Water-in-oil nanostructured emulsions: towards the structural hierarchy of liquid crystalline materials

Abstract

We present novel water-in-oil (W/O) emulsions with a nanostructured oil phase that resemble soft materials such as creams, pastes and spreadable materials used in cosmetics, pharma and food applications. These emulsions have a broad structural hierarchy that involves 50 to 90 volume percent of micron sized water droplets (2–50 µm) confined by a continuous hydrophobic film that itself is made of a lyotropic nanostructure. This nanostructure can be modulated into inverse bicontinuous cubic, micellar cubic, inverse hexagonal or microemulsion phases. The novelty of these W/O nanostructured emulsions lies in (i) their preparation, which does not require any emulsion stabilizer, (ii) their hierarchical structure and intrinsic properties, which can be fine-tuned by varying temperature, water content and amount of oil and (iii) their ability to be loaded with hydrophobic, amphiphilic and hydrophilic functional molecules. Here, we present a systematic study along with the principles behind these dense nanostructured emulsions prepared, for the first time, from a monoglyceride system. High interfacial area, continuous architectural motif, enhanced water storage capacity and extensive tunability of these nanostructured emulsions open up new avenues in various scientific and technological applications.