Search

Your search keyword '"Antzutkin, Oleg N."' showing total 490 results
Start Over Author "Antzutkin, Oleg N."
490 results on '"Antzutkin, Oleg N."'

2. Properties of Confined Ammonium Nitrate Ionic Liquids

Author

Filippov, Andrei and Antzutkin, Oleg N.

Subjects
Physics - Chemical Physics
Abstract

Ethylammonium nitrate (EAN) and propylammonium nitrate ionic liquids confined between polar glass plates and exposed to a strong magnetic field demonstrate gradually slowing diffusivity, a process that can be reversed by removing the sample from the magnetic field. The process can be described well by the Avrami equation, which is typical for autocatalytic (particularly, nucleation controlled) processes. The transition can be stopped by freezing the sample. Cooling and heating investigations showed differences in the freezing and melting behavior of the sample depending on whether it had been exposed to the magnetic field. After exposure to the magnetic field, the sample demonstrated a change in the state of residual water. Generally, our findings confirm our previous suggestion that alteration of the dynamic properties of confined ammonium nitrate ionic liquids exposed to a magnetic field is related to the alteration of real physical-chemical phases., Comment: 12 pages, 5 figures

Published
2018

6. Acceleration of diffusion in ethylammonium nitrate ionic liquid confined between parallel glass plates

Author

Filippov, Andrei, Gnezdilov, Oleg I., Hjalmarsson, Nicklas, Antzutkin, Oleg N., Glavatskih, Sergei, Furó, Istvan, and Rutland, Mark W.

Subjects
Physics - Chemical Physics, Condensed Matter - Soft Condensed Matter
Abstract

The bulk self diffusion of the ethylammonium cation and the nitrate anion can both be described by respective single diffusion coefficients. Diffusion of the anion is 1.7 times higher than that of the cation. This indicates no tight association of the ions in the ionic liquid. For the ethylammonium cation confined between glass plates the effective diffusion coefficient along, as well as normal to the confining glass plates is higher by a factor of 1.86 as compared to that in the bulk. The same time, NMR T2 relaxation of protons of NH3 group of the EA cation is faster by a factor of 22 than that in bulk. 2H NMR spectra of selectively labeled CH2 and CH3 groups of EA do not demonstrate any ordering of the EA between the glass plates. We suggested that these data favor a model where a bulk isotropic sponge like structure of EAN is saved in the confinement, but sizes of connecting channels increases. Those leads to faster translational diffusion and faster exchange processes of protons of NH3 group, in comparison with the bulk., Comment: 11 pages, 5 figures, 1 table

Published
2017
Full Text
View/download PDF

7. Chemical Bonds Formed in Solid Wood by Reaction with Maleic Anhydride and Sodium Hypophosphite.

Author

Kim, Injeong, Antzutkin, Oleg N., Shah, Faiz Ullah, Karlsson, Olov, Jones, Dennis, and Sandberg, Dick

Subjects
*MALEIC anhydride, *X-ray photoelectron spectroscopy, *NUCLEAR magnetic resonance, *WOOD, *MAGIC angle spinning
Abstract

The reaction of wood with maleic anhydride (MA) and sodium hypophosphite (SHP) has been identified as a viable modification method, with macroscopical properties indicating formation of cross-linking to explain the results. However, the chemical reaction between wood and the modification reagents has not been studied yet. To resolve this, the reaction was studied with solid-state 13C cross-polarization magic-angle-spinning (CP-MAS) and 31P MAS nuclear magnetic resonance (NMR) and X-ray photoelectron spectroscopy (XPS) to reveal the formation of bonds between wood components, MA and SHP during the treatments to explain the formation of cross-linking and the possible fixation of phosphorus in wood. XPS, solid state 13C and 31P MAS NMR revealed the maleation of wood in the absence of SHP, whilst its presence led to forming a succinic adduct observed through the C-P bond formation, as evidenced by the loss of the maleate C=C bonds at around 130 ppm and the upfield shift of the peak at 165–175 ppm, which was also significantly smoothed, as well as the increase in a peak at 26 ppm due to the reaction between the maleate group and SHP; however, the C-P-C bond could not be unambiguously rationalized from the obtained data. On the other hand, a resonance line at 16 ppm in 31P MAS NMR and the peaks in the XPS P 2p spectrum suggested the formation of a cross-linked structure at low concentrations of SHP, which was more likely to be phosphonate (C-P-O) than organophosphinic acid (C-P-C). The results herein provide a greater fundamental understanding of the mechanisms involved in the reaction of wood, MA and SHP, providing further scope for improved treatment systems in the future. [ABSTRACT FROM AUTHOR]

Published
2024
Full Text
View/download PDF

8. Density functional theory study of physisorption of ionic liquid pairs on hydroxylated and oxygen terminated α-SiO2 (001) surfaces.

