Changes in the surface resistance of polyethylene based composite films modified by multi-walled carbon nanotubes (MWCNTs) as a result of laser treatment are studied. Composites containing uniformly distributed nanotubes throughout their volume are prepared by mechanical melt mixing. The composite surfaces are treated by a 1064 nm fiber laser while varying the pulse duration within the 3-120 ns range and the source power within the 0.6-21 W range, so that the surface energy density during processing is 0.1-18.3 J/cm2. The influence of laser treatment parameters on the surface structure of composites is studied by scanning electron microscopy and Raman spectroscopy, and the surface resistance is determined using a four-electrode circuit. It is established that the surface resistance of the MWCNT-modified polymer composites can be either decreased by 30-50 times or increased by up to 140 times by tuning the laser treatment parameters.

Оксиды Ca3Co4O9 синтезированы методом Печини и твердотельным методом. Для компактирования использовались метод искрового плазменного спекания (SPS), холодное прессование с последующим взрывным сжатием (метод взрыва) и метод быстрого горячего прессования (RHP). Компактирование методом взрыва с добавлением связующего AlN привело к максимальной добротности при комнатной температуре ZT300K = 0.161. Добавление многослойных углеродных нанотрубок (CNTs) в оксиды, синтезированные методом Печини, ведет к ухудшению характеристик. Увеличение концентрации CNTs в Ca3Co4O9, синтезированных твердотельным методом и компактированных RHP методом, ведет к увеличению добротности ZT300K до 0.048 в Ca3Co4O9+3 wt%CNTs.

Проведено исследование влияния лазерной обработки пленок композитов на основе полиэтилена, модифицированного многостенными углеродными нанотрубками (МУНТ) на изменение их поверхностного сопротивления. Композиты с равномерным распределением нанотрубок по объему были получены путем механического смешения в расплаве. Обработку поверхности композитов проводили с использованием волоконного лазера с рабочей длиной волны 1064 нм. В процессе обработки варьировали длительность импульсов в диапазоне 3 – 120 нс и мощность источника в диапазоне 0.6 – 21 Вт, так что поверхностная плотность энергии при обработке составляла 0.1 – 18.3 Дж/см2. Влияние параметров лазерной обработки на структуру поверхности композитов исследовали методами растровой электронной микроскопии и спектроскопии комбинационного рассеяния, поверхностное сопротивление определяли с использованием 4-х электродной схемы. Установлено, что для полимерных композитов, модифицированных МУНТ, возможно как уменьшение поверхностного сопротивления до 30 – 50 раз так и его увеличение до 140 раз в зависимости от параметров лазерной обработки.

Carbon–silica composite materials (CSCMs) containing different amounts of silica and carbon components are obtained using two silica precursors (silica sol and silane) and multiwalled carbon nanotubes (MWNTs). At the initial stage of obtaining CSCMs by method 1, a fine MWNT powder is subjected to impregnation by moisture capacity with silica sol; in accordance with method 2, MWNTs are treated with tetraethoxysilane and then subjected to hydrolysis and polycondensation. The silica (SiO2) content in the composites is varied in a range of 3–60 wt

Уважаемые коллеги!Благодарим Вас за проявленный интерес к Четвертой российской конференции «Графен: молекула и 2D кристалл» и желание принять участие в её работе.Конференция проходит в научно-образовательном центре города Новосибирска -Академгородке.Мероприятие посвящено актуальным направлениям исследований и разработок в области углеродных и низкоразмерных материалов.Проведение конференции поможет координации усилий ученых в решении современных проблем материаловедения и привлечению молодых исследователей для решения актуальных научных задач.Оргкомитет выражает особую благодарность НГУ, Центру компетенций НТИ «Моделирование и разработка новых функциональных материалов с заданными свойствами», компаниям «Диаэм», «НТ-МДТ Спектрум Инструментс» и корпорации "Графеновая Долина" за финансовую поддержку и журналам Аналитика, Наноиндустрия и РЭНСИТ за информационную поддержку.Искренне надеемся, что пребывание в Новосибирском Академгородке и в стенах Новосибирского государственного университета оставит множество положительных эмоций и

