Аннотация:The interaction of a lightly cross-linked cationic hydrogel based on poly(diallyldimethylammonium chloride) with oppositely charged water-soluble dyes (Alizarin Red S monohydrate and Pyrocatechol Violet) was studied. The effective absorption of dye by gel in the systems studied results in the gel collapse. The absorption spectra of the gel-dye complexes were studied and it was found that dye molecules immobilized in the gel and those in an aqueous solution have different absorption spectra at the same dye concentration. Stability of the gel-dye complexes in aqueous NaCl and Al-2(SO4)(3) solutions was studied as dependent on the salt concentration. The complexes are stable in these salt solutions, the fraction of separated dye not exceeding 10% of the absorbed amount in the entire concentration range studied. The absorption spectra of the gel-dye-Al3+ complexes were studied. They indicate formation of the intracomplex dye-metal ion compounds in gel, which leads to additional contraction of the gel.