COF/Hydrogel Composites: From Interface Design to Multifunctional Applications

Covalent organic frameworks (COFs) have emerged as premier candidates for advanced functional materials due to their permanent porosity, high crystallinity, and tunable chemical structures. However, their inherent rigidity and poor processability often limit their direct application in flexible and integrated devices. Integrating COFs with hydrogel matrices offers a synergistic solution, combining the molecular-level precision of COFs with the superior mechanical flexibility, high water content, and biocompatibility of hydrogels. This review systematically summarizes the recent progress in COF/hydrogel composites, focusing on interface design strategies including physical blending, in-situ growth, and covalent cross-linking. We highlight how these design principles modulate the synergistic effects between the components to enhance ion transport, catalytic activity, and mechanical durability. Furthermore, we provide a comprehensive overview of their multifunctional applications in environmental remediation (heavy metal and organic pollutant removal), energy storage (zinc-ion batteries and supercapacitors), biosensing (wearable strain sensors and clinical diagnostics), and biomedical engineering (diabetic wound healing and bone tissue regeneration). Finally, the current challenges and future perspectives of COF/hydrogel composites are discussed, aiming to provide a roadmap for the development of next-generation soft-matter materials.