Spectral characteristics of the neutral-red organic dye in aqueous glycerol solutions and polyvinyl alcohol films

The subject of the study was the optical properties of aqueous glycerol solutions of the neutral-red organic dye and polyvinyl alcohol (PVA) films into which this dye is introduced from these solutions. The purpose of the work was to examine the spectral characteristics of the neutral-red organic dye in aqueous glycerol solutions and PVA films in the ultraviolet, visible, and near-infrared ranges and to investigate the features influenced by the polymer matrix. Method. The method involved preparation of solutions by mixing glycerol, water, and dye in appropriate proportions and producing films by drying dye-containing water–glycerol mixtures on glass substrates. Absorption spectra, in the wavelength range of 190–1100 nm, were obtained using a spectrophotometer. Main results. Results showed that the characteristic absorption bands of the dye were significantly affected by the polymer matrix, whereas the addition of glycerol resulted in only minor changes. A noticeable shift in the infrared absorption peak of water, due to glycerol, was observed in the solution spectra. Practical significance. The investigated PVA-based film materials with color additives, including those plasticized with glycerol, have potential applications in the fabrication of optical filters, flexible polarizers, and other components used in applied optics.