Effect of Dispersed Polymeric Nanoparticles on the Bulk Polymerization of Methyl Methacrylate

We proposed a methodology to investigate the effect of dispersed nanoparticles (NPs) on bulk polymerization of methyl methacrylate (MMA), based on DSC experiments and modeling of the bulk polymerization kinetics. As examples, we have applied it to polymeric NPs, polytetrafluoroethylene (PTFE) and polystyrene (PS), and compared the results with those from linear PMMA and cross-linked PMMA (cPMMA). The presence of dissolved linear PMMA enhances the MMA bulk polymerization kinetics, as if the system was prepolymerized at a conversion equal to the dissolved amount of the linear PMMA. The dispersed cPMMA also enhances the MMA polymerization kinetics, but the enhancement decreases as the cross-linker in the cPMMA increases. The PTFE NPs behave like (inert) dead volume, while the PS NPs do enhance the MMA polymerization kinetics due to their slight swelling in MMA. Therefore, we can conclude that dispersed nonswellable polymeric NPs behave like inert dead volume, and swellable polymeric NPs enhance the MMA bulk polymerization kinetics and the enhancement extent increases as the swelling extent increases. The CryoSEM image of the bulk PMMA shows grainlike microstructure when the NPs are present.