Amorphous carbon (AC) is present in the bulk and on the surface of nanostructured carbon materials (NCMs) and exerts a significant effect on the physical, chemical and mechanical properties of NCMs. Thus, the determination of AC in NCMs is extremely important for controlling the properties of a wide range of materials. In this work, a comparative study of the effect of heat treatment on the structure and content of amorphous carbon in deposited AC film, nanodiamonds, carbon black and multiwalled carbon nanotube samples was carried out by TEM, XPS, XRD and Raman spectroscopy. It has been established that the use of the 7-peak model for fitting the Raman spectra makes it possible not only to isolate the contribution of the modes of amorphous carbon but also to improve the accuracy of fitting the fundamental G and D2 (D) modes and obtain a satisfactory convergence between XPS and Raman spectroscopy. The use of this model for fitting the Raman spectra of deposited AC film, ND, CB and MWCNT films demonstrated its validity and effectiveness for investigating the amorphous carbon in various carbon systems and its applicability in comparative studies of other NCMs.

Composite carbon–silica materials (CCSM), differing in the content of carbon and silica components, were obtained using two silicon dioxide precursors (silica sol and silane) and multi-walled carbon nanotubes (MWNTs). At the initial stage of obtaining CCSM by method 1, impregnation of finely dispersed MWCNT powder with silica sol was used, method 2 was carried out using treatment of MWCNTs with tetraethoxysilane followed by hydrolysis and polycondensation. The content of silica (SiO2) in the composites varied from 3 to 60 wt %. After drying and appropriate heat treatment at 250–350°C, the composite materials were studied by various physicochemical methods: nitrogen porosimetry, electron microscopy, X-ray fluorescence analysis, and synchronous thermal analysis. Significant differences in parameters were found depending on the chemical composition of CСSM, including textural characteristics. Thus, with an increase in the SiO2 content, the specific surface area of composite materials increased (by a factor of 2), and maxima were observed on the distribution curves over pore diameters (at 20–40 nm).The composite carbon–silica materials were tested as adsorbent for the preparation of heterogeneous biocatalysts (BC) for the low-temperature synthesis of esters; the active component of these BC was lipase immobilized exclusively on the carbon surface of nanotubes. With a decrease in the content of MWCNTs in the composite materials, the enzymatic activity and operational stability of biocatalysts, measured in the reaction of esterification of heptanoic acid (C7) with butanol (C4), decreased monotonically, reaching a 2–8-fold drop in activity at the maximum content of SiO2 (58 wt %).

Уважаемые коллеги!Благодарим Вас за проявленный интерес к Четвертой российской конференции «Графен: молекула и 2D кристалл» и желание принять участие в её работе.Конференция проходит в научно-образовательном центре города Новосибирска -Академгородке.Мероприятие посвящено актуальным направлениям исследований и разработок в области углеродных и низкоразмерных материалов.Проведение конференции поможет координации усилий ученых в решении современных проблем материаловедения и привлечению молодых исследователей для решения актуальных научных задач.Оргкомитет выражает особую благодарность НГУ, Центру компетенций НТИ «Моделирование и разработка новых функциональных материалов с заданными свойствами», компаниям «Диаэм», «НТ-МДТ Спектрум Инструментс» и корпорации "Графеновая Долина" за финансовую поддержку и журналам Аналитика, Наноиндустрия и РЭНСИТ за информационную поддержку.Искренне надеемся, что пребывание в Новосибирском Академгородке и в стенах Новосибирского государственного университета оставит множество положительных эмоций и

In this work, we studied the possibility of using composites based on multi-walled carbon nanotubes (MWCNTs) decorated with silicon (Si) and silicon carbide (SiC) particles as an anode material in lithium-ion current sources. MWCNTSi and MWCNT-SiC composites (with different Si/SiC ratios) were obtained by high-temperature heat treatment of MWCNT-Si at different temperatures (1040 and 1350 °C). The structure and phase composition of the composites were characterized by TEM and XRD methods. The determination of the specific capacity of composites as an anode material was carried out at current densities from 0,05 to 2 A/g.

