V. A. Petrova

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.

Study of polyelectrolyte complexes of chitosan and sulfoethyl cellulose

The complexing of polycation chitosan and polyanion sulphoethyl cellulose during the formation of polyelectrolyte simplex membranes using the layer-by-layer deposition of a solution of one polyion on a gel-like film of another one has been studied. The structural characteristics of the multilayer composites and their components have been analyzed by X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray microanalysis. A technique is proposed for studying the structure of surface layers of thin polymer films (15–20 μm) using a portable DIFREI-401 diffractometer. It is shown that the sequence of layer deposition during the formation of membrane films does not affect their structural characteristics. The interaction between positively charged chitosan groups (-NH3+) and negatively charged sulfoethyl cellulose groups (-SO3−) during the growth of polyelectrolyte complexes results in a packing of chitosan chains in the multilayer film.

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.

Synthesis and Microbiological Stability of Graft Copolymers of N-Vinylpyrrolidone and Chitosan

The kinetics of homogeneous graft polymerization of N-vinylpyrrolidone on chitosan, initiated by ammonium peroxodisulfate, was studied in relation to the reactant concentrations. The reaction orders with respect to the monomer, initiator, and matrix polymer were determined. The compositional nonuniformity and microbiological stability of the copolymer were evaluated.

Composite Fibers Based on Chitin and Cellulose

Composite fibers were produced by mixing of chitin and cellulose solutions with subsequent molding from these solutions under standard conditions. The effect of composition of systems on the structural modification and the deformation-strength characteristics of the fibers was studied.

Preparation and analysis of multilayer composites based on polyelectrolyte complexes

A method for preparing multilayer film composites based on chitosan has been developed by the example of polymer pairs: chitosan–hyaluronic acid, chitosan–alginic acid, and chitosan–carrageenan. The structure of the composite films is characterized by X-ray diffractometry and scanning electron microscopy. It is shown that the deposition of a solution of hyaluronic acid, alginic acid, or carrageenan on a chitosan gel film leads to the formation of a polyelectrolyte complex layer at the interface, which is accompanied by the ordering of chitosan chains in the surface region; the microstructure of this layer depends on the nature of contacting polymer pairs.

Chemical and structural transformations in chitosan films in the course of storage

Changes in the functional composition of chitosan films in the course of storage under ambient conditions were examined by conductometric titration and IR spectroscopy. The deformation-strength and thermal properties of the films were studied, and their supramolecular structure was analyzed by X-ray diffraction.

Comparative Study of Reactivity of Cellulose, Chitosan, and Chitin-Glucan Complex in Sulfoethylation

Sulfoethylation of the chitin-glucan complex, isolated from mycelium of the mold fungus Aspergillus niger, by substitution with sodium β-chloroethylsulfonate or addition of sodium vinylsulfonate is examined. A comparative study is made of the reactivity of the chitin-glucan complex, chitosan, and cellulose in the both reactions. The sorption characteristics of the sulfoethylated products with respect to Cu(II) and Cr(III) are determined.

Molecular mobility of chitosan and its interaction with montmorillonite in composite films: Dielectric spectroscopy and FTIR studies

The interaction of chitosan in the basic form with montmorillonite at different concentrations in composite films is studied with the use of dielectric spectroscopy and FTIR measurements. It is shown that the interaction of amino groups and primary hydroxyl groups of chitosan with local charges on the surfaces of montmorillonite nanoparticles is responsible for a change in the system of intramolecular and intermolecular hydrogen bonds that is typical for polysaccharides. The glass-transition temperature of chitosan in the composite systems is measured.

Dehydration of Organic Solvents by Evaporation through Membranes Based on Polyelectrolytic Complexes

Evaporation of binary aqueous-organic mixtures through composite membranes with coatings based on polyelectrolytic complexes including different combinations of polyelectrolytic polycations and polyanions was studied. The possibility of efficient dehydration of organic solvents by their pervaporation was demonstrated.