Surface Of Track Membranes Research Articles

Electrical properties arrays of intersecting of nanowires obtained in the pores of track membranes

In the following work by means of matrix synthesis the nanowire arrays of Fe–Ni alloy with elemental composition close to permalloy (Fe0·20Ni0.80) were obtained. In capacity of matrix the polyethylene terephthalate (PET) track membranes with angular distribution of pores within the range of ±30° and the diameter of pores in 100 nm were used. As a result, via electrochemical deposition method the metal-polymer composite in the form of nanowire arrays in the polymeric matrix were obtained. The distribution of pores over the surface of track membranes and the average amount of nanowire intersections under a variety of lengths of the grown nanowires were calculated. The resistivity of metal-polymer composite arrays, formed with nanowires of varying length, was measured. The growth boundary conditions and the lengths of nanowire arrays that are essential for obtaining of conducting metal-polymer composite were determined.

Studying the Mechanics of Membrane Permeabilization through Mechanoelectricity.

In this research, real-time monitoring of lipid membrane disruption is made possible by exploiting the dynamic properties of model lipid bilayers formed at oil-water interfaces. This involves tracking an electrical signal generated through rhythmic membrane perturbation translated into the adsorption and penetration of charged species within the membrane. Importantly, this allows for the detection of membrane surface interactions that occur prior to pore formation that may be otherwise undetected. The requisite dynamic membranes for this approach are made possible through the droplet interface bilayer (DIB) technique. Membranes are formed at the interface of lipid monolayer-coated aqueous droplets submerged in oil. We present how cyclically alternating the membrane area leads to the generation of mechanoelectric current. This current is negligible without a transmembrane voltage until a composition mismatch between the membrane monolayers is produced, such as a one-sided accumulation of disruptive agents. The generated mechanoelectric current is then eliminated when an applied electric field compensates for this asymmetry, enabling measurement of the transmembrane potential offset. Tracking the compensating voltage with respect to time then reveals the gradual accumulation of disruptive agents prior to membrane permeabilization. The innovation of this work is emphasized in its ability to continuously track membrane surface activity, highlighting the initial interaction steps of membrane disruption. In this paper, we begin by validating our proposed approach against measurements taken for fixed composition membranes using standard electrophysiological techniques. Next, we investigate surfactant adsorption, including hexadecyltrimethylammonium bromide (CTAB, cationic) and sodium decyl sulfate (SDS, anionic), demonstrating the ability to track adsorption prior to disruption. Finally, we investigate the penetration of lipid membranes by melittin, confirming that the peptide insertion and disruption mechanics are, in part, modulated by membrane composition.

Modification of polyethylene terephthalate track etched membranes by planar magnetron sputtered Ti/TiO2 thin films

This study investigates the surface modification of polyethylene terephthalate track-etched membranes by planar magnetron sputtering of titanium and titanium dioxide thin films to improve its hydrophilicity and photocatalytic activity. After cold plasma treatment to enhanced adhesion, Ti thin films were deposited by planar magnetron sputtering and TiO2 thin films by reactive magnetron sputtering in an Ar-O2 gas atmosphere. The morphology of the deposited thin films was characterised using atomic force microscopy and scanning electron microscopy. The pores retained a mostly circular shape. However, the modified track membrane's surface pore diameter reduced from 0.2 µm to 0.15 µm for Ti coated samples and 0.08 µm for Ti-TiO2 coated samples. Structural studies using X-ray photoelectron spectroscopy, energy-dispersive X-ray spectroscopy and Raman spectroscopy of Ti and TiO2 thin films revealed the intricate composition of the sputtered thin films which was a result of the complexity of sputtering on top of the porous polymer support. Additional investigations in surface wettability and bandgap showed a significant change in the track membrane surface's hydrophilicity and photocatalytic properties after depositing TiO2-Ti, adding to the self-cleaning properties of the coated TM. The bandgap of the film was 3.1 eV and of the indirect type. Both Ti and TiO2-Ti sputtering over the TM surface significantly reduced the water contact angle from 72° for untreated PET to 43° and 45° for Ti-TM and TiO2-Ti-TM, respectively. This study shows that planar magnetron sputtering is a viable approach to surface modification of a porous polymeric support, such as track-etched membranes. The sputtered coating enhanced membrane hydrophilicity, thereby reducing the chance of surface fouling by organic substances, which leads to improved self-cleaning properties.

