Multidimensional Integrated Architectonics for Hierarchical Hydrogels with Enhanced Thermal Conductivity for...

To be the wound dressings that alleviate progressive thermal injury, hydrogels require to have high thermal conductivity, excellent mechanical properties, and outstanding biocompatibility, which are hard to achieve simultaneously. Inspired by the multiscale structure of spider silk, we developed a hierarchical hydrogel architecture. This architecture includes molecular-scale hydrogen bonds between oxygen plasma-treated graphene fibers (OPGFs) and poly(vinyl alcohol) (PVA), as well as within PVA molecular chains. It also features nanometer-scale ordered crystalline domains in the PVA matrix and micrometer-scale highly oriented OPGFs. The hydrogel was prepared using OPGFs assisted by a magnetic field, directional freezing, and salting-out treatment. This hierarchical structure reduces the interfacial thermal resistance between OPGFs and PVA, as proven by molecular dynamics. Finite element simulations show that the improvement in the hydrogel's thermal conductivity during the salting-out process is primarily due to the increase in PVA's intrinsic thermal conductivity. Additionally, the oriented OPGFs create directional thermal pathways. PVA/OPGFs hydrogels have a thermal conductivity of 1.71 W/(m·K), 322% higher than that of pristine PVA hydrogel. PVA/OPGFs hydrogels exhibit robust mechanical properties and good biocompatibility, indicating their vast potential as burn wound dressings. In vivo tests show that PVA/OPGFs hydrogels quickly reduce thermal damage in burn wounds and accelerate healing. Furthermore, the PVA/OPGFs hydrogels demonstrated good electrical conductivity and outstanding sensing capabilities, indicating that they can monitor motion under stress and serve as electrical stimulation carriers, showing great potential for integrated therapeutic monitoring in intelligent wound dressings. The strategy of constructing multiscale structures expands the potential applicability of hydrogels in biothermal management.