Multifunctional Chiral Nematic-Structured Cellulose Nanocrystal–Polyaniline Aerogels for Enhanced and Intelligent Electromagnetic Wave Absorption

Chiral structures capable of inducing asymmetric polarization of electromagnetic waves have emerged as a promising strategy to boost the electromagnetic wave absorption (EMA) performance. Herein, a series of biobased, multifunctional aerogels composed of chiral nematic cellulose nanocrystals (CNCs) and polyaniline (PANI) are fabricated to simultaneously achieve a robust and stimuli-responsive EMA performance, good thermal insulation, and flame retardancy. The unique integration of three-dimensional conductive networks and helically ordered architectures synergistically enhances electromagnetic wave attenuation via intensified multiple scattering, interfacial polarization, and chiral-induced cross-polarization effects, thereby ensuring superior EMA performance. The optimized CNC/PANI aerogel exhibited an excellent reflection loss of -47.9 dB and an ultrabroad effective absorption bandwidth of 7.9 GHz. The helically porous architecture, together with thermally generated char species, effectively impedes heat spread and combustion, enabling an aerogel with good thermal insulation and flame retardancy. Moreover, the reversible transition between the conductive and insulating states of the aerogel under acidic/alkaline conditions allows intelligent modulation of the EMA performance, offering a stimuli response mechanism. This work advances the design of bioderived chiral-structured materials with tunable and enhanced EMA property, providing new avenues toward multifunctional and adaptive electromagnetic applications.