A silsesquioxane-based flexible polyimide aerogel with high hydrophobicity and good adsorption for liquid pollutants in wastewater

A type of silsesquioxane-based flexible polyimide aerogel was synthesized by 3,3′,4,4′-benzophenonetetracarboxylic dianhydride (BTDA), 4,4′-diaminodiphenyl and octa(aminopropylsilsesquioxane) (POSS-NH2) with a facile thermal curing and atmospheric drying process. POSS-NH2 was introduced into the polyimide backbone as a cross-linking agent. The obtained aerogel possessed high hydrophobicity with a water contact angle exceeding 143°. And the aerogels showed good cyclic adsorption capacity for various organic solvents, such as acetone, methanol, ethyl acetate, etc. After 15 adsorption experiments, the original adsorption capacity of the aerogels (more than 3 times their own weight) was still maintained. SEM and BET confirmed that the introduction of POSS-NH2 could form a larger pore structure inside the aerogel, thereby achieving an improvement in adsorption performance. The results indicated this kind of aerogel might be flexibly utilized as adsorbent materials for oil pollutants and harmful organic reagents in the field of wastewater treatment.