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研究了[N,O]螯合钒(Ⅲ)催化剂([PhN C(CH3)CH C(Ph)O]VCl2(THF)2(2a),[PhN CHC6H4O]VCl2(THF)2(2b)和[PhN CHC(Ph)CHO]VCl2(THF)2(2c)催化乙烯和丙烯的共聚合行为.聚合得到了不同丙烯插入率(0 mol%~20 mol%)和较窄分布(M w/M n<3.0)的聚合物.借助高温核磁13CNMR和高温GPC对所得聚合物的共单体插入率、序列结构、分子量及分布进行测试.研究表明,助催化剂、再活化剂、聚合温度以及反应时间等条件对聚合活性、聚合物分子量以及共单体插入率有重大影响.通过计算亚甲基序列分布(x i)以及聚合物链中连续亚甲基数均序列长度n0和n2+,证实了上述条件还能够对聚合物微结构起到微调作用.此外,虽然催化剂的共聚合活性相当,而且所得聚合物中共单体插入率也很接近,但是通过比较不同催化剂所获的聚合物的x i,n0和n2+,所得聚合物的序列结构却有明显差别,2a催化体系最不容易发生单体的反向插入,而且链结构中存在更多长的亚甲基序列.通过Fineman-Ross方法计算出单体的竞聚率乘积r E×r P≈1.0,说明共单体的插入不受链末端单体单元种类的影响,使得k11/k12=k21/k22,催化剂2a~2c均能催化乙烯与丙烯共聚合得到理想的无规共聚物.
The effects of the [N, O] chelating vanadium (Ⅲ) catalysts on the catalytic activity of [PhN C (CH 3) CH C (Ph) O] VCl2 (THF) 2 (2a), [PhN CHC6H4O] The copolymerization behavior of ethylene and propylene catalyzed by [PhN CHC (Ph) CHO] VCl2 (THF) 2 (2c) n <3.0), and the results showed that the cocatalyst, reactivator, polymerization temperature and reaction time And other conditions have a significant impact on the polymerization activity, the molecular weight of the polymer and the monomer insertion rate. By calculating the methylene sequence distribution (xi) and the length of continuous methylene number sequence n0 and n2 + in the polymer chain, it was confirmed that the above conditions It is also possible to fine tune the microstructure of the polymer.In addition, although the copolymerization activity of the catalyst is comparable and the monomer insertion rate in the resulting polymer is also very close, by comparing the xi, n0 and n2 +, there is a clear difference in the sequence structure of the obtained polymer. The 2a catalytic system is the least prone to reverse insertion of the monomer, and More long methylene sequences exist in the structure.The monomer reactivity ratio, r E × r P≈1.0, calculated by the Fineman-Ross method shows that the insertion of comonomer is not affected by the chain end monomer unit type , Making k11 / k12 = k21 / k22, catalysts 2a ~ 2c can catalyze the copolymerization of ethylene and propylene to obtain the ideal random copolymer.