Chemical deposition of copper sulfide films in the surface of polyethylene by the use of higher polythionic acids

Abstract

Films of copper sulfides of varying composition are formed in a surface matrix of polyethylene by a sorption—diffusion method using solutions of higher polythionic acids, H₂S_nO₆ (n > 6), as sulfuring agents. In the first stage of the process, elemental sulfur diffuses into the polymer when keeping it in a solution of higher H₂S_nO₆. In the second stage, a film of nonstoichiometric Cu_xS (x= 1.12-1.95) is obtained when the sulfured PE is treated with a solution of copper (I—II) salt. The physical properties of the copper sulfide film depend on the thickness and the composition of the film. The films obtained are formed from three-phases: jarowwite (Cu_1.12–1.18S), anilite (Cu_1.7–1.8S), and djurleite (Cu_1.91-1.95S). The sulfide with composition close to CuS has the highest electrical conductivity.