The article is devoted to the design, development and application of a new generation of binders for various dispersed systems, including soil, ground, sand, waste rock and others. The binders are formed by interaction of oppositely charged polyelectrolytes, both chemically stable and (bio)degradable. The fundamental aspects of interpolyelectrolyte reactions are discussed; the IPC structure and properties of the resulting interpolyelectrolyte complexes (IPCs) allow considering them as unique and universal binders. Numerous results of laboratory experiments and field trials of the IPC formulations are presented. In particular, large-scale tests have been done in the Chernobyl accident zone where the IPC binders were shown to be effective means to suppress water and wind erosion thereby preventing a spread of radioactive particles (radionuclides) from contaminated sites. Ecologically friendly IPC compositions are described, including those based on commercially available polymers; prospects for improving their efficiency and extending the range of their possible use are discussed.

Abstract-Substitution reactions between weakly crosslinked anionic hydrogels (network sodium polyacrylate or network sodium poly(2 acrylamido-2-methyl-1-propanesulfonate)) and nonstoichiometric inter-polyelectrolyte complexes formed by a blocking linear sodium polyacrylate and lyophilizing poly(N,N’-diallyl-N,N’-dimethylammonium chloride) in aqueous media have been revealed and studied. It has been found that both sulfonate and carboxylate networks take up a linear polycation via the formation of a stoichiometric interpolyelectrolyte complex, a phenomenon that results in the collapse of the network. In this case, the blocking polyacrylate anions are quantitatively expelled from the particles of the nonstoichiometric watersoluble complex into the environment and occupy lyophilizing polycations uniformly, a circumstance that results in their precipitation and, consequently, the termination of the substitution reaction. This outcome suggests the presence of feedback in the studied processes. The result for carboxylate networks is completely new and nontrivial; it is indicative of the important role of macromolecular architecture in selecting the direction of a process.

Обнаружены и изучены реакции замещения между слабо сшитыми анионными гидрогелями (сетчатого полиакрилата натрия или сетчатого поли-2-акриламидо-2-метил-1-пропансульфоната натрия) и нестехиометричными интерполиэлектролитными комплексами, образованными блокирующим линейным полиакрилатом натрия и лиофилизирующим поли-N,N-диаллил-N,N-диметиламмоний хлоридом, протекающие в водных средах. Установлено, что как сульфонатная, так и карбоксилатная сетка поглощают линейный поликатион, образуя с ним стехиометричный интерполиэлектролитный комплекс, что приводит к коллапсу сетки. При этом блокирующие полиакрилат-анионы количественно вытесняются из частиц нестехиометричного водорастворимого комплекса в окружающую среду и равномерно заселяют лиофилизирующие поликатионы, что вызывает их осаждение и, как следствие, прекращение реакции замещения. Это свидетельствует о наличии обратной связи в исследуемых процессах. Результат, достигнутый для карбоксилатных сеток, представляется совершенно новым и нетривиальным, он свидетельствует о важной роли архитектуры макромолекул в выборе направления процесса.

Small unilamellar liposomes, 40-60 nm in diameter, composed of anionic diphosphatidylglycerol (cardiolipin, CL(2-)) or phosphatidylcerine (PS(1-)) and zwitter-ionic egg yolk lecithin (EL) or dipalmitoylphosphatidylcholine (DPPC), electrostatically complex with polystyrene microspheres, ca. 100 nm in diameter, grafted by polycationic chains ("spherical polycationic brushes", SPBs). Polymer/liposome binding studies were carried out using electrophoretic mobility (EPM), dynamic light scattering (DLS), fluorescence, conductometry, differential scanning calorimetry (DSC), and cryogenic transmission electron microscopy (cryo-TEM) as the main analytical tools. By these means a remarkably detailed picture emerges of molecular events inside a membrane. The following are among the most important conclusions that arose from the experiments: (a) binding of liposomes to SPBs is accompanied by flip-flop of anionic lipids from the inner to the outer leaflet of the liposomal membrane along with lateral lipid segregation into "islands". (b) The SPB-induced structural reorganization of the liposomal membrane, together with the geometry of anionic lipid molecules, determines the maximum molar fraction of anionic lipid (a key parameter designated as ν) that ensures the structural integrity of liposomes upon complexation: ν=0.3 for liposomes with conically-shaped CL(2-) and ν=0.5 for liposomes with anionic cylindrically-shaped PS(1-). (c) The number of intact liposomes per SPB particle varies from 40 for (ν=0.1) to 13 (ν=0.5). (d) By using a mixture of liposomes with variety of encapsulated substances, multi-liposomal complexes can be prepared with a high loading capacity and a controlled ratio of the contents. (e) In order to make the mixed anionic liposomes pH-sensitive, they are additionally modified by 30 mol% of a morpholinocyclohexanol-based lipid that undergoes a conformational flip when changing pH. Being complexed with SPBs, such liposomes rapidly release their contents when the pH is reduced from 7.0 to 5.0. The results allow loaded liposomes to be concentrated within a rather small volume and, thereby, the preparation of multi-liposomal containers of promise in the drug delivery field.

