Vera M. Elinson

Water permeability of poly(ethylene) terephthalate track membranes modified in plasma

Abstract The properties of poly(ethylene) terephthalate track membranes (PET TM) subjected to effect of plasma of the RF-discharge in air have been investigated. The influence of conditions of a plasma treatment on the surface properties and hydrodynamic characteristics of the membranes has been studied. It has been found that the effect of the air plasma on the membranes studied results in a formation of asymmetric track membranes with a higher flow rate; the structure and chemical composition of their superficial layer are changed. It was shown that the presence of the modified layer on the membrane surface caused changing in their hydrodynamic characteristics — the water permeability of the membranes, processed in plasma, in a greater degree depends upon pH of a filtered solution.

Production of asymmetric track membranes by gas-discharge method

An investigation of the structure and surface of poly(ethylene) terephthalate (PET) track membranes (TM) treated with a plasma RF-discharge in non-polymerizing gases has been performed. It was arranged that the effect of non-polymerizing gas plasma on the TM results in etching a surface layer of the membranes. The membrane pore size and the shape change in this case. It is shown that it is possible to change the structure of track membranes directly by gas-discharge etching. Depending on the choice of discharge parameters, it is possible to achieve etching conditions either in part of the channel or along the whole length of the pore channels. In both cases membranes with asymmetric pores are formed, which possess a higher porosity and flow rate.

Production of asymmetric track membranes with a high permeability and separation selectivity

Abstract An investigation of the structure and surface properties of poly(ethylene) terephthalate track membranes (PET TM) with a changed pore profile subjected to the plasma RF-discharge is performed. It was arranged that effect of the non-polymerizing gas plasma on the membranes of researched sample leads to formation of asymmetric membranes possessing a higher flow rate. Choice of optimal discharge parameters allows one to etch the membrane in its layer. In this case in the membrane layer not affected by plasma, the mean pore diameter remains at its initial level. Preserving the initial (nominal) pore diameter allows one to perform the filtration processes with no decrease of separation selectivity. It is shown that the introducing of the polymerizing gas, cyclohexane, into the composition of plasma-forming gas provides improved hydrodynamic properties of asymmetric membranes.

Plasma-chemical modification of the structure and properties of poly(ethylene terephthalate) track membranes

A process of extraction of the low-molecular products of the synthesis from the poly(ethylene terephthalate) track membranes modified by plasma has been investigated. It is shown that the deposition of a thin polymeric hydrocarbon film by cyclohexane plasma on the membrane surface with preliminary treatment in a plasma of non-polymerizing gases, for example oxygen, allows one to produce membranes possessing a high productivity. Their advantages are much better hydrodynamic properties and a small amount of the low-molecular products of the synthesis extracted by organic solvents.

Modification of Poly(Ethylene Terephthalate) Track Membrane Properties by Plasma Chemical Method

Properties of poly(ethylene terephthalate) track membrane (PET TM) exposed to an allyl alcohol radiofrequency plasma after pre-activation its surface in an oxygen plasma were studied. The influence of plasma treatment conditions on basic membrane characteristics, i.e. pore size and shape, wettability, and water permeability, was studied. It has been shown that the plasma treatment of membrane can significantly improve its performance characteristics.

Modified by air plasma polymer tack membranes as drainage material for antiglaucomatous operations

The morphological and clinical studies of poly(ethylene terephthalate) track membranes modified by air plasma as drainage materials for antiglaucomatous operations were performed. It was demonstrated their compatibility with eye tissues. Moreover, it was shown that a new drainage has a good lasting hypotensive effect and can be used as operation for refractory glaucoma surgery.

Surface and electrochemical properties of polypropylene track membrane modified by plasma of non-polymerizing gases

The surface and electrochemical properties of polypropylene track membrane treated by plasma of nitrogen, air, and oxygen are studied. The effect of the plasma-forming gas composition on the surface morphology is considered. The membrane surface microrelief formed during the gas-discharge etching is found to change. Moreover, the non-polymerizing gas plasma treatment induces oxidation of the membrane surface layer and generates oxygen-containing functional groups, mostly carbonyl and carboxyl. The higher membrane roughness and its hydrophilization is shown to lead to its better wettability. In addition, the presence of polar groups in the membrane surface layer modifies its hydrodynamic and electrochemical properties so that water permeability and conductivity of modified membranes increase.

X-ray study of silicon distortion on deposition of diamond-like films

Abstract Diamond films are of special interest for passivation, because of their chemical stability and electric characteristics. However, the problem of about crystal surface distortion on film deposition is crucial for microelectronics applications. An X-ray study of radiation defects created in the silicon subsurface region during ion plasma etching and covering the crystal with diamond-like carbon films has been carried out. The distorted layer thickness (several nanometres) has been determined to be close to the ion penetration depth and the main radiation defects near the crystal surface turn out to be interstitial like. It has been found that the silicon crystal surface under the diamond-like film, deposited by magnetron sputtering of graphite in argon at the optimal bias voltage equal to -100 V, is very smooth on an atomic scale (the damaged layer thickness was equal to 3.7 A).