In Situ NMR Monitoring of Living Radical Polymerization Reaction Kinetics and Catalyst Evolution

摘要

Copper mediated living radical polymerization has been investigated by online 'H NMR spectroscopy. The reaction was followed by in-situ H NMR spectroscopy that results in accurate information on the polymerization. An example is given whereby living radical polymerizations is studied in the presence of ethylene glycol groups in monomer, initiator and solvent. Methyl ether poly(ethylene glycol) macroinitiators of various sizes are shown to initiate living polymerization of methacrylates, but exhibit poor initiator efficiency. The living radical polymerization of methyl ether poiy(ethylene glycol) methacrylate macromonomers is demonstrated and the unusual high rate of polymerization observed is compared to that of the polymerizations with ethylene glycol containing macroinitiators. The H NMR study of the catalyst complex in the presence of ethylene glycol groups leads us to conclude that there is possible competitive co-ordination at the copper between ligand and ethylene glycol groups. This influences the Cu(Ⅰ) / Cu(Ⅱ) equilibrium, resulting in the high observed polymerization rate.