Resolving Toughness‐Conductivity Conflict in Hydrogels via F‐Heat‐S Strategy for Advanced Soft Electronics

ABSTRACT

Polyvinyl alcohol (PVA) hydrogels hold great promise for flexible electronics, electronic skin, and soft robotics, yet simultaneously achieving high strength, toughness, and conductivity remains challenging. Inspired by metallurgical processing, we develop an efficient “freeze‐thaw → heat treatment → salting‐out” (F‐Heat‐S) strategy to fabricate a heterogeneous PVA hydrogel with exceptional mechanical properties and conductivity. Heat treatment refines crystalline domains and creates a pre‐layered structure that templates the microstructural evolution during salting‐out, thereby unlocking the full reinforcing potential of the process. During the salting‐out process, the asymmetric structure of the hydrogel simultaneously achieves the permeation of conductive ions and the densification of the polymer, endowing the hydrogel with enhanced mechanical properties and conductivity. The optimized hydrogels overcome the intrinsic softness and weakness of conventional PVA hydrogels, delivering a tensile strength of 9.43 ± 0.19 MPa, toughness of 25.90 ± 1.19 MJ m ⁻³ , conductivity of 2.55 ± 0.17 S m ⁻¹ , and freeze resistance. Notably, this strategy is universally applicable to a wide range of PVA‐based hydrogels, offering a robust and scalable route to high‐performance hydrogels for next‐generation humanoid robot sensors and flexible ionic devices.