A Versatile Approach to Stabilize Liquid-Liquid Interfaces using Surfactant Self-Assembly

Stabilizing liquid-liquid interfaces, whether between miscible or immiscible liquids, is crucial for a wide range of applications, including energy storage, microreactors, and biomimetic structures. In this study, a versatile approach for stabilizing the water-oil interface is presented using the morphological transitions that occur during the self-assembly of anionic, cationic, and nonionic surfactants mixed with fatty acid oils. The morphological transitions underlying this approach are characterized and extensively studied through small-angle X-ray scattering (SAXS), rheometry, and microscopy techniques. Dissipative particle dynamics (DPD) as a simulation tool is adopted to investigate these morphological transitions both in the equilibrium ternary system as well as in the dynamic condition of the water-oil interface. Such a versatile strategy holds promise for enhancing applications such as liquid-in-liquid 3D printing. Moreover, it has the potential to revolutionize a wide range of fields where stabilizing liquid-liquid interfaces not only offers unprecedented opportunities for fine-tuning nanostructural morphologies but also imparts interesting practical features to the resulting liquid shapes. These features include perfusion capabilities, self-healing, and porosity, which could have significant implications for various industries.|This article presents a versatile method for stabilizing the water-oil interface by inducing morphological changes in surfactant aggregates using oleic acid. This approach enables liquid-in-liquid 3D printing of complex structures with features such as self-healing, perfusion, and porosity. Morphological transitions as the underlying mechanism were confirmed and characterized by small-angle X-ray scattering, rheometry, and microscopy, along with simulations. image