Vinyl/Vinylene functionalized highly branched polyethylene waxes obtained using electronically controlled cyclohexyl‐fused pyridinylimine‐nickel precatalysts

Abstract

ABSTRACTA series of 8‐(2,6‐dibenzhydryl‐4‐R‐phenylimino)‐5,6,7‐trihydroquinoline ligands have been prepared in which the nature of 4‐R substitutions vary from electron withdrawing to electron donating. The treatment with NiCl2.6H2O or (DME)NiBr2 afforded the corresponding complexes of nickel chloride (4‐R = Me Ni1, Et Ni2, tBu Ni3, CHPh2 Ni4, Cl Ni5, and F Ni6) and nickel bromide (4‐R = Me Ni7, Et Ni8, tBu Ni9, CHPh2 Ni10, Cl Ni11, and F Ni12). X‐ray diffraction study of complexes Ni3, Ni6, and Ni10, revealed that Ni3.1/2H2O and Ni6.H2O adopted unsymmetrical and symmetrical chloride‐bridged dinuclear structures respectively, while Ni10.H2O is found as mononuclear specie forming distorted‐square planer geometry. In the presence of either diethylaluminum chloride (Et2AlCl) or modified methylaluminoxane (MMAO), all the nickel complexes (Ni1–Ni12) displayed high activities (up to 1.91 × 106 g(PE) mol (Ni)−1h−1. Highly branched polyethylene waxes with low molecular weights (Mw ≤ 2.6 kg/mol) and narrow molecular weights distributions (Mw/Mn ≤ 1.96) incorporated with vinylene and vinyl groups were obtained. The effects of 4‐R substitutions to the nickel chloride and bromide pre‐catalysts and reaction conditions on the catalytic performance and the properties of the resulting polyethylene were the subject of a detail investigation. The positive influences of using electron‐withdrawing 4‐R substitutions and bromides were observed. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018, 56, 1269–1281