Binary systems based on fatty acids and alcohols as bio-based thermochromic phase change materials for thermal energy storage

In this study, bio-based thermochromic phase change materials (TPCMs) were obtained for potential energy storage applications. The phenomenon of thermochromism enables the observation of color changes in TPCMs during phase transitions. Three-component thermochromic systems were prepared using bromocresol purple as the organic dye, stearic acid as the color developer, and behenyl alcohol as the organic solvent. Simultaneously, both fatty acid and alcohol acted as phase change materials. Different mass ratios of the components were prepared and analyzed. The resulting TPCM mixtures were examined by Fourier transform infrared spectroscopy, thermogravimetric analysis, differential scanning calorimetry, and thermal imaging. The obtained TPCMs exhibited high melting enthalpy (ca. 150–200 J g −1 ) in the temperature range of 50–70 °C, good thermal stability up to approximately 190 °C (T3% ≈ 190 °C), and a pronounced thermochromic response (Δ E ≈ 30). These materials show potential for application not only as phase change energy storage media, but also as colorimetric indicators.