Synthesis of polyethylene thermoplastic elastomer by using robust α-diimine Ni(II) catalysts with abundant tBu substituents
Synthesis of polyethylene thermoplastic elastomer by using robust α-diimine Ni(II) catalysts with abundant tBu substituents
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DOI：
10.1002/pol.20210017
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发表时间：
2021-02-25
影响因子：
3.4
通讯作者：
Dai, Shengyu
中科院分区：
文献类型：
--
作者：
Li, Shuaikang;Zhao, Yihua;Dai, Shengyu
利用高温聚合条件和烷烃溶剂，通过α -二亚胺-镍催化乙烯聚合合成聚乙烯热塑性弹性体在工业生产中是非常理想的。在这篇贡献中，我们构建了一系列具有丰富的Bu-t取代基的高度立体要求的α -二亚胺Ni（II）催化剂。这些镍催化剂在高温下（高达90℃）对己烷中的乙烯聚合进行了测试，并证明在高达90℃的温度下具有热鲁棒性。通常，这些镍催化剂可以生成高支化（约70-80/1000℃）的聚乙烯，具有很高的分子量（M-n高达55.79 x 10(4) g/mol），所得聚乙烯表现出热塑性弹性体的特征，具有优异的弹性恢复（SR高达84%）。与一些类似的α -二亚胺Ni（II）催化剂进行比较，结果表明，轴向远端Bu-t取代基的存在不仅有利于催化剂在烷烃中的溶解，而且提高了所得聚乙烯的弹性恢复值。
The synthesis of polyethylene thermoplastic elastomers via alpha-diimine-nickel-catalyzed ethylene polymerization using polymerization conditions of elevated temperatures and alkane solvents is highly desirable in industrial production. In this contribution, we constructed a series of highly sterically demanding alpha-diimine Ni(II) catalysts with abundant Bu-t substituents for this purpose. These nickel catalysts were examined for ethylene polymerization in hexanes at elevated temperatures (up to 90 degrees C) and proved to be thermally robust at temperatures as high as 90 degrees C. Generally, these nickel catalysts can generate highly branched (ca. 70-80/1000 degrees C) polyethylenes with very high molecular weight (M-n up to 55.79 x 10(4) g/mol) and the resultant polyethylenes displayed characteristics of thermoplastic elastomers with excellent elastic recovery (SR up to 84%). Compared with some similar alpha-diimine Ni(II) catalysts, it is shown that the presence of axial remote Bu-t substituents not only facilitates the dissolution of the catalyst in alkanes, but also improves the elastic recovery value of the obtained polyethylene.