Vol 87, No 1 (2025)

In present work, the effect of additional treatment of detonation nanodiamond (DND) powder of basic purification on the surface composition of DND particles, their electrokinetic properties, as well as aggregate stability in solutions of indifferent electrolyte (NaCl) in a wide pH range was studied. It has been found that a higher degree of purification of the samples and an increase in the number of protonated carboxyl groups on the surface of the DND particles due to additional acid and thermoammonia treatment leads to a shift in the position of the isoelectric point (IET) from pH 7.0 for the initial sample to pH 6.3 and pH 6.0, respectively. It is shown that the coagulation thresholds of hydrosols at natural pH and the position of stability zones in 10^–3 M sodium chloride solution are in full compliance with the IET values. The highest thresholds are observed at pH 5.8 for the initial DND, while for the dispersion of DND particles after thermoammonia treatment, fast coagulation occurs already at a concentration of 10^–4 M. It is also shown that the aggregate stability zones for additionally treated DND samples almost coincide. In the case of DND of basic purification, the stability zone expands in the area of positive zeta-potential, and in the area of negative values stability is not observed, probably due to the partial dissolution of surface impurities at high pH and their transition in ionic form to the solution, which causes coagulation of DND particles.

Porous cross-linked polyelectrolyte microspheres with diameter from 1 to 5 μm based on para-styrene sulfonate or copolymer of para-styrene sulfonate with vinyl acetate were synthesized. The content of sulfonate groups in the obtained polyelectrolyte microspheres is more than 2 mmol/g. It was shown that introduction of hydrophobic comonomer significantly increased the degree of swelling of polyelectrolyte microspheres. It was found that the value of adsorption of model compounds (fuchsin, methylene blue) significantly exceed the concentration of sulfonate groups. Morphology, structure of the surface layer of polyelectrolyte matrices were studied by optical and scanning electron microscopy, FTIR spectroscopy, specific surface by the BET method.

A system of rheological equations is presented, obtained on the basis of structural-kinetic representations, which describes viscous and elastic properties of structured liquids, namely concentrated suspensions, emulsions, micellar solutions, solutions and polymer melts. The structural model equations hold for equilibrium steady-state flow and for equilibrium oscillating flow. The equations are suitable for approximating rheological curves $\tau \left(\stackrel{.}{\gamma }\right)$, $N_1\left(\stackrel{.}{\gamma }\right)$, $G^{,,}\left(\omega \right)$, $G^{,}\left(\omega \right)$, at individual intervals of shear rate or oscillation frequency. Each such interval corresponds to a certain state of the structure. As an example, the results of approximation of shear viscosity curves for polymer solution, micellar solution and emulsion are given.

Antibacterial coatings are used in the food and textile industries, in the construction industry, in biotechnology and medicine. The review considers the main types of coatings that prevent fouling with biomacromolecules and microorganisms: anti-adhesive, contact, release-based, multifunctional and intelligent (“smart”) coatings. For each type of coating, the most relevant and effective active substances and their mechanism of action are described. Despite the widespread use of anti-adhesive surfaces and contact coatings, they have many disadvantages that limit the scope of their application and reduce activity and durability. Numerous studies show that multifunctional and intelligent coatings have high potential for practical application and further research on their modification to obtain universal and cost-effective coatings. The main problem of the practical application of such surfaces is the imperfection of methods for assessing the stability and antibacterial properties of the coating in laboratory conditions.