The influence of oxide nanoparticles on the kinetics of free radical methyl methacrylate polymerization in bulk

A series of poly(methyl methacrylate) (PMMA) nanocomposites were synthesized using free radical polymerization in bulk, by addition of 1 vol% of oxide nanoparticles (silica, alumina, and titania), differing in the nature and type. The influence of nanofiller presence on the kinetics of methyl methacrylate (MMA) free radical polymerization was investigated. For this purpose, the kinetic model that includes the contribution from the first‐order reaction and the autoacceleration was applied on data obtained following the isothermal polymerization at 70°C by differential scanning calorimetry (DSC). The effect of the size and the surface nature of nanofillers on the interfacial layer thickness (d), as well as the influence of d on the glass transition temperature (T_g) of PMMA hybrid materials was studied. It was found that hydrophilic particles accelerated the initiator decomposition and affected the monomer polymerization on the surface, which caused the formation of thicker interfacial layer compared to the one around hydrophobic fillers. The addition of smaller nanoparticles size decreased the glass transition temperature of pure poly(methyl metacrylate). The linear increase of PMMA T_g value with increasing the polymeric interfacial layer was determined. The T_g values of pure PMMA and PMMA nanocomposite with d of 1.4 nm were estimated to be the same. POLYM. COMPOS. 34:1342–1348, 2013. © 2013 Society of Plastics Engineers