Ternary nanocellulose-based aerogels with biomimetic tracheal microstructure for synergistically enhanced thermal insulation, flame retardancy and mechanical robustness

Nanocellulose-based aerogels are promising materials for thermal management and are regarded as the third-generation aerogels. However, their practical use is hindered by trade-offs among mechanical robustness, thermal conductivity, and flame retardancy. Herein, we reported a ternary composite aerogel with a biomimetic tracheal microstructure, designed to synergistically enhance thermal insulation, flame retardancy, and mechanical robustness. The optimized layered double hydroxide (LDH)-modified sample (M_1.0-PT) achieved an ultra-low radial thermal conductivity of 26.5 mW/m·K, attributed to the synergistic suppression of solid conduction (LDH phonon scattering) and gas convection (air entrapment). For flame retardancy, the M_1.0-PT aerogel showed a limiting oxygen index (LOI) of 40.4% and a UL-94 V-0 rating, enabled by LDH’s catalytic char formation and polyvinyltrimethoxysilane’s crosslinked network. Moreover, the aerogels exhibited a compressive modulus of 102.8 kPa, nearly double that of the TOCNF aerogel (53.3 kPa) due to the anchoring reinforcement of LDH and the structural support of the tracheal microstructure. The biomimetic structure and multi-component synergy provided a new strategy for designing high-performance aerogels, with potential applications in lithium-ion battery thermal management and building insulation.