Solvatochromic characterization of organic-inorganic polymer hybrids with pyridinium N-phenolate betaine dyes

We have estimated the local polarity in organic-inorganic polymer hybrids by employing solvatochromic pyridinium N-phenolate betaine dyes. Solvatochromic polymer was prepared by introducing Reichardt's betaine dye in the side chain of poly(2-methyl-2-oxazoline), and the model compound for the dye unit was also prepared. Polymer hybrids were prepared from these compounds and mixtures of various proportions of tetramethoxysilane (TMOS) and methyltrimethoxysilane (MeTMOS). The electronic absorption spectra were measured by the diffuse reflectance method. It was found that the local polarity in the polymer hybrids was affected by both the TMOS:MeTMOS ratio and the presence of the organic polymer. In addition, it was suggested that the dye molecules are preferentially surrounded by the organic polymer rather than the siloxane network in the polymer hybrids.