O. V. Alekseeva

The influence of fullerene additives on the structure of polystyrene films

It was shown by electron microscopy and X-ray diffraction that a polystyrene solid with a three-level hierarchical structure was formed when the solvent was evaporated from a solution of polystyrene in o-xylene (polystyrene molecules stuck together united to form a framework). The kinetics of the transformation of formerly dissolved molecules into aggregates could be described by a Fokker-Planck-type equation. Fullerenes introduced into a solution of polystyrene in amounts less than 0.1 wt % transformed aggregated polystyrene molecules into nanocrystals and accelerated the formation of aggregates. The influence of fullerenes on the kinetics of the processes could be correctly described in the continuum approximation taking into account aggregation rate fluctuations.

Effect of polyoxomolybdate nanocluster doping on the dielectric characteristics of polyvinyl alcohol nanocomposite films

Electrophysical parameters of polyvinyl alcohol (PVA) films comprising nanocluster molybdenum-based polyoxometalates (POMs), namely electrical conductivity, dielectric loss tangent, and dielectric permittivity, have been studied. Frequency and concentration curves have been plotted for these properties, which characterize the relaxation parameters of polymeric macromolecules and interactions of the polymer with spheroidal Keplerate POMs (Mo132 and Mo72Fe30) and toroidal POMs (Mo138).

An investigation of the structural and thermodynamic properties of polystyrene fullerene-containing films

Polystyrene films doped with small additives of fullerenes (w = 0–1 × 10−3) are obtained. The nonmonotonic dependence of the glass transition point on composition with a minimum at w = 1 × 10−4 is revealed by the DSC method. It is concluded that there is a plasticizing action of small amounts of filler at w < 1 × 10−4 and domination of the effect of intermolecular interactions of fullerene with polystyrene at w > 1 × 10−4. It is established by small-angle X-ray scattering that composites containing fullerenes in the amount w > 1 × 10−4 are characterized by the greatest mobility of the segments in the modified polymer chains.

Sorption properties of fullerene-modified polystyrene

Polystyrene is modified with fullerene, and composite films are obtained. The kinetics of sorption of heavy metal ions from aqueous electrolyte solutions on the initial and modified polystyrene films is studied. The efficiency of sorption of copper ions of the modified polymer is found to be four times higher than on the unmodified samples. The selectivity of sorption on the composite can be presented with the following order: Cu(II) ≥ Cd(II) > Ni(II) > Zn(II). The interaction between polystyrene and fullerene is studied by IR spectroscopy.

Hydroxyethyl cellulose/bentonite/magnetite hybrid materials: structure, physicochemical properties, and antifungal activity

Bentonite/magnetite powder was synthesized and characterized using laser diffraction, scanning electron microscopy, X-ray diffraction, low-temperature nitrogen adsorption–desorption technique, and magnetization measurements, revealing it to be a ferromagnetic material with mesopores. Hydroxyethyl cellulose was filled with bentonite/magnetite particles by mechanical dispersion to produce hybrid film materials that were studied using various methods. X-ray diffraction analysis showed that the interlayer distance in the clay was increased due to intercalation of polymer molecules. A concentration effect of the filling agent on the tensile properties of the hybrid material was revealed. Infrared (IR) spectrometry indicated an increase in the density of the hydrogen-bonding network. Microbiological tests showed that the HEC/bentonite/magnetite films exhibited antifungal effect against Candida albicans.

Sorption of heavy metal ions by fullerene and polystyrene/fullerene film compositions

The kinetics and equilibrium of the process of sorption of heavy metals from aqueous electrolyte solutions by polystyrene, fullerene, and polystyrene/fullerene composites have been studied. The kinetics of sorption of copper, nickel, zinc, and cadmium ions by the studied sorbents is described by the pseudo-firstand pseudo-second-order kinetic models. The rate constants of the process of sorption are determined. It is established that the equilibrium isotherm of sorption of copper ions by fullerene is related to the Langmuirtype isotherms. The sorption capacity of a monomolecular layer with reference to the Cu(II) ions is determined as equal to 14.6 mmol/g. Based on the calculated Henry constants, it is shown that the sorption efficiency increases in the series polystyrene < composition < fullerene.

Synthesis, structure, and properties of a bentonite–magnetite composite

A bentonite–magnetite composite is obtained by means of bentonite intercalation with iron oxide Fe3O4. Using the methods of electron microscopy, low-temperature nitrogen vapor adsorption–desorption, and XRD phase analysis, the composite morphology, structure, and texture have been investigated. It is shown that the synthesized bentonite–magnetite composite can be used as a sorbent for wastewater purification from organic pollutants.

Sorption of heavy metal ions by cellulose modified with fullerene

Celulose was modified by impregnation of the polymer with a solution of C60 nanocarbon particles in ortho-xylene. Specific features of the sorption kinetics of Cu(II),Ni(II), and Cd(II) ions on cellulose and composite materials were researched. Pseudo-first- and pseudo-second-order kinetic models were used to determine the quantitative characteristics of the process. It was demonstrated that the sorption efficiency of metal ions on fullerene-containing cellulose substantially increases. The improvement of the sorption properties of the modified polymer is due to the increase in the concentration of active sorption properties and to a change in the structure of the sorbent.

Hydrodynamic and bulk properties of dextrans in liquid media

Bulk and viscous properties of solutions of dextrans of different molecular weights in formamide, water, and dimethyl sulfoxide were studied. The fractal dimension of the biopolymer was estimated from the hydrodynamic data.

Viscosity and Electrophysical Characteristics of Solutions Containing Nanocluster Polyoxometalates and Polyvinylpyrrolidone

The physicochemical characteristics of solutions intended for preparing composites that contain a water-soluble polymer, polyvinylpyrrolidone (PVP), and nanocluster polyoxometalates (POMs) based on molybdenum with Keplerate (Mo132 and Mo72Fe30) and toroidal structure (Mo138) are studied. Concentration dependences of the kinematic viscosity of solutions upon changes in the absolute and relative contents of the polymer component are obtained along with the frequency dependences of the dielectric loss tangents of such solutions that correlate with them. The data allow us to confirm the composition of POM—polymers associates that form, and to estimate the relaxation parameters of ions in solutions.