Facile, efficient functionalization of polyethylene via regioselective copolymerization of ethylene with cyclic dienes
Facile, efficient functionalization of polyethylene via regioselective copolymerization of ethylene with cyclic dienes
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DOI：
10.1002/pola.23942
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发表时间：
2010-04
期刊：
影响因子：
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通讯作者：
Miao Hong;L. Pan;W. Ye;Dongpo Song;Yue-sheng Li
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文献类型：
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作者：
Miao Hong;L. Pan;W. Ye;Dongpo Song;Yue-sheng Li
研究了双(β-氨基酮)钛配合物[PHN=C(R-2)CHC(R-1)O](2)TiCl2(1a：R-1=CF3，R-2=CH3；1b：R-1=t-Bu，R-2=CF3；1c：R-1=Ph，R-2=CF3)催化乙烯与环状双烯[双环戊二烯(DCPD)和2，5-降冰片二烯(NBD)]的共聚反应。在改性的甲基铝氧烷存在下，这些配合物在乙烯与DCPD或NBD的共聚反应中表现出很高的催化活性，得到了高分子量的单峰分布的共聚物。H-1和C-13-核磁共振谱表明，乙烯/DCPD在催化剂作用下的共聚反应是通过降冰片烯环链进行的。催化剂1a和1c有生成交替共聚物的趋势。更值得注意的是，在配体上含有大量取代基的催化剂1b和1c在没有交联剂的情况下促进了乙烯/NBD的共聚，提供了含有环内双键的共聚物。在催化剂1c上，NBD的掺杂率高达27.2%。此外，通过竞聚率、二联体单体序列和平均序列长度的测量，进一步证实了共聚物的微观结构。在温和的条件下，乙烯/DCPD或乙烯/NBD共聚物的环内双键可以完全转化为环氧、胺、硅烷和羟基等极性基团。通过环氧化物的开环反应，首次为羟化聚乙烯的合成提供了方便。(C)2010年威利期刊公司J Polym Sci Part A：Polym Chem 48：1764-1772,2010
The copolymerizations of ethylene with cyclic dienes [dicyclopentadiene (DCPD) and 2,5-norbornadiene (NBD(] using bis(beta-enaminoketonato)titanium complexes [PhN = C(R-2)CHC(R-1)O](2)TiCl2 (1a: R-1 = CF3, R-2 = CH3; 1b: R-1 = t-Bu, R-2 = CF3; 1c: R-1 = Ph, R-2 = CF3) have been investigated. In the presence of modified methylaluminoxane, these complexes exhibited high catalytic activities in the copolymerization of ethylene with DCPD or NBD, affording high molecular weight copolymers with unimodal molecular weight distributions. H-1 and C-13-NMR spectra reveal ethylene/DCPD copolymerizations by catalysts la c proceeds through the enchainment of norbornene ring. Catalysts la and 1c showed a tendency to afford alternating copolymers. More noticeably, catalysts 1b and 1c bearing bulky substituents on the ligands promote ethylene/NBD copolymerization without crosslinking, affording the copolymer containing intracyclic double bonds. The NBD incorporation as high as 27.2 mol % has been achieved by catalyst 1c. Moreover, the microstructures of the copolymers were further confirmed by the measurement of reactivity ratios and dyad monomer sequences as well as mean sequence lengths. The intracyclic double bonds of ethylene/DCPD or ethylene/NBD copolymers can be fully converted into polar groups such as epoxy, amine, silane, and hydroxyl groups under mild conditions. Convenient synthesis of hydroxylated polyethylene can be provided for the first time through the ring opening reaction of epoxide. (C) 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1764-1772, 2010