Hydrophobization of Track Membrane Surface by Magnetron Sputter Deposition of Ultra-high Molecular Weight Polyethylene

Method for the formation of polymer coatings on the poly(ethylene terephthalate) track-etched membrane surface by magnetron sputter deposition of ultra-high molecular weight polyethylene in a vacuum is considered. The surface morphology and chemical structure of nanoscale coatings have been investigated. It is shown that the application of the ultra-high molecular weight polyethylene-like coatings leads to hydrophobization of the membrane surface, the degree of which depends on the coating thickness. Besides, the usage of this modification method leads to smoothing of structural inhomogeneity of the membrane surface, a decrease in pore diameter, and alteration of pore shape. The investigation of the chemical structure of deposited coatings by XPS method showed that they contain a significant concentration of oxygen-containing functional groups. The composite membranes of the developed sample can be used in the process of desalination of seawater by the method of membrane distillation.

Modification of track membranes with ion-plasma sputtered tungsten

This paper presents data on the modification of track membranes, based on polyethylene terephthalate, with magnetron sputtered tungsten. The initial and metallized track membrane surfaces were analyzed by microscopy, and a comparison completed. The maximum coating thickness was established to be 70 nm, upon which the pore diameter on the surface of the metalized membrane did not change. The change in the hydrophobicity of the track membrane surface after sputtering was determined. It was shown that the tungsten metallization of the surface significantly reduced the contact angle for membrane wetting from 68° to 29°, and this reduction was observed only after 30 days. The change in the optical characteristics of the track membrane after tungsten metallization was shown by measuring the optical density over a wide wavelength range (310–990 nm). The main electrical characteristics of metallized polyethylene terephthalate films and metallized track membranes were also investigated. It was established that the sputtering of tungsten on all the samples under study sharply reduced their dielectric properties and converted them to semiconductors, because the surface and specific electrical resistance decreased by almost 20 orders of magnitude.

MODIFICATION OF TRACK-ETCHED MEMBRANES BY LOW-TEMPERATURE PLASMA

Published data appearing in the last decade on the modification of track-etched membranes with the use of low-temperature plasma are considered. Some schematic description of setups and methods for sample processing in discharges of various types in atmosphere of non-polymerizing gases and by plasma polymerization, also by using of such plasma-chemical methods as magnetron sputtering of polymer targets and electron-beam dispersion of polymers in vacuum are presented. Some modern physicochemical methods for studying of changes occurring on the surface of membranes are described. Some typical examples of changes in the contact properties of the track-etched membrane surface and their chemical composition by means of X-ray photoelectron spectroscopy and Fourier-IR spectroscopy are given. Using the methods of atomic force microscopy and electron microscopy, some examples of morphological changes occurring on the surface of track membranes and in the volume of pores are presented. It is shown that the modification of track membranes by low temperature plasma leads to the creation of “smart” membranes, which possess some unique properties. This allows to significantly expand the areas of their application. Modified membranes can be used as thermosensitive elements and mechanochemical membranes with a “chemical valve”.The plasma treatment allows also significantly change the biocompatibility of the surface of track-etched membranes and use them in medicine and biology. By means of some special techniques, studies of the adsorption and growth of cellular and biological structures on the surface of modified track-etched membranes are presented.The possibility of the modified track membranes using as a highly effective biocompatible drainage material in the surgical treatment of refractory glaucoma, as well as implants in the treatment of bullous keratopathy is shown.Forcitation:Kravets L.I.,Gilman A.B. Modification of track-etched membranes by low-temperature plasma. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2018. V. 61. N 4-5. P. 4-30

Immobilization of silver nanoparticles obtained by electric discharge method on a track membrane surface

