Surfactant Mixtures and Their Effects on Controlling Size and Shape in Pure and Mixed Oil Drops

Droplets of some oils, such as hexadecane, when being around the size of 10-30 μm, stablised by surfactants and slowly cooled down, can spontaneously undergo shape transformations and related self-emulsification, which means breaking down to smaller droplets by itself. In this project, I used optical microscope to monitor the shape changing. I found that the stability of droplets during shape transformation is related to the rotator phases formed between the oil and the water. I also investigated the minimum surfactant requirements for inducing self-shaping of oil droplets and competitive adsorption effects. My work from this project features in Soft Matter.

Image: Shape transformations of oil droplets under cooling. Depending on the size and cooling rate, different shapes can be formed.