| Abstract: | Nanocomposite films based on cross-linked polyvinyl alcohol (PVA) and phosphotungstic acid (PTA), in which PTA plays the roles
of photochromic component and catalyst of the chemical cross-linking of PVA with glutaric aldehyde (GA), were synthesized.
The formation of chemical cross-links in a polymer matrix of nanocomposite films occurring during their formation from PVA-PTA-GA
aqueous solutions, was confirmed by IR spectroscopy. It was found that the cross-linkage of a polymer matrix imparts water
resistance to PVA/PTA nanocomposites and changes their photochromic properties. By analyzing the electronic absorption spectra
of photocolored films, it was shown that PTA anions in the matrix of non-cross-linked PVA upon photoreduction receive only
one electron, while not only one-electron but the two-electron reduction of PVA anions occurs in a cross-linked PVA matrix.
The photocolorabilty of films based on cross-linked PVA is thus two times higher than that of films based on non-cross-linked
PVA. It was found that the rate of discoloration of photocolored PVA/PTA films increases with an increase in the degree of
cross-linking of a polymer matrix. |
