活性负离子丁苯共聚的偶联反应

Coupling reaction of living anionic copolymerization of butadiene and styrene

以正丁基锂为引发剂、丁二烯和苯乙烯为单体、自制不对称醚为结构调节剂、二乙烯基苯(DVB)为偶联剂,采用负离子共聚法合成丁苯共聚物,考察了偶联时间和偶联温度对偶联反应的影响,并与常规偶联剂四氯化锡进行了对比。对不同偶联时间下偶联产物的支化结构进行了表征分析。结果表明,随着偶联时间的延长,丁苯共聚物的分子量分布加宽,偶联效率增大,偶联10 min时的偶联效率可超过50%,最高达58.2%;偶联产物的重均臂数增大,可达9臂,均优于采用四氯化锡者。当偶联温度为40~70℃时,偶联温度对偶联效率的影响较小。未偶联聚合物溶液的特性黏数与聚合物相对分子质量的关系曲线接近呈线性,符合Mark-Houwink方程;随着偶联时间的延长,支化曲线偏离线性,偶联产物的支化程度增强,支化比率逐渐下降。

Poly （butadiene-co-styrene） was syn- thesized by anionic copolymerization, using n-BuLi as initiator, butadiene and styrene as monomer, self- made asymmetric ether as modifier, divinyl benzene （DVB） as coupling agent, effects of coupling time and coupling temperature on coupling reaction with DVB were investigated compared with those using with SnCl4 as coupling agent, and the branching structures of coupled polymers at different coupling times were characterized. The results showed that with increasing coupling time, the polydispersity in- dex of the coupled polymers broaden, coupling effi- ciency increased and reached over 50% （maximum 58. 2%） when coupling time was 10 min, andbranching arms increased and went up to 9. The polydispersity index, coupling efficiency and branching arms of coupled polymer with DVB were all superior to those with SnCl4. Coupling efficiency changed a little in the range of 40 -70 ℃. The plot of logarithm of intrinsic viscosity vs logarithm of weight-average molecular weight of uncoupled poly- mers closed to linear and accorded with Mark-Hou- wink equation. With increasing coupling time, those curves deviated from the linearity, the branching de- gree increased and branching ratio decreased.