Ultimately, the composition and block lengths of the Dow "Chain-Shuttling" process for catalytic synthesis of olefin block copolymers are determined by the rates of propagation and transalkylation with chain transfer reagents. Are there practical methods for studying these kinetics? The time-evolution of polymer molecular weight distributions are accessible by gel permeation chromatography and rich in kinetic information. Chromophore-labeling reagents and UV detection enable detailed information to be extracted from a single gel permeation chromatogram. Specifically, active site counts, the rates and reversibility of chain-transfer between Hf-polymeryls and diethyl zinc, and the extent to which catalysis conforms to living behavior are revealed by quantitative gel permeation chromatography with pyrene labels. These studies suggest a practical route to elucidating the kinetics of chain-shuttling catalysis under conditions used commercially.

Chromophore-labeled gel permeation chromatography applied to the study of hafnium pyridylamide catalyzed polymerization of 1-octene in the presence of diethyl zinc

251st National Meeting (2016)

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