Preparation of ethylene/1-octene copolymers from ethylene stock with tandem catalytic system

摘要

Tandem catalysis offers a novel synthetic route to the production of linear low-density polyethylene. This article reports the use of homogeneous tandem catalytic systems for the synthesis of ethylene/1-octene copolymers from ethylene stock as the sole monomer. The reported catalytic systems involving a highly selective, bis(diphenylphosphino)cyclohexylamine/Cr(acac)(3)/methyl-aluminoxane (MAO) catalytic systems for the synthesis of 1-hexene and 1-octene, and a copolymerization metallocene catalyst, rac-Et(Ind)(2)ZrCl2/MAO for the synthesis of ethylene/1-octene copolymer. Analysis by means of DSC, GPC, and C-13-NMR suggests that copolymers of 1-hexene and ethylene and copolymers of 1-octene and ethylene are produced with significant selectivity towards 1-hexene and I-octene as comonomers incorporated into the polymer backbone respectively. We have demonstrated that, by the simple manipulation of the catalyst molar ratio and polymerization conditions, a series of branched poly-ethylenes with melting temperatures of 101.1-134.1 degrees C and density of 0.922-0.950 g cm(-3) can be efficiently produced. (c) 2007 Wiley Periodicals, Inc.