Synthesis of ethylene‐1‐hexene copolymers from ethylene stock by tandem action of bis(2‐dodecylsulfanyl‐ethyl) amine‐CrCl3 and Et(Ind)2ZrCl2

Abstract In this work, ethylene‐1‐hexene copolymers were synthesized with a tandem catalysis system that consisted of a new trimerization catalyst bis(2‐dodecylsulfanyl‐ethyl) amine‐CrCl 3 /MAO ( 1 /MAO) and copolymerization catalyst Et(Ind) 2 ZrCl 2 /MAO ( 2 /MAO) at atmosphere pressure. Catalyst 1 trimerized ethylene with high activity and excellent selectivity in the presence of a relatively low amount of MAO. Catalyst 2 incorporated the 1‐hexene content and produced ethylene‐1‐hexene copolymer from an ethylene‐only stock in the same reactor. Adjusting the Cr/Zr ratio and reaction temperature yielded various branching densities and thus melting temperatures. However, broad DSC curves were observed when low temperatures and/or high Cr/Zr ratios were employed due to an accumulation of 1‐hexene component and composition drifting during the copolymerization. It was found that a short pretrimerization period resulted in more homogeneous materials that gave unimodal DSC curves. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3562–3569, 2007