Ultralow Dielectric Fluorinated Polyimide Aerogels Crosslinked by Amide-Modified Carbon Fibers

Abstract As high-frequency communication technologies shift carrier frequencies into the millimeter-wave regime, legacy protective substrates show increasingly poor electromagnetic transparency, creating a fundamental mismatch between their wave-transmitting capability and the stringent low-loss requirements of next-generation communication architectures. Polyimide aerogel substrates, characterized by ultralow dielectric constant and loss, sufficient mechanical strength, and moisture resistance, have garnered significant attention. 2,2′-Bis(trifluoromethyl)-4,4′-diaminobiphenyl (TFMB) as a fluorinated monomer and more economical modified carbon fibers as crosslinkers were introduced to prepare a polyimide aerogel. The polyimide aerogel exhibits an exceptionally high porosity of >93%, with an average pore size ranging from 15.2 to 27.0 nm. Their dielectric constant ranges from 1.05 to 1.11, with dielectric loss between 0.112% and 1.025% (8.2–12.5 GHz). With their unique combination of ultralow density, excellent mechanical properties, high thermal stability, low thermal conductivity, and moisture resistance, our polyimide aerogels are highly promising for high-frequency communication applications.