Tandem catalysis offers a promising 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-hexene copolymers from ethylene stock as the sole monomer. The reported catalytic systems employ the tandem action between an ethylene trimerization catalyst, (eta(5)-C5H4CMe2C6H5)TiCl3 (1)/modified methylaluminoxane (MMAO), and a copolymerization metallocene catalyst, [(eta(5-)C(5)Me(4))SiMe2((BuN)-Bu-t)]TiCl2 (2)/MMAO or rac-Me2Si(2-MeBenz[e]Ind)(2)ZrCl2 (3)/MMAO. During the reaction, 1/MMAO in situ generates 1-hexene with high activity and high selectivity, and simultaneously 2/MMAO or 3/MMAO copolymerizes ethylene with the produced 1-hexene to generate butyl-branched polyethylene. We have demonstrated that, by the simple manipulation of the catalyst molar ratio and polymerization conditions, a series of branched polyethylenes with melting temperatures of 60-128 degreesC, crystallinities of 5.4-53%, and hexene percentages of 0.3-14.2 can be efficiently produced. (C) 2004 Wiley Periodicals, Inc.