Polyelectrolyte microspheres find applications in many fields such as ion exchange columns, fuel cell membranes, and catalysis, to name a few. Synthesis of these microspheres by inverse emulsion polymerization offers various advantages due to the increased specific surface area and high surface charge density. The surface charge density of the obtained polyelectrolyte microspheres is a hundred times higher than that of either particles obtained by dispersion copolymerization of styrene and styrenesulfonic acid or sulfonated microspheres. The morphology, chemical structure, and electro-surface properties of the synthesized microspheres were studied by transmission and scanning electron microscopy, FTIR-spectroscopy, and conductometric and potentiometric titrations, respectively. Using the potentiometric titration it is possible to characterize the structure of the surface layer of polyelectrolyte microspheres as entirely as possible. The study of the ion-exchange capacity of polyelectrolyte microspheres shows that ion-exchange capacity is 2.1 meq g(-1) in this case, which is more than 2 times higher than that of sulfonated microspheres, and 20 times higher than that of particles obtained by dispersion copolymerization.

Crosslinked cationic particles 200–600 nm in diameter have been synthesized via emulsifier-free copolymerization of methyl methacrylate and 2-aminoethyl methacrylate hydrochloride in the presence of cross-linking agents ( N , N ' - methylenebisacrylamide, triethylene glycol dimethacrylate, and diethylene glycol dimethacrylate). It has been shown that polymer particles with a maximum concentration of surface functional groups (1.42 µmol/m 2 ) and a stable structure of a surface layer are formed only in the presence of ethanol (20 vol %). The synthesized particles efficiently adsorb biologically active substances, and their dispersions are stable against aggregation in buffer solutions at pH 7.0.

Cross-linked cationic particles 150–300 nm in diameter have been synthesized via single-stage emulsifier-free copolymerization of methyl methacrylate and 2-aminoethyl methacrylate hydrochloride in the presence of cross-linking agents (ethylene glycol dimethacrylate and N,N'-methylenebisacrylamide). Factors that enable one to control the morphology and polydispersity of the resulting particles have been determined. It has been shown that the dispersions of the particles are aggregatively stable in physiological solutions and after the sorption of biologically active molecules. The synthesized particles can be used for efficient revealing tick-borne encephalitis virus via latex agglutination reaction, with the analysis time being no longer than 10 min.

Droplet microfluidics offers exquisite control over the flows of multiple fluids in micro-scale, enabling fabrication of advanced microspheres with precisely tuneable structures. The main goal of this work was to design monodispersed carboxylated polystyrene microspheres with a developed pore structure (a specific surface area more than 200 m(2)/g) using microfluidic technology. We investigated the influence of the composition of monomer phase for the stable formation of droplets. Under the stable region, the resulting microspheres (with diameter 50 mu m) showed narrow size distribution having a coefficient of variation of below 2%. The obtained microspheres are characterised by morphology and surface structure by means of electron microscopy. The structure of cross-linked microspheres is investigated by solid-state(1)H NMR spectroscopy. Finally, these microspheres have great potential for the effective sorption of biologically active substances (bovine serum albumin).

Monodisperse dye-containing crosslinked particles are promising for application in novel optical chemical sensors due to their intrinsic sensitivity. However, preparation of these particles in aqueous media still remains a challenge, since luminophores inhibit radical processes or else cannot embed into polymer chains because of difference in monomer reactivity ratios. In this work, novel dye-containing monodisperse crosslinked particles were prepared and characterized. In order to obtain dye-containing monodisperse crosslinked particles, we studied seed copolymerization of styrene in the presence of divinylbenzene. The influence of nature and concentration of the used comonomers and co-solvents on shape, size distributions and surface characteristics of the particles formed was investigated. Shapes and diameters of the particles were analyzed by DLS, TEM and SEM. The data of SEM and optical spectroscopy studies demonstrated that the synthesized particles were able to self-assemble into thin-film three-dimensional ordered structures. Finally, the structures under study are promising for development of sensor devices with optical response to acetone. [GRAPHICS] .

New single crystals, based on 2-methylbenzimidazole (MBI), of MBI-phosphite (C16H24N4O7P2), MBI-phosphate-1 (C16H24N4O9P2), and MBI-phosphate-2 (C8H16N2O9P2) were obtained by slow evaporation method from a mixture of alcohol solution of MBI crystals and water solution of phosphorous or phosphoric acids. Crystal structures and chemical compositions were determined by single crystal X-ray diffraction (XRD) analysis and confirmed by XRD of powders and elemental analysis. Raman spectroscopy of new crystals evidences the presence in crystals of MBI-, H3PO3-, or H3PO4- and water molecules. Dielectric properties of crystals reveal strong increase and low frequency dispersion of dielectric constant and losses at heating, indicating the appearance of proton conductivity. At low temperatures in MBI-phosphate-2, an increase of dielectric constant analogous to quantum paraelectric state is observed.

