Advances in the development of water-soluble nonstoichiometric polyelectrolyte complexes, which are characterized by high stability and can be involved in competitive interpolyelectrolyte reactions, are summarized and analyzed. The complexes remain stable over a wide range of external conditions (pH, ionic strength, temperature), but show a rapid, reversible and highly sensitive response to environmental changes outside this range by changing the phase state. The review considers methods of preparation and properties of nonstoichiometric polyelectrolyte complexes formed by interactions between oppositely charged polyelectrolytes. These reagents can be used for controlled modification of various surfaces, the preparation of soluble complexes functionalized by different molecules, the suppression and prevention of protein aggregation. The review briefly summarizes new types of soluble polyelectrolytes and polyelectrolyte complexes of different nature and with different structures, including biopolymers and dendrimers, suitable for solving problems in medicine and agricultural biotechnology. In order to evaluate the results achieved, there is a need to integrate and analyze the data on interpolyelectrolyte reactions, which are of most interest for a wide range of researchers. The bibliography includes 118 references.

Complexation between biopolymers, chitosan cationic polyelectrolyte and sodium carboxymethyl cellulose anionic polyelectrolyte, was studied. The composition of the interpolymer complex formed was...

The issue of water and wind erosion of soil remains critically important. Polymeric materials offer a promising solution to this problem. In this study, we prepared and applied an interpolyelectrolyte complex (IPEC) composed of the biopolymers chitosan and sodium carboxymethyl cellulose (Na-CMC) for the structuring of forest sandy soils and the enhancement of the pre-sowing treatment of Scots pine (Pinus sylvestris L.) seeds. A nonstoichiometric IPEC [Chitosan]:[Na-CMC] = [3:7] was synthesized, and its composition was determined using gravimetry, turbidimetry, and rheoviscosimetry methods. Soil surface treatment with IPEC involved the sequential application of a chitosan polycation (0.006% w/w) and Na-CMC polyanion (0.02% w/w) relative to the air-dry soil weight. The prepared IPEC increased soil moisture by 77%, extended water retention time by sixfold, doubled the content of agronomically valuable soil fractions > 0.25 mm, enhanced soil resistance to water erosion by 64% and wind erosion by 81%, and improved the mechanical strength of the soil-polymer crust by 17.5 times. Additionally, IPEC application resulted in slight increases in the content of humus, mobile potassium, mobile phosphorus, ammonium nitrogen, and mineral salts in the soil while maintaining soil solution pH stability and significantly increasing nitrate nitrogen levels. The novel application technologies of biopolymers and IPEC led to a 16–25% improvement in Scots pine seed germination and seedling growth metrics.

This article presents the results of the study of a new soil structuring agent—the interpolymer complex of a chitosan biopolymer and a synthetic polymer of polyacrylic acid—applied to the surface layer of a light chestnut soil (Kastanozem) in the East Kazakhstan region. The interpolymer complex was obtained by mixing equimolar polymer solutions. The composition of the [chitosan] : [polyacrylic acid] complex was determined by the physical and chemical methods and was equal to [1] : [9]. The mechanical strength of the interpolymer complex film was higher in comparison with the films of individual polymers. When applying the interpolymer complex on the soil surface by a two-solution method, a significant improvement of the structure and deflation resistance of the soil was observed. The resulting soil structural elements showed significant resistance to water erosion, which was about 99%. The obtained results indicate the possibility of using interpolymer complexes for structure formation and improving the anti-erosion properties of degraded soils.

The interpolyelectrolyte complex of the composition [chitosan]:[alginate] = [1]:[4] was prepared by mixing a hydrochloric acid solution of cationic polyelectrolyte chitosan and an aqueous solution of anionic polyelectro-lyte sodium alginate. The complex of chitosan and sodium alginate biopolymers was first used as a soil structurizer. Due to low humus and light mechanical composition, the dark chestnut soil of the dry-steppe zone of the East Kazakhstan region is subjected to erosion. Introducing a polymer complex into the specified soil contributed to the improvement of wind resistance, an increase in humidity, and a decrease in water per-meability. The soil surface treated with a complex of biopolymers showed pronounced resistance to the action of planar and trickle water erosion due to aggregation of particles with a diameter of < 0.01 mm. The fraction of soil particles obtained by mechanical destruction of structured aggregates with a diameter of 3-1 mm has a well-expressed ability to self-aggregate during the humidification - drying process. The results of the vegeta-tion and field experience in tillage with an interpolyelectrolyte complex showed a positive effect of the com-plex on the growth and development of radish of the Rubin variety and, as a result, an increase in radish yield by 2 times was achieved. The obtained results indicate the effectiveness of the structuring action of the chi-tosan-alginate complex for poorly structured soils.

Тhe application of biopolymers as reducing agents and stabilizers for the chemical synthesis of silver nanoparticles is considered.