THE FORMATION OF REINFORCING FILLERS IN A POLYMER MATRIX BY SOL-GEL METHOD

В работе изучены способы формирования наночастиц диоксида кремния и диоксида титана золь-гель методом в молекулярной сетке полимера. Для этого проводили гидролиз тетраэтоксисилана и тетрабутоксититана в ультразвуковом поле. Продукты выделяли, термически обрабатывали для удаления побочных продуктов и воды и изучали методами оптической микроскопии, ИК-спектроскопии, совмещенным дифференциально-термическим и термогравиметрическим анализом. В результате получены высокодисперсные, наноразмерные, гидрофобные с высокоразвитой удельной поверхностью частицы. Они содержат на поверхности остаточные алкокси- и гидроксильные группы. Размеры диоксида кремния составляют 10-50 нм, диоксида титана - 50-150 нм. На размер частиц и способность к агломерации существенное влияние оказывает способ смешения компонентов. Проведен гидролиз тетраэтоксисилана и тетрабутоксититана в среде водной эмульсии полидиметилсилоксанового каучука с помощью ультразвукового диспергирования. Из полученных составов удалялась вода, их отверждали и изготавливали образцы для физико-механические испытаний. Прочность при растяжении для резин, наполненных диоксидом кремния, увеличивается с 0,7 до 3,0 МПа, относительное удлинение повышается со 100% до 140 %. Вулканизаты, наполненные диоксидом титана, имеют прочность при разрыве 0,4-2,7 МПа, относительное удлинение 100-160 %.Наилучшие результаты получены при проведении совместного гидролиза тетраэтоксисилана и тетрабутоксититана. Прочность при растяжении у данных образцов составляет 3,5 МПа, относительное удлинение 180 %. Предложенная методика одновременного золь-гель синтеза в ультразвуковом поле диоксида кремния и диоксида титана позволяет улучшать физико-механические показатели вулканизатов на основе низкомолекулярного полидиметилсилоксанового каучука. The methods of formation of silicon dioxide and titanium dioxide nanoparticles by sol-gel method in a polymer molecular grid are studied. For this purpose, hydrolysis of tetraethoxysilane and tetrabutoxytitane was carried out in an ultrasonic field. The products were isolated, thermally treated to remove by-products and water, and studied by optical microscopy, IR spectroscopy, combined differential thermal and thermogravimetric analysis. As a result, highly dispersed, nanoscale, hydrophobic particles with a highly developed specific surface area were obtained. They contain residual alkoxy and hydroxyl groups on the surface. The dimensions of silicon dioxide are 10-50 nm, titanium dioxide - 50-150 nm. The size of the particles and the ability to agglomerate are significantly influenced by the method of mixing the components. Hydrolysis of tetraethoxysilane and tetrabutoxytitane was carried out in an aqueous emulsion of polydimethylsiloxane rubber using ultrasonic dispersion. Water was removed from the obtained compositions, they were cured and samples were made for physico-mechanical tests. The tensile strength for rubbers filled with silicon dioxide increases from 0.7 to 3.0 MPa, the elongation increases from 100% to 140%. Vulcanizates filled with titanium dioxide have a tensile strength of 0.4-2.7 MPa, elongation of 100-160%. The best results were obtained during the joint hydrolysis. The tensile strength of these samples is 3.5 MPa, the elongation is 180%. The proposed method of simultaneous sol-gel synthesis in an ultrasonic field of silicon dioxide and titanium dioxide allows improving the physical and mechanical properties of vulcanizates based on low molecular weight polydimethylsiloxane rubber.

Physiological and biochemical mechanisms of the hen’s body recovery from dermanyssosis associated with deacarization

