In-situ synthesis of MOF nanoparticles in double-network hydrogels for stretchable adsorption device

Metal-organic framework (MOF) composites shaped by hydrogels have the advantages of abundant pores, diverse functional groups, and excellent flexibility, showing tremendous potential in many fields. However, many used hydrogels are prepared by chemical cross-linking or polymerization reactions, and the synthesized MOF microparticles are aggregated and easily fall out. Here, we report the in-situ synthesis of MOF nanoparticles (< 100 nm) in the poly(vinyl alcohol)@alginate double-network hydrogels, which are further used for fabricating stretchable MOF hydrogel tubes. The high-modulus nanoparticles can serve as strong crosslinks and enhance the entanglements of polymer chains, improving the mechanical properties of the composites significantly. Furthermore, the porous nanoparticles endow the hydrogels with unique recovery behavior from compression and good adsorption properties. This study opens up new horizons in the controllable preparation of soft MOF hydrogel composites for many promising applications.