二乙烯基苯异构体对聚二烯烃负离子活性链偶联反应的影响

Influence of divinylbenzene isomers on coupling reaction of diene anionic polymerization

采用负离子聚合法,以二烯烃类为单体、环己烷为溶剂、四氢呋喃为调节剂、n-BuLi为引发剂,用二乙烯基苯(DVB)混合物以及单独的对位或间位DVB(p-DVB、m-DVB)异构体为偶联剂合成星形聚合物。考察了偶联剂种类和用量、温度、单臂数均分子量以及单体种类对星形聚合物偶联效率、平均臂数的影响。结果表明,3种偶联剂的偶联效率由高到低依次为m-DVB、DVB混合物、p-DVB,m-DVB的偶联效率能达到92.0%;3种偶联剂得到聚合产物的平均臂数由多到少依次为p-DVB、DVB混合物、m-DVB;当温度为50℃时,聚合产物的偶联效率最高;偶联效率随偶联剂用量的增加而提高;单臂数均分子量的增大会使偶联效率降低;采用3种不同单体进行负离子聚合时,偶联效率按丁二烯、异戊二烯、丁二烯-苯乙烯的顺序依次降低。

The star-shaped polymer was synthe- sized by anionic polymerization with different dienes as monomers, cyclohexane as solvent, tetrahydrofu- ran as regulator, n-BuLi as initiator and divinyl- benzene（DVB） blend or m-DVB, p-DVB as cou- pling agents respectively. The effects of species and amount of coupling agent, coupling temperature, number-average molecular weight per arm as well as different monomers on coupling efficiency and average arm number were studied. The results indicated that the sequence of coupling efficiency for the three kinds of coupling agent from high to low was m-DVB, DVB blend, p-DVB, and that of m-DVB could up to 92. 0% ; the sequence of the average arm number of polymerization products for the three kinds of cou- pling agent from more to less was p-DVB, DVB blend, m-DVB. The coupling efficiency of polymeri- zation products was the highest when the temperature was 50 ℃. The coupling efficiency increased with the increase of coupling agent amount and reduced with the increase of number-average molecular weight per arm. The monomer order of coupling efficiency from high to 10w was butadiene, isoprene, styrene-butadi- ene when anionic polymerization was conducted with the three different monomers.