In the present study, wound healing ferroelectric membranes doped with zinc oxide nanoparticles were fabricated from vinylidene fluoride-tetrafluoroethylene copolymer and polyvinylpyrrolidone using the electrospinning technique. Five different ratios of vinylidene fluoride-tetrafluoroethylene to polyvinylpyrrolidone were used to control the properties of the membranes at a constant zinc oxide nanoparticle content. It was found that an increase of polyvinylpyrrolidone content leads to a decrease of the spinning solution conductivity and viscosity, causing a decrease of the average fiber diameter and reducing their strength and elongation. By means of X-ray diffraction and infrared spectroscopy, it was revealed that increased polyvinylpyrrolidone content leads to difficulty in crystallization of the vinylidene fluoride-tetrafluoroethylene copolymer in the ferroelectric β-phase in membranes. Changing the ratio of vinylidene fluoride-tetrafluoroethylene copolymer and polyvinylpyrrolidone with a constant content of zinc oxide nanoparticles is an effective approach to control the antibacterial properties of membranes towards Staphylococcus aureus. After carrying out in vivo experiments, we found that ferroelectric hybrid membranes, containing from five to ten mass percent of PVP, have the greatest wound-healing effect for the healing of purulent wounds.

The microstructure of the binary polymer brushes in the selective solvent was studied using the numerical lattice self-consisting field approach. The case was considered when the selectivity to the solvent (the Flory–Huggins parameter $\chi$) was varied only for one type of chains (responsive chains) while the others (non-responsive chains) remained hydrophilic ($\chi$ = 0). In such a brush, with an increase in the hydrophobicity of the responsive chains, a transition occurs between two two-layer microstructures. In the initial state the ends of the longer responsive chains are located near the external surface of the brush and those of non-responsive chains are inside the brush. When the hydrophobicity of the responsive chains becomes high enough then the reversed two-layer microstructure is formed, when the ends of non-responsive chains are located near the brush surface and the responsive chains collapse on the brush bottom. In contrast to previous works, the stiffness parameter (Kuhn segment length p) for one or for both types of chains was varied and its effect on the mechanism and characteristics of the transition was studied. If the stiffness of only responsive chains increases, then the transition occurs with the formation of an intermediate three-layer microstructure, where a layer of responsive chains is located between layers formed by non-responsive ones. If both types of chains have the same p, then the transition occurs gradually without the formation of an intermediate three-layer microstructure. For both cases, the effect of p on the critical value of ${\chi }^{*}$, corresponding to the transition point and on the steepness of the transition was investigated.

Polymer brushes, as modifying coatings, significantly improve the tribological properties of various contacting surfaces. The friction that arises when an external load is applied and the polymer brushes laterally shift relative to each other is determined by their interaction energy and the depth of interpenetration. If the brushes are immersed in a lowmolecular-weight solvent, the friction force can be controlled by varying the solvent quality through changes in external conditions, such as temperature, chemical composition of the solution, and so on. It should be noted that theoretical studies on the effect of solvent quality on the tribological properties of brushes are practically absent. To determine the influence of solvent quality on the interaction of flat polymer brushes, two complementary approaches were used: analytical and numerical self-consistent field methods. In both cases, a coarse-grained model of polymer brushes was employed. The solvent quality in the model was defined through the Flory-Huggins parameter for polymer-solvent interaction. A quantitative assessment of the overlap zone width, osmotic pressure, and friction force arising when the brushes approach each other was conducted. A theoretical description of the friction force in the low shear rate regime was proposed based on the Brinkman equation for two compressed brushes sliding against each other. It was shown that, with constant total polymerization degree, grafting density, and lateral sliding speed of the brushes relative to each other, the width of the overlap zone decreases following a power law with increasing inter-plane distance, regardless of solvent quality. Under conditions of strong compression of flat polymer brushes, the friction force approaches a certain limiting value, while the friction coefficient tends to zero, independent of solvent quality. In the moderate pressure region, the friction coefficient significantly increases with a decrease in the solubility of the grafted polymers under the same applied external load and the composition of the flat polymer brushes. The analytical method showed high agreement with the data from the numerical simulations. The obtained results allow for predicting the tribological properties of polymer brushes depending on solvent quality and, consequently, predicting the effect of external conditions on the friction force between modified surfaces.

