Dynamic Covalent Porous Networks Enabling Synergistic Microwave Attenuation

Lightweight, adaptive, and porous microwave (MW) absorbers with reprocessability are highly desirable for next-generation portable electronics and sustainable electromagnetic interference (EMI) shielding systems. Herein, we report a one-pot strategy for fabricating three-dimensional (3D) porous hydroxyl-terminated polybutadiene (HTPB)-single-walled carbon nanotube (SWCNT) vitrimer nanocomposites (NCs) through thermally induced esterification and porous engineering. The bioderived dynamic cross-linker facilitated rapid network formation, yielding adaptive covalent vitrimer architectures with superior self-healing, stress relaxation, and recyclability. Simultaneously, SWCNTs were incorporated to construct interconnected conductive pathways within the porous matrix, resulting in enhanced thermal stability and electrical conductivity. Moreover, the optimized porous vitrimer NCs exhibited excellent compression recovery and superior structural integrity owing to synergistic dynamic covalent interactions and uniform nanotube dispersion. Even though the single surface porous NCs showed reflection-dominated shielding and the gradient porous matrix architecture improved absorption-dominated due to different impedance matching surface, resulting in an shielding effectiveness of 75 dB through multiple internal reflections, interfacial polarization, and synergistic conductive loss. Importantly, the vitrimer NCs retained their functionality over four reprocessing cycles, demonstrating their potential as lightweight, adaptive, and recyclable microwave attenuation materials for advanced EMI shielding applications.