The effect of poor solvent on the microstructures and thermal insulation performance of polyimide aerogels.

• Poor solvents were introduced into the reagent during the synthesis of PI precursor. • Submicron-scale pores are produced in aerogels owing to the poor solvents. • Aerogels in this work have low density (~91 mg cm−3) and low thermal conductivity. The sol–gel process is essentially a process of phase separation between micelles and solvent, so the influence of solvent composition on the result of phase separation will further affect the wet gel and the structure of the aerogel made by it. In this study, during the preparation of polyimide (PI) aerogels, poor solvents were introduced into the reagent during the synthesis of PI aerogel precursor, polyamic acids. The pore structure and thermal insulation performance changes of the PI aerogels caused by this behavior were studied. With the addition of poor solvent, submicron-scale pores were found inside the aerogel. In addition, the introduction of a small amount of poor solvent improved the thermal insulation performance of the prepared PI aerogel. [ABSTRACT FROM AUTHOR]