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 mu m, 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 (Delta E) 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 degrees C.