Thermosensitive luminous fiber based on reversible thermochromic crystal violet lactone pigment

The aim of this work is to investigate the luminescence color changes of thermosensitive luminous fibers (TLFs). These TLFs are comprised of rare-earth luminescent materials as the luminescence sources, reversible thermochromic crystal violet lactone (CVL) pigment as the luminescence conversion agent, and polyacrylonitrile (PAN) as the matrix. It was found that the TFLs could not only change their color, but also convert the luminescence upon temperature change based on a structural transformation of the CVL pigment. X-ray diffraction (XRD) measurements indicated that rare-earth luminescent materials maintained their basic crystal structure and the CVL pigment was not destroyed by the process of spinning. The scanning electron microscopy (SEM) images of TLFs at the microcosmic angle showed that the CVL pigments were evenly distributed in the PAN matrix and formed a luminescence filter on the surface of the fiber. The differential scanning calorimetry (DSC) and thermogravimetry (TGA and DTG) results indicate that the TLFs possess satisfactory thermostability below 212.6 °C. The color and luminescence of the TLFs were accurately exhibited on the CIE 1931 chromaticity coordinates. The thermosensitive capability of TLFs was qualitatively verified by observing them in water at 40 °C and it was found that the fibers had brilliant luminescence and vivid thermosensitivity.