Transparent thermochromic VO2/PAN nanocomposite films prepared by electrospinning-hot pressing technique

The global energy consumption in the building sector is enormous annually, and the energy consumed in the building part is mainly used for heating, ventilation, and air conditioning. Smart windows can effectively reduce the energy consumed for heating, ventilation, and air conditioning. Vanadium dioxide (VO2) has been widely used in the preparation of thermochromic smart window films due to its excellent properties, but the low luminous transmittance of VO2-based smart films has been one of the main issues limiting their application. In this paper, we utilized the electrospinning technology to prepare VO2/PAN nanocomposite films with polyacrylonitrile (PAN) as the matrix and VO2 as the filler. Then, the VO2/PAN nanocomposite films were heattreated by the hot pressing technique. The VO2/PAN nanocomposite films with excellent performance were finally obtained. VO2/PAN nanocomposite films had stable morphology, uniform VO2 distribution, and high thermal stability. Besides, the hot-pressing process could significantly improve the mechanical properties of the films, and the maximum tensile strength of VO2/PAN nanocomposite film was 24.15 MPa. Moreover, according to UV-vis spectra, when the loading of VO2 was 20 %, the luminous transmittance (Tlum) of VO2/PAN nanocomposite film was 68.66 % and the solar modulating ability (Delta Tsol) was 0.28 %. Hence, this research offered a new option for the preparation of energy-saving materials that could replace smart glass.