Photocurable polymethacrylate-silica nanocomposites: correlation between dispersion stability, curing kinetics, morphology and properties

A comprehensive study of model systems based on poly(ethylene glycol) dimethacrylate and two methacryloxy-modified silicas (Aerosil R7200 and R711) were investigated to find possible correlation between the stability of the monomer/silica dispersion, curing kinetics, composite morphology and physical and mechanical properties of the final hybrid material. The monomer/silica dispersions were cured photochemically. The investigated parameters: Zeta potential, polymerization rate and conversion, glass transition, surface roughness and mechanical properties were found to be synchronous; when plotted as function of silica content, they showed maxima or changes in the trend at the same filler loading. This threshold (optimum) silica content in the composition was about 5 wt.-% for the investigated systems. The results obtained are discussed in terms of the solvation cell (which influences dispersion stability) and the interphase layer formation as well as their changes below and above of the threshold filler content.