Constructing Polyimide Aerogels with Carboxyl for CO₂ Adsorption

In this study, mesoporous polyimide aerogels with carboxyl were successfully synthesized by the co-polymerization method at room temperature from pyromellitic dianhydride and 1,3,5-triaminophenoxybenzene, 3,5-diaminobenzoic acid, and 2,2'-dimethyl-4,4'-diaminobiphenyl. Compared to previously reported porous organic polymer materials, this aerogel has the advantage of a simple and efficient synthesis method. The thermal decomposition temperatures of the obtained polyimide aerogels are all above 400 °C and have excellent thermal stability. Among them, the largest specific surface area is 62.03 m²/g. Although the surface area of this aerogel is not large enough, it has considerable CO₂ adsorption properties. The adsorption capacity of CO₂ is up to 11.9 cm³/g, which is comparable to those of previously reported porous materials. The high CO₂ adsorption is attributed to the abundance of carboxyl groups in the polyimide networks. The mild and convenient synthesis method and high CO₂ adsorption capacity indicate that the polyimide aerogel with carboxyl is suitable as a good candidate material for CO₂ adsorption.