Multi‐Responsive Supramolecular Hydrogels Derived from Gemini Surfactants for Visual Recognition of Isomerization

Abstract

A new series of gemini surfactants containing azobenzene moieties with different alkyl chains (TMn, n denotes the number of carbon atom in alkyl chains) were successfully designed and synthesized. And then, their gelation abilities in water were evaluated in detail. It was found that stable supramolecular hydrogels could be formed at room temperature when n=8 (TM8), in which TM8 molecules self‐assembled into ordered bilayer aggregates via intermolecular hydrogen bonding and π‐π stacking interactions. Moreover, this kind of hydrogel exhibits excellent mechanical property and thermo‐reversibility. Interestingly, the TM8 molecule can be well‐recognized by α‐cyclodextrin (α‐CD) via host‐guest interactions. When α‐CD is added to the TM8‐H2O system, the corresponding hydrogel displays photo‐sensitive characteristics under irradiation of UV light (365 nm). As a conversion material, this multi‐responsive supramolecular hydrogel has great potentials in the smart switch field.