Facile and environment-friendly preparation of high-performance polyimide aerogels using water as the only solvent

This study described a facile and environmentally friendly method for preparing polyimide (PI) aerogels via a sol–gel process and freeze-drying without the use of organic solvents. The prepared PI aerogels showed excellent mechanical properties. Their compressive strength can reach 4 MPa, which was mainly due to the 3,3′,4,4′-biphenyl tetracarboxylic dianhydride (BPDA) and phenylenediamine (PDA) used in the synthesis of their fully aromatic backbone. The PI aerogels obtained here showed low bulk densities (0.098–0.143 g cm−3), low shrinkage (10%), high specific surface areas (334–389 m2 g−1) and high porosity (92%). In addition, the PI aerogels exhibited excellent thermal stability and thermal insulation properties. The onset decomposition temperature of the PI aerogel was up to 560 °C while the thermal conductivity at room temperature was 0.036–0.038 W m−1 K−1.