Complex High-Internal Phase Emulsions that can Form Interfacial Films with Tunable Morphologies.

High-internal phase emulsions (HIPEs) were considered as an important functional material and have been the focus of intense development effort, but their fundamental attributes have hardly been altered at either the microcosmic or macroscopic level, which severely limits their practical applications in various areas. In this work, we report a general strategy for creating complex HIPEs that can form interfacial films at liquid interfaces. Double HIPEs and Janus HIPEs are both realized for the first time. They feature complex microscopic patterns with short-range anisotropy and exhibit non-Newtonian pseudoplastic flow behavior. By taking advantage of their response to a high-pH subphase, interfacial films can be successfully obtained, which are tunable in thickness and morphologies under compression. Complex HIPEs can greatly expand the applications of liquid materials, and the interfacial films of droplets represent an important step toward producing 2D soft materials with a unique functionality that can be broadly applied to biological processes.