Development of catalyst-transfer condensation polymerization. Synthesis of π-conjugated polymers with controlled molecular weight and low polydispersity

Abstract

We describe the development of chain-growth condensation polymerization for the synthesis of well-defined π-conjugated polymers via a new polymerization mechanism, catalysttransfer polymerization. We first studied the condensation polymerization of Grignard-type hexylthiophene monomer with a Ni catalyst as a part of our research on chain-growth condensation polymerization, and found that this polymerization also proceededin a chain-growth polymerization manner. However, the polymerization mechanism involving the Ni catalyst was different from that of previous chain-growth condensation polymerizations based on substituent effects; the Ni catalyst catalyzed the coupling reaction of the monomer with the polymer, followed by the transfer of Ni(0) to the terminal C - Br bond of the elongated molecule. This catalysttransfer condensation polymerization is generally applicable for thesynthesis of polythiophene with an etheric side chain and poly(p-pheneylene), as well as for the synthesis of polyfluorene via the Pd-catalyzed Suzuki-Miyaura coupling reaction. © 2007 Wiley Periodicals. Inc.