Polymer gel/organic dye complexes in aqueous salt solutions

The present work is devoted to the study of the complex formation of polymer gel with organic dye and their properties in the aqueous salt solutions. Two systems were studied: 1) polyelectrolyte gel based on poly(diallyldimethylammonium chloride) and water soluble oppositely charged organic dyes (alizarin red S and catechol violet) and 2) organogel based on poly(N-vinylcaprolactam) and dithizone. The collapse of the polyelectrolyte gels in the presence of oppositely charged dyes together with the effective absorption of dyes was observed. The shrinking degree and the dye absorption by the gel depends on the dye concentration. In the case of PVCa gel in organic media the dye absorption takes place. The main attention has been concentrated on the study of the behaviour of gel/dye complex immersed in the salt solution if dye is the chelating ligand for metal ions. It was shown that polyelectrolyte gels generally form stable complexes with oppositely charged dyes. The behaviour of PVCa-dithizone-chloroform system was studied in AgNO₃ aqueous solution. The release of dithizone to the external aqueous solution of AgNO₃ reservoir is completely suppressed. Absorption spectra of gel/dye and gel/dye/metal ion systems were studied. It was shown that metal ions penetrate inside the gel phase and the dye/metal ion complexes form within the gel. The dependence of the optical density for the systems of gel/dye/metal ion on the salt concentration is observed.