Fatigue-resistant Hydrogels with Programmable Crystalline Domain Crosslinking Enabled by Coordinated Thermal-Solvent Strategy

Abstract

Hydrogels are considered ideal candidates for ligament repair owing to their inherent flexibility, biocompatibility, and ease of processing. However, current hydrogel materials face critical challenges in artificial ligament applications, including insufficient strength, poor fatigue resistance, and the lack of real-time health monitoring capabilities, which severely limit their clinical use. Herein, a simple strategy for synergistically enhancing the mechanical strength of hydrogels through wet annealing and solvent exchange was developed. Wet annealing initially promotes the formation and growth of crystalline domains, while subsequent gradient solvent exchange with a deep eutectic solvent (DES) strengthens intermolecular interactions, inducing further growth of crystalline domains. As a result, a hydrogel (WE-PVA) with a high density of crystalline domains was constructed. Interestingly, WE-PVA exhibits excellent tensile strength (7.8 MPa), outstanding fatigue resistance (Γ = 4210 J·m-²), and long-term stability, highlighting its great potential for practical applications in artificial ligaments. Moreover, WE-PVA demonstrates remarkable sensing capabilities, enabling real-time monitoring of ligament status, further enhancing its functional value. This strategy provides a simple and versatile approach for designing hydrogels with both high strength and fatigue threshold, and holds significant promise for applications requiring superior mechanical performance.