Photochromic organic-inorganic polymer hybrids from spiropyran-modified poly(N,N-dimethylacrylamide)

Photochromic organic-inorganic polymer hybrids were prepared by the sol-gel reaction of tetramethoxysilane (TMOS) in the presence of spiropyran-modified poly(N,N-dimethylacrylamide) 3. The obtained polymer hybrids were characterized by thermogravimetric analysis (TGA) and FT-IR, and photochromic behavior was followed by electronic absorption spectroscopy. Upon an irradiation of ultraviolet light, an absorption around 557 nm appeared in the visible region and the color of the hybrid turned to be violet. The effect of silica gel on the isomerization behavior seemed to be relatively small.