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研究了(NdCl_3+FeCl_3)r phen-HA_2(i-Bu)_2体系聚合丁二烯。通过固定催化剂中稀土(或铁)含量而改变铁(或稀土)含量的方法,证明了此聚合体系中存在两种不同的对丁二烯聚合有很高催化活性的活性中心,即能使丁二烯聚合成高顺式产物的Nd活性中心,和使丁二烯聚合成几乎是等二元(cis-1,4和1,2构型),聚合物的Fe活性中心。所得产物具确两个T_g和产物分级后可得到cis-1,4为92%和1,2含量为54%的级分,为以上结论也提供了旁证。两种活性中心的催化活性受铝比、聚合温度等的影响,稀土活性体对聚合条件比过渡金属活性体有较宽的适应范围。对其聚合机理进行了探讨,认为两种活性中心分别按各自的聚合机理进行聚合反应。 相似文献
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Nd(OR)3-nCln-AlEt3催化体系对丁二烯的聚合 II.聚合物微观结构和催化剂诱导效应指数的关系 总被引:1,自引:0,他引:1
With a new series of binary catalyst Nd(OR)3-nCln-AlEt3 prepared in our laboratory, the effect to catalyst composition on the microstructure of polybutadiene was studied in detail. A linear relationship is found between the variation of the microstructure of the polymer obtained and the iductive effect index (I) which reprepresents the magnitude of the displacement of paired valence electrons on transition metal-halogen bond (MT-X) of the catalyst. This linear relationship also holds in dealing with the data published in the literature. 相似文献