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Keywords:

  • carbon dioxide;
  • kinetics (polym.);
  • living radical polymerization (LRP);
  • nitroxide-mediated polymerization;
  • radical polymerization
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Nitroxide-mediated radical polymerization based on TEMPO has been performed for methyl methacrylate under conditions of CO2-expanded monomer at 7 MPa and 90°C. The fraction of propagating radicals lost due to disproportionation with nitroxide, a well-known problem in NMP of methacrylates, decreased in the presence of CO2. This is consistent with deactivation between propagating radical and nitroxide proceeding more rapidly in the lower viscosity induced by CO2. However, the polymerization ceased at relatively low conversions of approximately 19% both with and without CO2, indicating that disproportionation between propagating radical and nitroxide is a major problem also in CO2-expanded MMA.