Scalable Polyaniline-Bridged Multifunctional Bamboo Fiber/Carbon Nanotubes Composite Foam via Ambient Drying for Thermal Protection and Electromagnetic Shielding

The scalable development of sustainable, high-performance cellulose foams is often impeded by energy-intensive drying processes and the structural vulnerability of porous networks under ambient conditions. In this paper, we report an ambient-pressure drying strategy to fabricate polyaniline-bridged multifunctional bamboo fiber (BF)/multiwalled carbon nanotubes (MWCNTs) composite foam. By employing 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) oxidized cellulose nanofibril (TOCNF) to uniformly disperse MWCNTs within the BF network, a hierarchical porous architecture with mechanical robustness and high electrical conductivity was constructed through ice-templating, Zn 2+ crosslinking, and hydrogen bonding, effectively resisting capillary-force-induced collapse without the need for freeze-drying or solvent exchange. The optimized Zn 2+ crosslinked polyaniline-bridged multi-walled carbon nanotubes/bamboo fiber/TOCNF composite foam (Zn-P 3 M 4 BC 1 ) exhibited an exceptional electromagnetic interference shielding effectiveness of 61.56 dB, with an absolute specific shielding efficiency (SSE/d) of 2 375.2 dB·cm 2 /g, surpassing most reported carbon-based and polyaniline (PANI)-based aerogels. Furthermore, the synergistic interplay between MWCNTs/PANI and phytic acid endowed composite foam with excellent flame retardancy (limiting oxygen index = 56.8%), low thermal conductivity (0.085 W/(m·K)), and reliable electrothermal and infrared camouflage performance. Overall, this work provides a scalable and energy-efficient route to multifunctional cellulose-based foams for electromagnetic protection, thermal insulation and adaptive infrared camouflage.