Journal of Materials Science and Chemical Engineering, 2014, 2, 1-7 Published Online November 2014 in SciRes. http://www.scirp.org/journal/msce http://dx.doi.org/10.4236/msce.2014.211001 How to cite this paper: Bera, T. and Fang, J.Y. (2014) Interaction of Surfactants and Polyelectrolyte-Coated Liquid Crystal Droplets. Journal of Materials Science and Chemical Engineering, 2, 1-7. http://dx.doi.org/10.4236/msce.2014.211001 Interaction of Surfactants and Polyelectrolyte-Coated Liquid Crystal Droplets Tanmay Bera, Jiyu Fang Department of Materials Science and Engineering, University of Central Florida, Orlando, USA Email: Jiyu.Fang@ucf.edu Received 17 August 2014; revised 11 September 2014; accepted 2 October 2014 Copyright © 2014 by authors and Scientific Research Publishing Inc. This work is licensed under the Creative Commons Attribution International License (CC BY). http://creativecommons.org/licenses/by/4.0/ Abstract It is known that the adsorption of surfactants at the liquid crystal (LC)/aqueous interface can in- duce a bipolar-to-radial director configuration of LC droplets dispersed in aqueous solution. In this paper, we study the effect of charged polyelectrolyte-coating on the interaction of surfactants and LC droplet cores by observing the director configuration of the LC droplet cores as a function of surfactant concentrations. It is found that surfactants can penetrate into the polyelectrolyte coating and react with the LC droplet cores to induce the bipolar-to-radial transition of the LC in- side the droplet cores. However, the concentration of charged surfactants required to induce the configuration transition of the LC droplet cores is affected by the charged polyelectrolyte coating. The effect is significantly enlarged with decreasing the alkyl chain length of charged surfactants. Our results highlight the possibility of engineering polyelectrolyte coatings to tune the interaction of LC droplets with analysts, which is critical towards designing LC droplet based sensors. Keywords Liquid Crystals, Droplets, Polyelectrolyte Coatings, Surfactants, Configuration Transitions 1. Introduction Liquid crystal (LC) droplets dispersed in aqueous solution are an interesting stimuli-responsive material [1]. They have been used as a model system for studying particle rotations [2] [3], optical momentum transfers [4], and optical vortex generations [5]. In recent years, LC droplets have also emerged as a unique optical probe for the detection of chemical and biological species and their reactions at the surface of the droplets [6]. The director configuration of LC droplets is known to reflect the balance between the elasticity and the surface anchoring of