Abstract A method for forming highly porous poly(3,4-ethylenedioxythiophene) polystyrenesulfonate (PEDOT:PSS) composite particles with an excess nonconductive PSS component via spraying into liquid nitrogen, followed by freeze-drying, was proposed. The additional PSS content both compensates for the excess charge of PEDOT and acts as a binder during the formation of a highly porous network. Electrorheological fluids, i.e., dispersions of highly porous particles in silicone oil, were obtained. PEDOT:PSS/PSS composite particles with various component ratios were considered as fillers. Operating ranges of electric field strength and the most promising composite fillers were determined. The electrorheological activity of PSS particles was revealed for the first time. The activation effect of a small amount of PEDOT in the porous particles on the electrorheological behavior of the fluids was established. The intensity of the electrorheological effect depends on the particles’ composition and the electrical properties of the fluids. The possibility of developing electrorheological fluids with tunable properties by varying the composition of PEDOT:PSS-based composite filler particles was demonstrated.

The paper presents the production of electrically conductive composite materials based on polyaniline (PANI) and commercially available microfibrous textiles with a fiber diameter of 12–20 μm. The initial and final samples were characterized using FTIR spectroscopy, X-ray diffraction analysis, and scanning electron microscopy. It was found that a thin continuous layer of PANI forms on the fibers first, followed by the growth of particles with various morphologies that depend on the pH of the medium. Thus, in a strongly acidic medium, the particles are granular, in a weakly acidic medium they are nanofibers, and in an alkaline medium they are microspheres. As the acidity of the medium increases, the specific conductivity of the samples increases, and the resulting composite materials have high electrical conductivity values (up to 3∙10− 2 S/cm) and can be used in organic electronics for the creation of microbial fuel cells.

An electrorheological behavior of the low-filled fluids (0.1, 0.5 and 1.0 wt%) containing porous composite microparticles of nanocellulose with polyethylene glycol (PEG) in olive oil was studied in a wide range of electric field strength. Porous particles were prepared by spraying from dispersion followed by solvent crystallization and freeze-drying. The fluids showed high response to electric field and stable cyclic operation during multiple stimulation. The static yield stress reaches about 500 Pa for the 1.0 wt% fluid under an electric field of 6 kV/mm which is record-breaking value for electrorheological fluids at such extremely low concentration. The mechanism of saturated polarization was identified by the yield stress dependence on the electric field strength. Electrical properties of fluids were analyzed by dielectric spectroscopy. The sedimentation stability of the samples vividly increases above the percolation threshold. The sedimentation ratio at 1.0 wt% of the filler content remains unchanged after a month. Natural and biocompatible materials such as cellulose, PEG and olive oil allow considering such fluids as an alternative to typical silicon oil-based ones and corresponding to green chemistry concept.

Low-filled (1 wt%) electrorheological fluids of highly porous composite microparticles of poly(3,4-ethylenedioxythiophene):polystyrene sulfonate/polyacrylamide in silicone oil were prepared. The prospects of electrorheological fluids developing with particles of the specified composition was demonstrated. Operating ranges of electric field strength were determined. For the first time, electrorheological fluids have been obtained with the response induced by poly(3,4-ethylenedioxythiophene) entirely. The results open up prospects for the development of novel electrorheological fluids with hybrid fillers.

Electrorheological fluids based on polydimethylsiloxane filled with polyaniline particles of different morphology, including commercial microparticles, high-aspect-ratio nanofibrils, and composite porous polyaniline/polyethylene glycol microparticles, were studied at low concentrations (≤ 2 wt%). The nanofibrils were synthesized by oxidative polymerization. The porous particles were obtained by spraying a dispersion followed by freeze-drying. The particle morphology and chemical structure were confirmed by electron microscopy, wide-angle X-ray scattering, and infrared spectroscopy. Varying the morphology of polyaniline enables simultaneous enhancement of the electrorheological response of the fluids and improvement of their sedimentation stability. The yield stress of the fluids increases with electric field strength and dispersed phase concentration, irrespective of the filler type. The most pronounced electrorheological effect among the fluids studied is observed for the 2 wt% suspension of polyaniline nanofibrils with the yield stress of ~150 pa at 7 kV/mm. For the first time, porous composite polyaniline-based particles are considered as a filler for electrorheological fluids. Fluids containing such a filler exhibit a rapid and stable electrorheological response along with enhanced sedimentation stability. Investigation of the electrical characteristics of the fluids clarifies the differences in electrorheological activity among the studied particle types. The calculated activation energy of the interfacial polarization process is strongly governed by the filler morphology. Notably, the porous composite polyaniline/polyethylene glycol particles exhibited the lowest activation energy, indicating the most efficient interfacial polarization due to their developed internal surface. The results demonstrate that by controlling the supramolecular structure of the filler, one can tune the performance of low-filled electrorheological fluids

