Textural landscapes of VOC-sensitive chiral liquid crystal-based materials

Abstract

Liquid crystal-based materials, in which liquid crystal molecules are confined and ordered in compartments, are dynamic materials yielding a variety of optical textures that can be tuned as a response to physical and chemical stimuli. While nematic and smectic-based gel materials have been reported as dynamic optical sensors to report volatile organic compounds (VOCs), chiral systems are less explored despite having the potential to yield extremely rich optical landscapes. Here, we report for the first time the confinement of chiral liquid crystal formulations by an interface formed by ionic liquid molecules. The resultant self-assembled ionic liquid/liquid crystal droplets are simultaneously immobilized on a gelatin matrix. The droplets feature a rich variety of unique topological states. We explored, by means of polarizing optical microscopy, the various droplet optical textures and categorized them with regard to their relative chirality parameter. We further investigated their optical response in the presence of gas analytes and discussed their potential utilization as dynamic liquid crystal-based optical VOC sensors. The newly generated soft materials with semi-selective VOC sensing capabilities can be further utilized in arrays of liquid crystal-based gas sensors for the analysis of complex gas samples using artificial olfaction approaches.