Author

Wang, Xiangjian, Antzutkin, Oleg. N., and Larsson, J. Andreas

Subjects
*ION pairs, *COMPLEX ions, *DENSITY functional theory, *FLUID inclusions, *ACTIVATION energy
Abstract

In this work, we investigate the ion pair tetramethylphosphonium cation, [P1,1,1,1]+, and bis(oxalato)borate anion, [BOB]−, as a model system for the study of ionic liquids interacting with both hydroxylated and oxygen terminated α-SiO2 (001) surfaces, using first-principles electronic structure theory. We use a single ionic pair and clusters of ion pairs, in order to have exclusively neutral supercell slab models. We use dispersion-corrected density functional theory (DFT) to ascertain that both the strong physical binding between the ions, dominated by ionic binding, and the weaker physical binding of ions to the different surfaces are correctly described. We have found that the binding of ion pairs is stronger to the hydroxylated α-SiO2 (001) surface compared to the oxygen terminated surface, which is attributed to the formation of H-binding with the oxygen atom(s) of the [BOB]− anion. Through rotation of ionic pair(s), we estimate the surface-ions energy barrier for translational movement and, thus, the strength of H-binding of the ions. At the surface of hydroxylated α-SiO2 (001), we have studied how water molecules form a network of H-binding with the OH groups of the surface and the [BOB]− anion, which offers an explanation for the reduction in the friction of ionic liquids on the inclusion of water. We suggest modeling protocols for simulation of ion pairs on surfaces, which can open up the possibility to use DFT to aid in designing and understanding the physicochemical mechanism of interactions of ionic materials (including ionic liquids) in various technological applications. [ABSTRACT FROM AUTHOR]

Published
2024
Full Text
View/download PDF

30. Molecular Architecture Effects on Bulk Nanostructure in Bis(Orthoborate) Ionic Liquids

Author

Hammond, Oliver S., Bousrez, Guillaume, Mehler, Filip, Li, Sichao, Shimpi, Manishkumar R., Doutch, James, Cavalcanti, Leide, Glavatskih, Sergei, Antzutkin, Oleg N., Rutland, Mark W., Mudring, Anja-Verena, Hammond, Oliver S., Bousrez, Guillaume, Mehler, Filip, Li, Sichao, Shimpi, Manishkumar R., Doutch, James, Cavalcanti, Leide, Glavatskih, Sergei, Antzutkin, Oleg N., Rutland, Mark W., and Mudring, Anja-Verena

Abstract

A series of 19 ionic liquids (ILs) based on phosphonium and imidazolium cations of varying alkyl-chain lengths with the orthoborate anions bis(oxalato)borate [BOB](-), bis(mandelato)borate, [BMB](-) and bis(salicylato)borate, [BScB](-), are synthesized and studied using small-angle neutron scattering (SANS). All measured systems display nanostructuring, with 1-methyl-3-n-alkyl imidazolium-orthoborates forming clearly bicontinuous L-3 spongelike phases when the alkyl chains are longer than C-6 (hexyl). L-3 phases are fitted using the Teubner and Strey model, and diffusely-nanostructured systems are primarily fitted using the Ornstein-Zernicke correlation length model. Strongly-nanostructured systems have a strong dependence on the cation, with molecular architecture variation explored to determine the driving forces for self-assembly. The ability to form well-defined complex phases is effectively extinguished in several ways: methylation of the most acidic imidazolium ring proton, replacing the imidazolium 3-methyl group with a longer hydrocarbon chain, substitution of [BOB](-) by [BMB](-), or exchanging the imidazolium for phosphonium systems, irrespective of phosphonium architecture. The results suggest there is only a small window of opportunity, in terms of molecular amphiphilicity and cation:anion volume matching, for the formation of stable extensive bicontinuous domains in pure bulk orthoborate-based ILs. Particularly important for self-assembly processes appear to be the ability to form H-bonding networks, which offer additional versatility in imidazolium systems.

