Colloidal latex / liquid crystal coatings for thermochromic textiles

Abstract

Latex is a colloidal dispersion of polymeric particles dispersed in water. They can be used to make complex dispersions of a complex mixture of pigments, surfactants etc. that are stable for long periods of time. In this paper we report cholesteric liquid crystals (CLCs) dispersed in a commercial water-based latex varnishes coated on fibers and fabrics. The CLC-latex coatings displayed bright, stable colors that change with temperature. The optical and stability properties of CLC-latex coated polyester fibers and fabrics are compared with previously reported LC materials. We find that the enhanced brightness of the latex coated materials is a result of the flattening of the phase separated CLC droplets during water evaporation from the latex varnishes. Owing to the stability of the commercial latex varnishes to UV irradiation and water exposure, these CLC-latex coatings are durable, environmentally friendly, inexpensive, and easy to coat on fibers and fabrics. The resulting smart textiles could be used for numerous biosensing, medical and decorative applications.