Controlled microphase separation and strain programming in hydrogel fibers toward biomimetic architectures and properties

In contrast to conventional high-strength, high-modulus fibers, spider silk uniquely combines high toughness, strength and diverse functionalities, enabling spiders to thrive in natural environments. However, replicating the sophisticated architecture and properties of spider silk through synthetic approaches, particularly via scalable fiber manufacturing processes, remains a formidable challenge. Herein, we report the tailored fabrication of spider silk-like structures in sodium polyacrylate and polyacrylamide (PANa-PAM) composite polymer hydrogel fibers via wet-spinning. The antisolvent-induced phase separation process modulates composite polymer microphase, yielding nascent PANa-PAM fibers abundant in hydrogen-bonded nanoclusters. Subsequent post-drawing for strain programming facilitates uniaxial polymer alignment and controlled crystallization. The optimized fiber comprises aligned microfibrils, polymer-rich rigid nanoclusters surrounded by polymer-loose regions, and β-sheet-like crystallites, closely mimicking the hierarchical architecture of natural spider silk. As a result, the composite fiber achieves a comprehensive set of spider silk-like properties and functionalities, including a toughness of 118.7 MJ m^-3, a tensile strength of 172.3 MPa, 50% elastic strain recovery, 96% damping efficiency, 60% supercontraction, and moisture sensitivity. This bioinspired wet-spinning of composite polymer hydrogels offers a pathway to replicate biological fiber structures and attributes, enabling the production of high-performance and intelligent fibers for wearable technologies.