Effect of subphase conditions on the formation of graphene Langmuir monolayer

This work was supported by grant from DAAD 4.9977.2017/5.2

Study of the surface microrelief of copper nanoparticles by the method of scanning probe microscopy

This work was supported by grants from the RFBR № 17-07-00407-а and № 17-32-50137-mol_nr

Investigation of copper nanoparticles by the method of scanning probe microscopy

В данной работе получали мицеллярный раствор с НЧ меди, стабилизированными ПАВ анионного типа — додецилсульфатом натрия (ДДС) C12H25NaO4S в щелочной среде при pH ≈ 10, в качестве восстановителя использовали гидразин гидрат (ГГ) N2H4∙H2O. Спектрофотометрическое исследование полученного раствора на спектрофотометре SHIMADZU UV-2550 в диапазоне длин волн 190-900 нм показало наличие пика поглощения излучения при длине волны 580 нм, соответствующего НЧ меди.In this work a micellar solution was prepared with copper NPs stabilized by an anionic surfactant — sodium dodecyl sulfate (SDS) C12H25NaO4S at pH ≈ 10. Hydrazine hydrate (HH) N2H4∙H2O was used as the reducing agent. Spectrophotometric study of the obtained solution by means of SHIMADZU UV-2550 spectrophotometer in the wavelength range 190-900 nm is showed the presence of a radiation absorption peak at 580 nm corresponding of copper NPs. The study of images of copper NPs on the glass substrates with an ITO layer (Indium Tin Oxide) was carried out by scanning probe microscopy (SPM) in atomic-force microscopy (AFM) and scanning tunneling microscopy (STM) by means of NanoEducator. The AFM images were obtained and the current-voltage characteristics of the copper NPs were recorded (Fig. 1 (a) and (б), respectively).Работа выполнена при финансовой поддержке гранта Российского научного фонда (проект №14-12-00275) и Национального исследовательского Саратовского государственного университета

Monitoring of copper nanoparticle penetration into dentin of human tooth in vitro

Study of the penetration depth of synthesized copper nanoparticles into cut samples of human dentin was conducted. The scanning electron microscopy was used to determine the elemental composition of fresh transverse cleavage of the dentin cut for determination of the copper nanoparticles penetration with an effective antiseptic effect. The morphology of the cut surface of the dentin of a human tooth was studied and the lower limit of the diffusion boundary was determined. It was found that copper nanoparticles penetrate into the dentin cut to a depth of ~ 1.8 μm with the diffusion coefficient of 1.8×10–11 cm2/s. Despite the rather small size of the synthesized copper nanoparticles (20-80 nm), a rather small penetration depth can be explained by the high aggregation ability of copper nanoparticles, as well as the ability of a micellar solution of sodium dodecyl sulfate, in which nanoparticles were stabilized, to form conglomerates in micelles of much larger sizes

Features of formation of Langmuir monolayers of porphyrin derivatives on the surface of aqueous solutions of copper nanoparticles

Abstract Meso-aryl-substituted porphyrin monolayers were obtained by the Langmuir method depending on the aliquots applied to the water surface and the composition of the subphase. Regardless of the composition of the subphase (pure water or a solution with copper nanoparticles stabilized by surfactant) porphyrin compression isotherms showed the formation of monolayers until a film collapse state is reached. The presence in the subphase volume of copper nanoparticles stabilized by a surfactant (sodium dodecyl sulfate) contributed to the formation of a more stable porphyrin monolayer. A significant difference in the values of the surface potential at the end of porphyrin monolayer compression depending on the composition of the subphase is established. This fact is very promising in the context of creating film heterostructures with improved operational properties.</jats:p

Effect of the composition and temperature of the subphase on the surface potential of the Langmuir monolayer of 8CB liquid crystal

Abstract The effect of the composition and temperature of the subphase on the effective dipole moment of the Langmuir monolayers of a liquid crystal 4-n-octyl-4’-cyanobiphenyl on the surface of pure water and an aqueous solution containing copper nanoparticles was studied. It is shown that the presence of nanoparticles in the subphase leads to increase of the area occupied by the monolayer in the condensed state, increase of the collapse pressure, and reduce of the surface potential at the end of monolayer compression. The effective dipole moments of liquid crystal molecules were calculated for monolayers formed under various conditions.</jats:p

Formation of Gibbs and Langmuir floating layers based on copper nanoparticles: temperature and concentration effects

Abstract This paper is devoted to study of the formation of Gibbs floating layers from aqueous solutions of copper nanoparticles (Cu NPs) stabilized by the sodium dodecyl sulfate surfactant. Langmuir floating layers of arachidic acid formed on the surface of a water subphase containing Cu NPs were also studied. Adsorption of copper nanoparticles on a monolayer of arachidic acid at different conditions has been investigated. In the experiments the amount of copper nanoparticles in the subphase and the temperature of the subphase were changed. The performed analysis showed that the increase of subphase temperature from 29 to 42 °C leads to the increase of the area occupied by Langmuir floating layers in a liquid-condensed state by 30 and 32 %, respectively. After a single transfer of the floating layer onto the highly oriented pyrolytic graphite substrates, their surface microrelief was investigated by atomic force microscopy (AFM). The AFM scans showed that the obtained copper nanoparticles films contained separate areas with copper particles and their aggregates. With an increase of surface pressure from 10 to 40 mN/m, an increase of the height difference of the surface microrelief from 4 to 7 nm and an increase of the large aggregates number with lateral dimensions about 100 nm were observed.</jats:p