The temperature dependences of the heat capacities of carbosilane dendrimers of the third and sixth generations with ethyleneoxide terminal groups are examined for the first time by means of precision adiabatic vacuum calorimetry at temperatures between 6.5 and 350 K. In this temperature range, physical transformations are observed and their standard thermodynamic characteristics are determined and discussed. The standard thermodynamic functions are calculated per nominal mole of a chosen unit using the obtained experimental data: C° p (T), H°(T) - H°(0), S°(T) - S°(0), and G°(T) - H°(0) in the interval T → 0 to 350 K, and the standard entropies of formation at T = 298.15 K. The low-temperature (T ≤ 50 K) heat capacity is analyzed using the Debye theory of specific heat and a multifractal model. The values of fractal dimension D are also determined, and conclusions on the investigated structures’ topology are drawn. The corresponding thermodynamic properties of the studied dendrimers are compared as well.

High-generation carbosilane dendrimers exhibit properties of both macromolecules and particles and are characterized by precise chemical architecture. Because of their highly flexible branching, carbosilane dendrimers are relatively pliable, allowing them to have different shapes and crystal structures. The characteristics of dendrimers as both molecules and particles provide a potential solution to the challenging problem of packing soft quasispherical objects into a well-organized three-dimensional structure, which is a fundamental problem in modern physics. However, crystallization of such dendrimers has yet to be observed. Here, we present a successful approach for directly crystallizing high-generation carbosilane dendrimers using the procedure of solvent vapor annealing. Furthermore, the identification of general features in the mesophases produced by multigeneration dendrimers, including the formation of face-centered cubic (FCC) plastic crystal mesophases and body-centered cubic-FCC transitions, provides insight into and reveals the general properties of the crystallization process resulting from symmetry breaking.

Poly(dimethyl siloxane)-MQ rubber molecular composites are easy to prepare, as it does not require a heterophase mixing of ingredients. They are characterized by perfect homogeneity, so they are very promising as rubber materials with controllable functional characteristics. The manuscript reveals that MQ resin particles can significantly, more than by two orders of magnitude, enhance the mechanical properties of poly(dimethyl siloxane), and, as fillers, they are not inferior to aerosils. In the produced materials, MQ particles play a role of the molecular entanglements, so rubber molecular weight and MQ filler concentration are the parameters determining the structure and properties of such composites. Moreover, a need for a saturation of the reactive groups and minimization of the surface energy of MQ particles also determine the size and distribution of the filler at different filler rates. An unusual correlation of the concentration of MQ component and the interparticle spacing was revealed. Based on the extraordinary mechanical properties and structure features, a model of the structure poly(dimethyl siloxane)-rubber molecular composites and of its evolution in the process of stretching, was proposed.

This paper covers the main scientific results and achievements of the Research Center for Applied Artificial Intelligence Systems of the Moscow Institute of Physics and Technology. Accomplishments in key research areas, such as (i) "Natural language analysis based on artificial intelligence methods" and (ii) "Artificial intelligence for robotics and uncrewed vehicle control," are described. Specifically, within (i), multimodal and recommender models have been studied and text has been shown to be promising from the point of view of modality fusion: the prevailing majority of successful multimodal products work with text modality, and embeddings of any modality can often be reduced to a text embedding. At the same time, applications of multimodal models are obviously little developed: the ability to formulate and solve particular business tasks with their help is in its initial state. Within area (ii), techniques and algorithms are developed for designing a control subsystem for a robotic vehicle intended for visual simultaneous localization and mapping in real time, which improve the quality of navigation under various weather conditions in various environments (urban, rural, highway, etc.). The implementation of this project would simplify the initial prototyping of systems for navigation, computer vision, and positioning of unmanned robotic complexes and devices due to rapid data processing. Additionally, the development of bipedal anthropomorphic robots is underway: research in this scientific-engineering area is actively conducted around the world, numerous scientific works are published, and various competitions are held. To achieve the multifunctionality and flexibility required for operation in a human-friendly environment, a robot should have a design and mechanics maximally similar to parameters human. These requirements are most closely met in bipedal anthropomorphic robots. The concept of a robot design satisfying these requirements has been developed, and its detailed design for prototyping has begun. Additionally, key publications on the presented topics are described, and educational activities of the Center are surveyed.

The emergence of a new type of organization of polymeric matter, namely, dendrimers has led to a change in concepts about the macromolecular world. High and strictly defined functionality, monodispersity, and the cascade principle of molecular structure formation made these systems unique objects, the interest in which has not faded to date. Carbosilane dendrimers are of particular importance owing to the stability and inertness of their molecular backbone, high reactivity of functional groups at the silicon atom, and also the possibility of providing good analytical control over the forming structure. A wide variety of synthetic approaches to the modification of terminal groups allows for considering them as hybrid systems for the elucidation of structure–property relationships. Based on the results of the analysis of a large number of variations of the main strategies for the synthesis of dendrimers, this review highlights the importance of studying the relationships between structure and properties using representative homologous series of new objects as a fundamental basis for exploring the dendritic form of polymeric matter.

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.

