The experimental evaluation of structure formation in solutions of individual polymers, as well as in their mixtures with other polymers in order to predict the properties of materials obtained on their basis was the aim of this work. We used chitosan, sodium salt of chitosan succinyl, sodium salt of carboxymethyl cellulose, and polyvinyl alcohol. Distilled water, 1 % acetic acid, and buffer systems based on acetic acid and sodium acetate with pH = 3.80, 4.25, and 4.75 were used as solvents. It was found that the type of aggregates formed in polymer mixtures is determined by the nature of the solvent and the concentration of the polymers in the initial solution. A correlation has been shown between the nature of aggregates formed in solutions and some physicochemical properties of film materials obtained from solutions, namely, the degree of enzymatic hydrolysis, as well as the rate and degree of water vapor sorption by film materials. Thus, the studies carried out show that by varying the nature of the solvent, the concentration and nature of the polymers in the initial solutions, it is possible to control the structure formation in mixed polymer solutions, and, therefore, the properties of the resulting composites.

The kinetics of controlled release of medicinal substances from chitosan films has been investigated. Correlation between values of coefficients diffusion and shares of medicinal substance connected with a polymeric chain has been established.It was shown that the greater proportion of the medicinal substance connected with a polymeric chain, the lower the value of diffusion coefficients and the index defining process of diffusion in the chitosan films, and the slower transport of medicinal substance from a polymeric matrix.

The aim of this work was the investigation of the formation of structures in solutions of individual polymers, as well as their blends with each other in buffer solvents with different values of pH. In this study we used a sample of chitosan (degree of deacetylation ~ 84 %, M = 130,000), which is a polycation when dissolved, and polyvinyl alcohol (r = 1.25 g/cm3, M = 5000). Buffer systems based on acetic acid and sodium acetate with pH = 3.8, 4.25, and 4.75 were used as solvents. Viscosimetry was used to determine the intrinsic viscosity, the degree of structuring, and the Huggins constant. The Kriegbaum method was used to determine the nature of the aggregates formed by the blend of the studied polymers. In the course of the research, it was shown that an increase in the pH of the acetate buffer used as a solvent was accompanied by a compression of the macromolecular coil (a decrease in intrinsic viscosity values), a deterioration in the quality of thesolvent (an increase in Huggins constant values), and an increase in the degree of polymer aggregation in a solution for chitosan polyelectrolyte. At the same time for a solution of polyvinyl alcohol the pH of the buffer practically did not affect the nature of the polymer-solvent interaction. It has been proved that polymer blends are characterized by an increase in aggregation processes and a decrease in the thermodynamic quality of the solvent in comparison with solutions of individual polymers. The size of the “combined” macromolecular coil, characterized by the intrinsic viscosity value for the polymer blend, which can be both above (buffer solvent with pH = 3.80) and below (buffer solvent with pH = 4.25 and 4.75) additivevalues, changed depending on the type of formed polymer-polymer aggregates (homo- or hetero-). It was established that the type of aggregates (homo- or hetero-) formed in solutions of polymer blends was determined not only by the thermodynamic quality of the used solvents, but also by the concentration of the polymers in the initial solutions

The rheological properties of the carboxymethylcellulose sodium salt solutions were studied. It was shown that in a certain concentration regime they exhibit thixotropic properties, i.e. are capable of a reversible decrease in viscosity. It was found that the presence of thixotropic structures in the area of intermediate concentrations, where supramolecular structures are uniquely formed, and the time required for their destruction is comparable with the time of the experiment, makes it possible to regulate some of the physicomechanical properties of materials formed from solutions by varying the level of polymer structure formation in the initial solution.

The study is devoted to the rheological behavior of aqueous solutions of pectin, a natural polysaccharide, which is a polyelectrolyte and has a spectrum of physiological activity. It is shown that the polyelectrolyte nature of the polymer introduces significant features into its rheological behavior. These features are manifested in the form of low values of the activation energy of viscous flow, in the absence of an anomaly in the viscous flow of solutions above the crossover point, as well as in the existence of a concentration region in which macromolecules are in contact with each other, but do not form a fluctuation network of meshes.