научный журнал по химии Коллоидный журнал ISSN: 0023-2912

Архив научных статейиз журнала «Коллоидный журнал»

  • ФОРМИРОВАНИЕ КАПЛИ РТУТИ НА ПОВЕРХНОСТИ ГРАФЕНА. КОМПЬЮТЕРНЫЙ ЭКСПЕРИМЕНТ

    ГАЛАШЕВ А.Е. — 2015 г.

    Методом молекулярной динамики исследован быстрый нагрев пленки ртути на графене, содержащем дефекты Стоуна–Уэйлса. Гидрированные края графенового листа выдерживали рост температуры на 800 K. По мере сворачивания пленки в каплю горизонтальная компонента коэффициента самодиффузии атомов Hg монотонно уменьшалась, а вертикальная компонента проходила через глубокий минимум, отражающий начало поднятия капли над подложкой. Формирование капли проявило себя в идущем вверх уширении вертикального профиля плотности и увеличении числа пиков в нем. При этом существенно сократилась протяженность функции радиального распределения ртути, выросла интенсивность ее первого пика. Образование капли приводит к уменьшению тупого краевого угла смачивания. Температурные изменения в графене выразились в росте интенсивности дополнительных пиков углового распределения ближайших соседей, колебательном характере напряжений, действующих в его плоскости, и почти линейном росте шероховатости.

  • ФОРМИРОВАНИЕ НАНОКОМПОЗИЦИЙ ПРИ ИСПАРЕНИИ КАПЕЛЬ ДИСПЕРСИЙ НАНОЧАСТИЦ СЕРЕБРА В МАЛОЛЕТУЧИХ И БИНАРНЫХ ДИСПЕРСИОННЫХ СРЕДАХ

    ВЫСОЦКИЙ В.В., ЗАЙЦЕВА А.В., РОЛДУГИН В.И., СЕНЧИХИН И.Н., УРЮПИНА О.Я. — 2015 г.

    Исследованы закономерности формирования нанокомпозиций в виде кольцевых осадков при испарении капель дисперсий наночастиц серебра кубической формы со средним размером 70 нм на гидрофильной (стекло) и гидрофобной (медь) подложках. Наночастицы были синтезированы полиольным методом в растворе этиленгликоля. В экспериментах исследовались также капли дисперсий тех же наночастиц в смеси этиленгликоль/этанол и в воде. Определены геометрические параметры и электропроводность формирующихся кольцевых осадков.

  • ЭВОЛЮЦИЯ МИКРОСТРУКТУРЫ КРИСТАЛЛОВ ФТОРИДА ЛИТИЯ ПРИ ИХ ВИБРОДИСПЕРГИРОВАНИИ В УЛЬТРАСЛАБЫХ ПОЛЯХ ТЕРМАЛИЗОВАННЫХ НЕЙТРОНОВ

    ЛИПСОН А.Г., ПУРЯЕВА Т.П., САВЕНКО В.И. — 2015 г.

    Методами адсорбционного (БЭТ), электронно-микроскопического и рентгеноструктурного анализа исследована кинетика вибродиспергирования кристаллических частиц фторида лития в условиях одновременного облучения материала потоком термализованных нейтронов малой интенсивности I = 100 нейтрон/(см2 с). Обнаружено, что стационарное состояние микроструктуры материала, реализующееся в порошке в процессе вибровоздействия, достигается намного раньше, нежели устанавливается предельная (равновесная) величина его внешней (удельной) поверхности. Определены константы скоростей реакций полигонизации и рекристаллизации, идущих в материале при его виброизмельчении. Оценено влияние нейтронного облучения на численные значения этих констант. Проанализирована энергетика происходящих в системе процессов с учетом тепловыделения, обусловленного поглощением нейтронов в материале.

  • ЭЛЕКТРОКИНЕТИЧЕСКИЙ ПОТЕНЦИАЛ И ФЛОКУЛЯЦИЯ СУСПЕНЗИЙ БЕНТОНИТА В РАСТВОРАХ ПАВ, ПОЛИЭЛЕКТРОЛИТОВ И ИХ СМЕСЕЙ

    БАРАНЬ Ш., МЕСАРОШ Р., МУСАБЕКОВ К., ТАУБАЕВА Р. — 2015 г.

