The Effects of Different Blending Methods on the Thermal, Mechanical, and Optical Properties of PMMA/SiO2 Composites

In this study, PMMA/SiO2 composites were fabricated with monodispersed SiO2 and PMMA using four distinct methods—physical blending, in situ polymerization, random copolymerization, and block copolymerization—to investigate the composites’ thermal, mechanical, and optical properties. In the physical blending approach, SiO2 nanoparticles were dispersed in a PMMA solution, while during in situ polymerization, silica nanoparticles were incorporated during the synthesis of PMMA/SiO2 composites. 3-methacryloxypropyltrimethoxysilane (MPS) was modified on the SiO2 surface to introduce the reactive double bonds. The MPS@SiO2 was either random- or block-copolymerized with PMMA through RAFT polymerization. The PMMA/SiO2 composites prepared via these different methods were characterized using FTIR, TGA, and DSC to determine their chemical structures, thermal degradation temperatures, and glass transition temperatures, respectively. Scanning electron microscopy (SEM) was employed to observe the microstructures and dispersion of the composites. This comprehensive analysis revealed that the PMMA/SiO2 composites prepared via block copolymerization exhibited thermal stability at temperatures between 200 and 300 °C. Additionally, they demonstrated excellent transparency (86%) and scratch resistance (≥6H) while maintaining mechanical strength, suggesting their potential application in thermal insulation materials.