title: Design of thermally stable amine-imine nickel catalyst precursors for living polymerization of ethylene: effect of ligand substituents on catalytic behavior and polymer properties.
abstract: Nickel complexes bearing amine-imine ligands with various backbone substituents were synthesized and employed as ethylene polymerization catalysts on activation with Et2 AlCl. The substituent on the backbone carbon atom of the amine moiety is decisive for the living nature of ethylene polymerization. A bulky amine-imine nickel precursor with a tert-butyl group on the carbon atom of the amine group can polymerize ethylene in a living fashion at an elevated temperature of 65 °C, which is the highest temperature of living polymerization of ethylene with late transition-metal catalysts. The wide applicable temperature range for living polymerization and sensitivity of the branch structure of the polyethylene to temperature enable precise synthesis of di- and triblock polyethylenes featuring different branched segments by sequential tuning of the polymerization temperature.
authors: DSAPM Lab, PCFM Lab, Institute of Polymer Science, School of Chemistry and Chemical Engineering, Sun Yat-Sen University, Guangzhou 510275 (P.R. China), Fax: (+86) 20-84114033.
authors: Haibin
authors: H
authors: Hu
authors: Lei
authors: L
authors: Zhang
authors: Haiyang
authors: H
authors: Gao
authors: Fangming
authors: F
authors: Zhu
authors: Qing
authors: Q
authors: Wu
keywords: N ligands; nickel; polymerization; polymers; substituent effects