Horn-Inspired Hierarchical Tubular Composites for Recoverable High-Energy Absorption.

Abstract

Recoverable energy-absorbing materials are crucial for advancing impact-resistant systems; however, they are typically limited by low energy dissipation (<1 MJ·m^-3). The horn of bighorn sheep (Ovis canadensis) exhibits outstanding energy dissipation and shape recovery, enabled by multiscale mechanisms including aligned tubules and lamellar keratin cells, along with hydration-driven self-recovery. Inspired by this hierarchical architecture, a recoverable porous energy-absorbing composite through a modified gelation-assisted self-assembly method is fabricated to construct a microtubular scaffold with lamellar-aligned nanoplatelets, which is subsequently infiltrated with a dynamic covalent epoxy matrix. The optimized composite exhibits exceptional energy absorption (10 MJ·m^-3), exceeding conventional recoverable architected materials by an order of magnitude, while simultaneously achieving high compressive strength (> 50 MPa), low density (1.1 g·cm^-3), and stable cyclic shape recovery performance. These mechanical properties arise from synergistic multiscale toughening mechanisms, including tubular buckling (macroscale), lamellar crack deflection and interfacial delamination (microscale), and matrix viscoelasticity (nanoscale). The epoxy matrix further contributes to reversible deformation and cyclic damage recovery. This study establishes a scalable biomimetic strategy for engineering lightweight, high-strength, and reusable materials with high energy dissipation, addressing critical challenges in potential protective applications.