Transparent poly(methyl methacrylate)/silica/zirconia nanocomposites with excellent thermal stabilities

Nanocomposites from poly(methyl methacrylate) (PMMA), silica (SiO2) and zirconia (ZrO2) were prepared using a novel non-hydrolytic sol-gel process. Silicic acid and zirconium oxychloride (ZrOCl2·8H2O) were used as the precursors of SiO2 and ZrO2, respectively. FT-IR and SEM results showed that nanometre-scaled SiO2/ZrO2 particles were uniformly distributed in and covalently bonded to the PMMA host matrix without macroscopic organic-inorganic phase separation, which was also confirmed by solvent extraction experiments. It was found that the transmittance of the nanocomposite films in the visible region remained above 95% even at 20 wt% inorganic content and increased proportionally with decreasing inorganic content. The thermal stability and the thermal decomposition kinetics of the composites were studied. The results indicated that the activation energy (Ea) of the thermal decomposition of PMMA main chains in the composites was increased due to the addition of inorganic moieties. This kind of composite material may have the potential for applications in optical devices.