Galina B. Melnikova

Актуальность создания покрытий на основе смесей полимеров обусловлена задачами современного материаловедения, в число которых входит получение материалов с заданными эксплуатационными характеристиками за счет изменения состава химических систем и изучение их свойств. В данной работе представлены результаты исследования структурно-механических характеристик и смачиваемости поверхности наноструктурированных пленок на основе смесей поливинилкарбазола (ПВК) и полиметилметакрилата (ПММА). Пленки ПВК, ПММА и смесей ПВК-ПММА сформированы методом Ленгмюра – Блоджетт (ЛБ) с использованием горизонтального способа осаждения на поверхности гидрофилизированных кремниевых пластин. Установлена корреляция данных атомно-силовой микроскопии (АСМ) о структурно-механических свойствах и смачиваемости покрытий. Показано, что при массовом содержании ПВК до 45 процентов в растворе смеси полимеров для сформированных ЛБ-пленок характерно нарушение структурной целостности и формирование сферических и вытянутых конгломератов. Согласно данным статической силовой спектроскопии, локальные значения модуля упругости и силы адгезии ЛБ-пленок на основе смесей ПВК-ПММА не зависят от количественного соотношения компонентов. Значения краевого угла смачивания (КУС) для смесей полимеров составили от 74,31⁰ ± 1,21⁰ до 80,11⁰ ± 1,55⁰ и определяются свойствами компонента, массовое содержание которого преобладает. Формирование плотной ЛБ-пленки на основе смеси полимеров, значительно различающимися молекулярными массами, возможно при содержании низкомолекулярного компонента в смеси до 15 масс. %, что подтверждено АСМ-данными для образца ПВК-ПММА с массовым содержанием компонентов 87,1 % – 12,9 %. Смачиваемость данной пленки отличаются от образцов гомополимеров, что расширяет перспективы применения данных полимеров.

Актуальность создания покрытий на основе смесей полимеров обусловлена задачами современного материаловедения, в число которых входит получение материалов с заданными эксплуатационными характеристиками за счет изменения состава химических систем и изучение их свойств. В данной работе представлены результаты исследования структурно-механических характеристик и смачиваемости поверхности наноструктурированных пленок на основе смесей поливинилкарбазола (ПВК) и полиметилметакрилата (ПММА). Пленки ПВК, ПММА и смесей ПВК-ПММА сформированы методом Ленгмюра – Блоджетт (ЛБ) с использованием горизонтального способа осаждения на поверхности гидрофилизированных кремниевых пластин. Установлена корреляция данных атомно-силовой микроскопии (АСМ) о структурно-механических свойствах и смачиваемости покрытий. Показано, что при массовом содержании ПВК до 45 процентов в растворе смеси полимеров для сформированных ЛБ-пленок характерно нарушение структурной целостности и формирование сферических и вытянутых конгломератов. Согласно данным статической силовой спектроскопии, локальные значения модуля упругости и силы адгезии ЛБ-пленок на основе смесей ПВК-ПММА не зависят от количественного соотношения компонентов. Значения краевого угла смачивания (КУС) для смесей полимеров составили от 74,31⁰ ± 1,21⁰ до 80,11⁰ ± 1,55⁰ и определяются свойствами компонента, массовое содержание которого преобладает. Формирование плотной ЛБ-пленки на основе смеси полимеров, значительно различающимися молекулярными массами, возможно при содержании низкомолекулярного компонента в смеси до 15 масс. %, что подтверждено АСМ-данными для образца ПВК-ПММА с массовым содержанием компонентов 87,1 % – 12,9 %. Смачиваемость данной пленки отличаются от образцов гомополимеров, что расширяет перспективы применения данных полимеров.

Electrochemical sensors were developed using track-etched polyethyleneterephthalate (PET TeMs) membranes modified by UV-initiated graft copolymerization of N -hydroxymethyl acrylamide (NHMA) and 2-hydroxyethyl methacrylate (HEMA).

