Scanty-water oil-in-water emulsion glasses synthesized through a low-energy process: Nucleation and growth mechanism

The solid-like oil-in-water (O/W) emulsion can be classified into two types, gelator-induced gel and gelator-free glass, based on the requirement of gelator addition and solidification mechanisms. In this work, the O/W emulsion glass with scanty-water belonging to the gelator-free type was successfully fabricated through a low-energy process even when the content of aqueous surfactant solution was as low as 1 wt%. In an attempt to develop this scanty-water O/W glass, two newly designed approaches subject to mechanical agitation were proposed. The first approach of glass formation was induced by the growth of glass nuclei, which is similar to the mechanism of crystal growth. In the second approach, the water content in the emulsion was diluted by oil addition, leading to the direct transformation from emulsion to glass. Both approaches undergo a crossover associated with the jamming transition. According to rheological measurements, our emulsion glasses possess solid-like behaviors such as elastic modulus and yield stress. Moreover, the O/W glass with scanty-water can be strengthened by reducing the water content.