A thermochromic luminous polyurethane based on long persistent luminescent phosphors and thermochromic pigment

Abstract

A thermochromic luminous polyurethane (TLPU), which can reversibly change its color and can exhibit fluorescence emission with the change in temperature, was prepared through incorporating long persistent luminescent phosphors (SrAl₂O₄:Eu²⁺,Dy³⁺) and thermochromic pigment (TP). X-Ray Diffraction (XRD) patterns, differential scanning calorimetry (DSC) curves, thermogravimetic analysis results (TG), UV-vis absorption spectra (UV), reflectance spectra and fluorescence spectra were obtained to characterize the properties of the resultant samples. The phosphorescence colors were directly related to the temperature because of the inner phase transition of the thermochromic pigment on heating. TLPU was red in daylight under low temperature conditions and turned white as the temperature rose. After the stoppage of excitation and in the dark, it emitted yellow light while cooling and turned green as the temperature increased.