Mechanism of microemulsion polymerization of methyl methacrylate: Experimental evidence

Free radical polymerization of methyl methacrylate in emulsion and microemulsion media was studied for the understanding of the mechanism of the polymerization process. Average particle size of the poly(methyl methacrylate) (PMMA) latex formed during microemulsion polymerization was observed to be ≈ 45 nm. Nuclear magnetic resonance data indicated a larger number of interactions for β-methylene protons of PMMA synthesized in microemulsion, indicating dominant isotaciticity in the polymer. Activation energy of degradation of the products was calculated by Broido's method and was found to be 44.70 kJ/mol and 65.47 kJ/mol for PMMA synthesized from microemulsion and emulsion media, respectively. Solution properties of the above polymers were also studied. Intramolecular expansion factors indicate a more rigid structure for PMMA synthesized from microemulsion medium.