    Изучено влияние катионных и анионных ПАВ и полиэлектролитов, а также их бинарных смесей на электрокинетический потенциал и степень агрегации/размер флокул частиц в суспензиях бентонита. Варьировали количества введенных в суспензию указанных реагентов, состав и соотношение положительных и отрицательных зарядов в смеси, плотность зарядов полиэлектролитов, порядок введения компонентов смеси в систему. Показано, что добавки катионных ПАВ или полиэлектролитов и их смесей приводят к существенному уменьшению отрицательных значений дзета-потенциала частиц и изменению знака их заряда. Добавки анионных ПАВ или полиэлектролитов обуславливают двукратный рост -потенциала вследствие адсорбции отрицательно заряженных ионов ПАВ/полимерных сегментов на отрицательно заряженной поверхности частиц глины за счет некулоновских сил. В присутствии смесей анионных и катионных полиэлектролитов, независимо от их состава и порядка введения компонентов в суспензию, частицы приобретают отрицательный -потенциал, характерный для частиц, адсорбирующих только анионный полиэлектролит. Для смесей слабо и средне заряженных анионных и катионных полиэлектролитов наблюдали синергизм флокулируюшего действия. Этот эффект имел место даже для смесей с многократным избытком отрицательно заряженных сегментов по сравнению с положительно заряженными. Наблюдаемые закономерности объяснены особенностями структуры адсорбционных слоев смесей полиэлектролитов – сосуществованием тонкого слоя адсорбированных катионных полимерных цепей с большим числом контактов с поверхностью и протяженного слоя анионного полиэлектролита (длинные петли и хвосты макромолекул), в котором “утоплен” слой катионного полимера. Электрокинетический потенциал и способность частиц к агрегации (по механизму образования полимерных мостиков) в растворах смесей анионного и катионного полиэлектролитов определяется, в первую очередь, величиной адсорбции анионного полимера.

  • ЭЛЕКТРОКОНВЕКТИВНЫЕ СТРУКТУРЫ, ФОРМИРУЮЩИЕСЯ В СЛОЕ МАГНИТНОГО КОЛЛОИДА

    ДИКАНСКИЙ Ю.И., ЗАКИНЯН А.Р., КОРОБОВ М.И. — 2015 г.

    Экспериментально исследованы процессы образования ячеистых и лабиринтных электроконвективных структур в тонком слое магнитного коллоида под действием постоянного электрического поля. Измерено время образования структур, показано, что оно убывает с увеличением электрического поля и росте электрической проводимости среды. Установлено, что постоянное магнитное поле, сонаправленное с электрическим полем, уменьшает время образования электроконвективных структур, а также величину критического электрического поля, при котором они возникают.

  • ЭЛЕКТРООПТИЧЕСКИЕ ИССЛЕДОВАНИЯ ЭЛЕКТРОФОРЕЗА КОЛЛОИДНЫХ ЧАСТИЦ МАГНЕТИТА В КЕРОСИНЕ В ПОЛЕ ПРИЭЛЕКТРОДНОГО ОБЪЕМНОГО ЗАРЯДА

    ЕРИН К.В. — 2015 г.

    Исследованы особенности электрооптического эффекта изменения прозрачности слабопроводящих магнитных коллоидов на основе керосина в приэлектродной области при воздействии импульсного электрического поля. Построена модель эффекта, учитывающая влияние на электрофоретическое движение коллоидных частиц параметров приэлектродного объемного заряда. Рассчитаны временные зависимости прозрачности, которые оказались в удовлетворительном согласии с экспериментальными данными.

  • AGGREGATES OF POLY-FUNCTIONAL AMPHIPHILIC MOLECULES IN WATER AND OIL PHASES

    GRIMES B.A., KOVALCHUK K., MEHANDZHIYSKI A., RICCARDI E. — 2014 г.

