Efficient functional group introduction into polyolefins by copolymerization of ethylene with allyltrialkylsilane using nonbridged half-titanocenes
Efficient functional group introduction into polyolefins by copolymerization of ethylene with allyltrialkylsilane using nonbridged half-titanocenes
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DOI：
10.1021/ma800031h
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发表时间：
2008-02-26
期刊：
影响因子：
5.5
通讯作者：
Nomura, Kotohiro
中科院分区：
文献类型：
--
作者：
Liu, Jingyu;Nomura, Kotohiro
导言。通过金属催化配位聚合将反应官能团精确、高效地引入到聚烯烃中，以获得理想的性能，如提高熔体抗裂性、涂装性和粘附性，以及与其他材料的兼容性等，引起了人们的极大关注。1通过操纵特定的聚合链转移途径实现了同时控制反应官能团的方法之一。1，2-5通过共聚引入也被认为是另一种有前途的方法，6-9尽管由于催化剂中毒和中心金属与官能化单体的相互作用，乙烯或丙烯与(受保护的)极性单体的直接共聚会遇到困难。6.乙烯与某些烯基硅烷[CH2d CH(CH2)nSiH3]，n)1，2，4，6等的共聚反应。使用(双核)连接的半钛烯已被认为是一条很有前途的路线；8然而，随着共聚单体含量的增加，活性通常会降低(S)。这些硅烷(S)还起到链转移试剂(S)伴生的作用。烯丙基三甲基硅烷(ATMS)与乙烯的共聚也是已知的，3c但催化活性和共聚物中的Mn值都随着ATMS含量的增加而降低。这是因为ATM机也起到链转移试剂的作用，这是因为在插入笨重的ATM机后，β-氢被优先消除。10在本文中，我们提出了用含有阴离子辅助给体配体的半钛烯类化合物(方案1)，通过乙烯与烯丙基三烷基硅烷的共聚，高效地合成了含SiR3(R)Me(IPR)基团的高相对分子质量共聚物。选择了Cp‘TiCl2(O-2，6-iPr2C6H3)[Cp’)C5Me5(1)，tBuC5H4(2)][Cp‘TiCl2(O-2，6-iPr2C6H3)[Cp’]。还选择了11，12Cp‘TiCl2(NdCtBu2)[Cp’)C5Me5(3)，Cp(4)]，特别是因为4对1-己烯13a和降冰片烯的共聚是有效的。14CP*-芳氧基类似物(1)在乙烯与ATMS共聚反应中的催化活性随ATMS初始浓度和/或乙烯压力的增加而增加(1-6次)。所得聚合物为经1H和13C(DEPT)核磁共振谱确证的聚(乙烯-co-ATMS)S，14共聚物具有较高的相对分子质量，分子量分布均匀(MN)(2.23-2.87)×104。MW/mN)2.27-2.79)。通过~1H核磁共振谱积分比估算共聚物中的ATMS含量，14随着ATMS浓度的增加和/或在低乙烯压力下的增加。值得注意的是，ATMS的含量(43.4mol%，ATMS1.05M，RUN 1)与在类似条件下制备的聚(乙烯-1-戊烯)(48.5mol%，1-戊烯1.52M)中的1-戊烯含量比较接近。因此，事实清楚地表明，1在不降低MN值的情况下有效地结合了ATM。这应该是与普通茂金属3c共聚中的独特对比，在该共聚中，由于ATMS插入后有利于β-H的消除，随着ATMS含量的增加，MN值降低。3C在乙烯/1-己烯共聚反应中表现出比1更好的1-己烯掺杂率的叔丁基碳氢化合物(2)在相同的条件下表现出中等的催化活性(运行7-10)。然而，自动取款机与…的合并方面有了显著的改进
Introduction. Precise, efficient introduction of reactive functionality into polyolefins via metal-catalyzed coordination polymerization attracts considerable attention for obtainment of desirable properties, such as increased melt-fracture resistance, paintability, and adhesion and such as compatibility with other materials. 1 One of the approaches to simultaneously control reactive functionalities were achieved by manipulating specific polymerization chain transfer pathways. 1a, 2-5 The introduction by the copolymerization has also been considered as the other promising approaches, 6-9 although the direct copolymerization of ethylene or propylene with (protected) polar monomers would face difficulties because of the catalyst poisoning and interaction of centered metal with functionalized monomers. 6 The copolymerizations of ethylene with certain alkenylsilanes [CH2d CH (CH2) nSiH3], n) 1, 2, 4, 6, etc.] using (dinuclear) linked half-titanocenes have been known as a promising route; 8 however, the activity generally decreased upon increasing the comonomer content (s). 8b These silane (s) also play a role as the chain transfer reagent (s) accompanied. 8b The copolymerization of ethylene with allyltrimethylsilane (ATMS) by certain metallocenes was also known, 3c but both the catalytic activities and the Mn values in the copolymers decreased upon the ATMS contents. This is because that ATMS also play a role as the chain transfer reagent due to the favored β-hydrogen elimination after bulky ATMS insertion. 10 In this paper, we thus present that highly efficient synthesis of high molecular weight copolymers containing SiR3 (R) Me, iPr) group has been achieved by copolymerization of ethylene with allyltrialkylsilanes by half-titanocenes containing anionic ancillary donor ligands (Scheme 1).Results and Discussion. Cp′ TiCl2 (O-2, 6-iPr2C6H3)[Cp′) C5Me5 (1), tBuC5H4 (2)] were chosen, because the complexes demonstrate unique characteristics for some ethylene copolymerizations. 11, 12 Cp′ TiCl2 (NdCtBu2)[Cp′) C5Me5 (3), Cp (4)] were also chosen, especially because 4 were effective for the copolymerization with 1-hexene13a as well as norbornene. 13b The results are summarized in Table 1. 14 The catalytic activity (calculated based on the polymer yield) in the copolymerization of ethylene with ATMS by the Cp*-aryloxo analogue (1) increased upon increasing the initial ATMS concentration and/or ethylene pressure (runs 1-6). The resultant polymers were poly (ethylene-co-ATMS) s identified by both 1H and 13C (dept) NMR spectra, 14 and the copolymers possessed high molecular weights with uniform molecular weight distributions (Mn)(2.23-2.87)× 104. Mw/Mn) 2.27-2.79). The ATMS contents in the copolymer, estimated by integration ratios in the 1H NMR spectra, 14 increased by increasing the ATMS concentration and/or at low ethylene pressure. Note that the ATMS content (43.4 mol%, ATMS 1.05 M, run 1) was relatively close to 1-pentene content in poly (ethylene-co-1-pentene)(48.5 mol%, 1-pentene 1.52 M) prepared under the similar conditions. 15 The fact thus clearly demonstrates that 1 efficiently incorporates ATMS without decrease in the Mn values. This should be a unique contrast to that in the copolymerization by ordinary metallocenes, 3c in which the Mn values decreased upon increasing the ATMS contents due to the favored β-H elimination after ATMS insertion. 3c The tert-BuC5H4 analogue (2) which showed better 1-hexene incorporation than 1 in the ethylene/1-hexene copolymerization16 exhibited moderate catalytic activities under the same conditions (runs 7-10). However, notable improvements in the ATMS incorporation …