Ex situ methods (TEM, XRD, and Raman spectroscopy) have been used to study the processes occurring at the multi-walled carbon nanotube/silicon interfaces (MWCNT/Si) during heat treatment of MWCNT-Si composites containing highly dispersed Si particles deposited on the surface of MWCNTs by CVD method. It has been established that during heat treatment, starting from 900 degrees C, the formation of SiC particles occurs. A further increase in temperature leads to the formation of polycrystalline SiC particles and a significant shortening of MWCNTs due to the reaction between Si particles and the surface of MWCNTs. It is shown that one can control the size of the formed SiC crystallites by varying the time and temperature of heat treatment. The kinetic dependences of the SiC formation process were studied within the Avrami-Erofeev model. The activation energy for the formation of SiC is estimated at 470 kJ/mol. The influence of heat treatment on the electrical conductivity and porosity of MWCNT-Si composites in the pressure range of 25-175 MPa has been studied.

The increasing resistance of bacteria and fungi to antibiotics is one of the health threats facing humanity. Of great importance is the development of new antibacterial agents or alternative approaches to reduce bacterial resistance to available antibacterial drugs. Due to the complexity of their properties, carbon nanomaterials (CNMs) may be of interest for a number of biomedical applications. One of the problems in studying the action of CNMs on microorganisms is the lack of universally standardized methods and criteria for assessing antibacterial and antifungal activity. In this work, using a unified methodology, a comparative study of the antimicrobial properties of the CNM systemic kit against common opportunistic microorganisms, namely Escherichia coli and Staphylococcus aureus, was carried out. Multiwalled carbon nanotubes (MWNTs), catalytic filamentous carbon with different orientations of graphene blocks (coaxial–conical and stacked, CFC), ionic carbon (OLC), and ultrafine explosive nanodiamonds (NDs) were used as a system set of CNMs. The highest antimicrobial activity was shown by NDs, both types of CFCs, and carboxylated hydrophilic MWCNTs. The SEM results point out the difference between the mechanisms of action of UDD and CFC nanotubes.

Уважаемые коллеги!Благодарим Вас за проявленный интерес к Четвертой российской конференции «Графен: молекула и 2D кристалл» и желание принять участие в её работе.Конференция проходит в научно-образовательном центре города Новосибирска -Академгородке.Мероприятие посвящено актуальным направлениям исследований и разработок в области углеродных и низкоразмерных материалов.Проведение конференции поможет координации усилий ученых в решении современных проблем материаловедения и привлечению молодых исследователей для решения актуальных научных задач.Оргкомитет выражает особую благодарность НГУ, Центру компетенций НТИ «Моделирование и разработка новых функциональных материалов с заданными свойствами», компаниям «Диаэм», «НТ-МДТ Спектрум Инструментс» и корпорации "Графеновая Долина" за финансовую поддержку и журналам Аналитика, Наноиндустрия и РЭНСИТ за информационную поддержку.Искренне надеемся, что пребывание в Новосибирском Академгородке и в стенах Новосибирского государственного университета оставит множество положительных эмоций и

Федеральное государственное бюджетное учреждение наукиИнститут неорганической химии им.А. В. Николаева Сибирского отделения Российской академии наук

The problem of the loss of homogeneous fluidization and the formation of large clumps of MWCNTs during their catalytic synthesis in a fluidized bed reactor has been studied experimentally and theoretically in terms of the impact of catalyst properties and synthesis process parameters. It has been shown that two factors play the most important role in the formation of large clumps of MWCNTs, namely, the ability of high-performance catalyst to produce agglomerates of MWCNTs with high cohesion, and a high concentration of catalyst particles in the fluidized bed volume. A relationship has been established between chemical components of the catalyst, its structure and cohesive properties of the MWCNT agglomerates formed on it. An approximate semi-analytical scheme for calculating the formation and growth of large fractal agglomerates (clumps) of MWCNTs during their catalytic synthesis in a fluidized bed has been developed. This approach is based on the model of sequential coagulation of MWCNT agglomerates starting from the primary ones, and made it possible to formulate the requirements for characteristics of the catalyst and parameters of the synthesis process, which ensure homogeneous fluidization in the reactor.