A series of carbosilane dendrimers of the 4th, 6th, and 7th generations with a terminal trimethylsilylsiloxane layer was synthesized. Theoretical models of these dendrimers were developed, and equilibrium dendrimer conformations obtained via molecular dynamics simulations were in a good agreement with experimental small-angle X-ray scattering (SAXS) data demonstrating molecule monodispersity and an almost spherical shape. It was confirmed that the glass transition temperature is independent of the dendrimer generation, but is greatly affected by the chemical nature of the dendrimer terminal groups. A sharp increase in the zero-shear viscosity of dendrimer melts was found between the 5th and the 7th dendrimer generations, which was qualitatively identical to that previously reported for polycarbosilane dendrimers with butyl terminal groups. The viscoelastic properties of high-generation dendrimers seem to follow some general trends with an increase in the generation number, which are determined by the regular branching structure of dendrimers.

New non-functional methylsiloxane dendrimers possessing a sparse structure with a trimethylsiloxy outer layer containing a flexible dimethylsiloxane link between branch points have been synthesized. Two alternative synthetic protocols were employed, namely, a divergent scheme comprising an additional stage of generating a spacer –OSiMe2– group with sodium ethoxy(dimethyl)silanolate, and a hybrid method using monofunctional dendrons with a sparse structure.

In order to develop the compositions based on a new generation of environmentally friendly fillers that can improve mechanical characteristics, rubber compounds based on a model butyl rubber, polymethylsilsesquioxane (PMSS), and an MQ copolymer are explored. The effect of the organosilicon fillers on the rheological properties of the resulting rubber-based suspensions is evaluated. It is found that the introduction of 20 wt % of PMSS into the rubber already leads to the viscosity anomaly, while the MQ copolymer does not produce such an effect. The variation range of the moduli during a cross-linking process is significantly higher for the compositions containing the MQ resin. At the same time, absolute magnitudes of the storage and loss moduli for the systems with PMSS are much higher. One of the reasons for this behavior may be stronger adsorption of the rubber molecules on PMSS particles, which leads to the formation of a mixed network of the rubber with physical and chemical bonds.

Recently developed non-functional derivatives of polymethylsilsesquioxane (PMSSO) dendrimers of the first to fifth generation were characterized by 1H, 13C and 29Si NMR spectroscopy. The self-diffusion and NMR relaxation of PMSSO dendrimers in dilute solutions of toluene and melts were investigated in a wide temperature range (-50-80 °C). The hydrodynamic radii of dendrimers were determined from the self-diffusion coefficients measured in diluted solutions according to the Stokes-Einstein equation. The hydrodynamic radius of PMSSO dendrimers as a function of molecular mass follows a power law with the scaling exponent of 0.32 ± 0.02 in the investigated temperature range. The temperature dependences of the self-diffusion coefficients of dendrimers were described by the Arrhenius-type equation. The activation energies of self-diffusion of dendrimers in diluted toluene solutions are identical for different generations while the dependence of activation energy for dendrimers in melts shows a maximum for the third generation (G3) dendrimer. Taking into account the absence of specific interactions in PMSSO dendrimer melts the observed behavior was ascribed to the manifestation of interpenetration of dendrimer molecules. For low generations (G1 and G2) the short length of the branches does not considerably affect the translational diffusion while for higher generations (G4 and G5) the densification of the structure prevents significant interpenetration.

The temperature dependence of the heat capacity of a first-generation siloxane dendrimer with terminal trimethylsilyl groups is determined for the first time via high-precision adiabatic vacuum calorimetry in the temperature range of 6 to 347 K, and by differential scanning calorimetry in the temperature range of 330 to 410 K. An anomalous change in heat capacity is detected in the range of T = 42–76 K. A transition is observed in the range of T = 137–153 K, due to devitrification of the dendrimer. The thermal stability of the compound is studied via thermogravimetric analysis. The obtained experimental data are used to calculate standard thermodynamic functions of the dendrimer in the temperature range T → 0 to T = 400 K, along with the standard entropy of its formation at T = 298.15 K.

In this work, we report results of the calorimetric study of the second (G2[OSi(CH3)(3)](12)) and fourth (G4[OSi(CH3)(3)](48)) generation siloxane dendrimers with trimethylsilyl terminal groups. The heat capacities of dendrimers were precisely measured in the temperature range T = (5520) K using a fully automated adiabatic calorimeter and a heat-flux differential scanning calorimeter. In the above temperature interval, the physical transformations of the studied compounds were detected, and its thermodynamic characteristics were determined. The fundamental thermodynamic functions (the enthalpy [H degrees(T) - H degrees(0)], the entropy [S degrees(T) - S degrees(0)], the Gibbs energy [G degrees(T) - H degrees(0)]) of dendrimers were calculated over the range from T -> 0 to 520 K using the experimentally determined heat capacities of the investigated compounds. The standard entropies of formation of dendrimers G2[OSi(CH3)(3)](12) and G4[OSi(CH3)(3)](48) were evaluated at T = 298.15 K. The obtained thermodynamic data of the investigated dendrimers were compared with those of the studied earlier siloxane dendrimers G1[OSi(CH3)(3)](6) and G3[OSi(CH3)(3)](24), which represent the structurally related homologous series of organosilicon dendrimers. As a result, the dependences between thermodynamic properties of the studied siloxane dendrimers and their molecular mass were established. (C) 2020 Elsevier Ltd.

