(430a) Interfacial Engineering of Liquid Crystalline Materials

This presentation will describe recent progress in the engineering of interfaces of liquid crystalline materials. In particular, the talk will address the design of interfaces that permit subtle chemical and biochemical transformations to be amplified into ordering transitions in liquid crystals that occur on optical scales. Principles that are broadly applicable to the design of responsive, soft materials, and offer the basis of a new class of chemical and biological sensors, will be outlined. Two examples will be detailed to illustrate the challenges and opportunities. First, the design of surfaces that present transition metal ions that form coordination complexes with liquid crystals will be addressed. Ligand-exchange reactions involving these surface-immobilized metal ions will be shown to trigger ordering transitions in the liquid crystals. These systems permit reporting of parts-per-billion (by volume) concentrations of targeted toxic gases. Second, liquid crystal-in-water emulsions will be discussed, with a focus on understanding the influence of confinement and interfacial chemistry on the ordering of the liquid crystals within the droplets. Recent experimental observations have unmasked size-dependent ordering of the liquid crystalline droplets that is not predicted by classical theories of liquid crystals. These ordering transitions will be shown to be exquisitely sensitive to certain classes of biological lipids. Overall, the presentation will highlight fundamental challenges and technological opportunities related to the interfacial engineering of liquid crystals.