    The solvation and aggregate formation of complex amphiphilic molecules such as tetra-acids in polar and nonpolar phases are studied via Molecular Dynamics simulations. The nonpolar core of tetra-acid molecules is found to be effectively impermeable for water molecules resulting in a low solubility in the polar solvent, while nonpolar solvent molecules sufficiently solvate the amphiphilic molecules considered, enabling an open conformation of their molecular structure. The rigidity of the core region of the tetra-acid molecules has been found to play a crucial role in their behavior in both polar and nonpolar phases. In the polar phase, simulations have shown that tetra-acids form micelle-like structures with a small aggregation number, confirming previous experimental work. The identification of a case of study in which micelle-like structures can form only with a small aggregation number enables the study via Molecular Dynamics of micelle–micelle interactions. Micelle stability and dispersion in the polar phase under different conditions can be therefore investigated. In the nonpolar phase, the preferential interactions between carboxyl groups, the affinity of the tetra-acids with the solvent molecules, and the structural characteristics of the central core moiety of the tetra-acids have been found to possibly induce a web like array, or network.

  • AGGREGATION BEHAVIOUR AND THERMODYNAMICS OF MIXED MICELLIZATION OF 1-HEXADECYLPYRIDINIUM BROMIDE AND IONIC LIQUID IN ETHYLENE GLYCOL/WATER BINARY MIXTURES

    CHUNSHENG LIU, CHUNYU HAN, DONG FANG, GENXIANG LUO, LEI SUN, YI HE — 2014 г.

    Micellar behavior of binary combinations of ionic liquid, 1-tetradecyl-3-methylimidazolium bromide, with conventional cationic surfactant 1-hexadecylpyridinium bromide was investigated by means of conductometry to study the effect of cosolvent and water content and temperature. The critical micelle concentration and the degree of counterion association were calculated from the conductometry data. Thermodynamic parameters were obtained from the temperature dependence of the critical micelle concentration. The standard Gibbs energy of micellization increased with the increasing percentage of cosolvent as well as the mole fraction of C14mimBr. The standard enthalpy and standard entropy of micelle formation were both decreased with the increasing temperature and the concentration of cosolvent. The entropy contribution was larger than the enthalpic one in pure water, whereas in the ethylene glycol/H2O mixture the enthalpy contribution was predominant.

  • DILATIONAL RHEOLOGY OF SPREAD AND ADSORBED LAYERS OF SILICA NANOPARTICLES AT THE LIQUID–GAS INTERFACE

    LIGGIERI L., LIN S.-Y., LOGLIO G., MILLER R., NOSKOV B.A., RAVERA F., YAZHGUR P.A. — 2014 г.

    This short review is devoted to recent achievements in studies of the dilational surface rheological properties of the systems containing complexes of silica nanoparticles with conventional surfactants. It is shown that there is a surfactant concentration range where the dynamic surface elasticity reaches extremely high values up to 1000 mN/m. This result can explain the formation of very stable foams and emulsions containing nanoparticles. In some surfactant concentration ranges the adsorption layer is characterized by a non-linear response to small compressions or expansions of the liquid surface. Possible causes of this behavior and the mechanism of main relaxation processes are briefly discussed.

  • FORMATION AND PROPERTIES OF HYDROPHOBIC CEO2 NANOPARTICLES

    LI LIU, XINGPING ZHOU, XUESHUANG ZHENG — 2014 г.

    Uniform hydrophobic cerium oxide (CeO2) nanoparticles in a cubic structure with an average size of 4.6 nm were obtained by a novel oil–water interface method in the presence of 0.40 M NaOH. Effects of reactants concentration, oxidation reaction temperature, and the type of surfactants on the final products were investigated. The products were characterized by X-ray diffraction, transmission electron microscopy, UV-visible spectroscopy, room-temperature photoluminescence spectroscopy and contact angle measurements. The products exhibited high luminescence and strong hydrophobicity. The data suggest that Ce(OH) (x < 4) is a precursor complex for the formation of CeO2 nanoparticles in liquid phase and its concentration controls the size of CeO2 particles. The adsorption of the surfactant influences the formation of the hydrophobic particles of CeO2 by the oil–water interface method.

  • HYDRODYNAMIC PERMEABILITY OF A MEMBRANE COMPOSED OF POROUS SPHERICAL PARTICLES IN THE PRESENCE OF UNIFORM MAGNETIC FIELD

    ANATOLY FILIPPOV, BAL GOVIND SRIVASTAVA, PRAMOD KUMAR SINGH, PRAMOD KUMAR YADAV, SATYA DEO — 2014 г.