Mechanical and mathematical models for calculating the physical and mechanical properties of single- and multilayer materials of nanometer thickness, selecting the contact point taking into account the type of interaction of the cantilever with the surface of the material, their advantages and disadvantages are presented. The possibility of calculating the thickness of multilayer materials by solving the inverse problem is shown. The structure and local physical and mechanical properties of Langmuir–Blodgett films based on poly(methyl methacrylate) and composite films containing 41.7; 83.3; 167; 333 mol of SiO₂ nanoparticles per 1 mol of polymer were analyzed using atomic force microscopy. The AFM1 program has been developed for analyzing static force spectroscopy data, which implements the selection of the contact point according to the Johnson–Kendall–Roberts (JKR) model, and the calculation of the elastic modulus values according to the Hertz, JKR, Hsueh–Miranda, Makushkin, and Menčik models. A comparison of the calculated values of the elastic modulus and coating thickness was carried out using the above models. It was found that the film thickness values calculated using the Makushkin model correlate with the experimental data obtained by creating an artificial defect in the film. The results obtained are relevant for diagnostics and analysis of the properties of new functional nanomaterials.

Electrochemical sensors have been developed based on polyethylene terephthalate track-etched membranes (PET TeMs) modified by photograft copolymerization of N-vinylformamide (N-VFA) and trimethylolpropane trimethacrylate (TMPTMA). The modification, structure and properties of the modified PET TeMs were thoroughly characterized using scanning electron microscopy (SEM) and atomic force microscopy (AFM), thermogravimetric analysis (TGA), Fourier-transform infrared (FTIR) spectroscopy, gas permeability measurements and contact angle analysis. Optimal membrane modification was achieved using C = 10% (N-VFA), 60 min of UV irradiation and a UV lamp distance of 10 cm. Furthermore, the modified membranes were implemented in a two-electrode configuration for the determination of Eu³⁺, Gd³⁺, La³⁺ and Ce³⁺ ions via square-wave anodic stripping voltammetry (SW-ASV). The sensors exhibited a linear detection range from 10⁻⁷ M to 10⁻³ M, with limits of detection of 1.0 × 10⁻⁶ M (Eu³⁺), 6.0 × 10⁻⁶ M (Gd³⁺), 2.0 × 10⁻⁴ M (La³⁺) and 2.5 × 10⁻⁵ M (Ce³⁺). The results demonstrated a significant enhancement in electrochemical response due to the grafted PET TeMs-g-N-PVFA-TMPTMA structure, and the sensor showed practical applicability and consistent performance in detecting rare earth ions in tap water.

Electrochemical sensors based on PET track-etched membranes (TeMs) photograft copolymerization of N-vinylformamide (N-VFA) and trimethylolpropane trimethacrylate (TMPTMA). The modification, structure and properties of the modified PET TeMs were thoroughly characterized using scanning electron microscopy (SEM) and atomic force microscopy (AFM), thermogravimetric analysis (TGA), Fourier-transform infrared (FTIR) spectroscopy, gas permeability measurements and contact angle analysis. Parameters affecting the degree of membrane modification were identified and optimized. Moreover, the modified membranes were employed for the detection of Eu3+, Gd3+, La3+, Ce3+ ions using square wave anodic voltammetry (SW-ASV). The sensors exhibited linear detection range from 10-7 M to 10-3 M, with limits of detection of 1.0 × 10-6 M (Eu3+), 6.0 × 10-6 M (Gd3+), 2.0 × 10-4 M (La3+) and 2.5 × 10-5 M (Ce3+). The results demonstrated a significant enhancement in electrochemical response due to the grafted PET TeMs-g-N-PVFA-TMPTMA structure. Furthermore, tests conducted in tap water confirmed that the constructed sensors are suitable for real-world applications, providing reliable accuracy and reproducibility for rare earth element ion detection.

Composite coatings of silicon dioxide nanoparticles of polyethylcyanoacrylate and heptadecafluorotetra hydrodecyltriethoxysilane oligomers obtained on steel and silicon substrates by spin coating method. The highest values of the water contact angle are 150° and 151° with a wetting hysteresis less than 2.0° and hexadecane contact angle 125.6° ± 1.5° и 126.0° ± 2.0° for coatings obtained on silicon and steel surfaces, respectively, from a suspension containing 6.6 mass.% SiO₂ nanoparticles in ethylcyanoacrylate.

