Selenopentathionate anions are sorbed–diffused into polyamide films treated with solutions (0.025–0.2 mol · dm^–3, 30–50 °C) of potassium selenopentathionate, K₂SeS₄O₆, not acidified or acidified with hydrochloric acid. Sorption–diffusion from acidified solutions proceeds more intensively: the concentrations of selenium and sulfur diffused from an acidified solution are about 5 times higher as compared with those obtained using a non acidified solution of the same concentration and at the same temperature. The concentration of sorbed selenopentathionate ions increases with increasing the temperature and concentration of K₂SeS₄O₆ solution and the duration of treatment. The SeS₄O₆^2– anions diffused into polyamide gradually decompose, and the decomposition products – sulfate ions and SO₂ – are washed out from the polymer, but elemental selenium remains in it. Therefore, the polyamide films, depending on the degree of SeS₄O₆^2– ion decomposition, change from colourless to yellow, brown or red. Copper sulfide and copper selenide layers are formed in the surface of polyamide film if the chalcogenized polymer is treated with a water solution of copper(II / I) salt: the anionic particles containing sulfur and selenium atoms of low oxidation state react with the copper ions. The conditions of polymer initial chalcogenation (the concentration and temperature of K₂SeS₄O₆ solution) determine the amount of copper and the composition of chalcogenide layer: the content of copper in the polyamide film increases with an increase of the concentration and temperature, and varies from 0.2 · 10^–2 to 33.5 · 10^–2 mg/cm². Results of X-ray structural analysis confirmed formation of mixed copper sulfide – copper selenide layers in polyamide surface. The phase composition of the layer changes depending on the duration of initial treatment in K₂SeS₄O₆ solution: Cu_xS–Cu_ySe layers are composed of the low-conductive chalcocite, Cu₂S, electrically conductive digenite, Cu_1.8S, djurleite, Cu_1.9375S, anilite, Cu_1.75S, and of copper selenides – bellidoite, Cu₂Se, umangite, Cu₃Se₂, klockmannite, CuSe, krutaite, CuSe₂ and Cu₂Se_x. Therefore, the phase composition determines the electrical characteristics of the layers: their sheet resistance may vary from 12.2 Ω / □ to 4.8 MΩ / □. The determination of layer composition (to a depth of 1 nm) studied by the method of X-ray photoelectron spectroscopy confirmed the formation of copper sulfides and selenides of various phases. The determined regularities enable formation by the sorption–diffusion method of mixed copper sulfide and copper selenide layers of a desirable composition and electrical conductance, using selenopentathionate as a polyamide chalcogenation agent.

Keywords: selenopentathionate, polyamide, sorption-diffusion, copper chalcogenides layers