N-alkyl-2-pyridinemethanimine mediated atom transfer radical polymerisation of styrene:: the transition from heterogeneous to homogeneous catalysis

The polymerisation of styrene was studied using Cu((I))/Cu((II))-based atom transfer radical polymerisation catalysts in conjunction with a variety of N-alkyl-2-pyridinemethanimines as complex ligands. Increasing the length of alkyl chain on the ligand from propyl to octyl resulted in a catalyst complex with improved solubility in xylene, and enabled the production of polymers of narrower molecular weight distribution. The molecular weight distribution was further narrowed by changing the solvent to a more polar system, diglyme, in which case polymers with (M-w/M-n) = 1.1-1.2 were produced, and the catalyst system generated shows possibility of being amenable to kinetic study. The narrow molecular weight distribution is consistent with a soluble catalyst promoting rapid exchange of a halogenated chain end into an active form. Crown copyright (C) 1999 Published by Elsevier Science Ltd. All rights reserved.