Hierarchical Structural Engineering of Ultrahigh-Molecular-Weight Polyethylene.

Nature has inspired the design of next-generation lightweight architectured structural materials, for example, nacre-bearing extreme impact and paw-pad absorbing energy. Here, a bioinspired functional gradient structure, consisting of an impact-resistant hard layer and an energy-absorbing ductile layer, is applied to additively manufacture ultrahigh-molecular-weight polyethylene (UHMWPE). Its crystalline graded and directionally solidified structure enables superior impact resistance. In addition, we demonstrate nonequilibrium processing, ultrahigh strain rate pulsed laser shock wave peening, which could trigger surface hardening for enhanced crystallinity and polymer phase transformation. Moreover, we demonstrate the paw-pad-inspired soft- and hard-fiber-reinforced composite structure to absorb the impact energy. The bioinspired design and nonequilibrium processing of graded UHMWPE shed light on lightweight engineering polymer materials for impact-resistant and threat-protection applications.