    This work concerns the flow of an incompressible viscous fluid past a porous sphere in presence of transverse applied uniform magnetic field, using particle-in-cell method. The Brinkman equations are used in porous region and the Stokes equations for non-porous region. At the fluid-porous interface, the stress jump boundary condition for tangential stresses along with continuity of normal stress and velocity components are used. Four known boundary conditions on the hypothetical surface are considered and compared: Happels, Kuwabaras, Kvashnins and Cunninghams (Mehta–Morses condition). The hydrodynamic drag force experienced by a porous spherical particle in a cell and hydrodynamic permeability of membrane built up by porous spherical particles are evaluated. The patterns of streamlines are also obtained and discussed. The effect of stress jump coefficient, Hartmann number, dimensionless specific permeability of the porous particle and particle volume fraction on the hydrodynamic permeability and streamlines are discussed. Some previous results for hydrodynamic drag force and dimensionless hydrodynamic permeability have been verified.

  • INHIBITIVE EFFECT OF POTASSIUM METHYLSILICONATE ON HYDRATION SWELLING OF MONTMORILLONITE

    JIANG G., LI Y., WANG J., XUAN Y. — 2014 г.

    Herein we report on a study on the inhibition effect of potassium methylsiliconate on hydration swelling of montmorillonite. The results of linear swelling tests showed that potassium methylsiliconate exhibits a high performance as an effective shale inhibitor in drilling fluids. The inhibition mechanism was investigated by means of a variety of methods including Fourier transform infrared spectroscopy, X-ray diffraction, transmission electron microscopy, and zeta potential measurements. The high degree of inhibition is a result of the synergy of action of potassium cations and methylsiliconate anions. Methylsiliconate anions form a hydrophobic shell around each montmorillonite particle through the adsorption on the edge sites, thus inhibiting the penetration of water into the interlayer. The potassium ions promote the formation of a less hydratable structure of montmorillonite through cation-exchange interaction.

  • MICELLAR SOLUTIONS OF IONIC SURFACTANTS AND THEIR MIXTURES WITH NONIONIC SURFACTANTS: THEORETICAL MODELING VS. EXPERIMENT

    ANACHKOV SVETOSLAV E., DANOV KRASSIMIR D., KRALCHEVSKY PETER A. — 2014 г.

    Here, we review two recent theoretical models in the field of ionic surfactant micelles and discuss the comparison of their predictions with experimental data. The first approach is based on the analysis of the stepwise thinning (stratification) of liquid films formed from micellar solutions. From the experimental stepwise dependence of the film thickness on time, it is possible to determine the micelle aggregation number and charge. The second approach is based on a complete system of equations (a generalized phase separation model), which describes the chemical and mechanical equilibrium of ionic micelles, including the effects of electrostatic and non-electrostatic interactions, and counterion binding. The parameters of this model can be determined by fitting a given set of experimental data, for example, the dependence of the critical micellization concentration on the salt concentration. The model is generalized to mixed solutions of ionic and nonionic surfactants. It quantitatively describes the dependencies of the critical micellization concentration on the composition of the surfactant mixture and on the electrolyte concentration, and predicts the concentrations of the monomers that are in equilibrium with the micelles, as well as the solutions electrolytic conductivity; the micelle composition, aggregation number, ionization degree and surface electric potential. These predictions are in very good agreement with experimental data, including data from stratifying films. The model can find applications for the analysis and quantitative interpretation of the properties of various micellar solutions of ionic surfactants and mixed solutions of ionic and nonionic surfactants.

  • POLYELECTROLYTE–SURFACTANT ASSOCIATION – FROM FUNDAMENTALS TO APPLICATIONS

    BJORN LINDMAN, FILIPE ANTUNES, MARIA MIGUEL, SAULE AIDAROVA, TOMMY NYLANDER — 2014 г.

