MoS₂-Embedded, Interpenetrating Network Composite Hydrogels that Show Controlled Release of Dyes and Tunable Strength

This paper describes a conceptual design of hierarchical composite hydrogels. The hydrogel materials comprise MoS₂ flakes and interpenetrating polymer networks, and further exhibit controlled release and tunable strength that are caused by the synergistic combination of select components. In terms of design, MoS₂ flakes initiate radical polymerization of chosen monomers and simultaneously provide physical cross-linking points, both of which afford a primary composite network. Then, the sequential formation of additional networks results in functional, hierarchical, composite hydrogels. Therefore, we were able to demonstrate double-network hydrogels as a stimuli-responsive vector for programmed release of cargo molecules in response to heat or light or to form triple-network hydrogels showing tunable mechanical strength owing to intermolecular interaction between charged monomers and MoS₂ flakes. The design concept would be expanded by incorporating other chalcogenides or functional monomers, which advance the properties and functionalities of materials and broadens the versatility of nanocomposite hydrogels.