Abstract Hybrid composites of gold nanoparticles (Au NPs) with polymer hydrogels are promising platforms for the development of new materials that can respond to external stimuli (chemical, physical, mechanical), reversibly absorb/release water and reagents, act as plasmonic sensors, and also be triggers of photochemical processes and photothermal actuators of micromechanical processes. In our study we have (1) proposed a one-step method for the synthesis of a hybrid composite of Au NPs with polyacrylamide hydrogel (PAAm) by the reduction of HAuCl 4 with acrylamide (AAm) and simultaneous radical polymerization of AAm in an aqueous solution, (2) optimized the conditions for obtaining a phase-stable product, (3) studied the effect of the initial concentrations of Au and AAm on the morphology and structure of Au NPs, (4) obtained and characterized plasmonic films from the Au NPs-PAAm composite and after thermal removal of the polymer matrix. The methods of UV-visible and photon correlation spectroscopy, X-ray diffraction, synchronous thermal analysis, transmission and scanning electron microscopy were used in the work. Graphical abstract

Hybrid composites of gold nanoparticles (Au NPs) with polymer hydrogels are promising platforms for the development of new materials that can respond to external stimuli (chemical, physical, mechanical), reversibly absorb/release water and reagents, act as plasmonic sensors, and also as catalysts for photochemical processes and photothermal actuators of micromechanical processes. We proposed a one-step synthesis of a hybrid composite of Au NPs doped into polyacrylamide (PAAm) hydrogel by reducing HAuCl4 with acrylamide (AAm) and simultaneous radical polymerization of AAm, initiated by (NH4)2S2O8, in the aqueous solution. The influence of initial concentrations of 0.26–10 mM Au and 0.1–1 M AAm on the morphology and structure of Au NPs, as well as on the phase stability of the products, was studied. At concentrations of 3 mM Au, 1 M AAm and 1.2 mM (NH4)2S2O8, а temperature of 60 °C and a heating time of 6 h, a stable product with a clearly defined SPR band with a maximum at 552 nm was obtained. It contained polycrystalline Au NPs in the form of spheroids, cuboctahedra, and rods up to 100 nm size. The product was used to obtain plasmonic films of Au NPs-PAAm composite after drying at 100 °C and gold after thermal removal of the polymer matrix at 550 °C.The work used UV-visible and photon correlation spectroscopy, X-ray diffraction, synchronous thermal analysis, transmission and scanning electron microscopy.

Проведено рентгенографическое исследование фазового состава продукта взаимодействия ацетата цинка с гидроперитом в дисперсной водной фазе обратномицеллярного раствора на основе оксиэтилированного ПАВ Brij 30 и декана в качестве дисперсионной среды. Обнаружено, что выделенный продукт, наряду с наночастицами ZnO2, содержит игольчатые микрокристаллы, которые по данным рентгеноструктурного анализа представляют собой лактат цинка дигидрат — [Zn(lact)2(H2O)2]: а = 6.0196(3) Å, b = 11.9068(4) Å, c = 14.3878(7) Å, Z = 4, пространственная группа P212121. Координационное окружение атома Zn — искаженный октаэдр: расстояния Zn—О 2.051(2)—2.099(3) Å, валентные углы ∠О—Zn—О 76.16° и 76.14°. Хелатные циклы имеют перегибы по линии О…О — 22.18° и 11.54°. Построена поверхность Хиршфельда (шаровидность комплекса 0.79, асферичность 0.16) и выполнен анализ межмолекулярных контактов. Проведен сравнительный кристаллохимический анализ с известной структурой [Zn(lact)2(H2O)2]·H2O.

ZnO2 nanoparticles (NPs) have been studied, which, due to their semiconducting and oxidizing properties, are promising for the development of new materials for optoelectronics, photocatalysis, sensorics, biomedicine, and theranostics. The synthesis of ZnO2 NPs in dispersed systems based on lipophilic surfactants has been tested. The possibility of simple synthesis of ZnO2 NPs ~5 nm in size by the reaction of Zn (CH3COO)2 and H2O2 in reverse micelles and emulsions of surfactants Brij 30, Span 80, and AOT has been shown. It has been found that the type of dispersed system and the nature of surfactants of the studied series have no strong effect on the size of NPs. The powder of ZnO2 NPs exhibits photoluminescence with an emission maximum at 520 nm; upon heating, it decomposes to ZnO with the release of oxygen and an exotherm with a maximum at 213°C. Using organosols of ZnO2 NPs and their mixtures with Au NPs, films were obtained on glass and polyethylene terephthalate substrates, as well as ZnO films by heating the ZnO2 films. The ZnO2 and ZnO films have a granular morphology, the composite ZnO2 and Au films have an island morphology based on spheroidal agglomerates of Au NPs with inclusions of ZnO2 nanocrystals.

