V. K. Lavrent’ev

Specific features of cellulose and chitin dissolution in ionic liquids of varied structure and the structural organization of regenerated polysaccharides

Solubility of cellulose, chitin, and chitosan in seven ionic liquids of varied structure was studied. It was found that pressure, temperature, and amount of an aprotic diluent (dimethyl sulfoxide) affect the dissolution of cellulose and chitin in an ionic liquid. The variation of the degree of polymerization of cellulose and chitin in ionic liquid solutions was studied. IR Fourier spectroscopy and X-ray diffraction analysis were used to examine the structural organization of hydrated cellulose and chitin films obtained.

Characteristics of composite films based on methyl cellulose and poly(N-vinylformamide) prepared from solutions in water and dimethyl sulfoxide

The stress-strain characteristics of composite films based on methyl cellulose and poly(vinylformamide) prepared from solutions of polymer blends in water and dimethyl sulfoxide are studied. The temperature of relaxation transitions in the mixed films and the concentration interval where the polymers are compatible are defined via the thermomechanical method and dynamic mechanical analysis. The effect of the nature of a solvent on the mechanism of crystallization of methyl cellulose, the stress—strain characteristics of the composite films, and the compatibility between the polymers is investigated.

Formation of organic-inorganic composite materials based on cellulose Acetobacter xylinum and calcium phosphates for medical applications

The formation of composites based on the cellulose Acetobacter xylinum and calcium phosphates has been investigated using X-ray diffraction, electron diffraction, electron microscopy, energy-dispersive analysis, and differential scanning calorimetry. It has been demonstrated that the planar morphology of calcium phosphate nanoparticles capable of interacting with nanofibrils of the cellulose matrix is an important factor providing interfacial contacts in the formation of organic-inorganic composite materials. It has been established that magnesium-containing calcium phosphates represent two-phase systems consisting of calcium magnesium phosphate Ca2.6Mg0.4(PO4)2 (whitlockite) and hydroxyapatite Ca5(PO4)3(OH). The biocompatibility of the composite materials based on two-phase calcium phosphate systems and the temperature range of their stability (∼20–250°C) determined by the thermal stability of the organic component have been investigated.

Formation of a composite from Se0 nanoparticles stabilized with polyvinylpyrrolidone and Acetobacter xylinum cellulose gel films

Formation of a composite from Se0 nanoparticles stabilized with polyvinylpyrrolidone and Acetobacter xylinum cellulose gel films was studied. The optimal sorption parameters at which the amorphous form of the selenium complex is preserved in the composite were suggested.

Properties of aqueous solutions of hydroxyethyl cellulose-poly(N-vinylformamide) blends and of the related composite films

The rheological properties of dilute and moderately concentrated aqueous solutions of hydroxyethyl cellulose-poly(N-vinylformamide) blends are studied. The stress-strain characteristics of the composite films are estimated. Dynamic mechanical analysis, the thermomechanical method, and the method of solvent-vapor sorption are used to determine the composition ranges of polymer compatibility and the temperatures of relaxation transitions in composite films. The structural organization of composite films is studied via X-ray diffraction analysis. The incorporation of one polymer into the matrix of another polymer entails changes in crystallization of the polymer dominating in the composite with respect to weight and causes an increase in the imperfectness of the crystal structure.

Interaction of Se0 nanoparticles stabilized by poly(vinylpyrrolidone) with gel films of cellulose Acetobacter xylinum

The sorption and desorption of poly(vinylpyrrolidone)-Se0 (PVP-Se0) nanoparticles on gel films of cellulose Acetobacter xylinum (CAX) are investigated. It is revealed that the hydrodynamic radius Rh of PVP-Se0 nanoparticles decreases from 57 nm in the initial solution (without CAX gel films) to 25 nm after the sorption of nanostructures on gel films and then increases to approximately 100 nm after the desorption of nanoparticles with water from dry samples of the CAX gel film-PVP-Se0 nanocomposite. It is found that selenium atoms do not penetrate into crystallites of the cellulose nanofibrils and replace water molecules sorbed by the primary hydroxyl groups of their walls. Poly(vinylpyrrolidone)-Se0 nanoclusters differ in the number and size upon their sorption inside the cellulose gel film and on the film surface.

Biogenic nanosized systems based on selenium nanoparticles: Self-organization, structure, and morphology

Selenium-containing biogenic nanosized systems based on polymer stabilizers (PSts) of different natures are obtained. A comparative investigation of the kinetic parameters of self-organization and the dimensional characteristics of forming nanostructures and their shapes is performed by means of light scattering, UV spectrophotometry, atomic force microscopy, and small angle X-ray scattering. The effect of the nature of PSts on the structural and morphological parameters (hydrodynamic radius, mean-squared radius of gyration, selenium core radius, and density) of selenium-containing nanostructures is established.

Properties of mixed aqueous solutions of methyl cellulose with polyethylene oxide and of composite films prepared from them

Rheological properties of mixed dilute and moderately concentrated aqueous solutions of methyl cellulose with polyethylene oxide were studied. Composite films were prepared from these solutions, and their physicomechanical properties and structural organization were examined.

Properties of carboxymethyl cellulose aqueous solutions with nanoparticle additives and the related composite films

The rheological properties of carboxymethyl cellulose aqueous solutions containing small amounts of purified montmorillonite and bentonite nanoparticles are studied. The viscosity of mixed solutions decreases after addition of 1 wt % nanoparticles. X-ray diffraction analysis shows that the films contain nanoparticles in the exfoliated state. An examination of the FTIR spectra of composite films suggests a shift in the absorption band due to Si-O groups. This phenomenon may be explained both by a change in the permittivity of the nanoparticle environment and by the formation of hydrogen bonds between Si-O groups and functional groups of cellulose ether. It is shown that the content of the added nanoparticles influences the mechanical characteristics of the films prepared from the systems of interest.

Properties of Aqueous Solutions Containing Blends of Poly-N-vinylformamide with Carboxymethyl Cellulose of Various Degrees of Ionization and of Composite Films of These Polymers

Rheological properties of mixtures of dilute and moderately concentrated aqueous solutions of poly-N-vinylformamide and carboxymethyl cellulose of various degrees of ionization were studied. Composite film materials were prepared, and their physicomechanical properties and structural organization were studied.