Silica fillers have been a cornerstone in chemical technology due to their versatility, availability, and ease of integration into various formulations. Recent advancements, including chlorine-free synthesis of alkoxysilanes, have paved the way for alternative materials like polymethylsilsesquioxane (PMSSO). This study explores the structural evolution and properties of a hydrophobic PMSSO xerogel, synthesized through hydrolytic polycondensation of methyltriethoxysilane (MTEOS). PMSSO exhibits exceptional hydrophobicity, high specific surface area, and compatibility with polymer matrices, making it a promising filler for applications in rubber products, lubricants, and cosmetics. We developed a straightforward synthesis method for producing PMSSO xerogel that avoids toxic solvents and organochlorosilanes, ensuring safety and sustainability. The reaction conditions, particularly the amount of alkali and neutralization parameters, were found to significantly influence the properties of the final xerogels, such as specific surface area. Optimization of the synthesis parameters allow for obtaining PMSSO xerogels with a specific surface area about 600 m2/g. These findings underscore PMSSO’s potential as a versatile, eco-friendly alternative to conventional silica fillers, offering tailored properties for diverse industrial applications.

The samples of PEGylated hyperbranched polymethylethoxysiloxanes with hierarchically organized structures were obtained. The magic angle spinning 1H–29Si variable contact time cross-polarization and static 1H multiple-quantum NMR experiments were performed in order to reveal the influence of the microstructure on the NMR parameters.

The inability to re-process thermosets hinders their utility and sustainability. An ideal material should combine closed-loop recycling and upcycling capabilities. This trait is realized in polydimethylsiloxane bottlebrush networks using thermoreversible Diels-Alder cycloadditions to enable both reversible disassembly into a polymer melt and on-demand reconfiguration to an elastomer of either lower or higher stiffness. The crosslink density was tuned by loading the functionalized networks with a controlled fraction of dormant crosslinkers and crosslinker scavengers, such as furan-capped bis-maleimide and anthracene, respectively. The resulting modulus variations precisely followed the stoichiometry of activated furan and maleimide moieties, demonstrating the lack of side reactions during reprocessing. The presented circularity concept is independent from the backbone or side chain chemistry, making it potentially applicable to a wide range of brush-like polymers.

Aerogels are a class of materials that have gained increasing attention over the past several decades due to their exceptional physical and chemical properties. These materials are highly porous, with a low density and high surface area, allowing for applications such as insulation, catalysis, and energy storage. However, traditional aerogels, such as pure silica aerogels, suffer from brittleness and fragility, which limit their usefulness in many applications. Herein, we have addressed this problem by using organosilicon compounds, namely polymethylsilsesquioxane derivatives, for the synthesis of aerogel-like materials. Specifically, we have developed a novel approach involving surfactant-free synthesis of microcapsules from partially PEGylated hyperbranched polymethylethoxysiloxane. Due to the highly diphilic nature of these compounds, they readily concentrate at the oil/water interface in aqueous emulsions encapsulating oil droplets. During the subsequent condensation, the organosilicon precursor is consumed for hexane encapsulation (yielding hollow microcapsules) followed by the formation of a continuous condensed phase. Concurrently, methyl groups ensure the hydrophobicity of the resulting materials, which eliminates the need of using additional reagents for their hydrophobization.

MQ resins have been prepared in acetic acid as an active medium from dimethylphenyl- or methyldiphenylethoxy-silane as the M-components and tetraethoxysilane as the Q-component. All prepared samples with M/Q ratios of 1:1, 1:1.5, 1:2, 1:3, and 1:4 were well soluble in organic solvents like toluene and THF. Compared to MQ resins with trimethylsilyl group as the M-component, the new MQ resins with phenyl substituents may possess improved compatibility to thermoplastic polymers, rubbers and coating formulations.

