用钼系催化体系催化异戊二烯聚合

Synthesis of polyisoprene catalysized by molybdenum catalyst system

研究了以增溶剂增溶的五氯化钼（简称Mo）为主催化剂、间甲酚取代的三异丁基铝（简称Al）为助催化剂的催化体系引发异戊二烯聚合的规律,考察了以辛醇、磷酸三丁酯和辛醇与磷酸三丁酯混合物作为增溶剂对催化活性的影响,探讨了在以辛醇为增溶剂的催化体系下,Al与Mo摩尔比、Mo与异戊二烯摩尔比及反应时间等对单体转化率和聚合物特性黏数的影响,并测定了聚合物相对分子质量及其分布,表征了其微观结构。结果表明,以辛醇作为增溶剂时催化体系具有较高的活性,聚合物特性黏数为0.6~1.7 dL/g。Al与Mo的摩尔比为8左右时催化剂显示出较高的活性,单体转化率和聚合物特性黏数均呈现先升高后降低的趋势;单体转化率随Mo与异戊二烯摩尔比增加而增大,在3×10-3左右时可达80%以上,聚合物特性黏数则与其成反比关系。随聚合时间延长单体转化率增大,至30 h左右时趋于平稳,聚合物特性黏数在5 h时到达峰值2 dL/g左右后开始下降。聚合物相对分子质量呈单峰分布,3,4-结构和1,2-结构的摩尔分数之和约为72%。

Isoprene was polymerized with main catalyst MoCl5（simplified as Mo） modified by solubilizers and co-catalyst Al（OPhCH3）（i-Bu）2（simplified as Al）.The effects of three different solubilizers of octanol,tributyl phosphate（TBP） and（TBP＋octanol） on catalytic activity and polymer′s intrinsic viscosity were studied,the effects of the Al/Mo（mole ratio）,Al/isoprene（Ip）（mole ratio） and the polymerization time on monomer conversion and polymer′s intrinsic viscosity were investigated in the MoCl3（OC8H17）2-Al（OPhCH3）（i-Bu）2 catalyst system,the relative molecular mass and its distribution were measured,and the microstructure of polymer was characterized.The results showed that the octanol could greatly improve the catalytic activity and the intrinsic viscosity ranged from 0.6 dL/g to 1.7 dL/g.The catalyst exhibited higher activity when Al/Mo was 8,both of the catalytic activity and polymer′s intrinsic viscosity increased at first and then decreased with the increase of Al/Mo.With increasing the Mo/Ip,the Ip conversion raised and achieved 80% at Mo/Ip of 3×10-3,but the intrinsic viscosity had a inverse relationship with Mo/Ip.The conversion increased with polymerization time and got stable after 30 h.However,the intrinsic viscosity reached the maximum of 2 dL/g at 5 h and then decreased.The gel permeation chromatography trace exhibited a relatively narrow unimodal molecular weight distribution.The mole fraction of 1,2-unit and 3,4-unit was about 72%.