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