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Poly(methyl methacrylate) films and poly(methyl methacrylate)/fullerene composite films were fabricated by casting from toluene solutions. The mass fraction of fullerene (C60) was varied from 0.05-3 wt. %. The effect of the fullerene (C60) content on the thermal degradation parameters of the composite films was evaluated by thermogravimetric (TG) analysis. It was found that the incorporation of C60 improved the thermal stability of the polymers. The films eventually decomposed in three stages. Incorporation of fullerene caused a change in the distribution of mass loss over the stages of degradation in comparison with the pristine polymer. Using differential scanning calorimetry (DSC), the phase transitions from the glassy state to the elastic one was studied for the examined polymeric materials. New data relating to the effect of C60 on the glass transition temperature of composites with low weight fractions of filler were obtained. Specifically, for films containing up to 0.1 wt. % of C60, a single glass transition temperature was found, whereas for composites with a higher concentration of filler, two glass transition temperatures were recorded. [ABSTRACT FROM AUTHOR]

The particle-size distribution in silica powder prepared by the sol-gel method has been determined by dynamic light scattering analysis. The average diameter of the particles was found to be 250 nm. Using a low-temperature nitrogen adsorption-desorption technique, it was found that the synthesised powder may be referred to as mesoporous materials. Polystyrene/silica composite films were fabricated by casting from o-xylene solutions. It was found, using thermogravimetry, that incorporation of silica leads to an increase in both the onset temperature of polymer degradation and in the temperature at which the maximum rate of weight loss occurs. Using differential scanning calorimetry, the phase transitions from the glassy state to the elastic one were studied for the polymeric materials. New data relating to the effect of silica on the glass-transition temperature, Tg, of composites with a low weight fraction of SiO2 were found. Specifically, we found a non-monotonic concentration dependence of the value of Tg. The present results advocate for employing silica as an effective filler for producing polymer composites with enhanced thermal properties. [ABSTRACT FROM AUTHOR]

The current research deals with the urgent task of creating highly efficient photocatalysts for wastewater treatment from various organic pollutants. For these purposes, we carried out a mechanochemical synthesis, heat treatment, and study of a non-toxic, thermally and chemically stable catalysts with a heterostructure based on Fe 2 TiO 5 pseudobrookite. The morphology and the properties of the as-prepared composites were characterized through different techniques. The chemical reactions occurring during the step-by-step heat treatment of the samples were proposed using info from XRD analysis, IR spectroscopy, thermal analysis, and mass spectra. The influence of the gaseous medium on the phase composition and the degree of crystallinity of materials has been established. The analysis of the elemental composition and morphology of powder particles was carried out at an annealing temperature in the range from 100 to 1000 °C in air. The photocatalytic activity of pseudobrookite was studied during the decomposition of the organic dye Rhodamine B, and the mechanism of photocatalysis associated with the absorption of photons and the formation of an electron-hole pair was considered. It was found that samples thermally treated in nitrogen were demonstrated greater catalytic activity than those treated in air. • Precursor of Fe 2 TiO 5 pseudobrookite was obtained by solid-phase synthesis. • Heating the obtaining powder resulted to the formation of the Fe 2 TiO 5 crystalline phase. • Powders exhibited photocatalytic activity upon discoloration of the Rhodamine B solution. • For the powder calcined in nitrogen, the photocatalytic activity was higher than that for air. [ABSTRACT FROM AUTHOR]

Abstract: Transport processes taking place during a metal anodic dissolution that accompanied by formation of the charged intermediate species are examined theoretically. Profiles of the component concentrations over the diffusion layer by quasi-equilibrium decomposition of intermediate species are calculated. It is shown that during the electrochemical process the anion’s concentration either increases or decreases as compared with its bulk value. What was the outcome depends on the stability constant of the complex species. For the first situation (increase in the anion’s concentration), analysis predicts the anion’s concentration limit depending on the stability constant of the intermediate particles. For the second case (decrease in the anion’s concentration), it is possible there is the limiting current value because of electroactive anion depletion in the near-electrode layer. [Copyright &y& Elsevier]

