高分子量聚异丁烯制备影响因素分析

Analysis of factors influencing preparation of high molecular weight polyisobutylene

以稀土金属钪正离子配合物为催化剂研究了异丁烯催化聚合反应,通过筛选催化体系、调节单体与催化剂配比、调控反应温度和反应时间等一系列影响因素,对聚异丁烯的分子量及其分布和玻璃化转变温度进行了考察。结果表明,在5种稀土金属钪正离子催化剂中,空间位阻相对较小的限制几何构型钪双烷基催化剂对异丁烯的催化活性最高;异丁烯单体与催化剂的物质的量之比越大,所得聚合物的数均相对分子质量就越高;聚合反应温度越低,聚合物的数均相对分子质量就越高,但当温度低于-60℃时聚合物的数均相对分子质量却大幅减小;聚合反应时间对聚合物相对分子质量变化的影响不大;此外,聚合反应温度和聚合反应时间对聚异丁烯玻璃化转变温度无明显影响。

Isobutylene polymerization was studied with the rare-earth metal scandium cationic complexes as catalysts and molecular weight and its distribution,and glass transition temperature of polyisobutylene were investigated by screening the catalyst system,adjusting the ratio of monomer to catalyst and regulating the reaction temperature and time.The results showed that the constrained-geometry-configuration scandium dialkyl catalyst which had relatively smaller steric hindrance had the highest catalytic activity for isobutylene polymerization among 5 kinds of rare-earth metal scandium cationic catalysts.The higher mole ratio of monomer isobutylene to catalyst was,the higher number-average relative molecular weight the resulting polymer had.The lower reaction temperature was,the higher numbe-average relative molecular weight of the polymer was,however,when the reaction temperature was below-60℃,the number-average relative molecular weight of the polymer decreased significantly.The reaction time had little effect on the change of the number-average relative molecular weight of the polymer.In addition,the polymerization reaction temperature and time had no significant effect on the glass transition temperature of polyisobutylene.