High-performance heterocyclic para-aramid aerogels for selective dye adsorption and thermal insulation applications

The high-performance polymer para-aramid (PPTA) is discovered to gel too soon during the polymerization process, resulting in poor processing performance. In this work, a homogeneous polymer solution containing heterocyclic para-aramid (HPPTA) was successfully synthesized by introducing 2,4-aminophenyl-5-aminobenzimidazole groups into the molecular chains of PPTA, and then HPPTA aerogel was prepared using a supercritical drying technique that took advantage of the HPPTA solution's excellent property of slow gelation. When the HPPTA polymer mass fraction was 1 wt%, the aerogel had the lowest density of 0.086 g cm −3 with a BET specific surface area of 376.59 m 2 g −1 . The HPPTA-2 aerogel had better adsorption performance for anionic dye methyl orange, with a maximum adsorption capacity of 319.47 mol g −1 ; however, its adsorption capacity for cationic dye methylene blue and neutral dye dimethyl yellow was very low, at only 19.68 and 0 mol g −1 , respectively. The selective adsorption ability of HPPTA aerogel made it a simple and scalable platform for removing anionic dyes from water solutions. Furthermore, the HPPTA aerogel has outstanding thermal properties for thermal insulation applications in severe environments due to the synergistic effect of the 3D porous structure inside the aerogel and the exceptional thermal stability of the HPPTA.