Liquid Crystal Coated Fabrics

Cholesteric liquid crystals (LC) have the optical property of reflected color because of their helical structure. Their color changes in response to a temperature change or mechanical stimuli due to changes in the helical pitch. Thus, incorporating such liquid crystals into fabrics is of interest to achieve responsive materials. To achieve responsive materials in this work, we examined liquid crystal fabric coatings. The effect of fabric type, emulsification of the liquid crystal before application, as well as the use of top coats on the responsive properties of the fabric were investigated. Specifically, six fabrics (knit cotton, twill cotton, twill lyocell, knit rayon/spandex blend, woven rayon/spandex blend, and woven nylon) were coated with liquid crystal alone, liquid crystal-polymer emulsion, or a liquid crystal-polymer emulsion with a polyurethane top coating. Image analysis in CIE L*a*b* color space was performed to determine if the color of the liquid crystal was affected by processing. Overall, emulsification and coating of the liquid crystal in a water soluble polymer improved the brightness (increased L-value). Processing (emulsification and application to the fabric) did shift the color compared to the liquid crystal alone as the color difference (ΔE) was 24.0 ± 5.0. Further analysis using UV-vis reflectance spectroscopy and polarized light microscopy are ongoing.