A study of the design and removable wooden elements of a two-part cabinet (four doors) from the collection of the Pushkin Museum of Fine Arts is presented. The cabinet is made in the style of the second French Renaissance of the Burgundian-Lyon school of the late 16th–early 17th centuries with renovation in the 19th century. X-ray tomography studies reveal areas of natural damage to the wood material caused by woodworm, the methods for joining the door parts, and areas of later modifications of the design. According to infrared (IR) spectroscopy data, it is established that all door parts are made of hardwood, presumably walnut.

This paper presents the studies of paste-inlay samples from decorative grooves on fragments of two vessels from the Early Iron Age burial mound Peschaniy IV (Remontnensky raion, Rostov oblast). Vessel 1 is similar in type to North Caucasian ceramics and vessel 2 is similar to the ceramics of the Crimean steppe. A comprehensive study included the following methods: scanning electron microscopy, energy-dispersive X‑ray microanalysis, X-ray diffraction analysis, infrared (IR) spectroscopy. The paste of North Caucasian vessel 1 was made of natrojarosite powder mixed with kaolinite and was fired at a temperature in the range of 450–600°C. The paste of vessel 2 was made of calcite. The morphological features of the calcareous platelets of coccolithophores found in the calcite confirm that the origin of the raw material of the paste is the territory of Crimea.

AIM:This study establishes the mechanism of stable emulsion capsules formation using sulfhydryl-free polysaccharides (xanthan gum, chitosan, and their mixtures), comparing ultrasonic versus conventional mechanical preparation methods. METHODS:Capsules were fabricated using both mechanical and ultrasonic processing, followed by comprehensive characterization through DLS, CLSM, CRYO electron microscopies, XPS, FTIR, AFM, XRD, and TGA. RESULTS:Ultrasonically processed xanthan gum/chitosan capsules exhibit a well-defined morphology (1 μm average size), stable surface characteristics (-19 mV zeta potential), and enhanced resistance to aggregation and coalescence. The results demonstrate not only formation of polyelectrolyte complexes in the mixed shells (with xanthan gum/chitosan ratios of 1 and 1.17 for mechanically and ultrasonically prepared capsules, respectively, with an initial 1:1 polymer solution ratio), but also reveals molecular scissoring effects. Structural characterization reveals semi-crystalline shell organization with significantly improved mechanical strength, as evidenced by the 48 kPa Young's modulus. The capsules exhibit excellent hemocompatibility (hemolysis rate < 0.02 μL/mL) for intravenous delivery applications. CONCLUSION:Our findings reveal fundamental insights into polysaccharide behavior on the phase interface under ultrasonication, demonstrating how acoustic energy drives molecular reorganization to create structurally superior capsules. This work provides a new paradigm for polysaccharide-based drug carrier design to create high-performance delivery systems with enhanced stability.

Fluorescence labeling of cells is a versatile tool used to study cell behavior, which is of significant importance in biomedical sciences. Fluorescent photoconvertible markers based on polymer microcapsules have been recently considered as efficient and perspective ones for long-term tracking of individual cells. However, the dependence of photoconversion conditions on the polymeric capsule structure is still not sufficiently clear. Here, we have studied the structural and spectral properties of fluorescent photoconvertible polymeric microcapsules doped with Rhodamine B and irradiated using a pulsed laser in various regimes, and shown the dependence between the photoconversion degree and laser irradiation intensity. The effect of microcapsule composition on the photoconversion process was studied by monitoring structural changes in the initial and photoconverted microcapsules using X-ray diffraction analysis with synchrotron radiation source, and Fourier transform infrared, Raman and fluorescence spectroscopy. We demonstrated good biocompatibility of free-administered initial and photoconverted microcapsules through long-term monitoring of the RAW 264.7 monocyte/macrophage cells with unchanged viability. These data open new perspectives for using the developed markers as safe and precise cell labels with switchable fluorescent properties.

