Polymer Track Membranes Research Articles

О численном моделировании трековых мембран, используемых в качестве коллиматоров рентгеновского излучения

In this work, we present the results of numerical modeling of distribution of the field amplitude inside micron-sized through cylindrical pores in polymer track membranes in the soft X-ray wavelength range 13.5–30.4 nm. The calculations were performed by numerically solving the 3D parabolic equation with a finite-difference method using an exact transparent boundary condition. The dependences of the X-ray transmittivity through a pore on the incidence angle as well as on the pore diameter were computed. For the membranes with some thicknesses and pore diameters, calculated angular dependences of the transmittance are compared with the measurements known from the literature. It is demonstrated that the calculations agree with the measurements if a transition layer on the inner surface of the pores, which accounts for the finite surface roughness, is introduced.

USE OF SPECTROSCOPIC METHODS FOR STUDYING MORPHOLOGY OF POLYMER TRACK MEMBRANES

The morphology of track membranes based on polyethylene terephthalate and polypropylene with different track diameters and their surface densities were studied by UV, IR, Raman spectroscopy, and scanning electron microscopy (SEM). The SEM method was used to plot the distribution curves of the number of tracks depending on their average size (diameter). Similar distribution curves were obtained using UV and IR spectroscopy. Good agreement was found between the data of independent methods of optical spectroscopy
 and SEM. It is shown that with an increase in the surface density of tracks, the background elastic scattering in the Raman spectra increases linearly. It is proposed to use the observed effect in the Raman spectra to estimate the surface track density of polymer track membranes.

KINETIC AND THERMODYNAMIC CHARACTERISTICS OF THE POTASSIUM HEXATIONOFERRATE (III) DECOMPOSITION CATALYTIC REACTION IN THE PRESENCE OF COMPOSITE TRACK-ETCHED MEMBRANES

The kinetic and thermodynamic parameters of the decomposition of an inorganic wastewater pollutant such as potassium hexacyanoferrate (III) (PHCF) in the presence of composite catalysts based on polymer track membranes (TeMs) and copper nanoparticles (NPs) was studied. Composite catalysts were prepared by electroless template synthesis using a nontoxic reducing agent - ascorbic acid. A systematic study of the process of electroless plating of copper NPs was carried out depending on pH, deposition time, and the number of activations of the polymer template. The structure of the porous composite catalysts was investigated by scanning electron microscopy and X-ray diffractometry. The catalytic properties of the obtained composites were examined in the temperature range of 10-25 °C for a series of samples synthesized with different deposition times. It was shown that the kinetics of the decomposition reaction of PHCF corresponds to the pseudo first-order reaction. Such thermodynamic characteristics as energy, entropy and enthalpy of activation are calculated. The stability of the properties of catalysts has been studied.

Phase transformations in CoZnO/CoZn nanostructures depending on the difference in applied potentials

The dynamics of phase transformations in CoZnO/CoZn nanostructures of the Zn – Hexagonal/ZnCo2O4 – spinel → Zn – Hexagonal/Co2.34Zn10.63 → Co– Hexagonal/Co2.34Zn10.63 type depending on the difference of the applied potentials is presented. As a production method, the method of electrochemical synthesis was used, in which polymer track membranes with pore diameters of 400 nm and a length of 12 μm were used as templates. The study found that at small potential differences (1.25–1.75 V), the presence of oxygen is observed in the structure of nanowires, which is introduced into the crystalline structure during the synthesis. In this case, an increase in the difference in the applied potentials above 1.75 V leads to an increase in the cobalt concentration in the structure of the nanowires accompanied by the displacement of oxygen and the formation of the Co/Zn structure with a stoichiometric ratio of 1:1. It was found that all the nanostructures under study during the life tests of the applicability of these nanostructures as cathode materials of lithium-ion batteries retained their operability after 400 cycles of life tests, which indicates their high resistance to degradation. Moreover, for samples containing a high concentration of cobalt in the structure, the lifetime reaches more than 800 cycles, which is explained by the high stability of these nanostructures to degradation processes.

Extraction of Ions from a Polar Solution Using a Surface-Modified Membrane Interface

Field-induced extraction of ions from a polar solution is implemented with the aid of an interface that represents a polymer track membrane with a conducting coating. A time-of-flight spectrum of ions extracted from a KI solution in a water–glycerol mixture is obtained using nanosecond electric-field pulses. Application of the conducting coating allows a significant decrease in the voltage of the extracting pulse and suppression of the effect of secondary processes on the composition of ions generated in a pulsed membrane ion source.