The purpose of the research is to study the efficacy of the insectoacaricide "5% D-cyphenotrine emulsion" against infestation of birds with Dermanyssus gallinae (dermanyssosis) after the deacarization of the poultry building and to characterize physiological and biochemical mechanisms of the recovery of Hy-Line hens after removed parasites.Materials and methods. A parasitological examination of the poultry farm found D. gallinae in one of the poultry buildings. Given positive results of the drug efficacy against the poultry red mite, we analyzed the morpho-physiological and physiological and biochemical parameters of the hen’s blood before and 10 and 20 days after the treatments. Changes in the ethological status of birds were recorded. We used 0.005% aqueous emulsion of "5% D-cyphenothrin emulsion" for treatment. To obtain it, the drug was diluted with water at a ratio of 1:1000 immediately before use.Results and discussion. After double treatment with "5% D-cyphenotrine emulsion" of the shop with hens from the test group, no live poultry red mite was found. Within 20 days after the disease reduction, representatives of this group showed high concentrations of cortisol which were 2.3–2.4 times (p < 0.001) higher than those of healthy hens. This indicates that the stress state of hens still remains after the parasitizing of D. gallinae. In addition, the recovery process takes a long time and with great stress for all systems of their body. This is also confirmed by a high level of lipid peroxidation. At the same time, high intensity of gluconeogenesis and, as a result, deterioration of lipid and protein metabolism were recorded in the hens in question. The positive results indicate an increasing need for additional energy expenditures which are paramount for the effective and well-timed implementation of adaptation mechanisms. It should be noted here that the values of all the above-mentioned indicators tend to normalize by the end of the study period. The changes noted in the blood of birds indicate the restoration of a number of body systems. The poultry red mite as an emergency factor affects the morphophysiology of the blood, in particular, the level of white blood cells, which is restored by the 10th day after deacarization, which triggers regenerative and reparative processes. There were also changes in the number of cells of the immune system, an increase in hemoglobin concentration to control values and optimization of behavior in representatives of the test group which are largely related to the normalized physiological activity of the thyroid gland after the poultry building deacarization. We found a partial recovery of the hen’s body systems after the poultry building deacarization with the drug "5% D-cyphenotrine emulsion", which is due to the long-term parasitizing of D. gallinae, a stressor of extreme strength.

The effectiveness of acaricidic drugs based on herbal raw material

Limitation the number of ixodes ticks is one of the most important tasks of modern science and requires the search for new, highly effective and environmentally hazardous acaricides, so our experiment was aimed at identifying acaricidal properties of essential oils and their individual active components in the population of ixodes ticks in Zaporizhzhia region. The study of acaricidal properties of essential oils was performed in the laboratory conditions. Tampons with wool were soaked in various concentrations of 0.5%, 1%, 3%, 5% and 10% aqueous emulsion of essential oils such as Caryophyllus floris aetheroleum and Limonis aetheroleum, and essential oils of Thymus serpyllum L., Рinus sylvestris L., Salvia officinalis L., Mentha x piperita L. and Eucalyptus viminalis Labill. The essential oils had a significant effect on the lifespan of adult ticks. The results showed the acaricidal effect of Thymus serpyllum essential oils. When searching the acaricidal and repellent properties of individual essential oils components thymole, menthol and citral showed the high activity as acaricides. In the same time, eugenol and borneol proved the effectiveness as repellent. Our research schowed that essential oils are promising as alternative methods of controlling the number of Ixodes ticks in areas where there are conditions for infection with tick infections.

RAFT-Mediated Radiation Grafting on Natural Fibers in Aqueous Emulsion

Using aqueous emulsion as the medium in radiation-induced graft polymerization (RIGP) offers an environment-friendly shift from organic solvents while increasing polymerization efficiency through known water radiolysis-based graft initiation. In the present paper, we further extend the applicability of RIGP in emulsion under the influence of reversible addition fragmentation chain transfer (RAFT) mechanisms. Emulsions prepared with Tween 20 showed good colloidal stability for several hours. Subjecting it to simultaneous irradiation with abaca fibers resulted in successful grafting, supported by gravimetric, IR, SEM, and TG analysis. A correlation was drawn between smaller monomer micelles and the enhancement of grafting driven by diffusion and surface area coverage. RAFT mechanisms were also conserved based on molecular weight evolution. RAFT-mediated RIGP in aqueous emulsion shows good potential as a versatile and green surface modification technique for natural fibers for various functional applications.