The mechanical behavior of porous chitosan particles with various diameters obtained by freeze drying is investigated. The morphology of the particles is visualized by scanning electron microscopy. It is shown that the particles have a predominantly spherical shape and a honeycomb-like structure with interpenetrating pores. The mechanical characteristics of the particle material are modeled using the neo-Hookean, second-order Yeoh, Blatz-Ko, and third-order Ogden foam hyperelastic models, based on the results of mechanical compression tests between parallel plates and numerical solution of the reverse-engineering problem using the finite-element method. Force-displacement curves are plotted for the proposed models and then verified in a similar full-scale experiment with particles of another diameter.

For the first time, a comparative analysis of 8 strains of the genus Shewanella isolated from various natural sources is carried out according to the level of the reducing activity of Ag+ to silver-containing nanoparticles (NPs). The characteristics of biogenic NPs in terms of shape, size, crystal-lattice parameters, hydrodynamic diameter, ζ potential, and optical characteristics are obtained using scanning transmission electron microscopy, dynamic light scattering, spectrophotometry, atomic emission spectroscopy, and assessment of the biocidal activity against various types of microorganisms, including the studied strains of the genus Shewanella. It is found that the shape of the NPs is close to spherical, the sizes vary from 2 to 30 nm, the samples are polydisperse colloidal systems. Analysis of crystal lattices of the NPs confirms the presence of AgNPs, as well as Ag2O2NPs and Ag3O4NPs in some samples. The results of atomic emission spectroscopy on the quantitative analysis of the content of Ag in the nanomaterial samples are obtained, on the basis of which strains with a high ability to form a Ag-containing nanomaterial are identified. The high sensitivity of gram-positive bacteria to AgNPs is established. Different levels of resistance of 8 strains of the genus Shewanella to the action of biogenic AgNPs are demonstrated. The results indicate the metabolic diversity of strains of the genus Shewanella isolated from various natural sources. The analysis of strains of the genus Shewanella according to the level of the reducing activity is relevant for the development of an effective technology for the “green” synthesis of biogenic NPs.

A comprehensive study of the cellulose particle shape effect on electrorheological activity of their suspensions in polydimethylsiloxane was performed. Microparticles, nanorods and porous composite particles of cellulose with polyethylene glycol were considered as a filler. The structure of particles was established by a set of complementary methods, such as electron microscopy, infrared spectroscopy, and wide-angle X-ray scattering. The rheological behavior of suspensions filled by various types of particles changes under an electric field. The yield stress increases with electric field strength. The role of particle shape on the electrorheological properties of suspensions was revealed. The values of the yield stress of suspensions increase from microparticles to nanorods and porous composite particles at the same concentration and electric field strength. Porous composite particles of cellulose, a novel filler obtained by freeze-drying, demonstrates an enhanced electrorheological response compared to micro- and nanoparticles. The yield stress reaches 450 Pa at 7 kV/mm at an extremely low concentration of 1.0 wt%. Moreover, the porosity of the particles significantly increases the sedimentation stability of cellulose suspensions in polydimethylsiloxane. The high porosity of the filler makes it possible to obtain highly efficient electrorheological fluids at a sufficiently low concentration of the dispersed phase.

Nonwoven microfibrous materials were electrospun from polystyrene solutions of concentrations 15-25 wt

A chemical modification of cellulose diacetate by phthalate and nitrate was performed to increase solubility in organic solvents and change the electrical properties. The role of substituents on the conductivity, permittivity, and polarizability of cellulose films is revealed. It has been shown that highly porous micro particles can be obtained from cellulose derivatives by a simple and technological freeze-drying method. The resulting micro sized aerogels have a predominantly spherical morphology and amorphous structure. Suspensions of porous particles of nitro- and phthalylated cellulose derivatives in silicone oil have an increased dielectric permittivity compared to cellulose diacetate particles. Produced particles are novel promising material with tunable electrical properties for advanced applications in composites, including for electrorheological fluids.

