(626a) Liquid Crystals Supported on Photocatalytic Surfaces

The long-range organization and high molecular mobility of liquid crystals (LCs) permit subtle changes in chemical interactions at solid surfaces to be amplified into dynamic LC responses on the optical scale. For example, prior studies have reported that LCs can be triggered to undergo orientational transitions at catalytic surfaces driven by dissociative adsorption, oxidation, and hydrogenation reactions. In this presentation, we will describe the results of a study in which we have explored how the photocatalytic activity of titania surfaces can influence the ordering of nematic LCs phases. Our approach integrates a range of surface characterization techniques such as polarization modulation infrared adsorption spectroscopy, ESI-mass spectrometry and X-ray photoelectron spectroscopy to experimentally characterize photocatalytic reactions in the presence of LCs. These measurements are complemented by first-principles calculations to obtain atomic-level insights into the interactions which govern the LC ordering. Our findings indicate that LCs can be actuated by surface photocatalytic processes to provide novel readouts of photocatalytic molecular transformations. For example, the LC response can be employed to identify competing interactions that involve water on the surfaces of photocatalysts. This presentation will also discuss the potential use of LCs to control the ligand environment of photocatalytic surfaces and thus their activity and selectivity.