Thermal Resistance Enhancement and Wettability Amelioration of Poly(benzimidazole-aramid) Film by Silica Nanocomposites

Polybenzimidazole (PBI) is a high-performance polymer known for its excellent thermal stability, mechanical strength, and chemical resistance, attributes that are derived from its unique structure comprising repeated benzene and imidazole rings. However, limitations such as relatively low thermal stability and moisture sensitivity restrict its application as a super engineering plastic. In this study, amide groups are incorporated into the PBI backbone to synthesize the copolymer poly(BI-<i>co</i>-A), effecting a structural modification at the molecular level. Additionally, silica nanospheres were composited into the poly(BI-<i>co</i>-A) film to further enhance its thermal performance. The resulting composite films exhibited remarkable thermal stability, with the temperature for 10% weight loss reaching as high as 761 °C. To address increased water absorption due to the high hydrophilicity of hydroxyl groups on the silica nanospheres' surface, a dehydration treatment was applied in an electric furnace. This treatment produced a highly thermoresistant poly(BI-<i>co</i>-A) nanocomposite film with reduced wettability, making it suitable for applications in humid environments.