Efficient incorporation of vinylcylohexane in ethylene/vinylcyclohexane copolymerization catalyzed by nonbridged half-titanocenes
Efficient incorporation of vinylcylohexane in ethylene/vinylcyclohexane copolymerization catalyzed by nonbridged half-titanocenes
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DOI：
10.1021/ma051439k
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发表时间：
2005-10-04
期刊：
影响因子：
5.5
通讯作者：
Itagaki, K
中科院分区：
文献类型：
--
作者：
Nomura, K;Itagaki, K
在过渡金属催化的配位聚合领域中，最具吸引力的课题之一是使用新设计的聚合催化剂来发展新型聚烯烃，因为传统催化剂从未观察到的独特性能可以被高度期待，特别是通过化学官能团和/或取代基的精确放置。虽然乙烯与r -烯烃共聚制备的共聚物，如1-丁烯、1-己烯和1-辛烯被广泛用于LLDPE，然而，乙烯（或丙烯）与乙烯环己烷（VCH）共聚的例子迄今为止还很有限。2-4例如，在过量VCH摩尔比下，使用Cp2ZrCl2、cp2zrme2 -甲基铝氧烷（MAO）催化剂（在25或70℃）进行乙烯/VCH共聚时，VCH含量较低（0.6-1.7 mol%），所得共聚物Mn值较低（（5.0-6.1）× 103）。2此外，rac-Me2Si [2- mebenz [e]-Ind] ZrCl2-MAO催化剂制备的乙烯/丙烯/VCH三元共聚物中的VCH含量较低（0.6-0.9 mol%），尽管这些共聚物是在相对较高的VCH浓度下进行的，与乙烯和丙烯相比。此外，在Cp2TiCl2、Cp2HfCl2、Cp2ZrCl2或[Me2Si-(Cp) 2] ZrCl2-MAO催化剂的存在下，VCH的二聚化反应具有完全选择性。4相比之下，一个众所周知的成功例子是VCH的等配位聚合，使用含有乙酰氨基酸配体的“暴露”半锆新世作为催化剂前驱体，5尽管催化活性可能不够充分。我们最近研究了1,1 -二取代r -烯烃，2-甲基-1-戊烯（2M1P），在原始的非桥接半茂钛Cp* TiCl2 (o - 2,6 - ipr2c6h3)(1, Cp*) C5Me5)-MAO催化剂下，即使在适度的2M1P/乙烯进料摩尔比下，也能有效地与乙烯共聚，得到高分子量、均匀组成的共聚物。由于普通过渡金属配合物（尤其是茂金属）的共聚效率不高，因此这些结果鼓励我们探索乙烯与其他传统上难以结合的单体（尤其是普通茂金属）共聚的可能性。因此，在本报告中，我们希望提出的第一个例子，VCH已有效地与乙烯共聚使用非桥接半茂钛。7
One of the most attractive subjects in the field of transition-metal-catalyzed coordination polymerization is the evolution of new polyolefins using newly designed polymerization catalysts because unique properties that have never been observed by the conventional catalysts can be highly expected, especially by the precise placement of chemical functionality and/or substituent. 1 Although copolymers prepared by the copolymerization of ethylene with R-olefin such as 1-butene, 1-hexene, and 1-octene are widely used as LLDPE, however, examples for the copolymerization of ethylene (or propylene) with vinylcyclohexane (VCH) have been limited so far. 2-4 For example, VCH contents in the ethylene/VCH copolymerization using Cp2ZrCl2, Cp2ZrMe2-methylaluminoxane (MAO) catalyst (at 25 or 70 C) under excess VCH molar ratios were low (0.6-1.7 mol%), and the resultant copolymer possessed low Mn values ((5.0-6.1)× 103). 2 Moreover, the VCH contents in the ethylene/propylene/VCH terpolymers prepared by rac-Me2Si [2-MeBenz [e]-Ind] ZrCl2-MAO catalyst were low (0.6-0.9 mol%), although these copolymerizations were performed under relatively high VCH concentrations compared to ethylene and propylene. 3 In addition, an efficient VCH dimerization took place with exclusive selectivity in the presence of Cp2TiCl2, Cp2HfCl2, Cp2ZrCl2, or [Me2Si-(Cp) 2] ZrCl2-MAO catalysts. 4 In contrast, one wellknown successful example is the isospecific coordination polymerization of VCH using an “exposed” half-zirconocene containing an acetamidinate ligand as the catalyst precursor, 5 although the catalytic activity may not be fully sufficient.We recently presented that the 1, 1-disubstituted R-olefin, 2-methyl-1-pentene (2M1P), has been efficiently copolymerized with ethylene by our original nonbridged half-titanocene Cp* TiCl2 (O-2, 6-iPr2C6H3)(1, Cp*) C5Me5)-MAO catalyst, even under moderate 2M1P/ethylene feed molar ratios, affording high molecular weight copolymers with uniform composition. 6 Since this copolymerization did not proceed efficiently by ordinary transition-metal complexes especially by metallocenes, these results thus encouraged us to explore the possibility of copolymerization of ethylene with the other monomers that have traditionally been difficult to be incorporated, especially by ordinary metallocenes. In this report, we thus wish to present the first example that VCH has been efficiently copolymerized with ethylene by using nonbridged halftitanocenes. 7