The phase composition of the interaction product of zinc acetate with hydrogen peroxide in a dispersed aqueous phase of a reverse micellar solution based on oxyethylated Brij 30 surfactant and decane as a dispersion medium is analyzed by powder X-ray diffraction (XRD). Along with ZnO2 nanoparticle, the isolated product is found to contain needle-like microcrystals that, according to the single crystal XRD analysis, are zinc lactate dihydrate [Zn(lact)2(H2O)2]: a = 6.0196(3) Å, b = 11.9068(4) Å, c = 14.3878(7) Å, Z = 4, space group P212121. The coordination environment of the Zn atom is a distorted octahedron: Zn–О distances are 2.051(2)-2.099(3) Å, ∠О–Zn–О bond angles are 76.16° and 76.14°. Chelate rings are bent along the О…О line at 22.18° and 11.54°. The Hirshfeld surface (complex sphericity 0.79, asphericity 0.16) is constructed and intermolecular contacts are analyzed. A comparative crystal chemical analysis with the known [Zn(lact)2(H2O)2]·H2O structure is performed.

The study addresses layer-by-layer formation processes and properties of gold nanoparticle films deposited from reverse micellar solutions of Brij 30 surfactant on rigid glass and flexible polymer (PET) substrates. The films are of interest for transparent electronics and optical sensorics. The spectrophotometric studies of film formation revealed linear relationships between the extinction of growing film at definite wavelengths and the number of nanoparticle deposition cycles, and their parameters were determined. The effects of concentrations of gold and 1,2-ethanedithiol as an interlayer linker in the initial solutions on the film growth were elucidated. Data on the composition, morphology, optical spectra, and surface resistance of gold nanoparticle films, and changes of these characteristics during heat treatment in air and in boiling ethanol were gained using X-ray diffractometry, scanning electron and atomic force microscopy, UV-Vis spectroscopy, and electrical resistance measurements.

The deposition of coatings of Au and ZnO nanoparticles (NPs) on glass, semiconductor silicon, polyethylene terephthalate, and polystyrene substrates was studied. Deposition was carried out using relatively concentrated dispersions of particles in ethanol (approximately 5–10 mM Au, ZnO), which showed limited time resistance to coagulation and sedimentation, but returned to their original dispersed state by ultrasonic treatment before each cycle of deposition of NPs. The NPs of Au and ZnO were stabilized by abietate and acetate ions, respectively. Simple coatings from Au or ZnO NPs and a combined coating from a mixture of Au and ZnO NPs, as well as two-layer combined coatings with alternating layers of Au/ZnO and ZnO/Au NPs, were obtained by drop casting and the proposed method of deposition from the capillary layer of the dispersion with the use of a linker. The formation of coatings on transparent substrates was studied by means of UV–Vis spectroscopy. Coatings were characterized by SEM, EDX, XRD, PL, UV–Vis and surface resistance methods. The effect of heat treatment on coatings characteristics was tested.

Изучены процессы послойного формирования и свойства пленок из наночастиц золота, нанесенных из обратномицеллярных растворов ПАВ Brij 30 на жесткие стеклянные и гибкие полимерные (ПЭТ) подложки. Эти пленки представляют интерес для прозрачной электроники и оптической сенсорики. В результате спектрофотометрических исследований формирования пленок установлены линейные зависимости в координатах экстинкция наращиваемой пленки на фиксированной длине волны–число циклов нанесения наночастиц и определены их параметры, а также охарактеризованы закономерности влияния на прирост пленок концентраций золота и 1,2-этандитиола как межслоевого линкера в применявшихся растворах. Методами рентгеновской дифрактометрии, сканирующей электронной и атомно-силовой микроскопии, УФ-видимой спектроскопии и измерением электрического сопротивления получены данные о составе, морфологии, оптических спектрах и поверхностном сопротивлении пленок наночастиц золота и их изменении при термообработке на воздухе и в кипящем этаноле.

