A new thermochromic crystal violet lactone/lactic acid/myristyl alcohol ternary mixture encapsulated with a...

Two thermochromic poplar-based composites, TPC-1 and TPC-2, were fabricated using a crystal violet lactone (CVL)/lactic acid/myristyl alcohol ternary mixture. The mass ratios for TPC-1 and TPC-2 were 10: 3: 200 and 10: 80: 200, respectively. TPC-1 exhibits a common thermochromic property, reversibly changing color from blue to the natural hue of poplar within the temperature range of 28-48 °C. In contrast, TPC-2 demonstrates a novel thermochromic behavior, shifting from light blue to dark blue within the range of 30-52 °C. This work elucidates the correlations between the distinctive mass ratios in the ternary mixtures, the resulting CVL structures, and the consequent thermochromic properties. The blue TPC-1 exhibits an open lactone ring with a HO-C=O in its CVL structure. Similarly, the light-blue TPC-2 displays an open lactone ring with a HO-C=O. However, the dark-blue TPC-2 features an open lactone ring with a HO-C=O and a C-O-C. TPC-2 is a ternary mixture encapsulated with a poplar-based cellulose/lignin/SiO₂ framework. This integrated framework chemically interacts with the ternary mixture, enhancing phase-changing properties, heat-saving capabilities and mechanical properties of TPC-2. Consequently, TPC-2 is a promising candidate for applications as a temperature-responsive, thermal energy-storing, and structural material in building interiors.