Effect of surface functionalization of SiO2 particles on the interfacial and mechanical properties of PEN composite films

In this paper, we have introduced a new effective approach to graft polyarylene ether nitrile containing carboxyl groups (PEN-COOH) on the surface of silica (SiO2) particles which were further confirmed by Fourier transform infrared spectra and transmission electron microscopy analyses. Polyarylene ether nitrile (PEN) composite films with SiO2-PEN particles were prepared through solution-casting method, which were characterized using parallel-plate rheometry, thermogravimetric and mechanical analysis, aimed at investigating the effect of surface functionalization of SiO2 particles on the thermal, mechanical and interfacial properties of PEN/SiO2 composite films. The rheological test indicated that SiO2-PEN particles presented better dispersibility and interfacial compatibility in the PEN matrix, which was further confirmed from scanning electron microscopy and Cole–Cole plots. The thermogravimetric analysis results revealed that the PEN/SiO2 composite films showed a slightly increase in 5% weight loss temperature (increased by 1–12 °C) and maximum decomposition rate temperature (increased by 2–5 °C) compared with purified PEN film. DSC curves showed that the glass transition temperatures were in the range of 168–172 °C. In addition, the mechanical properties of composite films were higher than that of pure PEN film even the SiO2-PEN particles loading reached 6 wt%. In sum, the surface functionalization of SiO2 particles was confirmed to be an effective method to improve the interfacial and mechanical properties of PEN/SiO2 composite films.