Simple and Sterically Open Nickel Catalyst for Ultrahigh Molecular Weight Polyethylene Synthesis,Macromolecules

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Simple and Sterically Open Nickel Catalyst for Ultrahigh Molecular Weight Polyethylene Synthesis
Macromolecules ( IF 5.1 ) Pub Date : 2023-11-22 , DOI: 10.1021/acs.macromol.3c01873
Chuang Song ₁ , Guoliang Mao ₂ , Xiukuan Yao _{1,

3} , Yuxing Zhang _{1,

3} , Wei Gao ₄ , Xiaohui Kang ₅ , Zhongbao Jian _{1,

3}

Affiliation

The suppression of chain transfer reactions to produce high-molecular-weight polymers is a long-standing issue in catalytic polymerization, especially in nickel-mediated olefin polymerization. Installing sterically hindered ligands into nickel catalysts has become a general principle for producing high-molecular-weight polyolefins, which are globally important plastics. Herein, we report a new concept for preparing ultrahigh-molecular-weight polyethylene (UHMWPE) using an extremely simple nickel catalyst. Bis(o-iminobenzosemiquinonato)nickel precatalysts derived from sterically open and redox-active noninnocent o-iminobenzoquinone ligands are easily prepared from commercially available compounds, which are air-stable and highly soluble. Activation at 20- or 50-fold of Et₂AlCl enables the nickel precatalysts to produce UHMWPEs (M_n up to 4,211 kDa) under ambient conditions. In particular, functionalized UHMWPEs are accessible at only 1 bar. Experimental evidence proposes the formation of a six-coordinate octahedral nickel active species and rules out the classical four-coordinate square-planar nickel active species. Density functional theory calculations further indicate the suppression of chain transfer by this unprecedented nickel platform with sterically open ligands.

中文翻译：

用于超高分子量聚乙烯合成的简单且空间开放的镍催化剂

抑制链转移反应生产高分子量聚合物是催化聚合中长期存在的问题，特别是在镍介导的烯烃聚合中。在镍催化剂中安装位阻配体已成为生产高分子量聚烯烃的一般原则，高分子量聚烯烃是全球重要的塑料。在此，我们报告了一种使用极其简单的镍催化剂制备超高分子量聚乙烯（UHMWPE）的新概念。衍生自空间开放且具有氧化还原活性的非无害邻亚氨基苯醌配体的双(邻亚氨基苯并半醌)镍预催化剂可以很容易地由市售化合物制备，其在空气中稳定且高度溶解。在 20 或 50 倍的 Et ₂ AlCl 下活化，使镍预催化剂能够在环境条件下生产 UHMWPE（M _n 高达 4,211 kDa）。特别是，功能化 UHMWPE 只需 1 bar 即可获得。实验证据表明形成了六配位八面体镍活性物质，并排除了经典的四配位方形平面镍活性物质。密度泛函理论计算进一步表明，这种前所未有的具有空间开放配体的镍平台可抑制链转移。

更新日期：2023-11-22

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