Self-healing hydrogels: mechanisms and applications in biomedical and environmental fields.

This review offers a critical synthesis of the rapidly developing topic of self-healing hydrogels, focusing on the unresolved trade-off between healing efficiency and mechanical robustness that currently restricts their practical application. By systematically analyzing the literature on dynamic covalent (e.g., Schiff base, boronate ester) and non-covalent (e.g., hydrogen bonding) mechanisms, we evaluate how specific molecular architectures affect performance in complicated environments. In terms of the human body (tissue engineering), dynamic covalent systems are the most stable; however, they often show slower healing kinetics than supramolecular networks, which can restore structure in a matter of seconds but frequently fail under load-bearing conditions. Furthermore, the study emphasizes that the hydrogels have high adsorption rates for heavy metals in environmental applications; still, their long-term reusability is often reduced due to the loss of strength under extreme pH conditions. Consequently, unlike previous general reviews, the current study draws a direct connection between the crosslinking density and the rate of self-repair, eventually suggesting that future research should focus on developing the orthogonal dual-network structures to separate the mechanical strength from the healing speed for both biomedical and industrial applications.