P-配合物对异戊二烯负离子聚合中3,4结构影响的研究  

Effect of P-complex on 3,4-Structure of Polyisoprene during Anionic Polymerization

作　　者：李天一[1] 陈波[1] 吴尚翰[1] 束民泽 管涌[1] 郑安呐[1] 

机构地区：[1]华东理工大学材料科学与工程学院上海市先进聚合物材料重点实验室超细材料制备与应用教育部重点实验室,上海200237

出　　处：《高分子学报》2014年第9期1204-1211,共8页Acta Polymerica Sinica

基　　金：国家自然科学基金(基金号50933002);国家重点基础研究发展计划(863计划;项目号2012AA040306);上海市重点学科和重点实验室项目(项目号B502;08DZ2230500)资助项目

摘　　要：在四氢呋喃(THF)与环己烷的混合溶剂中,以正丁基锂(n-BuLi)为引发剂,选取P配合物(Pcomplex)为调节剂,实现了异戊二烯(Ip)的负离子可控聚合,得到了高3,4结构率的聚异戊二烯(PI)(78.76%).采用1H-NMR对聚合物的结构进行了表征和分析.证实了由n-BuLi引发的负离子聚合,单体插入离子对之间参与聚合的速率及聚合结构取决于正负离子对之间的尺度,该尺度与单体插入所需求的尺度相当时,插入聚合速率最快,最容易.对Ip而言,单体插入离子对之间聚合形成3,4-PI时需求的尺度最小.Pcomplex由于其同时含有与Li+同源的锂原子以及空间位阻较大的苯、萘、蒽等基团,可通过改变活性种正负离子对之间的通道尺度,有效地促进3,4聚合反应,抑制1,2和1,4聚合反应,因而有效提高了PI 3,4结构率,使得Ip的聚合变得可控.相反,升高温度可以增加正负离子对之间的尺度,使得3,4聚合结构含量减少,1,4聚合结构含量增加,但温度越高,反式含量越多.Polyisoprene （PI） with high 3,4-structure content （78.76%） was synthesized by anionic polymerization using n-BuLi as the initiator and tetrahydrofuran/cyclohexane as the mixed solvent. P-complex was also introduced into the system to improve the controllability of the polymerization. The molecular structure was characterized by 1H-NMR. Results indicated that when n-BuLl was used as the initiator,the polymerization rate and molecular structure of the products were determined by the channel space between the ion pairs. When the channel space was compatible with the requirement for inserting of the monomers, the polymerization rate would be maximum. The channel space required for 3,4 polymerization of isoprene is the smallest. P-complex with same lithium atom as initiator and large steric hindrance can adjust the channel space between the cation- anion pairs. P-complex can partially block the channel space. Therefore, the introduction of a small dosage of P- complex could not only accelerate 3,4 polymerization,inhibit 1,2 and 1,4 polymerization effectively, but also increase the content of 3,4-PI. On the contrary, with the increase of the temperature, the channel space expanded,resulting in the decrease of 3,4-PI content and the increase of l, 4-PI content. The higher the temperature was,the more content of trans-1,4-PI would be.

关 键 词：负离子聚合 异戊二烯 聚合机理 微观结构 

分 类 号：O631.1[理学—高分子化学]