Ni(naph)_2-Al(i-Bu)_3-BF_3·OEt_2-ROH催化体系引发丁二烯聚合中水的作用

Influence of Water on Butadiene Polymerization with Ni (naph)_2-AI (i-Bu)_3-BF_3·OEt_2-ROH Catalyst System

研究了以加氢汽油为溶剂的Ni(naph)_2-Al(i-Bu)_3-BF_3·OEt_2-ROH(简称Ni-Al-B-ROH)催化体系引发丁二烯聚合中,水对聚合活性、微观结构、分子量及其分布的影响规律。实验结果表明,当H_2O/Al<0.33(摩尔比,下同)时,聚合活性随着H_2O/Al比增加而提高;H_2O/Al>0.33后,活性平缓下降,其活性峰值约在H_2O/Al=1/3处;当H_2O/Al=1.5时,催化剂完全失活。当Al/B≥1.0时,聚合物分子量随H_2O/Al比增加略有降低,而后变化平缓,trans-1,4/1,2值变小。但cis-1,4含量不变;随Al/B比增大,分子量线性增加,cis-1,4含量明显增加,trans-1,4/1,2值亦明显减小。在本实验条件下,本催化体系几乎无诱导期。

The polymerization of butadiene in hydrogenated gasoline with Ni (naph)_2-Al(i-Bu)_3-BF_3·OEt_2-ROH catalyst system (where R was linear alkyl group)has been investigated. The detailed studies concentrated on the influences of water on the catalytic activity,the microstructure,the molecular weight and its distribution of the polymer. The experimental results showed that the activity increased remarkably with increase of H_2O/Al mole ratio when H_2O/Al was smaller than 0. 33; the change in the activity tended to slow down when H_2O/Al was greater than 0.33. The activity reached a maximum when H_2O/Al increased to 1/3; when H_2O/Al=1. 5, the activity disapeared. Under the condition of Al/B≥1. 0, as H_2O/Al increased, the molecular weight decreased slightly at first, and then the change of the molecular weight tended to slow down, trans-1,4/1,2 value decreased, but cis-1,4 content changed little. With the increase of Al/B ratio the molecular weight increased linearly, cis-1,4 content increased obviously, and trans-1,4/1,2 value decreased greatly. For this system no induction period was observed under the conditions of this experiment.