Polyurethane–poly(2-hydroxyethyl methacrylate) semi- IPN–nanooxide composites

Two sets of hybrid polyurethane–poly(2-hydroxyethyl methacrylate) semi-interpenetrating polymer network–nanooxide composites with 0.25 or 3 wt% nanosilica or nanoalumina functionalised with OH, NH2 or CHLCH2 groups were prepared. A combination of atomic force microscopy, infrared spectroscopy, thermally stimulated depolarisation current measurement, differential scanning calorimetry and creep rate spectroscopy analysis of the nanostructure and properties of the composites was performed. The pronounced dynamic heterogeneity and the strong impact of oxide additives, basically suppression of the dynamics and temperature-dependent increasing modulus of elasticity, were observed. The effects correlated with either interfacial interactions (for silica) or the nanostructure (for alumina). A low oxide content strongly affected the matrix due to the formation of an unusual cross-linked, via double covalent hybridisation of three components, structure of the nanocomposites

Interactions of single and multi-layer graphene oxides with water, methane, organic solvents and HCl studied by 1H NMR

Abstract Contemporary characterisation techniques for graphenes are often performed for samples in a dried state or vacuum, which can lead to significant structural changes and difficulty in assessing the actual physical or physicochemical characteristics of graphenes in a colloid state. The interfacial phenomena between water or mixtures (of water with benzene, methane, or HCl) bound to single-layer graphene oxide (SLGO) and multi-layer graphene oxide (MLGO) in different dispersion media (CDCl3, CCl4, CDCl3/DMSO, air) were studied using low-temperature (200–280K) 1H NMR spectroscopy. Use of the NMR cryoporometry method allows determination of the textural characteristics of SLGO and MLGO depending on their hydration degree. It was found that SLGO in diluted suspensions is more agglomerated after freezing-thawing. This effect could be assigned to cryogelation of carbon sheets leading to a decrease in the specific surface area (from 1841 to 533m2/g) representing the area of sheets that are accessible for water that is unfrozen at subzero temperatures. The results obtained show that the cryoporometry method is appropriate for the investigation of the texture of both wetted and suspended graphene oxides

A quantum chemical study of the processes during the evaporation of real-life Diesel fuel droplets

International audienceEvaporation rate (γ) of molecules from Diesel fuel molecular clusters and nanodrops is analysed using the solvation model \SMD\ within quantum chemistry, the kinetic gas theory, and experimental or extrapolation data on temperature dependence of the enthalpy of evaporation and liquid density. The SMD/HF or SMD/DFT with the same 6-31G(d,p) basis set is used to estimate changes in the Gibbs free energy during the transfer of a molecule from a liquid medium into a gas phase (using the Gibbs free energy of solvation, ΔGs). The kinetic gas theory is used to estimate the collision rate of molecules/clusters/nanodrops in the gas phase. This rate depends on partial pressures, temperature, sizes and masses of molecules and clusters/nanodrops. Such solvents as n-dodecane, tetraline, benzene, and isopropyltoluene are used to analyse the effects of surroundings on the evaporation rate of the components of Diesel fuel: normal, iso and cyclic alkanes, 1–3 ring aromatics, tetralines and indanes (in the C12–C20 range). Compounds C14–C16 give the main contribution to Diesel fuel under consideration, and all cyclic organics have the C1–C6 aliphatic side groups. An increase in the molecular size of alkanes from n-octane to n-heptacosane or in the aromaticity of compounds results in a strong decrease in the γ values

Alumina-silica-titania adsorbent for hazardous azo and phtalocyanine dyes removal from textile baths and wastewaters – the impact of ionic surfactants

Two aspects of interfacial phenomena were discussed in the manuscript. The first one concerns the adsorptive removal of two azo dyes such as C.I. Acid Yellow 219 (AY219) and C.I. Direct Yellow 142 (DY142) as well as the phtalocyanine C.I. Reactive Blue 21 (RB21) on the alumina silicatitania oxide (4% wt. $Al_2O_3$ – 8% wt. $SiO_2$ – 88% wt. $TiO_2$; AST88) in the ionic surfactants presence. The second one deals with the determination of interaction mechanism in the dyes-AST88, dyes-surfactant-AST88 systems using the data obtained from the surface charge density and zeta potential studies. The sodium dodecyl sulphate (SDS) with anionic character and hexadecyltrimethylammonium bromide (CTAB) with cationic ones were used. The adsorption capacities of 205.2 mg/g for AY219, 36.5 mg/g for RB21 and 18 mg/g for DY142. The potentiometric titration and Doppler laser electrophoresis methods enable determination of sign and magnitude of charge located in both the surface and the slipping plane layers around the solid particles. The structure of electrical double layer was determined in the AST88 systems without as well as with dyes and with mixed dye + surfactant adsorbates