Polyelectrolyte-Mediated Colloidal Interactions at the Interfaces of Liquid Crystals

Nematic liquid crystals (LCs) are complex fluids within which molecules exhibit long-range orientational order leading to an anisotropic elasticity. When introduced into a LC host, colloidal particles (microcargo) elastically strain the LC and generate topological defects. Consequently, the microcargo experience strong repulsive forces near interfaces of LCs (e.g., LC-aqueous, LC-air interfaces). In this presentation, we will show that formation of polyelectrolyte and polyelectrolyte-surfactant complexes at a LC interface modulates the interactions of colloidal microcargo with that interface. We will describe elastic and electrical double layer interactions occurring at these interfaces and how the interplay of the two interactions is modulated by the formation of complexes of polyelectrolytes and surfactants. We will also illustrate how this competition of interactions can be used to trigger the release of microcargo from the LC.