Thermal properties of silica/poly(2,6-dimethyl-1,4-phenylene oxide) films prepared by emulsion polymerization

Abstract

Thermal properties of the silica/poly(2,6-dimethyl-1,4-phenylene oxide) films prepared via emulsion polymerized mixed matrix (EPMM) method are investigated, and the impact of the synthesis protocol on the silica content, compatibility between the organic and inorganic phases, and the thermal stability of these nanocomposites is studied. Two series of films, namely EPMM-1S and EPMM-2S, synthesized in one- and two-step process, respectively, with different combinations of surfactant and compatibilizer were prepared. The polymerization of the silica precursor in the films was confirmed by 29Si nuclear magnetic resonance, and its content was investigated by inductively coupled plasma mass spectroscopy analysis. Thermal properties of the EPMM films were investigated by differential scanning calorimetry and thermogravimetric analysis. The glass transition temperature (Tg) of EPMM films was greater compared to the neat PPO film. However, an increase in Tg was not related to the concentration of silica in the film, but rather to the quality of dispersion of synthesized nanoparticles. Despite a lower inorganic loading, EPMM-1S films had a greater Tg than EPMM-2S films. On the other hand, both the decomposition temperature and the activation energy for the decomposition were directly related to the silica content in the EPMM films. In general, regardless of the synthesis protocol, the presence of compatibilizer (ethanol) leads to greater inorganic content and improved thermal properties of the EPMM films.