Initiation Mechanism of Radical Polymerization Using Ammonium Persulfate and Polymerizable Amine Redox Initiators

Abstract A redox initiation system consisting of a polymerizable amine such as N-[(3-dimethylamino)-propyl] acrylamide(DMAPAA) or N-[(3-dimethylamino)-propyl] methacrylamide(DMAPMA) and ammonium persulfate(APS) used for aqueous polymerization of acrylamide(AAM) has been studied. It has been found that the rate equation of AAM polymerization is in good agreement with the redox initiated polymerization rate equation, and the overall activation energies of the polymerization obtained are 35.04 and 40.96 kJ/mol for APS/DMAPAA and APS/DMAPMA systems, respectively. Accordingly, the systems belong to redox ones. The initiation mechanism of the polymerizable redox systems has been investigated by means of electron paramagnetic resonance(EPR), Fourier-transform infrared(FT-IR) and ultra violet(UV) spectroscopies. Two kinds of radicals, alkylamino methyl radical and monomeric propagating radical have been detected by EPR spectroscopy. Based on experimental results the initiation mechanism of ammonium persulfate/polymerizable amine system is proposed.