Основная проблема современной полимерной науки — поиск путей дальнейшего развития полимерной цивилизации, к которой, несомненно, относятся живые организмы на Земле, без вредных последствий для этой самой цивилизации и планеты в целом. В обзоре рассмотрены подходы к решению проблемы накопления полимерных отходов в окружающей среде, а также обсуждены перспективные направления развития полимерных технологий, способных существенно сократить образование таких отходов. Отдельные разделы посвящены оригинальным методам аддитивных технологий, таким как экструдерные технологии печати мультислоевых пленок, 3D-печать высокотемпературными полиимидными материалами, новыми функциональными силоксановыми олигомерами, гидрогелями медицинского назначения. Значительное место уделено проблемам развития и применения биоразлагаемых материалов в медицине, упаковочной индустрии, сельском хозяйстве. Анализ европейского подхода к утилизации полимерных отходов показал его ограниченную применимость из-за высоких энергозатрат и нарушения углеродного баланса планеты. Изложены тезисы современного подхода к утилизации полимерного мусора, свободного от перечисленных недостатков. Библиография — 1233 ссылки.

Realization of self-healing polymer materials cannot rely on the wealth of active repair tools found in living systems but must focus entirely on the structural composition of the material and the properties of its constituents. Current challenges of the search for such compositions include healing of large-scale defects as well as the need for a healing process that is generated by the scission itself. Herein, we describe ionomer-rubber blends from poly(ethylene-co-methacrylic acid) and peroxide cross-linked ethylene-propylene-diene monomer (EPDM) that combine three types of cross-links: covalent links of a network of EPDM, clusters of aggregated ionic groups, and crystalline domains of longer ethylene sequences in the ionomer. Above the melting point of the latter, the components mix homogeneously, indicated by the clarity of the samples and supported by small-angle X-ray scattering (SAXS) and NMR. At ambient conditions, the samples are hard like a thermoplastic material. Self-healing after mechanical damage is enabled by two types of structural memory related to a hierarchy of deformation- and defect-caused stresses and their relaxation paths. Because of the solid-like character of the materials, damage-caused stress is retained by the micro deformation and rupture of the aggregates on small scales and on large scale-by the macroscopic shape memory effect of the deformed covalent network. When the samples get annealed at an elevated temperature, the former enables mending of fracture-caused surfaces and the latter-shape recovery. Based on a careful evaluation of the structural relaxation effects on the blends and their constituents (differential scanning calorimetry, NMR, and wide-angle X-ray scattering/SAXS), we demonstrate the repair of defects in the range of millimeters to centimeters by the defect-caused stresses. It is intrinsic to our concept that it holds only to damages such as scratches, small cuts, and microcracks, whereby the object is not fully fragmented, and that it will require thermal activation.

Hollow silica microspheres have been obtained in a surfactantfree templating process at neutral pH from silica sol of 2–10nm globular organic–inorganic silica particles with exposed hydrophobic siloxane part as well as hydrophilic reactive silanol groups. Due to small diffusion coefficient and amphiphilic nature, the sol particles stabilize an oil–water interface quickly. Initially they assemble via noncovalent interaction into a stable shell and then condense covalently, with fast initial stabilization/dispersion of oil–water emulsion improving the control and simplifying the microsphere formation process.

Dedicated the memory of Akademician Valery Vasilievich Lunin, a friend, colleague, teacher, founder and leader of the research into application of supercritical fluids in chemistry. This review analyzes the rapidly developing applications of supercritical fluids, mainly supercritical carbon dioxide, in catalysis, chemistry of high-molecular-weight compounds, and medicinal chemistry in Russia and abroad. It considers the methods of catalyst preparation based on impregnation of inorganic and organic supports with metal-containing compounds, immobilization of organometallic and metal complex reagents in matrices of oxide and polymer supports, and deposition processes employing supercritical fluids. An analysis is presented of the prospects for applying CO 2 and some organic compounds, such as aliphatic alcohols, in sub- and supercritical states as reactants and (or) solvents for catalytic reactions of hydrocarbon isomerization and cracking, hydrogenation, dehydrogenation, oxidation, etc., including the asymmetric reactions. The review discusses processes of synthesizing and modifying polymer materials for various purposes, including aerogels, foams, and composites impregnated with photochromes, in a supercritical fluid medium. Special attention is paid to supercritical one-pot processes, which make the techniques of obtaining new materials simpler, less expensive, and more efficient. The work investigates the effect of supercritical CO 2 on the morphology, gas separation characteristics, and dielectric properties of polymers. One of the promising applications of supercritical fluids in medicine is the use in transplantology and pharmacology, for example, for the preparation of drug polymorphs with higher bioavailability. The review also provides an overview of the recent data on the use of EPR spectroscopy for studying the properties of supercritical fluids, including those exhibited in the vicinity of the critical point and identifying the intermediates of chemical reactions in such media.

