Spectroscopic investigation of a gelling agent included in poly(dimethylsiloxane) gels

Poly(dimethylsiloxane) gels containing different amounts of cholesteryl anthraquinone-2-carboxylate (CAQ), used as a gelling agent, have been prepared and the phosphorescence spectra of CAQ contained in the gels were measured at 77 K. Two forms of CAQ, free and crystalline, were identified through the phosphorescence measurements, and the relative amounts were determined. It is shown that the relative amount of crystalline CAQ in the gel decreases with decreasing bulk CAQ content.