A General Route for Nanoemulsion Synthesis Using Low Energy Methods at Constant Temperature

The central dogma of nanoemulsion formation using low energy methods at constant temperature – popularly known as the emulsion inversion point (EIP) method – is that the continuous phase should be added to a mixture of dispersed phase and surfactant. Here, we demonstrate that the above order of mixing is not universal and a reverse order of mixing could be superior depending on the choice of surfactant and liquid phases. We propose a more general methodology to make nanoemulsions by studying the variation of droplet size with surfactant HLB for several model systems. Based on our understanding and experimental results, we utilize the reverse order of mixing for two applications: crystallization and formulation of pharmaceutical drugs with faster dissolution rates, and synthesis of alginate-based nanogels. The general route provides insights into nanoemulsion formation through low energy methods and also opens up possibilities that were previously overlooked in the field.