Dual‐Crosslinked Hydrogels With Enhanced Mechanical and Thermal Properties

ABSTRACT Creating artificial skin requires materials that can mimic the mechanical properties and structural integrity of natural skin. This study develops a dual‐crosslinking approach combining tannic acid—a naturally occurring, biocompatible polyphenol—with dynamic, covalent imine bonds. Hydrogels singly crosslinked with hydrogen‐bonded tannic acid achieved gel fractions of up to 90% but fragmented during handling, rendering them impractical for wound dressing applications. In this work, we performed sequential dual‐crosslinking, where ethylenediamine and aldehydes first form a covalent imine network, followed by the addition of tannic acid for hydrogen‐bonding reinforcement. This produced robust, handleable hydrogels with superior properties. The optimal formulation (0.25 ethylenediamine:0.5 tannic acid) achieved a maximum tensile strength of 2.17 MPa, elongation with a break at 1425%, and a toughness of 1.71 MJ/m 3 —exceeding human skin toughness twofold and representing two to three times improvements over systems crosslinked with tannic acid alone. Critically, dual‐crosslinked materials maintained structural integrity with 69% gel fraction, controlled swelling (1129%), and 92% water content suitable for wound healing. Comprehensive characterization by FTIR, thermogravimetric analysis, dynamic mechanical analysis at physiological temperatures, tensile testing, and swelling studies validated this bio‐inspired platform for mechanically robust, dimensionally stable artificial skin applications.