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Yampolskii Y.,RAS Topchiev Institute of Petrochemical Synthesis
Macromolecules | Year: 2010

The estimation of concentration of free volume elements or holes in polymers was analyzed. 129Xe NMR, and inverse gas chromatography, positron annihilation lifetime spectroscopy (PALS) were employed to determine the concentration of free volume elements. The methodology of PALS study of polymers involved obtaining lifetime spectrum of positrons, and consisted of three components with corresponding intensities Ii. It was found that the third component of the spectrum characterized by the longest lifetimes belonged to lifetime of orthopositronium, hydrogen-like bound state, the combination of electron and positron having parallel spins. The rate of mass transfer in polymers depended not only on average volume for spherical holes but also on the hole number density N or average distance between neighboring holes. The results show that the bigger holes are characteristic for some polymeric sorbents such as cross-linked polystyrene, where the radii as large as 13-15Å are observed.

Yampolskii Y.,RAS Topchiev Institute of Petrochemical Synthesis
Macromolecules | Year: 2012

This short Perspective conveys to the general reader of Macromolecules basic approaches of materials science of polymeric membranes for gas and vapor separation. The relations between the polymer structure and transport properties of rubbery and glassy membrane materials are considered. On the basis of acquired information, several methods for quantitative prediction of permeability were developed, and their comparative analysis is given in the Perspective. The past decade was marked by the appearance of a number of novel interesting membrane materials, which will be briefly described in the text. In conclusion, novel approaches for achieving highly permeable and permselective materials (e.g., mixed matrix membranes) will be considered as well as several relevant but not solved so far problems of membrane gas separation. © 2012 American Chemical Society.

Kurganov A.,RAS Topchiev Institute of Petrochemical Synthesis
Analytica Chimica Acta | Year: 2013

Monolithic columns invented in chromatographic praxis almost 40 years ago gained nowadays a lot of popularity in separations by liquid chromatographic technique. At the same time, application of monolithic columns in gas chromatography is less common and only a single review published by Svec et al. [1] covers this field of research. Since that time a lot of new findings on application and properties of monolithic columns in gas chromatography have been published in the literature deserving consideration and discussion. This review considers preparation of monolithic columns for GC, an impact of preparation conditions on column performance, optimization of separation conditions for GC analysis on monolithic columns and other important aspects of preparation and usage of monolithic capillary columns in GC. A final part of the review discusses the modern trends and possible applications in the future of capillary monolithic columns in GC. © 2013 Elsevier B.V.

Subbotin A.V.,RAS Topchiev Institute of Petrochemical Synthesis
JETP Letters | Year: 2015

Stationary structures formed on the surface of a liquid under the action of an electric field have been studied. With the use of the equations of electrohydrodynamics, it has been shown that cones are formed in a dynamic regime when the current of surface ions, which is induced by the tangential component of the electric field, dominates over the conductivity current in the bulk of a cone and the surface current induced by the flow of the liquid. The electric field strength both inside and outside the cone, as well as the velocity field inside the cone, has been determined. It has been shown that the angle of the cone depends on the current flowing on its surface. The characteristic size of the cone has been determined. © 2014, Pleiades Publishing, Inc.

RAS Topchiev Institute of Petrochemical Synthesis and Corium International | Date: 2015-06-22

A composition is provided, wherein the composition comprises a water-swellable, water-insoluble polymer, a blend of a hydrophilic polymer with a complementary oligomer capable of hydrogen or electrostatic bonding to the hydrophilic polymer. The composition also includes a backing member. Active ingredients, such as a whitening agent, may be included. The composition finds utility as an oral dressing, for example, a tooth whitening composition that is applied to the teeth in need of whitening. The composition can be designed to be removed when the degree of whitening has been achieved or left in place and allowed to erode entirely. In certain embodiments, the composition is translucent. Methods for preparing and using the compositions are also disclosed.

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