Reversible emulsification based on pH-responsive surfactant with dynamic imine bond

Abstract

Efficient demulsification of emulsions is crucial in heavy oil transportation, interfacial reactions, and emulsion polymerization applications. Surfactants that are responsive to the environment have the ability to alter their surface activity in a dynamic manner. However, these types of surfactants typically require a significant amount of energy and may be less efficient. The present study involved the preparation of a surfactant with dynamic covalent bonding and pH-responsive property. This was achieved through the creation of dynamic imine bonds between decyloxybenzaldehyde (DOBA) and sodium 3-amino-1-propanesulfonate (AP) via a Schiff base reaction to synthesize dynamic covalent surfactant CB. The present study aimed to investigate the impact of various pH environments on the conversion rate and interfacial tension of surfactant CB. To achieve this objective, 1H NMR, FTIR, and IFT tests were conducted. The results confirmed the reversible conversion of the dynamic imine bond with pH. Furthermore, the dynamic imine bonded surfactant demonstrated the ability to complete at least three emulsification-breakage cycles. The present investigation introduces a novel approach for the synthesis of pH-responsive surfactants through the utilization of dynamic covalent bonds.