В статті на основі архівних документів і періодики висвітлено початковий період біографії авіаконструктора Дмитра Павловича Григоровича (1883–1938 рр.): його навчання в Київському політехнічному інституті, діяльнiсть у київських громадських авіаційних організаціях — Повітроплавному гуртку КПІ та Київському товаристві повітроплавання; спроби будувати літаки власної конструкції, умови й характер роботи на авіаційних підприємствах країни до початку Першої світової війни, його видавнича і журналістська діяльність після від’їзду з України. Також уточнено деякі факти з біографії авіаконструктора (зокрема, стосовно його батьків і родини). До наукового обігу введено нові документи, раніше невідомі дослідникам.

We have studied the usefulness of alcoholic dispersions of Au nanoparticles (NPs) stabilized by isonicotinic acid (INA) and tris(2-aminoethyl)amine (TAEA) for manufacturing colloidal films on glass substrates and composites with nanosized carbon materials (based on nanotubes (NTs) and a porous carbon material (PCM)) and oxide powders (Al2O3, SiO2, and CeO2).

We studied the usefulness of dispersions of gold nanoparticles (Au-NPs) stabilized by abietic acid for manufacturing films on glass and silicon substrates and composites with nanosized and powder materials exemplified by SiO 2 and TiO 2 NPs, expanded graphite (EG), carbon nanotubes (CNTs), a porous carbon material (PCM), PCM containing 6% nitrogen, and CeO 2 powder.

The use of solutions of acrylamide (AAm) opens up new ways for easy one-step synthesis of ZnO nanoparticles (NPs) and their composites with polyacrylamide (PAAm). To obtain a nanocrystalline product in which the composition of NPs is close to {(ZnO) m (Zn2+) n }(CH3COO−)2n with n/m = 0.292, the hydrolysis of Zn(CH3COO)2·2H2O should be carried out in 96% ethanol. In this process, AAm plays the role of an organic base that accepts protons and does not act as a protective ligand. The ZnO NPs/PAAm composite is formed as a viscous transparent colorless hydrogel if the same reaction is carried out in an aqueous medium simultaneously with the radical polymerization of AAm initiated by (NH4)2S2O8. A solid composite can be isolated due to the destruction of the hydrogel by the addition of ethanol. In the composite, PAAm acts as a polymeric matrix in which ZnO NPs are distributed. The synthesis products were characterized by XRD, TEM, SEM, EDX, DLS, IR, Raman scattering, photoluminescence, and chemical analysis. The particles in both products were nanocrystals of hexagonal ZnO about a few nanometers in size. The powder of {(ZnO) m (Zn2+) n }(CH3COO−)2n NPs had a yellow photoluminescence with emission maximum at λ em = 590 nm. The photoluminescence band of the ZnO NPs/PAAm hydrogel had a maximum at λ em = 449 nm.

Gold nanoparticles (NPs) with the average core diameter d Au = 6.8 ± 1.6 nm have been synthesized in reverse micelles of the oxyethylated surfactant Brij 30. It has been shown that thin NP films can be produced directly from a micellar solution with the use of glass substrates functionalized with aminosilane. Synthesis of NPs and film formation have been studied by UV-Vis spectroscopy, photon correlation spectroscopy, X-ray diffraction, TEM, SEM, and AFM.

The kinetics of thiourea synthesis of CdS nanoparticles (NPs) in reverse microemulsions of Tergitol Np-4/n-decane was studied in the temperature range of 313-333 K by spectrophotometry, photon-correlation spectroscopy, and transmission electron microscopy. The formation of NPs is described by the kinetic model, including two consecutive steps: homogeneous nucleation in a solution as the first step and the autocatalytic growth of NPs due to heterogeneous reaction on a continuously increasing surface as the second step. Effective rate constants of the steps (k1 = 1.52 × 10-2-1.75 × 10-3 s-1 and k2 = 4.9 × 10-1-5.1 × 10-2 M-1 s-1) and effective activation energies (Ea1 = 156 and Ea2 = 149 kJ/mol) were estimated in the pseudo-first-order reaction with respect to cadmium (cCd = 0.9 mM, cThio = 9 mM). The obtained constants were used to calculate the dependence of nanoparticle diameter on the synthesis time (d3 ∼ t). The calculated values correlate well with experimental data of photon-correlation spectroscopy and transmission electron microscopy.