The effect the conditions of thermal treatment have on a specific surface and the number of primary adsorption centers is studied. The relationship between changing adsorption characteristics and changes in the structure of nanofibrous aluminum oxide is considered.

The size distribution of free volume holes in mesoporous, microheterogeneous polymer sorbents based on linear rubber-modified divinylbenzene copolymers has been studied. Analysis of the results of the study and published data has shown that positron annihilation lifetime spectroscopy (PALS) applied to microheterogeneous systems, in contrast to homogeneous systems, is not necessarily sensitive to mesopores that occur at the boundaries of heterogeneities and determine the sorption or membrane properties of the modified materials. To obtain the complete information, additional procedures such as low-temperature (BET) gas adsorption and thermally stimulated luminescence (TSL) need to be used. This circumstance is due to a considerably long distance between mesopores in heterogeneous systems and limited mobility of positronium during its localization in a pore. In addition to the BET data, which largely give information on mesopores, PALS appears useful for studying micropores. The TLS technique makes it possible to judge on heterogeneity of test materials. The minimal concentration of mesopores detectable by the positron technique in the systems of interest has been determined.

Electrochemical and structure characteristics of PtCoCr/C-catalyst with platinum content 50 wt % under model conditions and in cathode of membrane-electrode assembly (MEA) of hydrogen-oxygen fuel cell are studied. The metal-phase nanoparticles are shown to represent a Pt3Co alloy with partial inclusion of chromium, the nanoparticles surface being enriched with platinum. The platinum mass activity and the PtCoCr/C-catalyst high corrosion resistance do not depend on the amount of platinum deposited onto XC72 carbon black (20 or 50 wt %). Herewith the platinum surface area decreases in the same way as the carbon black specific surface area (measured with the BET method); the latter is 227, 169, and 105 m2/g for pure carbon black and that containing 20 and 50 wt % Pt, respectively. Testing of the 50PtCoCr/C-catalyst in the MEA cathode active layer in hydrogen-oxygen fuel cell showed performance not inferior to MEAs with pure-platinum systems, the catalyst being more stable.

The results of the finite element modeling of oscillations of porous anodic aluminum oxide (AAO) microcantilevers (MCs) are shown. The influence of porosity on the elastic moduli of AAO is studied using the investigated model. Analytical dependences of the influence of porosity on the elastic moduli are obtained. It is shown that this effect can be assumed to be approximately proportional to the square of the volume of the space between the pores.

Electrically conductive PVC layers are synthesized. The layers are filled with active carbons containing porous H+-conductive structures of hydroxyethylcyclam/sulfuric acid complexes crosslinked with cellulose fabric. They are interlaid with layers based on the same structures containing added benzene and hexane adsorbates and solvates. It is found that upon anode or cathode polarization of the layers as H+-conductive electrochemical bridges in air and in the vapor and liquid phases of benzene and hexane, either the electroreduction of H+ to H-2 or the electrooxidation of H2O to O-2 occurs in the areas of contact between active carbon particles and the complexes. The dependences of rates of H-2 and O-2 formation on the voltage are studied. The magnitudes of overvoltage and the constants of electrochemical reactions are found to depend on the composition of a layer.

Представлены результаты исследования электрохимических и структурных характеристик PtCoCr/C-катализатора с содержанием платины 50 мас. % в модельных условиях и в составе катода мембранно-электродного блока (МЭБ) водородно-кислородного топливного элемента (ТЭ). Показано, что наночастицы металлической фазы представляют собой сплав Pt3Co с частичным включением хрома, при этом поверхность наночастиц обогащена платиной. Массовая активность платины и высокая коррозионная устойчивость PtCoCr/C-катализатора практически не зависят от количества платины, нанесенной на сажу ХС72 (20 или 50 мас. %). При этом величина поверхности Pt снижается так же, как и удельная поверхность сажи по БЭТ, которая составляет (м2/г): 227, 169 и 105, при переходе от сажи к катализаторам с содержанием платины 20 и 50%. При испытаниях катализатора 50PtCoCr/C в составе активного слоя катода МЭБ в водородно-кислородном ТЭ достигнуты характеристики, не уступающие МЭБ с моноплатиновыми системами, при большей устойчивости катализатора.

