Multifunctional polyimide/rGO aerogels with stain-responsive ultrabroadband microwave absorption properties and thermal insulation

Abstract

Multifunctional, responsive electromagnetic wave-absorbing materials (EMAs) with comprehensive performance are crucial for adapting to the ever-changing and extreme electromagnetic environment. To meet the demands of various application scenarios, we developed a compressible and thermally stable polyimide/reduced graphene oxide composite aerogel (PGA) via unidirectional freeze-drying and thermal annealing process. Polyimide endows the composite aerogel with outstanding thermal resistance and superior mechanical strength, with a weight loss of only 5 % at 440 °C and a compressive stress of up to 100 kPa at 60 % strain. Benefiting from the synergistic effect of porous structure and reasonable components, PGA exhibits an excellent minimum reflection loss of −58.32 dB and a broadened effective absorption bandwidth of 7.98 GHz (10.02–18.00 GHz) at a thickness of 3.9 mm. More importantly, compressing aerogels can alter their pore structure and conductive network to achieve high dynamic tunability of electromagnetic parameters, thereby enabling responsive microwave absorption performance. Notably, the PGA-18 successfully realizes complete coverage of the X and Ku bands through strain-induced regulation, confirming its applicability in ultra-broadband electromagnetic wave absorption. Additionally, the axially aligned lamellar structure and high porosity of the aerogel effectively suppress convective heat transfer and reduce thermal radiation, thereby imparting excellent thermal insulation and infrared stealth capabilities under high-temperature conditions. This work provides new insights into the design of multifunctional ultrawider EMAs with tunable electromagnetic characteristics, helping enable the next-generation electronic devices and stealth equipment.