Synthesis and kinetic studies of PMMA nanoparticles by non-conventionally initiated emulsion polymerization

The aqueous emulsifier-free emulsion polymerization of methyl methacrylate (MMA) was studied under the catalytic effect of in situ developed bivalent transition metal-EDTA complex with ammonium persulfate (APS, (NH4)2S2O8) as initiator. Out of these, Cu(II)-EDTA system was selected for detailed kinetic and spectrometric study of polymerization. The apparent activation energy Ea, 34.5 kJ/mol, activation energy of initiator decomposition Ed, 26.9 kJ/mol, energy of propagation Ep, 29 kJ/mol and energy of termination Et, 16 kJ/mol were reported. The emulsion polymer (PMMA) latex was characterized through the determination of the size and morphology by scanning electron microscopy, the average molecular weight by GPC and viscosity methods and the sound velocity by ultrasonic interferometer. From the kinetic results, the rate of polymerization, Rp at 50 °C was expressed byRp=K[Cu(II)]0.35[EDTA]0.69[APS]0.57[MMA]0.75