Phase Transition Triggering in a Liquid Crystal Droplet

Liquid crystals (LCs) are a class of molecules that form a variety of phases easily influenced by external interactions. Of particular interest are rod-like LC molecules confined to a spherical geometry, which have a competition between interfacial tension and elastic deformations. The phase of the liquid crystal inside a droplet can be controlled using surfactants, influencing the boundary conditions, in an oil-in-water emulsion. Here, we test the effects of the surfactant sodium dodecyl sulfate (SDS) on the phase of polydisperse LC droplets in an aqueous background examining different diameter sizes and SDS concentrations. We trigger phase transitions by the increase or decrease of SDS concentration while observing an individual LC droplets held in place using an optical tweezer. The dynamic phase transitions are compared to previous molecular dynamic simulations that predicted the intermediate states of the LC inside the droplets. We observe a hysteresis in the SDS concentration that induces the phase transition from radial to bipolar and back as well as a fluctuation in state when the phase transition starts.