Structural chemistry and polymerization activity of copper(I) atom transfer radical polymerization catalysts

The use of structurally characterized copper(I) halide bipyridine complexes in styrene ATRP was examined. It was found that a preformed copper(I) bromide complex with dNEObipy of a 1-to-1 ligand to metal stoichiometry, complex-1, was an effective ATRP catalyst for styrene. Molecular weights evolved with conversion in correlation with the relation, DPn = ([M]o - [M]t) / [initiator]o, and the molecular weight distributions after early polymerization conversions remained low, Mw / Mn = 1.04 to 1.06. Added equivalents of free ligand had very little effect upon either the rate of polymerization or the evolution of molecular weights and molecular weight distributions with conversion. Thus, the kinetically optimum ratio of ligand to metal in these polymerizations was 1-to-1.