Liquid crystalline droplets in aqueous environments: electrostatic effects.

We demonstrate the strong impact of electrostatic properties on radial-bipolar structural transitions in nematic liquid crystal (LC) droplets dispersed in different aqueous environments. In the experimental part of the study, we systematically changed the electrostatic properties of both LC droplets and aqueous solutions. Mixtures of nematics were studied by combining LC materials with negative (azoxybenzene compounds) and strongly positive (cyanobiphenyl) dielectric anisotropy. The aqueous solutions were manipulated by introducing either polyvinyl alcohol, glycerol, electrolyte or amphiphilic anionic surfactant SDS into water. In the supporting theoretical study, we identified the key parameters influencing the dielectric constant and the electric field strength of aqueous solutions. We also estimated the impact of different electrolytes on the Debye length at the LC-aqueous interface. The obtained results are further analysed for chemical and biological sensing applications.