• Polystyrene/montmorillonite composite films were prepared via solution cast technique. • Plasma treatment of the produced films was carried out in low-pressure air plasma. • The water contact angle on the composite surface decreased after plasma treatment. • Plasma treatment of the composite led to an increase in MB adsorption efficiency. Polystyrene/montmorillonite (PS/MMT) composite films with high adsorption activity were prepared via solution intercalation technique followed by treatment of composite films in low-pressure air plasma. Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and scanning electron microscopy were used to investigate the impact of plasma on the elemental composition and morphology of the composite surface. It was revealed that plasma treatment of the PS/MMT composite led to an increase in wettability and adsorption performance. The removal kinetics of methylene blue dye from aqueous solutions was experimentally studied. It was determined that plasma processing of the composite resulted in a significant improvement of the MB adsorption process: the initial rate of the process increased by 4 times (from 1.2 × 10−8 to 4.8 × 10−8 mol/(g•min)). Adsorption kinetic curves are obeyed the pseudo-second order reaction equation. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract: The experimental data on the nickel anodic dissolution in water-organic sodium chloride solutions are presented. The analysis of obtaining results is carried out by the fractal geometry approaches. The fractal dimension values as quantitative characteristics of the metal surface energy heterogeneity are determined. It is shown that the fractal dimension depends on the solution composition. [Copyright &y& Elsevier]

• Two-component ionogels containing clay minerals and ionic liquids were prepared. • The thermal behavior of the synthesized ionogels and pristine ILs was investigated using DSC and TG techniques. • A confinement effect was revealed in the studied materials. • The glass-transition temperature shifted towards higher temperatures with the introduction of aluminosilicate. • The characteristic temperatures of thermal decomposition of ionogels were lower than those for the pristine ILs. Two-component ionogels containing clay minerals such as montmorillonite K 10 (Mnt- K 10), bentonite (Bent), and halloysite (Hly), as well as imidazolium-based ionic liquids (ILs) were prepared in present work. The ILs that were used in the synthesis included a bis(trifluoromethylsulfonyl) imide anion (TFSI-) and various cations: 1-ethyl-3-methylimidazolium (EMIm+), 1-propyl-3-methylimidazolium (PMIm+), 1-butyl-3-methylimidazolium (BMIm+), and 1-butyl-2,3-dimethylimidazolium (BDMIm+). The thermal behavior of the synthesized ionogels and neat ILs was investigated using differential scanning spectroscopy (DSC) and thermogravimetric analysis (TG). It was found that the thermograms of PMImTFSI, BMImTFSI, and BDMImTFSI showed inflections corresponding to glass-transition, which shifted towards higher temperatures with the introduction of aluminosilicate. The largest shifts compared to the neat ILs were observed for IL/Bent ionogels. It was assumed that the identified differences in the thermal behavior between the neat and clay-entrapped ILs (confinement effect) are associated with an increased role of ion-wall interactions compared to ion-ion interactions. When studying the thermal stability of the materials under consideration, two opposite trends were noted. On the one hand, the characteristic temperatures of thermal decomposition of the synthesized ionogels were lower than those for the neat ILs. But on the other hand, when introducing aluminosilicate into any IL, a decrease in the maximum rate of thermal decomposition was observed in accordance with series of IL > IL/Mnt- K 10 > IL/Hly > IL/Bent. [ABSTRACT FROM AUTHOR]

