二乙二醇单乙醚基钡-三异丁基铝-正丁基锂引发体系合成高反式1,4-聚丁二烯

采用二乙二醇单乙醚基钡-三异丁基铝-正丁基锂(BaDEGEE-TIBA-n-BuLi)三组分阴离子引发体系合成了不同反式1,4-聚丁二烯含量(质量分数最高可达92.1%)的高反式1,4-聚丁二烯(HTPB),HTPB的相对分子质量呈单峰分布,相对分子质量分布指数为1.35左右。考察了催化剂组分的配比(n(Ba)∶n(Li)和n(Al)∶n(Li))、聚合温度对HTPB微观结构的影响。实验结果表明,随n(Ba)∶n(Li)的增大,HTPB的含量增加,当n(Ba)∶n(Li)>0.30时,单体转化率显著下降;随n(Al)∶n(Li)的增大,HTPB的含量增加,当n(Al)∶n(Li)>1.00时,单体转化率明显下降;随聚合温度的降低,HTPB的含量略有增加。确定了合成HTPB的最佳工艺参数(n(Ba)∶n(Li)=0.20~0.40、n(Al)∶n(Li)=0.25~1.00、聚合温度60~80℃,探讨了BaDEGEE-TIBA-n-BuLi三组分阴离子引发体系合成HTPB的反应机理。

Synthesis of High trans-1,4-Polybutadiene with Barium Salt of Di(Ethylene Glycol) Ethylether-Triisobutyl Aluminum-n-Butyllithium Initiation System

High trans-1,4-polybutadiene(HTPB) with different trans-1,4-polybutadiene contents(highest mass fraction 92.1%) was synthesized by using anionic initiation system of n-butyllithium(n-BuLi),barium salt of di(ethylene glycol) ethylether(BaDEGEE) and triisobutyl aluminum(TIBA).The effects of mole compositions in the initiation system(n(Ba) ∶n(Li) and n(Al) ∶n(Li)) and polymerization temperature on HTPB microstructure were studied in detail.HTPB content in the products increased with the increase of ratios of n(Ba) ∶n(Li) and n(Al) ∶n(Li),but the conversion of monomer decreased rapidly when n(Ba) ∶n(Li)>0.30 and n(Al) ∶n(Li)>1.00.The optimum reaction conditions were concluded as n(Ba) ∶n(Li) 0.20-0.40,n(Al) ∶n(Li) 0.25-1.00,and polymerization temperature 60-80 ℃.Preliminary polymerization mechanism was proposed.