title: Synthesis, characterization, and heterobimetallic cooperation in a titanium-chromium catalyst for highly branched polyethylenes.
abstract: A heterobimetallic catalyst, {Ti--Cr}, consisting of a constrained-geometry titanium olefin polymerization center (CGC(Et)Ti) covalently linked to a chromium bis(thioether)amine ethylene trimerization center (SNSCr) was synthesized and fully characterized. In ethylene homopolymerizations it affords linear low-density polyethylene with molecular weights as high as 460 kg·mol(-1) and exclusively n-butyl branches in conversion-insensitive densities of ~18 branches/1000 carbon atoms, which are ~17 and ~3 times (conversion-dependent), respectively, those achieved by tandem mononuclear CGC(Et)Ti and SNSCr catalysts under identical reaction conditions.
authors.affiliation: Department of Chemistry, Northwestern University, Evanston, Illinois 60208-3113, USA.
authors.forename: Shaofeng
authors.initials: S
authors.lastname: Liu
authors.forename: Alessandro
authors.initials: A
authors.lastname: Motta
authors.forename: Massimiliano
authors.initials: M
authors.lastname: Delferro
authors.forename: Tobin J
authors.initials: TJ
authors.lastname: Marks