Photodegradation Behavior of Nanosilica-Filled PMMA Composite: Cooperative Effect of Mixed Solvents and Interfacial Functional Groups

Poly(methyl methacrylate) (PMMA) and its composites are widely used in industrial applications; therefore, their durability is of great concern. In this study, the photooxidative degradation behavior of nanosilica-filled PMMA composite films and the cooperative effect of mixed solvents containing tetrahydrofuran (THF) and chloroform (TCM), as well as interfacial functional groups, was investigated. The surface functional groups of nanosilica fillers, such as polar, aryl, and alkyl moieties, significantly affect the photodegradation kinetics and pathways for PMMA. The key process lies in the modulation of solvent-solvent reaction selectivity at the polymer-filler interface. Functional groups that selectively promote the chlorination reaction between THF and TCM accelerate PMMA photodepolymerization, while those that suppress this reaction hinder degradation. This interfacial effect is validated by trends in molecular weight loss, volatile product profiles, and MMA yields during aging. Our findings reveal that the photodegradation behavior of PMMA composites is not only governed by environmental conditions but also critically influenced by interfacial chemistry. In this way, this study provides novel insight into the interfacial aging process for polymer nanocomposites, as well as guidance for the rational design of PMMA-based materials with improved durability.