Coating systems using epoxy resin, organic silicon compounds (octadecyltrichlorosilane (OTS) and hydrolyzed heptadecafluoro tetrahydro decyltrimethoxysilane (HDFS)), and fluoropolymers (polytetrafluoroethylene (PTFE), and polyvinylidene fluoride (PVDF)), were applied to carbon steel. Epoxy (EP) coating and EP/OTS, EP/HDFS systems were produced via spin coating, while PTFE and PVDF layers were deposited using electron beam dispersion. Wettability, surface structure, and tribological properties were assessed through contact angle measurement, Fourier transform infrared reflection (FTIR), and tribotechnical test. Anticorrosion resistance was evaluated using electrochemical techniques, salt spray, and adhesion tests. Surface modifications with silicon compounds and fluoropolymers increased hydrophobicity, anticorrosion behavior and wear resistance. The water contact angles of EP, EP/OTS, EP/HDFS, EP/PVDF, and EP/PTFE were 84°, 108º, 116º, 96º, and 128º, respectively. Coating treatments reduced the friction coefficient. No corrosion was observed on treated surfaces after 336 hours in a salt spray chamber, while untreated EP showed rust after 96 hours. The hydrophobic systems based on epoxy resin, silicon compounds, and fluoropolymers are effective for protecting metal structures, with fluoropolymers providing higher protection to silicon compounds.

Pollution of the environment, in particular water sources, with heavy metals is a serious environmental problem. In this regard, it is relevant to develop new sensor systems that allow rapid tests and are not inferior in analytical parameters to classical methods for detecting heavy metals. Promising materials for creating such sensor systems are composite coatings based on polymer compounds with inorganic nanoparticles. The article presents the results of using poly(methyl methacrylate) (PMMA) coatings and PMMA nanocomposites with silicon dioxide nanoparticles (SiO₂ NPs) to develop capacitive sensors for analyzing the content of Ni²⁺ ions in water. The structural and morphological characteristics of a conductive nickel layer and nanostructured films based on poly(methyl methacrylate) were studied using atomic force microscopy. Based on the experimental data on the dependence of the capacitance characteristics of sensors on the concentration of Ni²⁺ in solutions, the operating characteristics of sensors were established: response time is 5 min; working range of concentrations of Ni²⁺ ions: 1 ‧ 10^–3 – 50 mM; lower detection limit ≈ 0.06 mg/l (maximum nickel concentration limit in water is 0.1 mg/l). It has been shown that the formation of a coating of the composition PMMA + NPs-SiO₂ (1 : 41.7 mol) on a conductive nickel layer using the spin-coating method leads to increasing the sensitivity of a sensor and its service life (up to seven cycles).

Stimuli-responsive membranes play an important role in the fields of biomedicine, food and chemical industries, and environmental applications, including separation of water–oil emulsions. In this study, we present a method to fabricate pH-sensitive membranes using UV-initiated RAFT graft copolymerization of styrene (ST) and acrylic acid (AA) on poly(ethylene terephthalate) (PET) track-etched membranes (TeMs). The optimization of polymerization conditions led to successful grafting of polystyrene (PS) and poly(acrylic acid) (PAA) onto PET TeMs, resulting in membranes with stable hydrophobicity and pH change responsiveness. The membranes show a contact angle of 65° in basic environments (pH 9) and 97° in acidic environments (pH 2). The membranes were characterized by atomic force microscopy (AFM), scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX), thermogravimetric analyses (TGA), Fourier transform infrared spectroscopy (FTIR), contact angle (CA) methods. The PET TeMs-g-PS-g-PAA exhibited good performance in separating water–oil emulsions with a high efficiency of more than 90% and flux for direct chloroform–water 2500 L m⁻² h⁻¹ and reverse emulsions of benzene–water 1700 L m⁻² h⁻¹. This method of preparing stimuli-responsive membranes with controlled wettability and responsiveness to environmental pH provides versatility in their use in separating two types of emulsions: direct and reverse.