Preparation of composite membranes by plasma polymerization of thiophene

The structure and electrotransport properties of poly(ethylene terephthalate) track membranes modified by thiophene plasma have been investigated. We studied the influence of a degree of oxidation by iodine and UV-irradiation of a polymer layer obtained by plasma on the membrane characteristics. It is shown that the deposition of the polymer on the surface of the track membrane by plasma polymerization of thiophene in radio-frequency discharge in case of forming a semipermeable layer results in creation of composite membranes having in a solution of electrolytes asymmetry of conductivity - a rectification effect. It is caused by presence in the membranes of two layers with functional groups various in nature, and also by changing of the pore geometry. It is shown that doping of this polymer layer by iodine or photo-oxidation causes increase in the density of a positive charge on its macromolecules, which results in changing the electrochemical properties of the membranes treated by plasma. This allows one to obtain a wide spectrum of polymeric composite membranes with the asymmetry of conductivity. Such type membranes can be used for creation of chemical and biochemical sensors