The radical polymerization of n-butyl acrylate in organic, aqueous, and water–alcohol media in the presence of poly(acrylic acid) containing a trithiocarbonate group within the chain is studied for the first time. It is shown that in nonselective solvents (1,4-dioxane and DMF) poly(acrylic acid) serves as a reversible addition–fragmentation chain-transfer agent and the triblock copolymer poly(acrylic acid)–block–poly(n-butyl acrylate)-–block-poly(acrylic acid) is formed. In aqueous and aqueous–organic media (under conditions of emulsion, dispersion, and miniemulsion polymerizations as well as polymerization-induced selfassembly), the block copolymer being formed additionally serves as a stabilizer of polymer–monomer particles. The sizes of these particles and the molecular-mass characteristics of the resulting polymers may be controlled via variation in the concentration ratio of the components. It is found that, during polymerization in aqueous media, there is the formation of spherical polymer particles that preserve their morphology in thin films prepared via precipitation of the synthesized dispersion.

This review considers interpolyelectrolyte complexes, with a particular emphasis on advanced macromolecular co-assemblies based on polyionic species with nonlinear topology and on polymer-inorganic hybrids formed by interpolyelectrolyte complexes containing metal ions and/or metal nanoparticles.

Joint micellization of two amphiphilic diblock copolymers is studied by velocity sedimentation, transmission electron microscopy, electrophoretic mobility measurements, and static light scattering. One of the diblock copolymers is a strong polyelectrolyte (polystyrene-block-poly(N-ethyl-4-vinylpyridinium bromide)), while the second one is a weakly charged or uncharged copolymer (polystyrene-block-poly(acrylic acid) or polystyrene-block-poly(4-vinylpyridine)). It is shown that the mixing of the diblock copolymers in a selective aqueous-organic solvent (DMF-methanol-water) leads to the formation of joint (hybrid) micelles and that the composition of these micelles is close to the composition of the polymer mixture. Micelles consist of an insoluble polystyrene core and a mixed corona composed of blocks of a strong polyelectrolyte and a weakly charged or uncharged copolymer. Aqueous dispersions of mixed micelles are obtained with the use of the dialysis technique, the spherical morphology of the micelles is ascertained, and their three-layered structure is proposed. The nonlinear dependence of the molecular mass of micelles on their composition is found. The decisive effect of electrostatic repulsion between strong polyelectrolyte units on the thermodynamics of micellization and the dispersion stability and molecular-mass characteristics of the mixed micelles is demonstrated.

The interaction of amphiphilic block copolymers comprising an anionic block (polyacrylate or polymethacrylate) and a hydrophobic block (polystyrene, poly(butyl acrylate) or polyisobutylene) with lightly crosslinked poly( N,N -diallyl- N,N -dimethylammonium chloride) is studied for the first time. It is shown that the cationic hydrogel can sorb anionic amphiphilic block copolymers via electrostatic interaction with the corona of block copolymer micelles. The rate of sorption of block copolymer polyelectrolytes is significantly lower than the rate of sorption of linear polyions and is controlled by the lengths of the hydrophilic and hydrophobic blocks and the flexibility of the latter blocks. The sorption of amphiphilic block copolymers is accompanied by their self-assembly in the polycomplex gel and formation of a continuous hydrophobic layer impermeable to water and the low-molecular-mass salt dissolved in it.