Effect of the interfacial structure on the thermal stability of poly(methyl methacrylate)–silica hybrids

Poly(methyl methacrylate)–silica hybrid materials, P(MMA-MA5)–SiO2 or P(MMA-GMA5)–SiO2, were synthesized from the in situ reaction of the methyl methacrylate (MMA) with maleic anhydride (MA) or glycidyl methacrylate (GMA), then hydrolyzed with 3-aminopropyl methyl diethoxysilane (APrMDEOS) and tetraethoxysilane (TEOS) by a sol–gel process. The thermal stability and the apparent activation energies (Ea) of the PMMA moieties in the hybrids under air and nitrogen, evaluated by van Krevelen’s method, were studied by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). P(MMA-GMA5)–SiO2 hybrids with the flexible chain of the coupling agent had the lower glass transition temperature (Tg) and Ea. Moreover, the structure of the coupling agent influences the thermal and thermo-oxidative degradation of the PMMA within the hybrids.