Specific features of chitosan-montmorillonite interaction in an aqueous acid solution and properties of related composite films

The rheological properties of chitosan solutions in a 2% aqueous solution of acetic acid with added montmorillonite nanoparticles and the mechanical properties and structural organization of chitosan-based composite films are studied. The interaction between the polymer functional groups and surface charges of nanoplatelets is confirmed by conductometric and potentiometric measurements. With the use of a X-ray diffraction analysis, it is shown that the nanoparticles in films are in the exfoliated and intercalated states. The incorporation of up to 10 wt % modified montmorillonite nanoparticles into the chitosan matrix results in a successive increase in rigidity and a decrease in the elongation at break.     

Materials based on cellulose fabric and PVC with porous structures formed by jointed aza- and oxa-aza-crown macromolecules

A material with porous structures formed by jointed aza- and oxa-aza-crowns with peripheral OHgroups is synthesized on the basis of cellulose fabric and PVC transformed into hydroxyethylcyclam. Mesopores are mainly observed on the fiber surface. The specific surface of the material is 6 m²/g; the volume of free space is 0.112 cm³/g. Assuming the internal pores have a disk-like shape, their width is estimated at 2 nm. The material sorbs vapors of aliphatic and aromatic hydrocarbons, alcohols, aldehydes, ketones, amines, amides, nitriles, and sulfoxides. It also swells to a limited degree in organic solvents. When sulfuric acid or sodium hydroxide is sorbed in the pores, compounds of them with H⁺- and OH^–-conducting systems of hydrogen bonds are formed.     

Simulation of the processes of polarization switching in ferro- and antiferroelectric polymer systems

The ordering of ferroelectric and antiferroelectric polymer systems in an external electric field is studied by the Monte Carlo method. The threshold value of electric field strength at which the antiparallel packing of chains is converted into parallel is calculated. The hysteresis curves are studied and compared to experimental data.     

Multinuclear compounds of s-elements with sterically hindered <Emphasis Type="Italic">о</Emphasis>-semiquinonates and catecholates

Alkali metals form mutinuclear compounds with redox-active singly and doubly reduced derivatives of sterically of hindered о-benzoquinones. Complexes [Na₆(Cat)₃(THF)₇]?4THF, [Na₅(Cat)₂(SQ)(THF)₅], [Na₄(SQ)₄(THF)₄]?THF?C₆H₁₄, [Na₄(3,5-SQ)₄(THF)₄], [K₄(SQ)₄(THF)₄]?4THF and [Li₃(SQ)₃(THF)₃]?THF (Cat is catecholate, SQ is semiquinonate) possessing high sensitivity to atmospheric oxygen were synthesized and their structures were determined. Magnetochemical measurements and quantum chemical calculations revealed that variation of the alkali metal and/or change in the structure of the polymetallic core significantly affect the energy of exchange interaction between the unpaired electrons of the paramagnetic ligands framing the polynuclear metal core formed by s-elements.     

A phenomenological model for hydrocarbon high-temperature autoignition

A four-step phenomenological chemical–kinetic model is presented that is believed to apply to many aspects of combustion of most hydrocarbons at temperatures above about 1000 K. The mechanism involves chain initiation through reactive collision of fuel and oxidizer molecules, fuel consumption in a step that removes radicals, oxidizer consumption in a step that produces radicals and a chain termination step. An expression for the autoignition time is derived on the basis of this model and is applied to describe the ignition of propane–air mixtures and a few other hydrocarbons. It is shown that excellent agreement with ignition times obtained from detailed chemistry can be achieved by this model.     

Kinetic study of the reaction of nucleophilic cyclopropanation of C60 fullerene with halogenated maleopimarimide

The kinetics of nucleophilic fullerene cyclopropanation by halomethyl ketones with a diterpene fragment has been studied by the Bingel method, and the influence of the biologically active cyclopropanating agent on the process has been estimated. It has been revealed that favorable conditions for carrying out the reaction result in maximum monofunctionalized methanofullerenes formation with the maximum yield.     

Studying the physical properties of entangled electron spin states in a solid body

A concept for the experimental study of the physical properties of entangled electron spin states in a solid body is proposed. The construction of the experimental setup is developed. New-generation electron spin detectors are created. Test measurements of the electron spin polarization by two simultaneously operating Mott detectors are carried out. It is found that Bell’s inequalities are satisfied in the traditional measurement mode (without time coincidences of the pulses).     

Use of galvanostatic coulometry in the analysis of arbidol drug

Arbidol is proved to easily and completely react with electrogenerated bromine in the ratio 2: 9; so procedures for the arbidol quantification in the neat substance and drugs are developed, the RSD value does not exceed 2%. A procedure for the coulometric determination of water in the arbidol substance using the Fisher method is proposed.