Morphological Evolution, Mechanical Properties and Hygroscopicity Behaviour of Hydrogel Fibres
Hydrogel fibres exhibit exceptional moisture-absorbing capacity and high specific surface area, yet their internal structural dynamics directly govern mechanical strength and hygroscopic performance. This review critically examines thirty years of global research on hydrogel fibres, focusing on morphological evolution, mechanical reinforcement strategies, and moisture-absorption mechanisms. Key preparation techniques—microfluidic spinning, electrospinning, extrusion spinning, wet spinning, gel spinning, and 3D printing—are evaluated for their influence on fibre architecture. The review identifies hydrogen bonding as a central factor in mechanical integrity and hygroscopicity, and discusses trade-offs between swelling rate, tensile strength, and flexibility. Recent advances in conductive, biocompatible, and transparent hydrogel fibres have enabled applications in smart clothing, tissue engineering, chemical separation, and brain-computer interfaces. However, persistent challenges include structural instability under cyclic loading, uncontrolled swelling, and scalability barriers. By synthesizing empirical data from 32 key studies, this work provides a roadmap for optimizing fibre performance through judicious selection of starting materials and process parameters. The analysis underscores the need for standardized testing protocols and predictive models linking internal morphology to macroscopic properties. Future directions emphasize hybrid material systems and continuous manufacturing routes to unlock transformative potential in healthcare, textiles, and intelligent wearables.