Anastassiya A. Mashentseva

The effect of oxidation pretreatment of polymer template on the formation and catalytic activity of Au/PET membrane composites

This paper reports on the synthesis and structure elucidation of the track-etched membranes with embedded gold nanotubes (prepared in etched-only and COOH-enriched PET track-etched membranes) as well as comparative testing of the catalytic activity of prepared composites. The carboxylic group functionality was enriched by successive oxidation by hydrogen peroxide and UV. “As-prepared” and oxidized membrane composites were examined for catalytic activity using reduction of 4-nitrophenol (4-NP) by NaBH4. The catalytic activity of Au/PET-Ox composite was found to be 23% more effective than Au/PET-Etch composites. Nanocomposites were also investigated by XRD, XPS and SEM techniques.Graphical Abstract

Effect of thermal annealing on the structural and conducting properties of zinc nanotubes synthesized in the matrix of track-etched membranes

Results of studies of the effect of thermal annealing on the structural and conducting properties of ordered arrays of zinc nanotubes prepared by electrochemical deposition in track-etched membranes based on polyethylene terephthalate (PET) have been described. The dimensions, chemical composition, and crystal structure of the synthesized samples have been integrally analyzed using scanning electron microscopy, X-ray diffraction, and energy dispersive analysis. It has been shown that the thermal annealing of zinc-based nanotubes makes it possible to control the formation of an oxide phase in the nanostructures. The presence of the ZnO oxide phase in an amount of no more than 10 wt % leads to a decrease in the resistivity and an increase in the conductivity. In addition, by changing the crystal structure of Zn nanotubes by thermal annealing, it is possible to prepare ordered arrays of n-type semiconductors with considerable prospects of widespread use in nanoelectronics and nanooptics.

Composites based on polyethylene terephthalate track-etched membranes and silver as hydrogen peroxide decomposition catalysts

The synthesis of composite materials based on silver nanotubes and PET track-etched membranes (TMs) has been studied. A systematic study of the catalytic properties of the resulting composites has been conducted using the example of the hydrogen peroxide decomposition reaction. Changes in the catalytic properties of the composites as a function of the pore density of the initial PET template and the duration of the chemical template synthesis of silver nanotubes have been analyzed. The Ag/PET TM structure has been studied by SEM; the phase composition and the crystallite sizes have been analyzed by X-ray diffraction. To study the kinetic parameters of the reaction in a temperature range of 25–45°C, the activation energies of both the composite samples and the PET film with silver nanoparticles deposited on the surface have been calculated; it has been found that the lowest activation energy is exhibited by Ag/PET TM composites with a pore density of 1 × 109 ion/cm2. Optimum synthesis conditions providing the formation of Ag/PET TM composite catalysts that preserve their integrity and mechanical strength during testing and mediate the studied reaction at the highest rate have been determined. The stability of the catalyst properties has been studied; it has been shown that, at 25°C, the catalyst activity decreases by 35% after the third test run.

Variation of polymer-template pore geometry as a means of controlling the magnetic properties of metallic nanostructures

The influence of pore geometry of polyethylene terephthalate track-etched membranes on the structural, conducting, and magnetic characteristics of cobalt nanotubes (NTs) synthesized by electrochemical deposition has been studied. It has been found that there are significant differences in average size of crystallites and texture coefficients between various forms of cobalt nanotubes. Thus, the α-Co hexagonal closepacked phase dominates in Co-NT samples with cylindrical and hourglass pore shapes and the β-Co facecentered cubic phase prevails in conical Co nanotubes. Measurements of the magnetic properties have shown that the coercivity of cylindrical Co nanotubes is almost two times that of the conical forms because of crystal anisotropy of nanotube-forming cobalt crystallites.

Modification of Track-Etched PET Membranes by Graft Copolymerization of Acrylic Acid and N-Vinylimidazole

Photoinduced graft polymerization of N-vinylimidazole (VI) and graft copolymerization of N-vinylimidazole with acrylic acid (AA) onto track-etched polyethylene terephthalate membranes (PET TeMs) with a pore diameter of 450 ± 15 nm have been systematically studied. The effect of different parameters, such as irradiation time, monomer concentration, and solvent nature, has been examined. The samples have been characterized using the instrumental techniques of FTIR and XPS spectroscopies, thermogravimetry, and scanning electron microscopy. The copolymer composition has been determined spectrophotometrically using the Toluidine Blue and Acid Orange dyes. Optimal conditions of AA and VI copolymerization have been found. It has been shown that the surface of modified PET TeMs is reach in functional groups which makes them a promising material for the development of nanosensors and nanocatalysts.

Controlled template synthesis and properties of cobalt nanotubes

This study has been focused on the influence of the conditions of electrochemical template synthesis (i.e., potential difference and temperature of electrolyte solutions) on the structural and conductive properties of cobalt nanotubes. Polyethylene terephthalate track-etched membranes with a pore density of 1 × 109 ions/cm2 have been used as a template. Scanning electron microscopy, X-ray diffraction, and energy dispersive analysis have been used for a comprehensive elucidation of the dimensionality, chemical composition, and crystal structure of the synthesized samples. The optimum conditions for the synthesis of cobalt nanotubes with a minimum crystallographic anisotropy have been determined. It has been shown that controlling the synthesis conditions by changing electrolyte solution temperature and applied potential difference, one can vary the electrical and conductive properties of cobalt nanotube arrays, which have promising application in magnetic recording storage devices, high-precision magnetic field sensors, and optical devices.