Laboratory of Molecular Engineering of Polymer Nanomaterials

Unlike the initial monomers, the properties in polymers are averaged due to the distribution by molecular weight (length of the polymer chain). Therefore, polymers are often characterized not by individual characteristics (molar mass, melting point) but by an average one. However, there are such molecules that consist of a large number of monomeric units, which is characteristic of polymers, but having an individual structure inherent in monomers. These are dendrimers. By their structure, dendrimers are hierarchical molecules with an iterative structure. Thus, the dendrimer molecule is symmetrical with respect to the branching center from which the rays radiate. Next, each of the rays branches out and gives the next generation – that is, a set with a large number of rays and branching points. Theoretically, the growth and branching of the dendrimer can continue indefinitely, however, based on considerations of Van der Waals repulsion and ray packing density at high generations, this becomes impossible. Dendrimers are of great interest from the point of view of drug delivery systems and gene material due to the presence of voids of a strictly defined volume inside the molecule. In addition, dendrimers play an important role in catalysis due to the possibility of attaching a large number of active centers to the rays of the dednrimer.

The hydrophobicity of surfaces is determined by two factors: the surface structure at the nano- and micro-levels and the surface energy, depending on the chemical composition of the surface. Among the most widely used surface modifiers that reduce surface energy, three main groups can be distinguished: siloxanes, compounds with long hydrocarbon chains and compounds with perfluoroalkyl substituents. The latter are of particular importance because they have the lowest surface energy among the known ones, which causes not only their high hydrophobization characteristics, but also their extremely low adhesion to surfaces, which leads to a decrease in the service life of such coatings. In general, low mechanical stability is the main problem of hydrophobic and superhydrophobic coatings on fabrics. To overcome this disadvantage, researchers have proposed several methods. For example, the creation of covalent bonds between the coating and the fabric surface made it possible not only to create coatings that maintain an edge wetting angle of 145 degrees after 10 machine washing cycles, but also to achieve superhydrophobicity even without additional structural modification of the surface.

interest in polyborsiloxanes (PBS) arose due to the unusual, unique properties of the so-called "polyborsiloxane liquids". Such liquids can have both plastic, elastic and elastic properties, but at the same time behave like Newtonian liquids. The combination of viscoelastic properties of rheological fluids based on PBS opens up the possibility of their use as damping fluids and, in particular, for protective materials against impacts. Upon impact on such a material, it behaves like an elastic Hooke body, dissipating the impact energy into heat. But, unlike various polymer analogues that crack after mechanical action, viscoelastic rheological fluids can flow, and due to the restructuring of labile non-covalent bonds, they exhibit a self-healing effect, which allows the use of protective materials based on them repeatedly.