摘要
以正丁基锂(n-BuLi)为引发剂,环己烷为溶剂,在40～70℃下进行异戊二烯(Ip)阴离子聚合的研究。考察了极性调节剂四氢呋喃(THF),结构调节剂P-配合物对异戊二烯聚合特点及聚异戊二烯(PI)结构的影响。分别采用GPC、~1H-NMR以及~7Li-NMR对P-配合物、引发剂以及聚合物的结构进行了分析。结果表明,当聚合温度远高于聚异戊二烯的玻璃化温度时,转化率-时间曲线仅出现加速拐点而不会出现转化率停滞平台。用先前提出的缔合引发剂引发聚合并崩解,以及通过控制离子对之间距离可实现对聚异戊二烯结构进行控制新见解,解释了以往在阴离子聚合中难以解释的问题。当把P-配合物加入到以n-BuLi为引发剂的聚合体系中,由于锂被P-配合物和n-BuLi共享,从而强化了两者之间的结合。而P-配合物较大的空间体积封堵了部分的离子对通道,使得聚异戊二烯中3,4结构链节显著增加至50%以上。
Polyisoprene （PI） was synthesized by anionic polymerization using n-BuLi as initiator, cyclohexane as solvent at 40--70℃. The effects of THF and P-Complex on the polymerization and PI structure were investigated. The P-Complex, initiator and PI were characterized by GPC,1H-NMR and 7Li-NMR. Results showed that there only existed an acceleratory point of inflexion in the conversion-time curve instead of the stationary-conversion platform when the polymerization temperature was much higher than PI^s glass transition temperature. Same queries in the anionic polymerization theory which could hardly be understood before being explained with the new hypothesis proposed recently. The aggregated initiator can initiate the anionic polymerization and confine the aggregated supramolecules, but they will disintegrate thoroughly during the following polymerization. Furthermore, the polymer structure can be controlled by changing the distance between ion pairs. When P-Complex was added in the polymerization system initiated by n-BuLi, the reaction was intensified because the lithium was shared by both P-Complex since and n-BuLk Therefore, the content of poly-3, 4 isoprene increased to more than 50% in the polymerization since the interspace between the ion pairs was blocked by P-Complex with big bulk.
出处
《华东理工大学学报（自然科学版）》
CAS
CSCD
北大核心
2012年第4期429-435,共7页
Journal of East China University of Science and Technology
基金
国家自然科学基金(5093302)
上海市重点学科建设项目(B502)
关键词
异戊二烯
阴离子聚合
结构
控制
isoprene
anionic polymerization
structure
control
