Sonochemically Synthesized Ultrastable High Internal Phase Emulsions via a Permanent Interfacial Layer

In this work, we demonstrate sonochemically synthesized high internal phase emulsions (HIPEs), which feature high stability due to a permanent layer at the oil-water interface that nearly any material can form as long as it can be cross-linked during acoustic cavitation. Compared to conventional HIPEs prepared by homogenization emulsification, these ultrasonically prepared HIPEs exhibit excellent performance, including high tolerance to environmental shock (e.g., pH and surfactant) and excellent processability, as well as the capacity to structure liquid oil and provide controlled delivery for bioactive compounds. By changing the acoustic intensity, we can also easily tune the morphology, rheological properties, porosity, and closed-/open-cell structure of the porous materials. Furthermore, this unique type of HIPE is potentially sustainable because it can be stabilized solely by natural materials, such as proteins and polysaccharides, even at 0.5 wt %, without introducing any additional surfactants or synthetic particles. These findings suggest this sonochemical technique holds promise as a versatile, scalable, and environmentally friendly route for synthesizing ultrastable and fully natural HIPEs. Additionally, the material performance shown herein provides a proof-of-concept for the design of multifunctional HIPEs in various applications.