Tuning the stability of liquids by controlling the formation of interfacial surfactants

Abstract

Currently, maintaining the stability of liquids by nanoparticle surfactants is being widely investigated, while stabilizing liquids by supramolecular polymer surfactants is rarely involved. Herein, we combined small organic molecules dissolved in water with an amine group-functionalized hydrophobic polymer dissolved in oil to form surfactants at the liquid–liquid interface via electrostatic interactions. Then, interface assembly occurred to form supramolecular polymer surfactants with strong binding energy, thus avoiding the possibility of leaving the interface when the volume of droplets is reduced. Comparing the assembly of planar and non-planar organic small molecules at the interface by means of interfacial tension, wrinkling tests, compression–relaxation experiments, and laser confocal microscopy and scanning electron microscopy, we provide a strategy to tune the stability of liquids by controlling the surfactants formed at the interface. Its significance to the current market is demonstrated in the fields of catalysis, energy storage, separation, drug encapsulation, and preparation of sensors and microcapsules.