Composite poly(ethylene terephthalate) track membranes containing immobilized silver nanoparticles with the aim of using them for surface-enhanced Raman scattering spectroscopy have been obtained and studied. A dispersion of negatively charged silver nanoparticles has been synthesizes by the method of pulsed electrical discharge between silver electrodes immersed in distilled water. To ensure the electrostatic deposition of nanoparticles onto the track membrane surface, it has been modified with polyethyleneimine. The composition and morphology of the surface of the obtained composite membranes have been studied by X-ray photoelectron spectroscopy and scanning electron microscopy. Aggregation of nanoparticles on the surface has been analyzed. The coefficient of Raman-scattering enhancement has been determined by the example of rhodamine 6G molecules adsorbed on a membrane with immobilized silver nanoparticles.

Influence of low-temperature plasma and γ radiation on the surface properties of PET track membranes

Physical and chemical properties of the surfaces of polyethylene-terephthalate (PET) track membranes (TMs) exposed to low-temperature atmospheric plasma and to γ radiation produced by 60Co isotopes are studied. It is established that the exposure to plasma leads to changes in the chemical composition of the surface and increases the number of polar (carbonyl and carboxyl) functional groups in a thin near-surface layer of a TM. The surface energy is also shown to grow owing to its polar component and surface reconstruction. The reconstruction consists in the growth of surface roughness owing to oxidation-reduction reactions, followed by the appearance of destructive areas. These changes promote a lyophilic behavior of the track-membrane surface. Subsequent γ irradiation of the surface is shown to reduce the plasma-modified TM undulation, while decreasing the number of destructive areas and bringing the material into a more equilibrium state.

Potential use of nuclear track membranes in ophthalmology

Potential use of a nuclear track-etched membrane as a semipermeable membrane for fluid transport and maintenance of the cornea in a slightly dehydrated state for its transparency has been studied. The track membrane TOMTREK based on polyethylene terephthalate (PET) with a pore diameter of 0.4 μm and a density of 5 × 106 pore/cm2 has been used in the experiments. The pores have been formed by bombarding the polymer PET with 41.5-MeV 40Ar8+ ions. After bombardment, the membrane was subjected to chemical treatment in an alkali solution. Contact angle θ on the track membrane surface has been measured using the sessile drop method. Disks of a 10 mm diameter have been cut from plasma-treated membrane samples. An appropriate shape has been imparted to the model by incising and sealing the disk edges.

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.

Polymer Composite Nanomembranes with Asymmetry of Conductivity

This paper describes a structure and electrotransport properties of poly(ethylene terephthalate) track membrane (PET TM) modified by plasma of thiophene. It is shown that the deposition of the polymer on the track membrane surface by plasma polymerization of thiophene in case of forming a semipermeable layer results in creation of composite nanomembrane having in electrolyte solutions of asymmetry of conductivity - a rectification effect. It is caused by presence in the membrane of two layers with various functional groups, and also by changing of the pore geometry. Such type membranes can be used for creation of chemical and biochemical sensors.

Modification of the track membrane surface by ultrathin films of polysiloxane block copolymers

Modification of the surface of PETP (Dacron) track membranes by ultrathin films of polysiloxane block copolymers provides new composite membranes with a hydrophobic surface and retained pore space. It is demonstrated that a uniform distribution of a nanodimensional modifier (fullerene) in a polymer matrix can be achieved, which ensures a high strength of the composite layer.

Structure of Conducting Polymer Films Prepared on the Surface and in the Pores of Poly(ethylene terephthalate) Track Membranes by Template Synthesis

The results of a structural study of conducting polymer coatings deposited onto poly(ethylene terephthalate) (PET) track membranes by template synthesis are reported. The following aspects of the quality of polymer coatings were studied: the ratio between film and granular polymers, the polymer distribution over the surface of track membranes, and the thickness of polymer layers on the opposite sides of track membranes. The fraction of granular polypyrrole (PPy) on the surface and in the pores of a film increased with pore diameter. A decrease in the polymerization temperature decreased the amount of granular PPy on the surface of membranes, whereas the effect of granular PPy on the water permeability of track membranes remained unchanged. A more homogeneous distribution of PPy over the surface of track membranes can be obtained by density equalization of reacting solutions; however, the fraction of granular PPy on the membrane surface increased in this case. It was found that polymer coatings on the two sides of the surface of a membrane template had different thicknesses. Poly(N-methylpyrrole) completely covered only one side of a track membrane facing a monomer solution.

