Deep eutectic solvent-mediated multiscale silk fibroin hybrid eutectogels with broadly tunable mechanics for flexible electronics and energy harvesting

Developing sustainable hybrid gels with simultaneous tunability and extensibility remains challenging due to the lack of hierarchical network design and synergistic interfacial interactions. Here, we introduce a deep eutectic solvent (DES)-mediated multiscale regulation (DMR) strategy to construct hierarchical networks with synergistic interaction for achieving broadly tunable mechanical properties in biomass-derived hybrid eutectogels. Using Bombyx mori silk fibroin (SF) as a model, DES hierarchically deconstructs macroscopic SF across micro-, nano-, and molecular scales. These multiscale structural units serve as hierarchical reinforcements within the polymer matrix, forming a synergistic hybrid network stabilized by multiple hydrogen bonds and electrostatic interactions. Consequently, the resulting multiscale hybrid eutectogels exhibit broadly tunable mechanical properties, with tensile strength spanning nearly two orders of magnitude (0.02–1.6 MPa) and modulus nearly three orders of magnitude (0.008–3.5 MPa), alongside excellent ionic conductivity and multifunctionality. Molecular dynamics simulations and spectroscopic analyses provide evidence supporting the proposed multiscale interfacial interaction mechanisms. Furthermore, we demonstrate proof-of-concept applications of these hybrid materials in advanced soft electronics, including an ultra-conformable wearable sensor for physiological monitoring and a load-bearing triboelectric nanogenerator (TENG) for self-powered systems. This multiscale composite design strategy offers a promising approach toward developing versatile biomass-based hybrid materials, with potential utility in flexible electronics and energy-harvesting devices.