Structural and magnetic properties of Ni-Fe nanowires in the pores of polymer track membranes

Abstract Nanowires of Ni1−xFex compounds were obtained by electrochemical deposition in pores of flexible polymer track membranes with pore diameters of 30 and 70 nm. The elemental composition and growth conditions, allowing to control the length and aspect ratio of the nanowire, were established. Magnetic and Mossbauer spectroscopy measurements show that the nanowires have pronounced ferromagnetic properties, and the magnetic moments of Ni-Fe nanoparticles are oriented mainly along the wire axis. In particular, the nanowires with a length of about 10 μm and a diameter of 30 nm consist of magnetic domains about 20 nm in size with magnetic moments oriented predominantly along the axis of the nanowire. Such materials can be considered as quasi-one-dimensional nanostructured ferromagnetic systems. A new theoretical model was used to describe the magnetic properties and calculate the basic physical parameters of nanowires.

Экстракция ионов из полярного раствора с использованием поверхностно-модифицированного мембранного интерфейса

The possibility of field extraction of ions from a polar solution was demonstrated using a polymer track membrane with a conductive coating as an interface. The time-of-flight spectrum of ions extracted from a KI solution in a water-glycerin mixture by a nanosecond electric field pulse was obtained. The use of a conductive coating made it possible to significantly lower the voltage of the extracting pulse and reduce the influence of secondary processes on the composition of ions generated in a pulsed membrane ion source.

Structure and Magnetic Properties of Nanowires of Iron Group Metals Produced by Matrix Synthesis

Abstract—Samples of arrays of nanowires are produced from iron, iron–cobalt and iron–nickel alloys via matrix synthesis based on polymer track membranes with pore diameters ranging from 30 to 300 nm. The influence of stress and pore diameter on the galvanic process and structure of nanowires is studied. The arrays of nanowires are examined by microscopy and X-ray diffraction. The magnetic properties are inspected via magnetometry and Mossbauer spectroscopy. The angular dependences of hysteresis loop shape are obtained and comprehensively discussed. As shown, decreasing the growth stress and/or increasing the pore diameter make the Mossbauer spectra of nanowires similar to those of bulk materials. Furthermore, the higher the growth stress is, the larger is the coercive force of nanowires. For the studied species of nanomaterials, the ability to control the magnetic properties during the synthesis is shown, as well.

Template Synthesis of Iron Microstructures Based on Track Membranes

Iron nanowires (NWs) were obtained by template synthesis using polymer track membranes in the framework of development of a general method for the synthesis of regular metal nanostructures. The surface topography of NWs was studied by scanning electron microscopy, and the local state of iron atoms was determined by Mossbauer spectrometry.

Radiation Stability of Metal Fe0.56Ni0.44 Nanowires Exposed to Powerful Pulsed Ion Beams

The resistance of Fe0.56Ni0.44 alloy nanowires (fabricated by template synthesis using polymer track membranes) 60 and 100 nm in diameter to radiation with powerful pulsed 85% C+ + 15% H+ ions (E = 20 keV, j = 100 A/cm2, τ = 90 ns) has been investigated. The conclusion that nanosized regions of explosive energy release, so-called thermal spikes, which are thermalized regions of dense cascades of atomic displacements heated to several thousand degrees (in which the thermal pressure can reach several tens of GPa), play an important role in the nanowire structure change is drawn. These are observed as melted nanosized regions on the nanowire surface. Calculations have shown that energy supplied by an ion beam during the action of a single pulse in the used mode (provided that thermal radiation and thermal conductivity serve as energy sinks) can be both sufficient and insufficient to completely melt nanowires depending on their orientation with respect to the ion beam. The bending and failure of nonmelted nanowires is explained by the generation and propagation of post-cascade shock waves.

Структура и магнитные свойства нанопроволок из маталлов группы железа, полученных методом матричного синтеза

Abstract —Samples of arrays of nanowires are produced from iron, iron–cobalt and iron–nickel alloys via matrix synthesis based on polymer track membranes with pore diameters ranging from 30 to 300 nm. The influence of stress and pore diameter on the galvanic process and structure of nanowires is studied. The arrays of nanowires are examined by microscopy and X-ray diffraction. The magnetic properties are inspected via magnetometry and Mössbauer spectroscopy. The angular dependences of hysteresis loop shape are obtained and comprehensively discussed. As shown, decreasing the growth stress and/or increasing the pore diameter make the Mössbauer spectra of nanowires similar to those of bulk materials. Furthermore, the higher the growth stress is, the larger is the coercive force of nanowires. For the studied species of nanomaterials, the ability to control the magnetic properties during the synthesis is shown, as well.

Шаблонный синтез микроструктур железа на основе трековых мембран

AbstractIron nanowires (NWs) were obtained by template synthesis using polymer track membranes in the framework of development of a general method for the synthesis of regular metal nanostructures. The surface topography of NWs was studied by scanning electron microscopy, and the local state of iron atoms was determined by Mössbauer spectrometry.

