Polyimide aerogels with optimized transmittance and thermal dimensional stability via dianhydride structure design

The PI aerogel based on DMBZ-PMDA exhibits high-temperature dimensional stability. • The specific surface area remains above 400 m 2 g −1 after treatment at 200 ℃. • The PI aerogel maintains high transmittance even after 200 °C heat treatment. • Heating shrinks the PI aerogel, enhancing its compressive strength. Polyimide (PI) aerogels combine a high specific surface area, high porosity, low thermal conductivity, and excellent high-temperature stability. However, their relatively low optical transmittance and insufficient dimensional stability at elevated temperatures limit their broader applications. In this study, three PI aerogels with distinct molecular structures were prepared by varying the dianhydride moiety, and their optical properties, mechanical performance, and thermal stability were systematically compared. Among them, the aerogel derived from 2,2′-dimethylbenzidine (DMBZ) and 1,2,4,5-benzenetetracarboxylic dianhydride (PMDA) exhibited the best light transmittance and thermal dimensional stability. By investigating the effects of heat treatment on the structures and properties of the materials, the structural evolution of the aerogel and the mechanisms underlying the related performance changes under high-temperature conditions were analyzed. After heat treatment at 200 ℃ under either Ar or air, the PI-PMDA aerogel retained a specific surface area above 400 m 2 g −1 and a transmittance exceeding 70% at 700 nm, indicating good preservation of its porous structure and optical performance. These results demonstrate that dianhydride structure design is an effective strategy for balancing optical transmittance and high-temperature dimensional stability in PI aerogels and provide a material basis for their potential use as support materials in future photothermal catalytic systems. Download: Download high-res image (313KB) Download: Download full-size image