The rheological measurements of star-shaped polydimethylsiloxanes with 8, 32 and 128 arms synthesized from carbosilane dendrimers of 2nd, 4th and 6th generations, respectively, revealed the Newtonian character of flow in the systems with 8 or 32 arms and a pseudoplastic character of flow in the 128-arm one. The activation energy of viscous flow was found to be 18.5kJmol−1 for all the objects.

The molar heat capacity of siloxane dendrimer of the third generation with trimethylsilyl terminal groups G3[OSi(CH3)3]24 was determined by precise adiabatic calorimetry and differential scanning calorimetry over the temperature range T = (6–570) K for the first time. The low-temperature structural anomaly and the glass transition were observed in the above temperature range, and the standard thermodynamic characteristics of the revealed transformations were determined and analyzed. The fundamental thermodynamic functions such as the enthalpy [H°(T) − H°(0)], the entropy [S°(T) − S°(0)], and the Gibbs energy [G°(T) − H°(0)] were calculated for the range from T → 0 to 570 K based on the experimentally determined molar heat capacity of the investigated compound. The standard entropy of formation ΔfS° of dendrimer G3[OSi(CH3)3]24 was evaluated at T = 298.15 K. The thermal stability of the studied compound was investigated by thermogravimetric analysis. The standard thermodynamic properties of siloxane dendrimer G3[OSi(CH3)3]24 were compared and discussed with the previously reported data for the studied G3 carbosilane dendrimers with different functional terminal groups on the surface layer.

Area photodetector devices (image sensors) are the main imaging element of digital X-ray systems used in medicine today. Since the cost of a medical diagnostics error is very high, the requirements imposed on the image sensor are very strict. We consider a sequence of procedures for the development of an area image sensor for biomedical X-ray investigations, which must reliably distinguish low-contrast details down to 80–100 µm. The development is aimed, in particular, at combining different parameters for different tasks, which require either a high frame rate at a low digit capacity or a wide dynamic range in the slow image sensing mode. The most important parameters of an image sensor are the fill factor of an optical pixel (photosensitive cell) and the quantum efficiency. The pixel layout and topology are proposed and a solution of merging the four neighboring photocells in a separate functional group (superpixel) with a large sensitive area and a potential well is found. The calculation and simulation allow us to develop specific recommendations and requirements on the photodetector for the developed X-ray sensitive panel, and determine the frame and bit rate ranges in the transmission lines.

In this work, the heat capacities of polymethylsilsesquioxane nanogels with blocking trimethylsilyl groups were measured in the range of T = (6-500) K by precise adiabatic calorimetry and differential scanning calorimetry for the first time. In the above temperature interval, the low-temperature anomalies and the glass transition were detected, and the standard thermodynamic characteristics of these physical transformations were determined and analyzed. The standard thermodynamic functions of nanogels were calculated for the range from T -> (0 to 500) K based on the obtained experimental results. The standard entropies of formation of nanogels in the devitrified state at T = 298.15 K were determined. The standard thermodynamic properties of the investigated nanogels were discussed. (C) 2018 Elsevier Ltd.

Multiple-quantum (MQ) NMR was used to characterize the organic phase distribution in a series of hybrid organic-inorganic gels namely methyltrimethoxysilane aerogel and QM resins (trimethylsiloxysilicate polymers) with different composition. The Gaussian model of distribution of MQ coherence intensities was used to determine the effective 1H spin cluster size (N). The growth of the effective cluster size with the time of excitation of MQ NMR coherences τ indicates the uniform distribution of organic moieties in the studied gels, but the growth rate is significantly slower than that of adamantane which was used for comparison as an example of the systems with uniform distribution of 1H spins. The growth rate was described by the exponents α in the scaling law of the form N~τα. The obtained values of α were 3.07 for adamantane, 1.27 for aerogel and 1.8 for QM resins. This difference was attributed to the surface distribution of the 1H spins in the studied gels. The growth rate of spin clusters in aerogel is slower in comparison with QM resins with different content of 1H spins which show similar growth rate among each other. This result was explained by the higher local concentration of 1H spins on the surfaces of silica regions in QM resins.

Branched perfluorohydrosiloxane with CF 3 CF 2 CF 2 C(CF 3 ) 2 (CH 2 ) 3 groups at the silicon atom was synthesized by a sequence of chemical reactions. The resulting compound was used as a modifying agent for carbosilane dendrimers of the 3rd and 6th generations. Dendrimers with perfluorohexyl terminal groups in surface layer are characterized by a complex of physicochemical methods. It is demonstrated that due to the branching of perfluoroalkyl terminal groups, obtained carbosilane dendrimers are soluble in organic and inorganic media. Differences in the solubility of small and large dendrimers are caused by the formation of the outer fluoride shell of different densities.