A novel photochromic PVA fiber aggregates contained H4SiW12O40

Poly(vinyl alcohol) (PVA)/H4SiW12O40 ultrafine fiber aggregates contained differential weight percentage of H4SiW12O40 to PVA (20, 60 and 80 wt.%, respectively) have been successfully prepared by electrospinning technique. By means of IR spectrum, wide-angle X-ray diffraction (XRD), and scanning electron microscope (SEM) techniques, the characterizations of the fiber aggregates have been reported. The photochromic property of the PVA fiber aggregates contained H4SiW12O40 has been found. The photochromic behavior of the fiber aggregates is investigated by means of UV-Vis spectra and electron spin resonance (ESR). The results show that the W atom of H4SiW12O40 is reduced via one-electron step and the color of the fiber aggregates changes from white to blue under ultraviolet irradiation. At the same time, alkoxy radicals form in PVA. The photochromism of the fiber aggregates is reversible in room condition. The ESR of the irradiated fiber aggregates indicates a conceivable photochromic mechanism.