Ion-beam modification of track membrane surface

An ion-beam method to modify the track membrane surface is suggested. An ion gun based on a magnetron sputterer is developed. This gun provides ion energies in the range of 5 eV–1 keV, ion current density up to 0.8 mA/cm2, and an ion beam aperture of 90 mm. After the track membrane surface has been irradiated by argon ions with an energy of 50–100 eV, the angle of surface-water contact decreases from 65°–75° to 10°–25°. If the irradiating ion energy is 300–800 eV, the angle of contact increases from 65°–75° to 90°–100°.

Methods of Track Membrane Surface Modification

Chemie Ingenieur TechnikVolume 73, Issue 6 p. 726-726 Article Methods of Track Membrane Surface Modification V.A. Pronin, V.A. Pronin Russian Federal Nuclear Center-All Russian Institute of Technical Physics, P.O. Box 245, Snezhinsk, Chelyabinsk region, 456770, Russia.Search for more papers by this authorV.I. Ostashev, V.I. Ostashev Russian Federal Nuclear Center-All Russian Institute of Technical Physics, P.O. Box 245, Snezhinsk, Chelyabinsk region, 456770, Russia.Search for more papers by this authorP.A. Loboda, P.A. Loboda Russian Federal Nuclear Center-All Russian Institute of Technical Physics, P.O. Box 245, Snezhinsk, Chelyabinsk region, 456770, Russia.Search for more papers by this authorB.V. Mchedlishvili, B.V. Mchedlishvili Shubnikov institute of crystallography of Russian academy of science. Leninsky prosp. 59, 117333, Moscow, Russia.Search for more papers by this authorA.N. Nechayev, A.N. Nechayev Shubnikov institute of crystallography of Russian academy of science. Leninsky prosp. 59, 117333, Moscow, Russia.Search for more papers by this author V.A. Pronin, V.A. Pronin Russian Federal Nuclear Center-All Russian Institute of Technical Physics, P.O. Box 245, Snezhinsk, Chelyabinsk region, 456770, Russia.Search for more papers by this authorV.I. Ostashev, V.I. Ostashev Russian Federal Nuclear Center-All Russian Institute of Technical Physics, P.O. Box 245, Snezhinsk, Chelyabinsk region, 456770, Russia.Search for more papers by this authorP.A. Loboda, P.A. Loboda Russian Federal Nuclear Center-All Russian Institute of Technical Physics, P.O. Box 245, Snezhinsk, Chelyabinsk region, 456770, Russia.Search for more papers by this authorB.V. Mchedlishvili, B.V. Mchedlishvili Shubnikov institute of crystallography of Russian academy of science. Leninsky prosp. 59, 117333, Moscow, Russia.Search for more papers by this authorA.N. Nechayev, A.N. Nechayev Shubnikov institute of crystallography of Russian academy of science. Leninsky prosp. 59, 117333, Moscow, Russia.Search for more papers by this author First published: 12 July 2001 https://doi.org/10.1002/1522-2640(200106)73:6<726::AID-CITE7261111>3.0.CO;2-OAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume73, Issue6Juni 2001Pages 726-726 RelatedInformation

The Size Statistics of Nuclear Track Holes on the Track Membrane Surface

Areal distribution functions of double and triple pores and their first moments were obtained within the framework of the statistical model of overlapping nuclear track pores (circular holes of equal diameter on the flat surface of a track membrane). The linear dimensions of multiple pores with reference to their configuration forms (for triplets) and their dependence of on membrane porosity were calculated.