Self-Healable and Super-Tough Double-Network Hydrogel Fibers from Dynamic Acylhydrazone Bonding and Supramolecular Interactions.

Jiachuan Hua,Chang Liu,Bin Fei,Zunfeng Liu

doi:10.3390/gels8020101

Abstract

Macroscopic hydrogel fibers are highly desirable for smart textiles, but the fabrication of self-healable and super-tough covalent/physical double-network hydrogels is rarely reported. Herein, copolymers containing ketone groups were synthesized and prepared into a dynamic covalent hydrogel via acylhydrazone chemistry. Double-network hydrogels were constructed via the dynamic covalent crosslinking of copolymers and the supramolecular interactions of iota-carrageenan. Tensile tests on double-network and parental hydrogels revealed the successful construction of strong and tough hydrogels. The double-network hydrogel precursor was wet spun to obtain macroscopic fibers with controlled drawing ratios. The resultant fibers reached a high strength of 1.35 MPa or a large toughness of 1.22 MJ/m3. Highly efficient self-healing performances were observed in hydrogel fibers and their bulk specimens. Through the simultaneous healing of covalent and supramolecular networks under acidic and heated conditions, fibers achieved rapid and near-complete healing with 96% efficiency. Such self-healable and super-tough hydrogel fibers were applied as shape memory fibers for repetitive actuating in response to water, indicating their potential in intelligent fabrics.

Highlights

Hydrogels are soft materials with a crosslinked network structure
The ketone groups on the DAAM allowed the formation of dynamic acylhydrazone bonds with the aadddipinicg daidhipyidcrdazihiydderazide (ADH), which led to the gelation of PAD single network (SN) hydrogels
The IC SN hydrogels were prepared by facile cooling down

Summary

Introduction

Hydrogels are soft materials with a crosslinked network structure. Macroscopic fibers developed from functional hydrogels are ideal candidates for smart textiles (e.g., fibrous actuators [1], hygiene textiles [2] and flexible sensors [3,4,5]). Recent strategies include mechanochemical self-strengthening (e.g., self-growing [11], strain-induced crystallization [12] and stored length releasing [13]), the introduction of sacrificial structures (e.g., interpenetrating network [9,14] and supramolecular interaction [15,16]) and the prevention of crack propagation (e.g., nanocomposites [17,18,19] and macromolecular microsphere composites [20,21]) Among these strategies, double-network (DN) structures have been the most successful strategy to construct strong and tough hydrogels since the pioneering work was conducted in 2003 [22]. To avoid the embrittling caused by fractured polymer strands, the development of a self-healable network is essential for durable and reliable hydrogel fibers

Methods

Results

Conclusion