Continuous Spinning of High‐Tough Hydrogel Fibers for Flexible Electronics by Using Regional Heterogeneous Polymerization

Abstract Hydrogel fibers have attracted substantial interest for application in flexible electronics due to their ionic conductivity, high specific surface area, and ease of constructing multidimensional structures. However, universal continuous spinning methods for hydrogel fibers are yet lacking. Based on the hydrophobic mold induced regional heterogeneous polymerization, a universal self‐lubricating spinning (SLS) strategy for the continuous fabrication of hydrogel fibers from monomers is developed. The universality of the SLS strategy is demonstrated by the successful spinning of 10 vinyl monomer‐based hydrogel fibers. Benefiting from the universality of the SLS strategy, the SLS strategy can be combined with pre‐gel design and post‐treatment toughening to prepare highly entangled polyacrylamide (PAM) and ionic crosslinked poly(acrylamide‐ co ‐acrylic acid)/Fe 3+ (W‐PAMAA/Fe 3+ ) hydrogel fibers, respectively. In particular, the W‐PAMAA/Fe 3+ hydrogel fiber exhibited excellent mechanical properties (tensile stress > 4 MPa, tensile strain > 400%) even after 120 days of swelling in the pH of 3–9. Furthermore, owing to the excellent multi‐faceted performance and one‐dimensionality of W‐PAMAA/Fe 3+ hydrogel fibers, flexible sensors with different dimensions and functions can be constructed bottom‐up, including the one‐dimensional (1D) strain sensor, two‐dimensional (2D) direction sensor, three‐dimensional (3D) pressure sensor, and underwater communication sensor to present the great potential of hydrogel fibers in flexible electronics.