Recent progress on the application of imine-based surfactants in emulsion systems: from delivery systems to...

Emulsions often face separation and degradation challenges under external stimuli such as pH shifts, temperature fluctuations, and ionic strength variations in complex mixtures during processing and storage. Conventional stabilization approaches often involve processing complexity, high energy cost, and risk of degrading sensitive components. Imine chemistry presents a transformative alternative by leveraging dynamic covalent bonds, where the reversible formation of a (C=N) linkage via condensation enables to create intelligent, responsive emulsions. Formation of imine-based surfactants through in situ reactions between amine and aldehyde precursors is a simple and shorter step that not only stabilizes interfaces but also confers unique functionalities, offering dynamic control over emulsion stability. These imine-based surfactants exhibit a highly tunable hydrophilic-lipophilic balance, reversible emulsification behavior, and exceptional pH responsiveness due to the acid-labile nature of the imine bond. This review critically evaluates the molecular design, synthesis, and interfacial mechanism of imine-surfactants, highlighting their application in developing responsive emulsion systems for targeted drug delivery, enhanced oil recovery, biosensing, and food production.