    Mixed polymer–surfactant systems have broad applications, ranging from detergents, paints, pharmaceutical, and cosmetic to biotechnological. A review of the underlying polymer–surfactant association in bulk is given. While ionic surfactants bind broadly to polymers, nonionics only do so if the polymer has a lower polarity and can interact by hydrophobic interactions. Water-soluble polymers, which have hydrophobic groups, form physical cross-links, hence they may be used as thickeners. The rheological behaviour is strongly influenced by various cosolutes; especially strong effects are due to surfactants and both a decrease and an increase in viscosity can occur. When the polymer–surfactant interactions are particularly strong, an associative phase separation can occur, like in the case where there is electrostatic attraction as well as hydrophobic; this and other types of phase separation phenomena are described. Except for linear ionic and nonionic polymers, the interactions between surfactants and cross-linked polymers, microgel particles and covalent macroscopic gels are analyzed, as well as the possibility of forming gel particles of interest for encapsulation purposes. Furthermore, the behavior of these mixed systems on surfaces is discussed. In particular, we consider the adsorption of mixtures of ionic polymers and oppositely charged surfactants on polar and nonpolar surfaces. Depending on concentration, an ionic surfactant can either induce additional polyion adsorption or induce de-sorption. Kinetic control of adsorption and, in particular, desorption is typical. Important consequences of this include an increased adsorption on rinsing and path dependent adsorbed layers. Recently, considerable attention has been given to the interaction between DNA and cationic surfactant, both as a means to understand the behaviour of DNA in biological systems and to develop novel formulations, for example for gene therapy. Here we review aspects such as DNA compaction, DNA covalent gels and DNA soft nanoparticles.

  • PREPARATION AND CHARACTERIZATION OF BIOSURFACTANT BASED ON HYDROPHOBICALLY MODIFIED ALGINATE

    CAIFENG LENG, FENGJUN JIA, KUNSHAN YUAN, SHAOPENG YAN, YI ZHENG, YUEQIN YU, ZHE LIU — 2014 г.

    Hydrophobic modified alginate (HM-alginate) was synthesized using a low-energy, environment-friendly process in aqueous solution, with sodium alginate and dodecyl glycidyl ether as starting materials. The HM-alginate was characterized using 1H NMR, and the reaction efficiency was about 40%. The HM-alginate aggregated in solution; the critical micelle concentration (CMC) was determined using surface tension and dynamic light scattering methods. We observed reasonable agreement between the CMC values obtained by the different techniques, and the CMC was 4.0 ? 10-4 g/mL. The zeta-potential of the HM-alginate in aqueous solution was about –82 mV, which is higher than –51 mV of the sodium alginate. Rheology measurements showed that the HM-alginate solution exhibits a Newtonian behavior at all shear rates, whereas the apparent viscosity is very low. The solubility of the liposoluble substance Sudan IV increased significantly with HM-alginate concentration. This result is promising for potential applications of HM-alginate as an ecology-safe material to encapsulate lipophilic substances.

  • RADIOTRACERS IN KINETICS OF ION-ISOTOPIC EXCHANGE REACTIONS USING ANION EXCHANGE RESINS INDION-103 AND INDION-870

    SINGARE P.U. — 2014 г.

    The kinetics of iodide and bromide ion-isotopic exchange reactions was studied by radio analytical technique using131I and 82Br as tracer isotopes. The parameters like specific reaction rate (min-1), amount of ions exchanged (mmol), initial rate of ion exchange (mmol/min) and log Kd were studied to evaluate the performance of nuclear and non-nuclear grade anion exchange resins Indion-103 and Indion-870. For iodide ion-isotopic exchange reactions under experimental conditions of 35.0°C, 1.000 g of ion exchange resins and 0.002 M labeled iodide ion solution, the parameters were 0.223 min-1, 0.300 mmol, 0.067 mmol/min and 18.7, respectively, for Indion-103, and those of 0.165 min-1, 0.251 mmol, 0.041 mmol/min and 16.2, respectively, for Indion-870. The similar tendency was observed during bromide ion-isotopic exchange reactions. The results suggest that Indion-103 shows greater performance than Indion-870 resin under similar experimental conditions.

  • SHAPE OF THE PARTICLES PRODUCED BY SEEDED DISPERSION POLYMERIZATION OF STYRENE

    ALIREZA HOSSEINZADEH, FARAMARZ AFSHAR-TAROMI, SAMIRA ABDOLBAGHI, SOLEYMAN HOSSEINZADEH, YOUNES SAADAT — 2014 г.

