Achieving Linearα‑Macro-olefins in Ethylene Polymerization through Precisely Tuned Bis(imino)pyridylcobalt Precatalysts with Steric and Electronic Parameters  

作　　者：Kainat Fatima Tahir Yanping Ma Qaiser Mahmood Geng Ren Areej Khalid Yizhou Wang Song Zou Tongling Liang Wen-Hua Sun 

机构地区：[1]Key Laboratory of Engineering Plastics and Beijing National Laboratory for Molecular Science,Institute of Chemistry,Chinese Academy of Sciences,Beijing 100190,China [2]Chemistry and Chemical Engineering Guangdong Laboratory,Shantou 515031,China [3]CAS Research/Education Center for Excellence in Molecular Sciences and International School,University of Chinese Academy of Sciences,Beijing 100049,China

出　　处：《Precision Chemistry》2024年第12期655-668,共14页精准化学(英文)

基　　金：financially supported by the Chemistry and Chemical Engineering Guangdong Laboratory(2111018 and 2132012);K.F.T.would like to express gratitude towards the ANSO Scholarship Program for their support.

摘　　要：Synthesis of functional polyethylene from ethylene alone is tricky and heavily dependent on both the type and structure of the precatalyst and the choice of cocatalyst used in the polymerization.In the present study,a series of cobalt precatalysts was prepared and investigated for ethylene polymerization under various conditions.By incorporation of strong electron-withdrawing groups(F and NO_(2))and a steric component(benzhydryl)into the parent bis(imino)pyridine ligand,the catalytic performance of these precatalysts was optimized.On activation with MAO or MMAO,these precatalysts with relatively open structure achieved unprecedented ethylene polymerization rates at 60℃(up to 27.6×10^(6)g mol^(−1)h^(−1))and remained effective at temperatures up to 100℃.Chain growth reactions were moderate,resulting in polyethylene with molecular weights up to 61.0 kg/mol and broad bimodal dispersity index.High crystallinity and melt temperature indicated a strictly linear microstructure,as further confirmed by high-temperature^(1)H/^(13)C NMR measurements.Of significant note that chain termination predominantly occurred throughβ-elimination(up to 84.5%),yielding vinyl-terminated long-chain olefins.These functionalα-macro-olefins are valuable as precursors for postfunctionalization,expanding the potential applications of polyethylene across various sectors.

关 键 词：Bis(imino)pyridylcobalt precatalysts ethylene polymerization moderate polymer molecular weight polyethylene linearα-macro-olefins β-elimination reaction 

分 类 号：O62[理学—有机化学]