Water-Soluble Elastomeric Carboxymethyl Chitosan as an Efficient Binder for Si Anodes of Lithium Ion Batteries

The binder acts a pivotal part in determining the mechanical and electrochemical performances of lithium-ion battery electrodes. Herein, a series of water-soluble Si anode binders based on carboxymethyl chitosan (C-Cs) and styrene-butadiene rubber (SBR) is developed. Water-soluble C-Cs and aqueous emulsion SBR solution are mixed to form C-Cs/SBR binders. The physical properties of the modified Si electrode are investigated through electrolyte swelling test, peeling test, and scanning electron microscopy. The mechanical strength provided to Cu foils and active substances by the C-Cs/SBR binder is higher than that produced by C-Cs. This performance can effectively reduce the stress/strain caused by the drastic volume change of the Si anodes during repeated uses and improve the electrochemical property of lithium-ion batteries. The initial thicknesses of the Si electrodes with polyvinylidene fluoride, C-Cs, and C-Cs/SBR20 binders are approximately 7.1, 7.2, and 6.9 µm, respectively. After 100 cycles, their initial thicknesses increase to 11.2, 12.4, and 7.2 µm and correspond to expansions of 57.8%, 72.2%, and 4.3%, respectively. The discharge capacity of Si electrodes containing C-Cs/SBR20 binder reaches to 1340 mAh·g−1 when the current density is 4 A·g−1, and reserves to be 1020 mAh·g−1 after undergoing 400 cycles of repeated use at 500 mA·g−1.

Fluorescein Hydrazide-Appended Metal–Organic Framework as a Chromogenic and Fluorogenic Chemosensor for Mercury Ions

In this work, we prepared a fluorescein hydrazide-appended Ni(MOF) (Metal–Organic Framework) [Ni3(BTC)2(H2O)3].(DMF)3(H2O)3 composite, FH@Ni(MOF). This composite was well-characterized by PXRD (powder X-ray diffraction), FT-IR (Fourier transform infrared spectroscopy), N2 adsorption isotherm, TGA (thermogravimetric analysis), XPS (X-ray photoelectron spectroscopy), and FESEM (field emission scanning electron microscopy). This composite was then tested with different heavy metals and was found to act as a highly selective and sensitive optical sensor for the Hg2+ ion. It was found that the aqueous emulsion of this composite produces a new peak in absorption at 583 nm, with a chromogenic change to a pink color visible to the naked eye upon binding with Hg2+ ions. In emission, it enhances fluorescence with a fluorogenic change to green fluorescence upon complexation with the Hg2+ ion. The binding constant was found to be 9.4 × 105 M−1, with a detection limit of 0.02 μM or 5 ppb. This sensor was also found to be reversible and could be used for seven consecutive cycles. It was also tested for Hg2+ ion detection in practical water samples from ground water, tap water, and drinking water.

Features of polymerization of methylmethacrylate using a photocatalyst – the complex oxide RbTe1.5W0.5O6

Radical polymerization of methylmethacrylate in an aqueous emulsion was carried out using the complex oxide RbTe 1.5 W 0.5 O 6 as a photoinitiator under visible light irradiation with λ= 400-700 nm. Studies of the process and reaction products using modern methods of physical and chemical analysis (GPC, IR, NMR, etc.) have shown that several directions of monomer transformations occur simultaneously in the reaction mixture. Polymethylmethacrylate, produced in the organic phase and characterized by Mn ~ 140-145 kDa, is a result of polymerization initiation by a hydroxyl radical formed due to complex transformations of electron-hole pairs during irradiation of the photocatalyst. Moreover, the interaction of the hydroxyl radical with OH groups on the complex oxide RbTe 1.5 W 0.5 O 6 surface and the subsequent formation of oxygen-centered radicals lead to grafting polymer macromolecules onto the photocatalyst surface. In addition, methylmethacrylate is able to oxidize to a cyclic dimer with terminal double bonds and then form a polymer with cyclic dimer links due to coordination by double bonds on the complex oxide RbTe 1.5 W 0.5 O 6 surface. The high activity of the hydroxyl radical made it possible to obtain the graft copolymer PMMA-pectin by grafting the polymer product onto the surface of the natural polymer-pectin. Comparison of the sponge morphology of the graft copolymer PMMA-pectin and the initial pectin samples using the scanning electron microscopy method showed a noticeable difference in their structural and topological organization. This fact is especially interesting in terms of studying the properties of the graft copolymer as a material for the scaffolds.

Synthesis of diblock copolymer spheres, worms and vesicles via RAFT aqueous emulsion polymerization of hydroxybutyl methacrylate

RAFT aqueous emulsion polymerization of hydroxybutyl methacrylate using a poly(glycerol monomethacrylate) precursor leads to diblock copolymer spheres, worms or vesicles. A pseudo-phase diagram is constructed and the vesicles are briefly evaluated as a Pickering emulsifier.