Preparation of polyimide-based composite aerogel for enhanced microwave absorption and thermal insulation

A lightweight, multifunctional polyamide acid (PAA)/carbonyl iron powder (CIP) composite aerogel with integrated thermal insulation and microwave absorption capabilities is developed via multi-structure design. With polydopamine (PDA) modified melamine foam (MF), this study achieves uniform dispersion of CIP and robust interfacial bonding. The results demonstrate that the PDA modification time and PAA content have a significant effect on the properties of composite aerogels. The composite aerogel achieves lowest thermal conductivity with 6   h modification time and 8% PAA due to the optimized structure. Moreover, the peak microwave absorption performance is attained with 18   h modification and 6% PAA, resulting from optimal interfacial polarization loss and impedance matching. This study achieves a balance between thermal insulation and microwave absorption performance through microstructure design, providing a solid foundation for advanced multifunctional materials.