Composites of montmorillonite K10 (MMT K10) and ionic liquid (IL) containing a 1-butyl-3-methyl-imidazolium cation ([BMIm]+) and various anions, such as bis (trifluoromethylsulfonyl) imide ([NTf2]−), trifluoromethanesulfonate ([OTf]−), and dicyanamide ([DCA]−) have been obtained in this work. A number of methods, such as dynamic light scattering (DLS), scanning electron microscopy (SEM), X-ray diffraction (XRD), thermal gravimetry (TG), differential scanning calorimetry (DSC), Fourier-transform infrared (FTIR) spectroscopy, and nitrogen adsorption–desorption have been used to characterize clay, and to study the structure and thermal behaviour of the composites. It has been found that the MMT K10 powder has a narrow particle size distribution with a peak at 246 nm and a mesoporous structure (SBET=195 m2/g). According to the FTIR spectra, MMT K10/IL interaction depends on the IL type. It has been identified that confined ionic liquid interacts with both clay and adsorbed water in accordance with the hydrophilicity and size of the anion, in the following order: [DCA]− > [OTf]− > [NTf2]−. Characteristic temperatures of glass transition, crystallization, and melting have been determined for the ionic liquids under study and their MMT K10 composites. It has been revealed that when IL is adsorbed on the surface of clay, the phase transitions in IL change. The greatest changes are observed in the case of BMImNTf2. By applying the method of thermogravimetric analysis, it is shown that composite formation is accompanied by a decrease in the IL thermal stability. Apparently, the highly developed surface of montmorillonite K10, obtained by acid treatment, plays a major role in the decrease in the IL's thermal stability. The influence of the IL anion on the thermal and spectral characteristics of an MMT K10/IL composite was studied for the first time. [ABSTRACT FROM AUTHOR]

In this study, an ionic liquid (IL), 1-butyl-3-methylimidazolium acetate, was used to prepare ionogels with microcrystalline cellulose (MCC) and halloysite (Hal). SEM, XRD, TG, DSC, FTIR spectroscopy, conductometry and mechanical tests were used to study the morphology, structure, thermal behaviour and electrophysical and mechanical characteristics of synthesised ionogels. XRD analysis showed a slight decrease in the interlayer space of halloysite in ionogels containing MCC, which may have been associated with the removal of residual water molecules resulting from hydrophilic IL anions and polymer macromolecules. A change in conductivity and glass-transition temperature of the ionic liquid was revealed due to intercalation into halloysite (a confinement effect) and modification with cellulose. For triple IL/Hal/MCC ionogels, the characteristic thermal degradation temperatures were higher than the corresponding values for IL/Hal composites. This indicates that the synthesised IL/Hal/MCC ionogels are characterised by a greater thermal stability than those of IL/Hal systems. [ABSTRACT FROM AUTHOR]

Organobentonite powder was synthesized and characterized using laser diffraction, X-ray diffraction, low-temperature nitrogen adsorption-desorption technique, and dynamic light scattering. Obtained powder was found as material with mesopores. The organobentonite particles were larger than pure bentonite one. Hydroxyethyl cellulose (HEC) was filled with organobentonite particles by mechanical dispersion, and produced composite films were researched by the number of methods. New data relating to structure, tensile properties, and antimicrobial activity of HEC/organobentonite composites were obtained. Using results of X-ray diffraction, the reflections assigned to crystal filler in polymer material were proved. Concentration effect of the filling agent on tensile properties of composite film was revealed. Data of infrared (IR) spectrometry indicated a decrease in the density of hydrogen-bond net in HEC/organobentonite composite as compared with pristine HEC. Using microbiological tests, it was found that the HEC/organobentonite films exhibited bacteriostatic action against S. aureus and fungistatic action against molds. [ABSTRACT FROM AUTHOR]

Polystyrene composite films with different content of C + C fullerene mix have been obtained from o-xylene solutions. The mass fraction of fullerene was varied from 0.01 to 0.1 mass%. The glass transition temperatures and specific heat capacities in range of 293-423 K have been determined for the films by DSC method. The plasticization of the polymer is observed in thermal properties of the films under influence of small fullerene additions. The values of T and C decrease and thermal coefficient of heat capacity b increase as fullerene content increases up to 0.02 mass%. The effect of interaction between polymer and fullerene molecules on thermal properties becomes evident at higher fullerene content in range from 0.02 to 0.1 mass%. At this the values of T and C increase and b coefficient decrease with increasing content of fullerene. Concentration dependence of C and b values is less steep for polymer composite films in elastic state at temperatures above T. Molecular interactions in the composites are discussed in view of our-self and literature data. [ABSTRACT FROM AUTHOR]