Surfactant-induced thermomechanical and morphological changes in TiO2-polystyrene nanocomposites

Nanocomposites of polystyrene and TiO2 colloidal nanorods with different loadings have been prepared by mixing pre-synthesized oleic acid capped colloidal TiO2 nanorods into commercial polystyrene via solvent blending using chloroform. The microstructure and morphology of the nanocomposites was evaluated by wide angle X-ray diffraction and transmission electron microscopy. The observations revealed that the surfactant plays an important role for interactions between the polymer and the filler. Differential scanning calorimetry showed that the glass transition temperature of the nanocomposites decreased which is consistent with the surfactant acting as a plasticizer in the polystyrene matrix. Thermogravimetric analysis revealed that the nanocomposites show no significant improvement in thermal stability as compared to the bare PS up to a temperature of 400 °C. However, after 400 °C, the TGA curve shifts a little to higher temperature as compared to the bare PS. The dynamic mechanical properties of the nanocomposites indicate that the storage modulus, loss modulus, and glass transition temperature do not change with increasing nanorods content of 2 and 4 wt% but decrease afterward for 8 wt%. Transmission electron microscopy images clearly show debonding characteristics in polystyrene matrix.