Radiation Stability of Metal Nanowires

The aim of this work is to investigate the radiation stability of pure nickel and iron– nickel Fe0.56Ni0.44 alloy nanowires fabricated by matrix synthesis using polymer track membranes and Ar+ and Xe+ (E = 20 keV, j = 300 μA/cm2) beam irradiation. The dependence of the stability of nanowires on their diameter, fluence, and type of implanted ions is investigated. The assumption that the thermalized regions of dense cascades of atomic displacements (thermal spikes) play an important role in the nanowire structure change is made. These regions are nanosized zones of explosive energy release and heated to several thousands of degrees.

Generation of ions in a pulsed ion source with an interface based on a polymer track membrane

The time-of-flight spectra of ions generated during the extraction of negative ions from the KI solution in water–glycerin mixture by high-strength electric field pulses are studied using a source with an interface based on a polymer track membrane. It has been shown that the ions formed in secondary processes of bombardment of the membrane surface make a considerable contribution to the observed spectra. It has been found that the peaks of negative hydrogen ions have the highest intensity in the spectrum, indicating effective emission of these ions during the bombardment of polyethylene terephthalate by secondary ions with an energy of about 6 keV. The main trends in the modification of the membrane interface to reduce the fraction of secondary ions in the ion beam have been outlined.

Track Pore Matrixes for the Preparation of Co, Ni and Fe Nanowires: Electrodeposition and their Properties

Specially prepared polymer track membranes were used as matrixes for the fabrication of nanosize metal wires. Nanowires of magnetic metals (Co, Ni and Fe) were prepared by electrodeposition into the pores. The nanowires properties and their dependence on electrodeposition conditions were investigated by XRD and Mossbauer spectroscopy. The specific features of electrodeposition process into nanosize pores are also shown.

Fluorescence energy transfer in quantum dot/azo dye complexes in polymer track membranes

Fluorescence resonance energy transfer in complexes of semiconductor CdSe/ZnS quantum dots with molecules of heterocyclic azo dyes, 1-(2-pyridylazo)-2-naphthol and 4-(2-pyridylazo) resorcinol, formed at high quantum dot concentration in the polymer pore track membranes were studied by steady-state and transient PL spectroscopy. The effect of interaction between the complexes and free quantum dots on the efficiency of the fluorescence energy transfer and quantum dot luminescence quenching was found and discussed.

Calculation of bulk etch rate’s semi-empirical equation for polymer track membranes in stationary and dynamic modes

One of the most urgent and extremely social problems in environmental safeties area in Kazakhstan is providing the population of all regions of the country with quality drinking water. Development of filter elements based on nuclear track-etch membranes may be considered as one of best solutions this problem. The values of bulk etch rate and activation energy were calculated in view the effect of temperature, alkaline solution concentration as well as stirring effect. The semi-empirical equation of the bulk etch rate for PET track membranes was calculated. As a result of theoretical and experimental studies a semi-empirical equation of the bulk etch rate V B =3.4∙10 12 ∙C 2.07 ∙exp(-0.825/kT) for 12 microns PET film, irradiated by ions 84 Kr 15+ (energy of 1.75 MeV/nucleon) at the heavy ion accelerator DC-60 in Astana branch of the INP NNC RK, was obtained.

Features of the primary functionalization and surface analysis of nanoporous pet track-etched membranes

Targeted modification of polymer track membranes offers the great opportunities for the development of membrane filters with improved characteristics, stimuli-responsible membranes and sensors. The effectiveness of chemical transformations with terminal functional groups depends on the completeness of the primary step i.e. oxidation of PET. In the paper, a review analysis of the oxidation reaction conditions and methods of surface PET TM analysis as well as experimental data of this reaction are studied. The shifting properties of the parent and modified membranes were demonstrated.

Use of polymer track membranes with nanostructured surface as drainage in antiglaucomatous operations

The morphological and clinical studies of poly(ethylene terephthalate) track membranes with a nanostructured surface as drainage materials for antiglaucomatous operations were performed. For nanostructuring of the membrane surface a treatment by plasma of non-polymerizing gasses was applied. It was demonstrated that a new drainage has compatibility with eye tissues and a good lasting hypotensive effect and can be used as operation for refractory glaucoma surgery.

Generation of an extraction electric field in an electromembrane ion source

A mechanism of generating an extraction field in an ion source in which a polymer track membrane with nanodimensional channels is used as an environment-vacuum interface is considered. A high electric field necessary for the effective extraction of ions from a liquid on the membrane surface into the gas phase is maintained by charging the vacuum surface of the membrane. Charging is provided by oppositely charged secondary ions resulting from the disintegration of primary cluster ions on the extraction electrode. A decrease in the source current observed when the vacuum surface discharges counts in favor of this mechanism. The extracted ion energy distribution in the neighborhood of the extraction zone is obtained by the retarding potential method. Various aspects of ion beam formation in the membrane ion source are discussed.