    In this work, seeded dispersion polymerization of styrene was carried out in the presence of various types of seed particles. We found that in the case of polystyrene and poly(methyl methacrylate) seeds, the shape of the resulting particles remained spherical. For styrene/poly(n-butyl methacrylate) (Pn-BMA) and styrene/poly(lauryl methacrylate) seeding particles, raspberry-like particles were produced along with those of occluded morphology. We studied the effects of various polymerization factors such as concentrations of a stabilizer, an initiator, and a monomer, a weight ratio of methanol to water, a type of initiator, weight ratio of styrene to Pn-BMA seed particles, and polymerization temperature on the formation of these raspberry-like particles. The experimental results showed that the increase of concentrations of the initiator and the stabilizer as well as that of methanol favors the formation of such particles by increasing their surface roughness. An increase of the temperature of polymerization had the same effect on the morphology of resulting product. We hypothesized that the nucleation and growth of specifically fine-structured polystyrene domains on the surface of the Pn-BMA particles guides the formation of non-linear morphology during seeded polymerization in colloidal solution.

  • SIO2-НАНОКОНТЕЙНЕРЫ НОВОГО ТИПА. ЗАЧЕМ УДАЛЯТЬ МИЦЕЛЛЫ ТЕМПЛАТА, ЕСЛИ ОНИ ФУНКЦИОНАЛЬНЫ?

    ВИНОГРАДОВА М.М., ДЕМЕНТЬЕВА О.В., КУЗНЕЦОВ Ю.И., ОГАРЕВ В.А., РУДОЙ В.М., ФРОЛОВА Л.В. — 2014 г.

    Предложен новый способ создания на основе мезопористых наночастиц кремнезема контейнеров для дифильных соединений той или иной природы. Он основан на использовании в качестве темплата при синтезе наночастиц мицелл целевого, т.е. подлежащего последующей “загрузке”, функционального соединения. Возможности и преимущества этого подхода продемонстрированы на примере синтеза частиц SiO2 на темплате из мицелл бромида цетилтриметиламмония, способного служить ингибитором сероводородной коррозии.

  • SYNTHESIS, CHARACTERIZATION AND APPLICATION OF MONODISPERSE GELATIN-STABILIZED SILVER NANOSPHERES IN REDUCTION OF AROMATIC NITRO COMPOUNDS

    CHAKRABORTY M., PARIKH P.A., VADAKKEKARA R. — 2014 г.

    Monodisperse colloidal silver nanospheres were synthesized by the reaction of silver nitrate, hydroxylammonium hydrosulphate (NH2OH)2 · H2SO4 and sodium hydroxide in the presence of gelatin as stabilizer. Colloidal nanospheres were characterized by UV-vis absorption spectroscopy, transmission electron microscopy, X-ray diffraction and dynamic light scattering. X-ray diffraction data confirmed that the silver nanospheres were crystalline with face-centered-cubic structure. Transmission electron microscopy analysis revealed the formation of homogeneously distributed silver nanoparticles of spherical morphology and size of the nanoparticles was in the range of 0.7–5.2 nm. Silver nanospheres were stable for more than two months when stored at ambient temperature. Size and size distribution were studied by varying pH, reaction temperature, silver ion concentration in feed solution, concentration of reducing agent and concentration of the stabilizing agent. Catalytic activity of silver nanospheres was tested for the reduction reaction of nitro compounds in sodium borohydride solution. Monodisperse silver nanospheres showed excellent catalytic activity towards the reduction of aromatic nitro compounds. The reduction rate of aromatic nitro compounds had been observed to follow the sequence (4-nitrophenol) > (2-nitrophenol) > (3-nitrophenol).

  • АГРЕГАТИВНАЯ УСТОЙЧИВОСТЬ ПОЛОЖИТЕЛЬНО ЗАРЯЖЕННОГО ЗОЛЯ , ПРИГОТОВЛЕННОГО НА ОСНОВЕ ВОЗДУШНО-СУХОГО НАНОПОРОШКА

    БОГДАНОВА Н.Ф., ВОЛКОВА А.В., ГОЛИКОВА Е.В., ЕРМАКОВА Л.Э., МОЛОДКИНА Л.М. — 2014 г.

    Результаты фотометрического исследования агрегативной устойчивости гидрозоля Al2O3, приготовленного на основе нанопорошка “Aeroxide Alu C”, в растворах NaCl при рН 4.5 и 5.5 обсуждены в рамках обобщенной теории Дерягина–Ландау–Фервея–Овербека. На основе анализа парных потенциалов взаимодействия в ансамбле частиц золя, содержащего изначально как первичные наночастицы, так и агрегаты наночастиц, сделан вывод о протекании коагуляции по безбарьерному механизму в дальнем потенциальном минимуме.