Microstructure controllable polyimide/MXene composite aerogels for high-temperature thermal insulation and microwave absorption

Abstract

Lightweight aerogels that integrate thermal insulation and microwave absorption have attracted much attention for applications in the aerospace industry. Nevertheless, using these aerogels in high-temperature environments continues to be a significant challenge. Herein, PI aerogels consisting of Ti₃C₂T_x MXene nanosheets (PI/MXene) were fabricated. The pore structure of PI/MXene aerogels was controlled using different freezing conditions. The rational microstructure endowed the aerogels with effective thermal insulation and microwave absorption properties at 200 °C. The comprehensive temperature-dependent heat transfer mechanism of the aerogels was well explored. Meanwhile, exploration of the temperature response to the intrinsic parameters of the aerogels revealed that the microstructure characteristics contributed prominently to microwave absorption at high temperature. Through microstructure regulation, the composite aerogels demonstrated a low thermal conductivity of 65.8 mW (m⁻¹ K⁻¹), as well as efficient microwave absorption with a minimum reflection loss (RL_min) of −33.5 dB (2.5 mm) and an effective absorption bandwidth (EAB) of 5.4 GHz at 200 °C. The results of this work suggest an inspiring approach for creating aerogels that possess both thermal insulation and microwave absorption capabilities, even in high-temperature environments.