Size distributions of elementary free volumes have been studied in mesoporous micro-heterogeneous polymer sorbents. Positron annihilation lifetime spectroscopy (PALS), low temperature gas adsorption (BET) and thermo-stimulated luminescence (TSL) measurements are employed as complementary instruments for the study. It is shown that small admixtures of rubbers are very effective for variations of the pore size distribution. While BET technique was very informative for measurements of mesopores(2-50 nm), positron annihilation was sensitive to micropores(<2 nm), but not for mesopores. The last specificity is explained by the limited positronium diffusion length in a polymer and also by inhomogeneous distribution of mesoporesin heterogeneous systems. TSL measurements gave information on sizes of rubber inclusions in compositions.

The dependence of high-temperature hydrogen activation on the structure of nanofibrous alumina (filament diameter of 5 nm) was shown. Due to self-organization, nanofibers are twisted in spirals and then in a second stage the spirals interlock and form alumina tubes, which then transform into bundles. In the process of hydrogen activation, the specific surface area changes and amorphous alumina nanowires develop into a nanocrystalline phase. TEM investigations showed that high-temperature hydrogen activation led to the self-organization of the alumina nanofibrous structure into hollow nanotubes with a diameter close to 30 nm.

The method of quartz-crystal microbalance was used to study the process of adsorption of water vapors in chitosan films formed on a solid support with a film thickness of 5 nm to 4 μm. It is found that the adsorption capacity of thin chitosan films with a thickness that is commensurable to the roughness of the support increases at a decrease in the thickness. The kinetics of desorption in chitosan films is also determined by the ratio of film thickness and support roughness: the desorption rate constant grows when the film thickness approaches the roughness of the support (nanosize range).

Методом кварцекристаллического микровзвешивания исследованы процессы адсорбции паров воды в сформированных на твердой подложке пленках хитозана толщиной от 5 нм до 4 мкм. Установлено, что адсорбционная емкость тонких пленок хитозана, толщина которых соизмерима с шероховатостью подложки, увеличивается при уменьшении толщины. Кинетика десорбции в пленках хитозана так же определяется соотношением толщины пленки и шероховатости подложки: с приближением толщины пленки к шероховатости подложки (наноразмерный диапазон) константа скорости десорбции возрастает.

Equilibrium adsorption of nitrogen, carbon dioxide, and argon was examined on the sodium and pyridinium forms of montmorillonite and on the hydrogen form of bentonite. The measurements were carried out at 303, 343, 373, and 400 K over pressure ranges of 0.1–90 MPa (Ar and N 2 ) and 0.1–6 MPa (CO 2 ). The amount of nitrogen vapor adsorbed was determined at 77 K and pressures from 0 to 0.1 MPa. The porous structure parameters of the studied samples were determined using adsorption isotherms of nitrogen, argon, and carbon dioxide vapors. At elevated temperatures and pressures >10 MPa, Ar and N 2 adsorption processes on the Na-form of montmorillonite and Ar adsorption on bentonite are activated, since the amounts of the gases adsorbed and adsorption volumes increase with temperature. No activated adsorption is observed for carbon dioxide adsorption on these adsorbents. A comparison of the excess adsorption isotherms of gases on the Py-form of montmorillonite and H-form of bentonite shows that adsorption in micropores predominates for the Py-form of montmorillonite, whereas for the Na-form of bentonite and H-form of bentonite adsorption occurs mainly in meso- and macropores.

The adsorption of water vapor on nanodiamond (ND) powders of detonation synthesis with various chemical states of the particle surface is investigated. The specific surface, porosity, and isotherms of water-vapor adsorption by ND powders are determined. It is shown that ND surface chlorination leads to a decrease of concentration of the primary adsorption centers determining the amount of water adsorbed. The data on the influence of the water vapor relative pressure on electrical conductivity G and dielectric permeability ɛ of the powders before and after chemical modification of ND are obtained. The interconnection between the amount of adsorbed water and ND electrical parameters is considered within percolation theory. It is shown that water-vapor adsorption leads to a giant increase in the dielectric permeability value and significant rise of conductivity near percolation threshold.