title: GPC and ESI-MS analysis of labeled poly(1-hexene): rapid determination of initiated site counts during catalytic alkene polymerization reactions.
abstract: Accurate active-site counts are necessary for the establishment of olefin polymerization kinetics, yet current techniques are often tedious and limited in sensitivity. Herein, we describe the development of a novel method for determining the fraction of initiated catalyst using standard gel-permeation chromatography (GPC). The first insertion of monomer into the chromophore-bearing zirconocene 1 generates a single equivalent of a labeled polymer chain. The polymer-bound label can be quantified as a function of polymer molecular weight using a GPC with a UV detector; simultaneous RI detection allows both the extent of monomer conversion and the molecular-weight distribution to also be established. We estimate that monomer to catalyst ratios of as high as 10,000:1 can be measured using this technique.
authors.affiliation: Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin 53706, USA.
authors.forename: Beth M
authors.initials: BM
authors.lastname: Moscato
authors.forename: Bolin
authors.initials: B
authors.lastname: Zhu
authors.forename: Clark R
authors.initials: CR
authors.lastname: Landis