(1976). Nuclear Tracks in Solids (Principles and Applications) Nuclear Technology: Vol. 30, No. 1, pp. 91-92.

Nuclear Tracks in Solids (Principles and Applications)

This review concerns the chemical structure and synthesis of perfluorinated sulfocationite membranes, among which Nafion, MF-4SC, Flemion, Aciplex-S, and Dow membranes are the most well-known representatives. Special attention is given to main mechanisms controlling the formation of microstructure and its relationship with transport processes and selectivity levels of membranes. Key approaches to the modification of ion-exchange materials, above all involving the synthesis of hybrid membranes containing nanoparticles of inorganic compounds, are described. It is noted that increases in the conductivity and selectivity levels of hybrid membranes are primarily related to changes in structure of pores and channels and in the distribution of the concentration of carriers in them. Some examples of the practical use of perfluorinated membranes in modern technologies are highlighted.

Perfluorinated ion-exchange membranes

Hybrid membranes containing inorganic nanoparticles

YFeO3 nanocrystals have been prepared via coprecipitation of yttrium and iron(III) chlorides with aqueous ammonia. The average size, morphology, and magnetic properties of the YFeO3 nanoparticles are shown to be highly dependent on the preparation procedure.

Synthesis and magnetic properties of YFeO3 nanocrystals

This article presents the preparation and study of the wetting properties of porous alumina membranes (PAMs) with a thickness of 25 to 75 μm and with a different pore sizes. The fabrication process features, scanning electron microscopy and atomic force microscopy characterization results are presented. The comparative analysis of PAM surfaces (outer and inner) and the effect of morphology of these surfaces on the wetting properties are discussed. Both alumina surfaces show significant morphology-dependent wettability. Measurements of the interfacial contact angle were made on the as-fabricated amorphous membrane and after pore widening with a range of pore diameters from 25 to 100 nm. The possible applications of PAMs for various membrane technologies is shown.

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Preparation and morphology-dependent wettability of porous alumina membranes.

Modern membranes are advanced technological products used in various fields of industry and science, and they are one of the necessary prerequisites for the development of these fields and for solving important social and ecological problems. It is difficult today to find a field of human activity that can exist without membranes. For this reason, membrane science and technology has always been given much attention at the federal level in the former USSR and now in Russia. In the USSR, research and development in this field was coordinated by the Interdisciplinary Scientific-Technological Corporation “Membranes,” and now these activities are supported on a competitive basis by the Federal Agency for Science and Innovations in accordance with the State Program of Research and Development “Industry of Nanosystems and Materials,” within the subprogram “Technology of Membranes and Catalytic Systems.” It should be emphasized that membrane technologies were in high demand even during the industrial crisis of the 1990s, and numerous small and medium level businesses engaged in the production of membranes and related devices. Presently, more than 50 domestic companies operate on the Russian membrane market, many of which (e.g., Voronezh-Akva Co. [1], GRASYS Co. [2], Aspekt Co. [3], and Ceramic Filter Co. [4]) have been created and managed by high-quality specialists of former military enterprises. Among the domestic manufacturers of membrane gas separation devices, GRASYS Co. [2] is also the most successful competitor on the international market, being one of the biggest suppliers of this equipment in Europe. The products from this company are fully adapted for use in all climate belts of Russia. The compact design of the gas separation units makes it possible to combine them with compression stations on the platforms of freight vehicles or in special containers. Stationary and mobile membrane nitrogen liquefaction plants are employed at oil and gas deposits and used to help extinguish fires in the coal, chemical, and petrochemical industries, and in various other fields (museums, exhibitions, archives, banks, computer centers, rooms with advanced electronic equipment, etc.). Since the beginning of the 1990s, the conversion

V. I. Roldugin

Papers

Membranes and nanotechnologies