Non-functional derivatives of polymethylsilsesquioxane (PMSSQ) dendrimers of first to fourth generation were synthesized for the first time using combination of divergent and convergent synthetic approaches. Obtaining of non-functional derivatives allowed investigating their properties not only in solution, but also in the bulk. While having practically identical chemical composition with linear polydimethylsiloxanes, PMSSQ dendrimers demonstrated increased density, a significant increase in the viscous flow energy, an absence of crystallization, and a gradual increase in the glass transition temperature with the generation.

The rheology of a rather special case of molecular nanoliquids formed by polymethylsilsesquioxane nanoparticles which occupy an intermediate position between colloidal particles and macromolecules has been studied. These objects are liquids, homogeneous up to submicron size in a wide temperature range. They demonstrate viscoelastic behavior with very strong dependence of viscosity on molecular weight of these nanoobjects. A new scaling model based on the concept of friction in viscoelastic outer layers describing this kind of behavior has been proposed. Relaxation properties of smaller nanoparticles can be described by a single-mode Maxwell model, while relaxation for larger particles takes place in a wide frequency rage covering three orders. Interpretation of the temperature dependence of viscosity within the framework of the standard WLF equation allowed us to find the “glass” (or gel)transition point. Transition from fluid to global gel-like state was clearly observed at this temperature. As part of finding on the nature of this transition, it was shown that no structural effects are related to this transition and it should be treated as a relaxation phenomenon.

Key prerequisites for the accelerated development of chemistry of silicones are considered in the context of the significance of organosilicon polymers for sustainable future. The principal trends in this field during the past two decades are analyzed and the quantum leap that occurred in the control of the structures and selective synthesis of macromolecules is pointed out. The problems of research into silicones are defined and the most promising approaches to the solution of these problems aimed at more active involvement of such systems into various areas of practical activity are demonstrated. The bibliography includes 166 references.

Three types of polymers: linear, hyperbranched polymers and dendrimers were modified via polymer-analogous reaction with the same fluorine-containing reagent to study the influence of the introduction of fluorinated units into the polymer structures on their properties. Quite an unusual feature of this approach is our focus on the investigation of polymer matrix properties rather than on surface activity, chemical inertness, solubility in supercritical CO2, hydrophobicity or oleophobicity studies, which are typical for fluorine-containing polymers; and the use of these fragments to develop matrix properties.

Three derivatives of poly(allylcarbosilane) dendrimers of the fifth generation with different terminal groups are synthesized. The influence of terminal groups on the properties of the dendrimers in bulk and solution is investigated by viscometry, precision adiabatic vacuum and differential scanning calorimetry, dynamic light scattering, and atomic force microscopy. It is shown that the surface layers of the dendrimers substantially affect their properties and behavior. The existence of the second relaxation transition and its dependence on the nature and structure of terminal groups are established. The experimental data indirectly confirm the assumed formation of intermolecular entanglement networks for higher generation dendrimers.

Synthesis of the six generations of polyallylcarbosilane dendrimers with tetrafunctional branching center and tetrafunctional base reagent is reported. Obtained dendrimers are compared to carbosilane dendrimers with less dense molecular structure synthesized before. Densification of the dendrimer structure alters some basic dendrimer properties as well as their dependence on generation.

Carbosilane dendrimers from the third to fifth generation with hydroxy groups in the surface layer of the dendrimer were synthesized, as well as their analogs with latent hydroxy groups. The dendrimers differ by the density of the carbosilane core and hydrophilic shell. The amphiphilic nature of the synthesized compounds was manifested already for more hydrophobic trimethylsilyl derivatives of dendrimers. This allowed one to observe the hydrolysis of these objects during compression of their monolayers at the water surface in the Langmuir bath. The parameters of the molecular structure of the dendrimers exert a determining effect on the rate and completeness of the hydrolysis.

Two different approaches of dendrimer based network preparation are described and problems of the dendrimers functionality's conversion control are the focus of discussion. Dendrimers of small size (G2), used as crosslinkers to the larger ones (G6) in the second approach, are shown to be an ideal "difunctional" linkage. The different nature of swelling-drying stresses in dendrimeric networks is considered and some requirements of the initial building blocks are discussed.