Thermally insulating and ultralow-k fluorinated polyimide aerogels with multi-level porous structure

A novel fluorine-modified polyimide aerogel (FPIA) was proposed via stepwise gelation. • The dual role of fluorine was revealed in refining hierarchical pore structure and suppressing phonon transport. • FPIA achieved a 60% reduction in thermal conductivity to 0.0211 W/(m·K). • FPIA exhibited wide-frequency ultralow dielectric constant and ultralow dielectric loss. • FPIA provides a viable material strategy for extreme-environment thermal and electrical management. Polyimide (PI) aerogels have shown promising applications in aerospace and microelectronics due to their excellent thermal stability and low density. However, the simultaneous achievement of thermal insulation and ultralow dielectric constant is extremely challenging, as the optimal nanostructures for these two properties often conflict. In this study, a new type of fluorine-modified PI aerogel (FPIA) was developed by introducing fluorine-containing monomers into the molecular chain and generating nano-sized multi-level pore structures through a stepwise gelation strategy, which enabled systematic control over the density, shrinkage, and nanoporous structure. The introduced fluorine groups not only effectively refined the pore structure but also significantly reduced the thermal conductivity of the material by enhancing the scattering of phonons by inhibiting the main thermal conductive pathway of lattice vibration. The prepared aerogel, featuring a high specific surface area (>300 m 2 /g) and a multi-level pore structure, achieves a synergistically balanced comprehensive performance via multi-objective trade-off optimization: the room-temperature thermal conductivity is reduced by approximately 60%, down to 0.0211 W/(m·K), and the dielectric constant is stable at approximately 1.22 within a 4–18 GHz wide frequency range and ultralow dielectric loss of approximately 0.005. This research not only provides a feasible preparation strategy for high-performance PI aerogels but also reveals the key role of fluorine modification in synergistically enhancing insulation and dielectric properties, laying the application foundation for the development of new-generation extreme environment thermal-electric management materials.