Synthesis, characterization, and properties of polystyrene/SiO ₂ hybrid materials via sol–gel process

Isocyanate‐functionalized polystyrene (P(St‐co‐TMI)) was successfully synthesized by solution free radical polymerization, which was then used to react with (3‐aminopropyl) triethoxysilane (APTES) to prepare a precursor of polystyrene/inorganic composites (PS/SiO ₂ ). To obtain PS/SiO ₂ composites with chemical bond, the precursor was mixed with triethoxysilane (TEOS) under the sol–gel reaction condition. The chemical bond between the PS and SiO ₂ particles made the crosslink network more stable and avoided aggregation compared with the physical connection and barely mechanical mixing. The Fourier transform infrared (FT‐IR) results indicate that the isocyanate group (NCO) was completely reacted with APTES. The field‐emission scanning electron microscopy results show that the morphology of composites and the distribution of the particles, which exhibit good compatibility between organic and inorganic phases, and the inorganic particles show good spatial uniformity. The differential scanning calorimetry shows that the glass transition temperature ( T _g ) of the PS/SiO ₂ composites was shifted to high temperature when the amount of APTES increased. The thermal degradation temperature of the PS/SiO ₂ composites increases with the increasing of APTES content. Master curves at 200°C are constructed for the storage and loss modulus as well as complex viscosity. POLYM. COMPOS. 36:482–488, 2015. © 2014 Society of Plastics Engineers