Developing of thermal energy storing visual textile temperature indicators based on reversible color change

The aim of this study was to fabricate cotton and wool fabrics with both of thermoregulation and thermochromic properties. For this aim, three-component thermochromic systems (TCTS) were microencapsulated and applied to the pure cotton and wool textile fabrics. In the study, TCTSs consisting of crystal violet lactone (CVL), bisphenol A (BPA), and myristyl alcohol were microencapsulated in shell of poly(methyl methacrylate-co-methacrylic acid) (P(MMA-co-MAA)) by emulsion polymerization method. Microcapsule wall structures were designed to exhibit affinity for cotton and wool fibres under appropriate reaction conditions. Microcapsules having spherical shape, compact morphology and average size of 23.24 µm were prepared successfully. These microparticles exhibited latent heat energy storage capacity of 197.7 J/g and considerable thermal stability required for textile application process conditions. P(MMA-co-MAA)/TCTS microcapsules were applied to the cotton and wool textiles by exhaustion method. In the method, a substrate takes the chemicals in the bath and the affinity between the chemicals and substrate molecules is determinant on exhaustion process. The structural, colorimetric and thermal characteristics of the microcapsule applied fabrics were analyzed. The fabrics had reversible color change with a function of temperature. Their colors were blue at room temperature and original color of the fabric at temperatures above activation point of the thermochromic system. Additionally, the cotton fabric stored the latent heat of 23.4 J/g while the wool fabric stored the latent heat of 62.1 J/g. They exhibited thermoregulation property resulting from the absorbed latent heat.