Acid Dissolution of Copper Oxides as a Method for the Activation of Cu(0) Wire Catalyst for SET-LRP

Here we reported the acid dissolution of copper oxides as a methodology for the activation of Cu(0) wire used as catalyst in single-electron transfer living radical polymerization (SET-LRP). In this method, the oxide layer on the surface of commercial Cu(0) wire was removed by dissolution in a concentrated acid such as nitric acid, glacial acetic acid and hydrochloric acid. SET-LRP of methyl acrylate catalyzed with Cu(0) wire activated with acids showed comparable k(p)(app) value to that of the nonactivated Cu(0) wire-catalyzed counterpart. However, the polymerizations catalyzed with activated Cu(0) wire proceeded with no initial induction period, predictable molecular weight evolution with conversion, and narrow molecular weight distribution. Regardless of the activation method, the chain end functionality of alpha,omega-di(bromo) poly(methyl acrylate) (PMA) prepared from SET-LRP initiated with a bifunctional initiator is extremely high, maintaining a 100% chain end functionality at similar to 90% monomer conversion. The degree of bimolecular termination increased as the polymerization exceeds 92% conversion. However, for binfunctional initiators this small amount of bimolecular termination at high conversion maintains a perfectly bifunctional polymer. Structural analysis by MALDI-TOF upon thioetherification of alpha,omega-di(bromo) PMA with thiophenol and 4-fluorothiophenol confirmed the high fidelity of bromide chain ends. (C) 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 49: 4241-4252,2011