N. P. Sokolova

Proton-conducting sorption-active cyclam-based layers on chemically modified PVC surfaces of cellulose fabric

At different concentrations of hydrochloric, sulfuric, and phosphoric acids, the conductivity of the following electrochemical cell was measured: anode-acid solution-in-air bridge-acid solution-cathode. Cellulose fabric, the fibers of which are encapsulated in polyvinyl chloride, the surface of which is chemically modified with porous layers of aggregates formed by acid molecules and salt groups of ethanol and acetate cyclams, served as the bridge. The range where the logarithmic conductivity is proportional to the acid concentration is found. In this range, the molar contents of acids and water in the layers are estimated, the presence of aggregates composed of acid hydrates and cyclam salt groups is determined, the structure of layer is studied, and the similarity between the H+ conductivity of the layers on fabric and the conductivity of membranes based on polymers involving the skeleton ammonia salt groups is followed. For the aggregate layers, the specific surface; the limiting volume of pores; and the adsorption capacities for water, alcohol, benzene, and hexane vapors are measured. The formation of aggregates is shown to produce an insubstantial effect on the adsorption characteristics of the surface. During migration of H+ ions in the fabric and on its surface, the following process was carried out in the electrochemical cell: adsorption of NH3, formation of NH4+ ions, and transfer of NH4+ ions to the catholyte. The migration velocity of H+ ions is shown to correspond to the measured current in the circuit, and NH4+ ions formed are found to be accumulated in the catholyte.

PVC materials with sorption-active surface of ethanol cyclam nanofilms

Materials with sorption-active nanofilms based on PVC materials with surface layers modified into ethanol cyclam nanofilms were obtained, based on which new functional materials with given properties can be developed. The properties and molecular structure of ethanol cyclam nanofilms with different sorption-active surfaces were studied using physicochemical research methods.

FTIR Spectroscopic Studies of Interactions of Stilbenes with Silicon Dioxide

Adsorption interactions of trans-stilbene and its hydroxy and methoxy derivatives with the surface of nanodispersed SiO2 aerogel were studied by diffuse-reflection FTIR spectroscopy. Stilbenes were found to adsorb at the aerosil via hydrogen bonding to silanol OH groups. The deepest modification of these groups was produced by 3,5,4′-trihydroxystilbene (resveratrol). Although the stilbenes adsorbed reversibly, the absorption spectra of the starting and desorbed resveratrol proved to differ. UV irradiation (λ = 285–305 nm) of adsorbed hydroxystilbenes changed the composition and properties of adsorbed layers. The changes include breaking of the hydrogen bonds between the hydroxystilbene molecules and the surface, destruction of the stilbenes involving cleavage of the double bond of the ethene fragment, dimerization, oxidation, and transformation into other compounds. The intensity of heterogeneous photolysis depends on the number and composition of functional groups in trans-stilbenes.

Synthesis and proton conductivity of adsorption-saturated and solvated porous hydroxyethylated cyclam layers on the surface of PVC-coated cellulose fabric

Porous layers of associates of adsorption-saturated and benzene- and hexane-solvated chloride and sulfate of hydroxyethylated cyclams with acid aqua complexes were synthesized on the surface of PVC-coated cellulose fabric. The porous structure of the layers includes a system of internal pores connected with the external pores via the diamine rings of the common walls of the hydroxyethylated cyclam nets; the internal pores are filled with the associates; the solvent molecules are adsorbed on the developed surface of the layers or solvate it. The H+ motion rate in a layer placed in solvent vapors or liquid solvents was measured; the layers were found to be nonlinear H+ conductors. The potential of H+ transition from the acid solution into the layer, the H+ mobility constant, and the field variation constant of the H+ mobility of the layer depend on the layer composition. The adsorption and solvation are accompanied by the formation of host-guest molecular complexes between the diamine rings of the cyclam nets and the benzene or hexane molecules, affecting the resistance of the associates to the incorporation of H+ ions and the H+ mobility in the associates.

