Preparation of a novel SiO₂/PMMA nanocomposite with high transparency, thermal stability, and superior surface hardness via gamma-radiation polymerization

Heat-resistant, highly surface-hardened, and transparent composites of poly(methylmethacrylate) (PMMA) play a significant role in modern devices. However, conventional PMMA-based composites with high nanoparticle loadings often compromise transparency for high surface hardness and heat resistance due to nanoparticle aggregation and poor interfacial compatibility. In this work, we successfully fabricated an exceptional composite (MSiO2/PMMA composites) with high transparency, superior heat resistance, and high surface hardness using gamma-ray irradiation-induced polymerization of methyl methacrylate (MMA) containing uniformly dispersed SiO2 that was modified by 3-methacryloxypropyl trimethoxysilane and trimethylchlorosilane. Specific silanes were utilized for polarity regulation to reduce the agglomeration of SiO2 nanoparticles and improve compatibility with MMA. Compared to pure PMMA, the 40-MSiO2/PMMA composite sample exhibited significantly improved thermal stability in terms of the temperature at 10% weight loss (T-10%), glass transition temperature (T-g), and decreased coefficient of thermal expansion (CTE). Furthermore, this composite achieves a very high surface hardness (pencil hardness of 6H versus H for pure PMMA) while maintaining transparency similar to PMMA. These MSiO2/PMMA composites open up new avenues to enhance the performance and durability of materials used in various industries such as electronics, optics, automotive, and aerospace.