Development of Hybrid Functional Thermoregulating and Thermochromic Microcapsules and Polyester Textiles

The aim of this research was to prepare a microencapsulated thermochromic system capable of thermal energy storage for thermal comfort and sensory applications in textiles and to demonstrate its efficacy when applied to polyester fabrics. Therefore, fluoran dye-based thermochromic systems (TSs) were prepared and microencapsulated in a poly(methyl methacrylate-co-methacrylamide) (PMMA-co-MAA) shell using the emulsion polymerization process. The systems contain a fluoran dye, phenolphthalein (PP), and 1-tetradecanol (TD). Scanning electron microscopy (SEM) images showed that the microcapsules were spherical and homogeneous in size. The microcapsules have a typical particle size of 12–15 μm, making them suitable for textile applications. The latent heat energy storage capacity of the microcapsules was satisfactory, with melting enthalpy values ranging from 144.2 to 176.1 J/g. Thermal gravimetric analysis (TGA) showed that the microcapsules disintegrated in two unique steps. The thermochromicity of the microcapsules was confirmed using a UV–Vis spectrophotometer, and photographic images were taken using a camera. The microcapsules were impregnated into 100% polyester fabric after causticizing and anionizing pretreatments. SEM images of the fabric showed the presence of packed, dense microcapsules within its structures. The fabric sample showed a darker color and improved color homogeneity. The hot-cold color measurements showed a total color difference (ΔE) of 19.08 to 23.97. The fabric sample containing microcapsules has a thermal energy storage capacity of 31.9 J/g when heated to 34.2°C.