Incorporation of Aramids into Polybenzimidazoles to Achieve Ultra-High Thermoresistance and Toughening Effects

Polybenzimidazoles (PBIs) are recognized for their remarkable thermal stability due to their unique molecular structure, which is characterized by aromaticity and rigidity. Despite their remarkable thermal attributes, their tensile properties limit their application. To improve the mechanical performance of PBIs, we made a vital modification to their molecular backbone to improve their structural flexibility. Non-π-conjugated components were introduced into PBIs by grafting meta-polyamide (MA) and para-polyamide (PA) onto PBI backbones to form the copolymers PBI-co-MA and PBI-co-PA. The results indicated that the cooperation between MA and PA significantly enhanced mechanical strain and overall toughness. Furthermore, the appropriate incorporation of aromatic polyamide components (20 mol% for MA and 15% for PA) improved thermal degradation temperatures by more than 30 °C. By investigating the copolymerization of PBIs with MA and PA, we unraveled the intricate relationships between composition, molecular structure, and material performance. These findings advance copolymer design strategies and deepen the understanding of polymer materials, offering tailored solutions that address thermal and mechanical demands across applications.