Switchable Photonic Bio‐Adhesive Materials. Issue 42 (2nd September 2021) - Kim, Minkyu
Abstract: A soft photonic bio‐adhesive material is designed with real‐time colorimetrical monitoring of switchable adhesion by integrating a responsive bio‐photonic matrix with mobile hydrogen‐binding networking. Synergetic materials sequencing creates a unique iridescent appearance directly coupled with both adhesive ability and shearing strength, in a highly reversible manner. The responsive photonic materials, having a physically hydrogen‐bonded chiral nematic organization, vary their adhesion strength due to a transition in cohesive and interfacial failure mechanism in humid surroundings. The bright color appearance shifts from blue to red to transparent and back due to a change in pitch length of the chiral helicoidal organization that also triggers coupled changes in both mechanical strength and interfacial adhesion. Such reversible strength‐adhesion‐iridescence triple‐coupling phenomenon is further explored for design of super‐strong switchable bio‐adhesives for synthetic/biological surfaces with quick remotely triggered sticky‐to‐nonsticky transitions, removable conformal soft stickers, and wound dressings with visual monitoring of the healing process, to colorimetric stickers for contaminated respiratory masks. Abstract : A soft photonic bio‐adhesive demonstrates large reversible changes in adhesion power and mechanical strength with concurrent self‐reporting colorimetric responses. This coupled behavior is derived by the humidity‐driven intercalation/removal of water molecules into a glucose‐containing hydrogen‐bonded polymer network within a liquid crystal polysaccharide matrix that triggers tightly correlated changes in mechanical strength, adhesion, and pitch length of the chiral nematic organization.