Li;Y. Kawakami
用13c核磁共振分析了消旋体2-（1-萘基）-2-苯基-5,5-二甲基-1-氧-2,5-二硅环戊烷阴离子开环聚合的立体选择性。讨论了引发剂、聚合温度和溶剂对聚合物弹性的影响。结果表明，以PhLi为引发剂的聚合反应，在-20℃条件下，可以得到具有丰富同时性的聚合物（r/m = 65/35）。由于由传播链端、单体和反正离子组成的非对映体中间体的稳定性或反应性不同，初步考虑了立体调节作用。由光活性单体制备的等规聚合物与由外消旋单体制备的富同规聚合物的Tg相似，但前者的热稳定性明显优于后者。
The stereoselective feature in the anionic ring-opening polymerization of racemic 2-(1-naphthyl)-2-phenyl-5,5-dimethyl-1-oxa-2,5-disilacyclopentane was investigated by 13 C NMR analysis of the dyad sequence of the resulting polymer. The influences of initiators, polymerization temperature, and solvents on the tacticity of the polymer were discussed. It was found that the polymerization using PhLi as an initiator could afford a polymer rich in syndiotacticity (r/m = 65/35 at -20 °C). The stereoregulation was tentatively considered due to the different stability or reactivity of the diastereomeric intermediates comprised of the propagating chain end, monomer, and countercation. The isotactic polymer prepared from the optically active monomer showed a similar Tg to that of the syndiotactically rich polymer prepared from the racemic monomer, but the former exhibited significantly better thermal stability than the latter.