Gravimetry, resistometry, and Fourier-transform infrared spectroscopy for monitoring the corrosivity of the atmosphere with the use of an iron-oxide nanocomposite sensor layer

The properties of a heterophase nanostructured metal-oxide layer produced by reactive sputtering in a vacuum followed by exposing to an oxidizing air environment at different evacuation degrees at 25°C are monitored with the use of diffuse reflectance Fourier transform infrared spectroscopy, resistometry, and gravimetry. According to the data of atomic force microscopy and infrared spectroscopy, as a result of the application of a metal to a glass substrate and subsequent oxidation, a metal-oxide nanocomposite film composed of metal-oxide nanoparticles with sizes of 20–30 nm covered with magnetite-hematite oxide shells is formed. It is shown that a metal-oxide nanocomposite layer can be used as a sensor in oxidizing environments. Gravimetric and resistometric sensor responses (the integral degree of oxidation) are almost proportional to the logarithmic rarefaction, which enables one to use metal-oxide sensors in broad ranges of pressure and rarefaction of the monitored atmosphere. Results of gravimetry and resistometry showed that the low-temperature oxidation of freshly sputtered iron films is accompanied by their partial oxide compaction. For overall monitoring of the formation of magnetite and its transformation into hematite, the above methods should be supplemented with a spectral method, such as Fourier-transform infrared spectroscopy.

Production of materials with sorption-active cyclam layer on polyvinyl chloride surface encapsulating cellulose matrix fibers

Materials with multifunctional sorption-active surfaces are produced based on polyvinyl chloride covering a cellulose matrix and yield an active cyclam layer. Factors that determine the chemical stability and the sorptivity of the material are determined. Conditions of the production and properties of the materials are studied using various physicochemical methods.

Synthesis of composites based on polymer binders and water-soluble strongly polar phthalocyanine aimed at developing functional nanomaterials

The results of spectral studies of novel polymer composites based on water-soluble polymer binders (polystyrene-alkyl(meth)acrylate film-forming emulsifier-free latexes) and water-soluble strongly polar phthalocyanine (WDP) are discussed. The high homogeneity of the composite materials produced at a phthalocyanine concentration below 10−3 or 10−2 mol/l dispersion phase is shown. Above this concentration, in addition to a homogeneous distribution of phthalocyanine, crystalline WDP inclusions are observed. The spectra of both kinds of WDP are comparable. Upon adding phthalocyanine to the polymer matrix, the shape of absorption bands assigned to hydrogen bonds changes.

Formation of surface layers upon evaporation of meso-tetra(benzo-15-crown-5)porphyrin on nanostructured iron surfaces

Morphology and spectral characteristics of the surface structures obtained upon the evaporation of meso-tetra (benzo-15-crown-5)porphyrin on the iron surface are studied with the use of digital optical microscopy, IR Fourier-transform spectroscopy, and x-ray diffraction analysis. During the interaction of porphyrin chloroform solution with nanostructured iron-based metal-oxide nanocomposite template, the process at the original template boundary is shown to initiate the formation of two polymorphous modifications of a porphyrin layer, namely, the aggregated layer and a transparent vitreous layer.

Cellulose fabric covered with a PVC coating filled with active carbon and a porous semiconductor layer with conductivity depending on adsorption coverage and solvation

A multilayer system that involves cellulose fabric covered with a PVC coating filled with active carbon and a porous layer composed of ethanol cyclams was synthesized and shown to be a high-resistance semiconductor due to the conductive properties of the part that consists of cyclams and active carbon. The effect of the inclusion of active carbon particles in the PVC coating and in the cyclam layer on the composition and structure of the whole system is discovered, and characteristics of the layer are determined. Systems that involve layers saturated with adsorbed vapors of ethanol, benzene, or hexane and those that involve layers solvated by the corresponding liquid solvents are synthesized. Adsorption and solvation are found to increase the electronic conduction of the layers. The specific resistance is shown to increase in a hexane < benzene < ethanol series, which correlates well with the increase in the number of solvent molecules per monomeric unit of the macromolecular ethanol cyclam network in the adsorption-saturated and solvated layers.

Synthesis and sorption properties of porous layers of cyclames on a modified polyvinyl chloride surface

The structure and adsorption properties of the porous layers of synthesized ethanol-cyclames and sodium acetate cyclames on a surface of polyvinyl chloride (PVC) encapsulating fibers of the asbestos tissue of chrysotile asbestos are studied. It is established that PVC is linked to the silicon-oxygen chains of magnesium hydrosilicate; the capsule ensures the stability of the asbestos tissue under the action of the concentrated solutions of acids and alkalis; its exterior reproduces the fiber surface and has a typical microrelief; and there are voids in the layers. We conclude that the specific surface of layers and the volume of the adsorption space are larger than those of the initial fibers, and the statistical capacity upon the adsorption of water vapor and polar and nonpolar organic molecules depends on the nature and affinity for cyclames.