Fabrication and reversible thermotropic characterization of polyurethane/dye microcapsules composite films for thermal management

In this study, the polyurethane/thermochromic dye microcapsules composite films with thermosensitive response have been prepared by solution casting technique. The structure and morphology of the thermochromic dye microcapsules and resulting composite films were characterized. Additionally, the mechanical properties and thermal stability were analyzed. Notably, the reversible thermotropic behavior and the phase change energy storage of the composite films for thermal management were investigated. The results revealed that, the thermochromic dye microcapsules exhibited a discoloration between 35 and 38 ℃. The composite film displayed a uniform color with a modulus of elasticity of 10.7±0.2 MPa when it contained 10 % thermochromic dye microcapsules. Moreover, the composite film exhibited excellent color changes upon heating and cooling, even after undergoing 100 cycles. Infrared thermal imaging confirmed the excellent heat retention properties of the composite film. Increasing the microcapsule content within the films can enhance energy storage capacity and thermal insulation. These composite films hold great potential applications in color conversion systems, daily body temperature monitoring, sensors and indoor thermal insulation.