In this work, we propose a convenient non-catalytic method for modifying hydroxyapatite (HA) with lactic acid to obtain a composite material suitable for traumatology fasteners. The affinity of the modified HA for the polylactide matrix increases, which has a positive effect on the composite mechanical properties. The modification process is carried out with lactic acids solutions in ethanol. It was shown that hydroxyapatite modified with 10-30% solutions retains its structure according to IR spectroscopy and X-ray diffraction analysis, and when modified with a 50% solution, calcium hydrophosphate is formed. Studies of the mechanical properties have shown that the modulus increases by almost 1 GPa for composites with modified HA compared to unmodified hydroxyapatite reaching a value close to that of native cortical bone tissue.

The mechanical behavior of porous particles of various diameters obtained by the cryolyophilization drying of frozen droplets of 1-wt % cellulose diacetate solution in 1,4-dioxane are studied. The morphology of the particles is visualized by scanning electron microscopy. It is shown that the particles have a predominantly spherical shape and a branched porous structure. The elastic and tangent moduli, Poisson’s ratio, and yield strength of the particle material are determined through mechanical tests of individual particles compressed between parallel plates. The results are then used to solve the reverse-engineering problem using the finite-element method. A bilinear stress-strain diagram taking into account the plastic properties of the particle material is obtained. Verification of the obtained model was carried out in a similar experiment upon the compression of particles of a different diameter.

Data on the determining influence of Shewanella oneidensis MR-1 (gram−) and Bacillus subtilis 168 (gram+) bacterial strains used for the biosynthesis of CdS nanoparticles (NPs) on the quantitative and qualitative composition of the protein coating and functional characteristics of the nanomaterial such as the biocidal and photocatalytic activity are presented. The novelty of the study is quantitative assessment of the proteins adsorbed on the surface of CdS NPs/Shewanella and CdS NPs/Bacillus. It is shown that the protein content on the surface of CdS NPs/Shewanella and CdS NPs/Bacillus substantially differs and is 34 and 5% of the total weight of the nanoparticles, respectively. The fundamental difference in the qualitative composition of the “protein corona” of CdS NPs/Shewanella and CdS NPs/Bacillus is confirmed. The presence of nitrogen-containing organic compounds of protein nature on the surface of the nanoparticles is confirmed by Fourier-transform infrared (IR) spectroscopy. The possibility of using biogenic CdS NPs as biocidal agents of a new generation against a wide range of microorganisms as well as photonanocatalysts for the decoloration of synthetic dyes is proven. A difference in the level of functional activity of CdS NPs depending on the strain used for their biosynthesis is found and higher biocidal and photocatalytic activity of CdS NPs/Bacillus in comparison with CdS NPs/Shewanella is shown. The need for selecting bacterial strains to produce nanoparticles with high functionality is demonstrated.

Nonwoven biodegradable materials are promising high-performance sorbents for oil spills cleanup. Nonwoven materials differing in characteristics (fiber diameter, fabric thickness, packing density) were prepared by electrospinning of polylactide solutions in hexafluoroisopropanol, chloroform, and dichloromethane. The mean fiber diameter varies from 2.3 to 6 μm, and the packing density, from 7.5 to 23

Poly( p -xylylene)–molybdenum oxide nanocomposite thin films of different thicknesses and inorganic filler content are synthesized by low-temperature vapor deposition polymerization. The structure of the nanocomposites and its evolution during thermal annealing is studied by wide angle X-ray scattering and X-ray absorption spectroscopy. It is found that the molybdenum oxide nanoparticles are amorphous in both the as-deposited and annealed composite films. The short-range order characteristic of orthorhombic molybdenum trioxide is preserved in the nanoparticles; however, a noticeable disordering of the structure together with a decrease in the effective oxidation state of molybdenum are revealed. Both an increase in the filler content and thermal annealing lead to a decrease in the bandgap of the composites, which is related to the increase in the nanoparticle size. It is shown that thermal annealing improves the stability of the resistive switching (RS) characteristics in memristors based on the synthesized nanocomposites, which creates an opportunity for the application of these materials as the active layer of memristive devices.