化学
聚合
位阻效应
催化作用
链式转移
循环伏安法
四氢噻吩
聚乙烯
乙烯
高分子化学
光化学
有机化学
自由基聚合
电化学
聚合物
物理化学
电极
作者
Fei Lin,Maria Voccia,Lukas Odenwald,Inigo Göttker‐Schnetmann,Laura Falivene,Lucia Caporaso,Stefan Mecking
摘要
Recent breakthroughs in the generation of polar-functionalized and more sustainable degradable polyethylenes have been enabled by advanced phosphinephenolato Ni(II) catalysts. A key has been to overcome this type of catalysts' propensity for extensive chain transfer to enable formation of high-molecular-weight polyethylene chains. We elucidate the mechanistic origin of this paradigm shift by a combined experimental and theoretical study. Single-crystal X-ray structural analysis and cyclic voltammetry of a set of six different catalysts with variable electronics and sterics, combined with extensive pressure reactor polymerization studies, suggest that an attractive Ni–aryl interaction of a P-[2-(aryl)phenyl] is responsible for the suppression of chain transfer. This differs from the established picture of steric shielding found for other prominent late transition metal catalysts. Extensive density functional theory studies identify the relevant pathways of chain growth and chain transfer and show how this attractive interaction suppresses chain transfer.
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