Polyethylene with CO content varying between 0.1-50% CO were synthesized with up to 170x higher activity and 15x larger M<sub>n</sub> than the commercial cationic Pd-bisphosphine complexes. Fine analysis of the polymer microstructure at low CO content suggests that the copolymerization does not follow the classical random Mayo-Lewis model. At low CO content, greater than statistical amount of alternated ketone segments are present in the polymer. We attribute this to a penultimate monomer effect, which may be either kinetic (insertion rate) or thermodynamic (monomer coordination) in origin. We characterize this phenomenon using the Merz-Alfrey-Goldfinger copolymerization equation, a variant of the Mayo-Lewis equation that considers the impact of the 2 previous monomers into the insertion of the 3<sup>rd</sup> one.

Penultimate monomer effect in late-transition metal catalyzed non-alternating ethylene/CO copolymerizations

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ACS Fall 2022

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