The present study investigates the interpenetration properties of two opposing monodisperse asymmetric polymer brushes under external pressure, utilizing a numerical self-consistent field method. The polymer brushes under consideration were composed of chemically identical units, had the same stiffness values, and differed in the grafting density values σ_1,2 and/or in the number of backbone units N_1,2. Both brushes were immersed in an athermal solvent. Contrary to our expectations, the interpenetration zone of various asymmetric brushes always had a symmetrical appearance. We propose an analytical scaling theory rationalizing the symmetry of the interpenetration picture and suggesting how the penetration length scales with the four brush parameters (σ_1,2; N_1,2). Analytical expressions for the interpenetration zone were proposed and verified by numerical SCF calculations. The interpenetration of the two opposing brushes was quantified by two integral parameters: i) the overlap integral, denoted by Γ, which represents the number of contacts between brushes; ii) and the number of monomer brush units in the foreign half-space, denoted by Σ. We demonstrate that a panoply of curves specifying Σ and Γ as functions of the external pressure for different asymmetric brush pairs collapse onto universal master curves once they are rescaled as suggested by the analytical theory.

The comb-like polymers are used to modify various surfaces due to their branched structure and a number of unique physical and chemical properties. With a sufficiently dense grafting, the macromolecules form a homogeneous polymer brush that completely covers the surface to be modified. Comb-like polymer brushes find applications as biomedical coatings, lubricants, sensors, targeted drug delivery systems, and many others. Given the wide demand for comblike polymer coatings, it is of practical importance to predict their conformational properties as a function of the architecture of the grafted polymers. Сomb-like polymer brushes have been reasonably well studied both theoretically and experimentally at low grafting densities. However, there are no analytical models that quantitatively describe the properties of these brushes under conditions of high grafting densities and near-limit stretching of the macromolecular backbones. To study the conformational properties of planar polymer brushes made of comb-like polymers, two complementary approaches have been applied: analytical and numerical methods of the self-consistent field. The former was used for analytical description of the volume fraction profile of monomeric units of grafted macromolecules under their stretching on a body-centered cubic lattice, and the latter was used for validation of the proposed analytical model by comparing its results with the numerical calculation data on a simple cubic lattice. A universal analytical formula has been obtained that describes the profile of the volume fraction of monomeric units of grafted comb-like macromolecules in a wide range of grafting density values under conditions of athermal low-molecular-weight solvent. The study proceeded with the quantitative estimation of the average thickness of polymer brushes and the average density of monomeric units at different effective grafting densities of comb-like polymers. This was achieved by determining the ratio of the actual grafting density to the maximum possible grafting density of macromolecules with a given architecture as well as at different branching of these macromolecules. It has been demonstrated that, under conditions of athermal solvent, there is an increase in the average thickness of the polymer brush and a decrease in the average density of monomer units, as the branching degree of grafted macromolecules increases at a fixed grafting density and contour length of the main chain of macromolecules. Furthermore, at elevated levels of branching in grafted chains, the observed dependence of the average density on the effective grafting density approaches a linear relationship. The proposed analytical stretching model on a body-centered cubic lattice showed high agreement with the data obtained by numerical simulation on a simple cubic lattice. The findings of this study provide a foundation for predicting the conformational properties of polymer brushes under conditions of high grafting density and the degree of branching of grafted comb-like macromolecules.

Bottle-brush polymers with aggrecan-like side chains represent a class of biomimetic macromolecules that replicate key structural and functional features of natural complexes of aggrecans with hyaluronic acid (HA) which are the major components of articular cartilage. In this study, we employ numerical self-consistent field (SCF) modeling combined with analytical theory to investigate the conformational properties of cylindrical molecular bottle-brushes composed of aggrecan-like double-comb side chains tethered to the main chain (the backbone of the bottle-brush). We demonstrate that the architecture of the brush-forming double-comb chains and, in particular, the distribution of polymer mass between the root and peripheral domains significantly influences the spatial distribution of primary side chain ends, leading to formation of a “dead” zone near the backbone of the bottle-brush and non-uniform density profiles. The axial stretching force imposed by grafted double-combs in the main chain, as well as normal force acting at the junction point between the bottle-brush backbone and the double-comb side chain are shown to depend strongly on the side-chain architecture. Furthermore, we analyze the induced bending rigidity and persistence length of the bottle-brush, revealing that while the overall scaling behavior follows established power laws, the internal structure can be finely tuned without altering the backbone stiffness. These theoretical findings provide valuable insights into relations between architecture and properties of bottle-brush-like supra-biomolecular structures, such as aggrecan-hyaluronan complexes.