用混合配体稀土催化剂制备窄分子量分布高顺式聚丁二烯

Preparation of polybutadiene with narrow molecular weight distribution and high cis-1,4-unit stereoregularity using mixed ligand supported neodymium based catalyst

以混合配体磷酸酯钕(简称Nd)/氢化二异丁基铝(简称Al)/二甲基二氯硅烷(简称Cl)催化体系催化丁二烯聚合,该催化剂在n(Al)/n(Nd)为10时即有高活性,所得聚合物具有窄分子量分布(分子量分布指数小于2.0)和高顺式-1,4-结构立构规整性(摩尔分数99%左右)。考察了n(Al)/n(Nd)、n(Cl)/n(Nd)、Cl种类、陈化时间及聚合温度和时间等对聚合的影响,结果表明,催化活性随着n(Al)/n(Nd)和n(Cl)/n(Nd)的增大以及陈化时间的延长而提高,同时聚合物的数均分子量普遍下降,分子量分布变宽;聚合物的顺式-1,4-结构含量基本不受反应条件的影响,均为摩尔分数99%左右,表明所形成的活性中心具有较高的稳定性。

Nd （ P204 ）2EHA （ simplified as Nd）/ HAl （i-Bu） 2 （ simplified as Al）/Me2 SiCl2 （ simplified as Cl） catalyst was examined for 1,3-butadiene poly- merization. The catalyst exhibited high activity at n（Al）/n（Nd） 10, and the resulting polymers had narrow molecular weight distribution （polydispersity index less than 2. 0） and high cis-1,4-unit stereoreg- ularity （mole fraction about 99% ）. The effects of n（Al）/n（Nd） and n（Cl）/n（Nd）, Cl type, aging time, and polymerization time and temperature on the polymerization were investigated. The results showedthat the catalytic activity increased with the increase of n（Al）/n（Nd） and n（Cl）/n（Nd） as well as the extension of aging time of catalyst, while the number-average molecular weight of the resulting polymer de- creased and the molecular weight distribution broa- dened. Regardless of reaction conditions, the mole fraction of cis-1,4-unit stayed around 99%, indica- ting the high stability of the generated active species.