In this study, a new method is proposed for producing polymer composites via the adsorption of multiwalled carbon nanotubes (MWCNTs) on the surface of polystyrene spheres (PS) to provide a cellular distribution of MWCNTs in the composite. The method makes it possible to control the cell size down to the submicron level and the conductivity of the composite in a wide range. The effect of the MWCNT concentration on the surface of PS on the structure of the resulting composites and their electrophysical properties are studied in the frequency range of 115 GHz–1.4 THz. The percolation nature of the composite conductivity was established. It was shown that the obtained composite is a regularly chaotic medium, and its regularity scale corresponds to the sizes of the PS. MWCNTs on the PS surface form two subsystems: the first is a pseudo-regular subsystem on the edges of cuboid-like PS, while the second subsystem consists of chaotically scattered MWCNTs with unclosed ends on the faces of PS. The first subsystem belongs to the regular part of the structure and mainly determines the properties of the medium at frequencies above 500 GHz. The second subsystem of nanotubes is characterized by a small electrodynamic scale comparable with the size of one PS cell and determines the effective properties of the composites at frequencies below 500 GHz.

In this article, we investigate the use of laser processing to create effective surface contacts on multi-wall carbon nanotube (MWCNT)/polyethylene composites.Due to the photothermal conversion effect induced by laser radiation, MWCNTs can enhance thermal destruction and removal of the polymer from the composite surface.The structure of pristine and lasermodified composites is characterized by Raman spectroscopy, optical and scanning electron microscopy.It was found that in pristine composites only a small part of MWCNTs is located directly on the surface of the film, which is associated with the high work of polymer adhesion to the nanotube surface and the surface tension forces of the polymer matrix melt.Scanning electron microscopy (SEM) and Raman scattering demonstrate that in the surface contacts formed under the action of laser radiation, the polymer matrix is removed from the near-surface layer.The presence of MWCNTs with an unchanged structure and a small amount of amorphous carbon material was confirmed by Raman spectroscopy.The conductivity of pristine and modified composites was characterized by a series of current-voltage characteristic measurements with the through-plane 4-point probe.It was found that laser treatment of the composite surface leads to an increase in the measured volume conductivity by 1-2 orders of magnitude, depending on the content of MWCNTs.At the same time, the removal of the near-surface layer of the polymer by laser treatment makes it possible to reduce the contribution of the contact resistance to the resistance of the composite measured by 2-point probe from 55-77 to 0.18-5.3%for composites with an MWCNT content of 2.5-4 wt%.

The effect of the residual catalyst for the synthesis of multi-walled carbon nanotubes (MWCNTs) on the electrophysical properties of MWCNT–polyethylene composites produced by melt mechanical mixing was studied. The residual catalyst content was varied by changing the MWCNTs synthesis time. The nanotubes used in the work were characterized using transmission and scanning electron microscopy, atomic emission analysis, X-ray phase analysis, and magnetic permeability measurements. The structure of the synthesized composites was studied using optical and scanning electron microscopy. The dependences of the specific magnetization on the applied magnetic field, bulk electrical conductivity on the volumetric content of the filler in the composite, and the frequency dependences of the reflection, transmission, and absorption of electromagnetic radiation in the range 0.01–18 GHz were obtained. It was established that the obtained composites are characterized by a uniform distribution of nanotubes in the polymer matrix, and the dependence of the bulk electrical conductivity on the content of MWCNTs in the composite has a percolation character. Variation in the synthesis time of nanotubes allows producing MWCNTs with a high content of ferromagnetic particles, which are an alloy close in stoichiometry to the composition of the active component of the catalyst. It was shown that the use of composites modified with MWCNTs with a high content of residual catalyst is more effective for absorbing electromagnetic radiation due to an increase in their magnetic losses.

