Preparation of polymeric composite nanomembranes with conductivity asymmetry

Structure and electrotransport properties of poly(ethylene terephthalate) track membranes modified in pyrrole plasma were studied. Physicochemical aspects of the conductivity asymmetry arising from the contact of two layers with functional groups of different nature and from changes in the pore geometry are discussed.     

Investigation of Morphology and Chemical Structure of Nanosized Polytetrafluoroethylene Films Deposited on the Surface of Track-Etched Membranes by Plasma Processing

The morphology and chemical structure of nanosized polytetrafluoroethylene films deposited on the surface of track-etched poly(ethylene terephthalate) membranes by means of radiofrequency magnetron sputtering and electron-beam sputtering of the polymer in a vacuum have been studied using atomic force microscopy and X-ray photoelectron spectroscopy. It has been established that the morphology of films formed with the use of these coating techniques varies considerably. This is due to the size of the deposited polymer particles. The particles formed by the electron-beam sputtering of polytetrafluoroethylene are larger than those produced by magnetron sputtering of the polymer. It has been shown that the chemical composition of the films deposited by electron-beam sputtering in a vacuum is more in line with the composition and structure of the initial polymer than the films obtained by radiofrequency magnetron sputtering.     

Synthesis of bilayer composite nanomembranes with conductivity asymmetry

The structure and electrochemical properties of polyethylene terephthalate track membranes modified in acetylene plasma are studied. It is found that polymer deposition on the track membrane surface using acetylene polymerization in plasma results in the case of formation of a semipermeable layer covering pores in formation of a composite nanomembrane featuring asymmetry of conductivity in solutions of electrolytes: a rectifying effect similar to that of a p-n junction in semiconductors. It is shown that the observed effect of conductivity asymmetry is caused by a significant decrease in the diameter of pores in the plasma-deposited polymer layer and a change in the pore geometry, same as existence of an interface between the initial membrane and polymer layer that have a different concentration of carboxyl groups in the surface layer. The impedance spectroscopy method allowed obtaining information on ion transfer in the studied membranes.     

Preparation of composite membranes by means of plasma polymerization of tiophene

The structure and the charge transport properties of poly(ethylene terephthalate) track membranes modified in a thiophene plasma were studied. It was found that polymer deposition on the surface of a track membrane via the plasma polymerization of thiophene results in composite membranes that, in the case of the formation of a semipermeable layer, exhibit conductivity asymmetry—rectifying effect—in electrolyte solutions. It was shown that chemical doping with iodine or photo-oxidation of the polymer layer produced in plasma leads to alteration in the electrochemical properties of plasma-modified membranes.