Construction of chitin/Ag composite aerogel with segregated structure for electromagnetic shielding.

The development of sustainable processing strategies for chitin is of great importance to fully exploit its potential in advanced materials. Herein, we present a novel strategy for transforming natural chitin into high-performance shielding materials through controlled structural design. The approach leverages the controllable swelling and partial surface dissolution of chitin microspheres in a cold aqueous alkali system. Through a freeze-thaw cycle combined with epichlorohydrin (ECH)-induced covalent cross-linking, a robust hydrogel with a well-defined segregated architecture was constructed, where hydrogen bond reformation and covalent linkages significantly enhanced the structural cohesion. On this basis, silver nanowires (AgNWs) were precisely confined at the microsphere interfaces, forming an integrated conductive network at low filler loading. The resulting aerogel exhibited an impressive electromagnetic interference (EMI) shielding effectiveness (SE), primarily due to the synergistic effect of its multi-porous structure and the segregated conductive pathways. Crucially, this segregated structure enhanced the EMI SE by approximately 400% compared to a randomly mixed composite with the same filler loading. This work establishes a fundamental and green pathway for the value-added transformation of chitin into functional materials with hierarchically designed structures and highlights the power of microstructural control in enhancing the performance of biopolymer-based composites.