Here, we report on the synthesis, characterization, and electromagnetic properties of the composites based on Fe2Co alloy nanoparticles, multi-walled carbon nanotubes (MWCNTs), and polystyrene (PS). The absorbing electromagnetic characteristics of Fe2Co/MWCNT-PS composites in the frequency range of 1-18 GHz have been tuned by controlling their dielectric and magnetic properties. For this, Fe2Co/MWCNT hybrids with a controlled composition and particle size of the Fe2Co alloy have been obtained by thermal decomposition of iron and cobalt carbonyls on the surface of MWCNTs with subsequent production of Fe2Co/MWCNT-PS membranes by vacuum filtration. The optimization of the conditions of the Fe2Co alloy particles formation as well as the study of the structure and morphology of the hybrids and membranes based on them have been carried out using HRTEM, HAADF-STEM, SEM, XRD, and TPD. The effect of the calcination temperature on the evolution of the chemical composition, structure, size, and morphology of supported Fe2Co nanoparticles has been thoroughly studied. In order to enhance the shielding properties of the material, a multilayer composite structure has been proposed and optimized, consisting of five alternating layers of Fe2Co/MWCNT-PS membranes and dielectric layers (neat PS) localized on a metal surface. The simulation results show that the proposed five-layer material, consisting of three layers of Fe2Co/MWCNT-PS membranes with thickness of 0.1 mm and two layers of PS with thickness of 0.5 mm, shows the highest efficiency of electromagnetic interference shielding (-14.2 dB at 17.5 GHz) as compared to a similar composite consisting of MWCNT-PS membranes (-5.4 dB at 17.5 GHz). Such multilayer structure is cost-effective and lightweight, which makes it a perspective material for EMI shielding. (c) 2020 Elsevier B.V. All rights reserved.

Проведено исследование проводимости трех типов композитов, полученных на основе полиэтилена (ПЭ) и многослойных углеродных нанотрубок (МУНТ) со средним диаметром 9.8 нм и аспектным отношением ~3000, 112, 36 путем механического смешения в расплаве. Структура данных композитов исследована методами оптической и растровой электронной микроскопии, рентгенофазовым анализом. С использованием циклических измерений вольт-амперных характеристик (ВАХ) и 3-точечной схемы измерений установлено, что плотность тока, пропущенного через композит, нелинейно увеличивается с ростом приложенного напряжения, а также для одного и того же напряжения при последовательном измерении ВАХ. На основании результатов измерения ВАХ определены концентрационные зависимости проводимости и их изменение для каждого типа МУНТ. Определено, что при получении композитов путем механического смешения в расплаве порог перколяции МУНТ, определяемый по третьему измерению ВАХ, снижается с уменьшением аспектного отношения нанотрубок в диапазоне 3000—36.

Методом газофазного химического осаждения (CVD), с использованием термического разложения моносилана (SiH4) в псевдоожиженном слое многослойных углеродных нанотрубок (МУНТ) получены композиты МУНТ—Si, содержащие наноразмерные частицы кремния, нанесенные на поверхность нанотрубок. С использованием ПЭМ, РЭМ, РФА, КР- и ИК-Фурье спектроскопии диффузного отражения исследована структура получаемых наночастиц Si в композитах на основе МУНТ с различными средними диаметрами. Размер получаемых частиц Si варьируется от 3 нм до 45 нм и возрастает с увеличением диаметра МУНТ. Основное количество осажденного кремния в наночастицах находится в аморфном состоянии с небольшими включениями нанокристаллического кремния (менее 3 нм). Проведена оценка удельной разрядной емкости полученных композитов в качестве анодного материала литий-ионных аккумуляторов.