Programmed cryogenic fabrication of cuttlebone-inspired lightweight cellular materials with enhanced energy absorption.

Lightweight engineering materials with high energy absorption are critical for various strategic fields. However, designing cellular materials that overcome the trade-off between density and energy dissipation remains challenging. Inspired by the wall-septum architecture of cuttlebone, we develop a lightweight cellular epoxy resin using a facile layer-by-layer freezing technique. The resulting material exhibits high compressive strength and specific energy absorption, reaching 34.5 J g-1 at a density of 0.55 g cm-3. The dense septa between porous wall layers in the wall-septum structure enhance structural stability against wall buckling and provide lateral confinement during compression. Such architecture also improves high-strain-rate impact strength, achieving 190% and 66% increase in dynamic specific energy absorption compared to conventional isotropic and unidirectional structures, respectively. Large-size energy-absorbing epoxy panels are readily fabricated and demonstrate impact protection performance under high-speed impact. This work provides a practical route to lightweight cellular materials with improved energy absorption efficiency.