The role of excess nitroxide in the SG1 (<i>N</i>‐<i>tert</i>‐butyl‐<i>N</i>‐[1‐diethylphosphono‐(2,2‐dimethylpropyl)] nitroxide)‐mediated polymerization of methyl methacrylate

Abstract

Abstract Methyl methacrylate (MMA) polymerizations have been conducted in the presence of large excesses of N ‐ tert ‐butyl‐ N ‐[1‐diethylphosphono‐(2,2‐dimethylpropyl) nitroxide] (SG1) at 110°C. It is demonstrated that such a protocol does not improve control/livingness in the nitroxide mediated polymerization (NMP) of this monomer, instead substantial levels of disproportionation between the nitroxide and propagating radical (PMMA • ) results. The extent of the disproportionation reaction increased with the SG1 concentration, eventually becoming the sole end forming event. Significant disproportionation between SG1 and PMMA • was also observed at substantially lower temperatures (45°C) in the presence of large excesses of SG1. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 2194–2203, 2007