The kinetics and mechanism of polymerization of methyl methacrylate radical in the presence of ortho-phosphoric acid☆

Abstract The photo-initiated homo-polymerization of methyl methacrylate (MMA) has been studied at 25°C in the presence of ortho -phosphoric acid as complex former. Post-polymerization accompanied by a mol.wt. increase has been found to occur in addition to an increase in reaction rate after ceasing photo-initiation in the system MMA-H 3 PO 4 . The factor responsible for the continuation of the post-polymerization in such a system has been found to be the macro-radicals whose active life is greatly prolonged in the presence of the complex former. The effects of various factors in the kinetics of the post-illumination process have been studied. A rapid drop of the bimolecular termination rate of the polymethylmethacrylate (PMMA) radicals has been found to be linked with a change of the configurational properties and the associations of the growing chains as a result of the complexing with H 3 PO 4 . A mechanism is suggested for the polymerization in the described system.