Single crystals of L-histidine phosphite (L-Hist · H3РО3) have been grown from aqueous solution by slow cooling method. The results of elemental analysis, of X-ray-diffraction studies of the crystal structure, and the habitus of the obtained crystals are given. The elastic and piezoelectric coefficients have been measured on the plates with the (010) natural faces by the method of electromechanical resonance for stretching vibrations in the temperature range 295–340 K. Elastic compliance values s33 and s22 and the corresponding elastic-moduli values, piezoelectric coefficients d23 and d22, coefficients of electromechanical coupling, and temperature coefficient of the resonance frequency are obtained. A comparison is given with other crystals, which are compounds of amino acids with phosphorous or phosphoric acid.

Cross-linked polymer particles containing centers of molecular recognition of toluene and prepared in the presence of luminophoric bromine-containing or hydroxyl-containing derivatives of 1,3-diphenyl-beta-diketonate boron difluoride using styrene, methacrylic acid, ethylene glycol dimethacrylate and divinylbenzene are obtained for the first time. The influence of cross-linked particle characteristics (core particle diameter, core/shell particle diameter, shell thickness, particle size distribution) on the luminescent properties of their films is shown. The stability of bromine-containing or hydroxyl-containing derivatives of beta-diketonate boron difluoride in different solvents (deuterotoluene, deuterochloroform) as well as at a temperature of 60 degrees C and in the presence of the initiator, alpha,alpha'-azoisobutyronitrile, that models the conditions of cross-linked polymer particle synthesis, is studied by H-1, B-11 and C-13 NMR spectroscopy. Furthermore, the sorption of ethanol by 3D-ordered structures based on the particles obtained is investigated by means of NMR spectroscopy and the changes of the luminescence spectra of such structures in the presence of toluene vapors are studied.

AbstractSingle crystals of L -histidine phosphite ( L -Hist · H_3РО_3) have been grown from aqueous solution by slow cooling method. The results of elemental analysis, of X-ray-diffraction studies of the crystal structure, and the habitus of the obtained crystals are given. The elastic and piezoelectric coefficients have been measured on the plates with the (010) natural faces by the method of electromechanical resonance for stretching vibrations in the temperature range 295–340 K. Elastic compliance values s _33 and s _22 and the corresponding elastic-moduli values, piezoelectric coefficients d _23 and d _22, coefficients of electromechanical coupling, and temperature coefficient of the resonance frequency are obtained. A comparison is given with other crystals, which are compounds of amino acids with phosphorous or phosphoric acid.

X-ray diffraction analysis and transmission electron microscopy were used to demonstrate that hydroxyapatite produced by the precipitation method is a powder composed of anisometric particles with longitudinal size of 70–100 nm and transverse size of 7–9 nm. The particles are constituted by crystallites with longitudinal sizes of 22–24 nm and transverse sizes of 8–10 nm. At a temperature of 600°C, the crystallite sizes grow, and the volume porosity and specific surface area decrease. Synthetic hydroxyapatite has a low thermal stability as compared with hydroxyapatite of biological origin.

2-methylbenzimidazole single crystals and films are obtained by evaporation from an ethanol solution. The films have a texture with a predominant orientation of the pseudotetragonal axis in the film plane. The blocks are split crystals of the spherulite type, in which the pseudotetragonal axis rotates around the block center. Dielectric hysteresis loops are investigated in the crystals and films in the temperature range of 290–350 K. In the films, loops are observed for both in-plane and out-of-plane electric-field orientation. The maximum value of polarization in the films is close to that observed in single crystals P s ~ 5 μC/cm 2 . The difference in the temperature behavior of the hysteresis loops in the crystals and films is associated with the specific structure of the blocks.

The polarization switching was studied in single crystals and thin films of 2- methylbenzimidazole (MBI) obtained by evaporation method from an MBI ethanol solution. Dielectric hysteresis loops were measured in the temperature interval 290-390 K and frequency range 20-1000 Hz for different amplitudes of the electric field. The Kolmogorov β-model with account of Mertz law is used for simulation of hysteresis loops. The temperature dependence of domain wall motion activation field Ea has been obtained. Mechanisms of polarization switching in single crystals and films of MBI are discussed. In MBI films, a comparison of polarization switching for in-plane and out-of-plane electric field orientation is presented.

The present article investigates the influence of dispersion medium on the aggregate stability of cross-linked poly-(methyl methacrylate) particles on the surface layer of which aliphatic amino groups are localized. It is shown that particle size depends on the ionic strength of dispersion medium. The research determines the optimal content of cross-linked agent, ethylene glycol dimetharylate that results in the formation of cationic particles being stable in saline. Particle modification is performed by bovine serum albumin and luminophore fluorescein 5(6)-isothiocyanate. Protein sorption is observed not to influence luminescent properties of the particles. It is also determined that due to the aggregate stability of particles obtained from 5wt% of ethylene glycol dimethacrylate in saline, the monodispersity and the absence of inversion of zeta potential in wide pH range is retained, such particles may be considered as perspective carriers of biologically active substances.

Методом безэмульгаторной эмульсионной сополимеризации метилметакрилата с N-винилформамидом и диметакрилатом этиленгликоля синтезированы положительно заряженные монодисперсные частицы. Прослежено влияние сшивающего агента на конверсию мономеров, а также на форму, распределение по размеру и поверхностные характеристики образующихся частиц. Показано, что введение 5 мас. % сшивающего агента в реакционную систему приводит к формированию частиц, -потенциал которых после гидролиза имеет положительные значения при значениях pH от 2 до 10.