Copper-Mediated Atom Transfer Radical Polymerization of 1,3-Dienes

Abstract

While controlled radical polymerizations (CRPs) have made dramatic progress over the last two decades, the atom transfer radical polymerization (ATRP) of the industrially significant dienes (e.g., butadiene and isoprene) still lags considerably behind that of other conventional monomers. Indeed, diene polymerizations are plagued by many drawbacks including low monomer boiling point, low rate of polymerization and Diels Alder dimerizations. However, as revealed by comprehensive kinetic studies of the effect of the complex interplay of all reaction variables (initiator, catalyst, ligand, solvent, temperature, ATRP procedure, reagent ratios, etc.) on the conversion dependence of Mn, PDI, halide chain end functionality (CEF) and rate, the ATRP-specific, dominant side reactions are the ligand induced quaternization and elimination sequence of the very labile polydiene-Cl/Br allyl halide chain end. Nonetheless, a rational selection of the reaction parameters, i.e., R-Br/CuBr or R-Br/CuBr2initiator/catalyst pairs, low polarity solvents, low nucleophilicity and basicity ligands or reducing agents, and of green, catalytic vs. stoichiometric ATRP procedures at 110 C, still enables the successful synthesis of well-defined polybutadiene and polyisoprene with controlled molecular weight, narrow polydispersity and high CEF, suitable for the preparation of complex macromolecular assemblies such as star or block copolymers

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oai:opencommons.uconn.edu:dissertations-6715Last time updated on 4/18/2020

This paper was published in OpenCommons at University of Connecticut.

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