Thermal and Mechanical Reinforcement of Poly(Methyl Methacrylate) via Incorporation of Polyhedral Oligomeric Silsesquioxane

A series of inorganic/organic nanocomposites were prepared by blending cage-like, hydroxyl-bearing polyhedral oligomeric silsesquioxane (HO–POSS) with poly(methyl methacrylate) (PMMA) in THF solvent. Fourier transform infrared spectrophotometry (FTIR) and ²⁹ Si–nuclear magnetic resonance ( ²⁹ Si-NMR) were employed to characterize the structures of the HO–POSS/PMMA nanocomposites. Scanning electron microscope (SEM) images showed that the as-prepared composite films were smooth, and no severe aggregation of HO–POSS was observed when POSS content was less than 1.0 wt.%. Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) results showed that the incorporation of small amount of nanosized HO–POSS reinforced the thermal stability of PMMA. When 1.0 wt.% of HO–POSS was incorporated into PMMA matrix, the T _g and T _d increased by 28.8 °C and 18.9 °C, respectively, due to the strong interaction between POSS cages and PMMA chains. However, higher POSS contents (>2.0 wt.%) deteriorated the thermal and mechanical properties of the nanocomposites owing to the phase separation in the composite matrix caused by the aggregation of POSS cages.