Facile Synthesis of Sustainable High Internal Phase Emulsions by a Universal and Controllable Route

We demonstrate a universal route for facile synthesis of high internal phase emulsions (HIPEs), requiring only the centrifugation of ultrasonically produced oil-loaded microspheres. By sonochemically cross-linking the dispersant layer at the oil/water interface, we can engineer these microspheres against coalescence under high centrifugal force, while simultaneously obtaining a high internal phase volume fraction up to 89.5%. The properties of these HIPEs and resulting porous materials can be controlled by simply adjusting the acoustic intensity. We can also deposit the non-cross-linked dispersed materials back to the microsphere surface, creating an extra electrostatic layer and polyelectrolyte complexes coating, thus further reinforcing the processability of HIPEs. Our strategy could work for nearly any material as long as it can be cross-linked during acoustic cavitation. Thus, these scalable HIPEs can be fully sustainable as they are solely stabilized by natural materials, such as proteins and polysaccharides (as low as 0.5 wt %), without introducing any additional surfactants or synthetic particles, or requiring the additional synthesis of Pickering emulsions.