Are carbodiimide-quenched polyethylene distributions representative of bulk polymer samples? Analysis of metallocene-catalyzed ethylene polymerization by ESI-MS, MALDI, GPC and NMR

摘要

Polyethylene molecular weight distributions observed by ESI-MS following the quench of a Cp_2ZrCl_2/MAO-catalyzed ethylene polymerization with N,N-dicyclohexylcarbodiimide do not agree with GPC or NMR analysis of methanol-d_1 quenched samples; factors contributing to the discrepant results include high sample polydispersities, polymer insolubility, and the incomplete quench of metal-polymer species. Kinetic analyses of molecular weight distributions obtained by ESI-MS are not representative of the predominate monomer-consuming pathways.