Published
2023
Full Text
View/download PDF

31. High Leach-Resistant Fire-Retardant Modified Pine Wood (Pinus sylvestris L.) by In Situ Phosphorylation and Carbamylation

Author

Lin, Chia-Feng, Karlsson, Olov, Das, Oisik, Mensah, Rhoda Afriyie, Mantanis, George I., Jones, Dennis, Antzutkin, Oleg N., Försth, Michael, Sandberg, Dick, Lin, Chia-Feng, Karlsson, Olov, Das, Oisik, Mensah, Rhoda Afriyie, Mantanis, George I., Jones, Dennis, Antzutkin, Oleg N., Försth, Michael, and Sandberg, Dick

Abstract

The exterior application of fire-retardant (FR) timber necessitates it to have high durability because of the possibility to be exposed to rainfall. In this study, water-leaching resistance of FR wood has been imparted by grafting phosphate and carbamate groups of the water-soluble FR additives ammonium dihydrogen phosphate (ADP)/urea onto the hydroxyl groups of wood polymers via vacuum-pressure impregnation, followed by drying/heating in hot air. A darker and more reddish wood surface was observed after the modification. Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, solid-state 13C cross-polarization magic-angle-spinning nuclear magnetic resonance (13C CP-MAS NMR), and direct-excitation 31P MAS NMR suggested the formation of C–O–P covalent bonds and urethane chemical bridges. Scanning electron microscopy/energy-dispersive X-ray spectrometry suggested the diffusion of ADP/urea into the cell wall. The gas evolution analyzed by thermogravimetric analysis coupled with quadrupole mass spectrometry revealed a potential grafting reaction mechanism starting with the thermal decomposition of urea. Thermal behavior showed that the FR-modified wood lowered the main decomposition temperature and promoted the formation of char residues at elevated temperatures. The FR activity was preserved even after an extensive water-leaching test, confirmed by the limiting oxygen index (LOI) and cone calorimetry. The reduction of fire hazards was achieved through the increase of the LOI to above 80%, reduction of 30% of the peak heat release rate (pHRR2), reduction of smoke production, and a longer ignition time. The modulus of elasticity of FR-modified wood increased by 40% without significantly decreasing the modulus of rupture., Validerad;2023;Nivå 2;2023-04-21 (joosat);Funder: OP RDE (Grant no.CZ.02.1.01/0.0/0.0/16_019/0000803); CT WOOD, Luleå University of TechnologyLicens fulltext: CC BY License

Published
2023
Full Text
View/download PDF

32. State of anion in ethylammonium nitrate enclosed between micrometer-spaced glass plates as studied by 17O and 15N NMR

Author

Filippov, Andrei, Antzutkin, Oleg N., Filippov, Andrei, and Antzutkin, Oleg N.

Abstract

Some aprotic and protic ionic liquids (ILs) containing nitrate anion demonstrate unusual dynamic behavior of cations when these ILs are enclosed in micrometer-spaced layers between glass plates. We applied 17O and 15N NMR spectroscopy to discover the state and transformations of 17O and 15N isotopically enriched nitrate anion of ethylammonium nitrate (EAN) enclosed between glass plates. 15N NMR spectra demonstrated preferential orientation of the principal axes of the nitrate anions perpendicular to the normal of the glass surface. Therefore, isotropic ionic liquid EAN, when placed within a micrometer-spaced enclosure, forms an ordered phase, which is similar to a liquid crystal. The peculiarity of this phase is that the cations do not have a predominant orientation. Other features of this phase that are typical for liquid crystal phases are the changed local and translational dynamics in comparison with the isotropic state and slow transformation occurring under the action of an external magnetic field., Validerad;2023;Nivå 2;2023-05-29 (joosat);Funder: J. C. and Seth M. Kempe; Swedish Foundation for Strategic Research (project EM16-0013)Licesn fulltext: CC BY License

Published
2023
Full Text
View/download PDF

46. A fixation mode of gold from solutions using heterogeneous reaction of cadmium dicyclohexyl dithiophosphate with H[AuCl4]. Structural and (13C, 31P) CP/MAS NMR studies and thermal behaviour of crystalline polymeric gold(I) dicyclohexyl dithiophosphate and bis(dicyclohexylthiophosphoryl) disulphide

Author

Ivanov, Alexander V., Korneeva, Eugenia V., Lutsenko, Irina A., Gerasimenko, Andrey V., Antzutkin, Oleg N., Larsson, Anna-Carin, and Sergienko, Valentin I.

Published
2013
Full Text
View/download PDF

48. State of anion in ethylammonium nitrate enclosed between micrometer-spaced glass plates as studied by 17O and 15N NMR.

Author

Filippov, Andrei and Antzutkin, Oleg N.

Abstract

Some aprotic and protic ionic liquids (ILs) containing nitrate anion demonstrate unusual dynamic behavior of cations when these ILs are enclosed in micrometer-spaced layers between glass plates. We applied 17O and 15N NMR spectroscopy to discover the state and transformations of 17O and 15N isotopically enriched nitrate anion of ethylammonium nitrate (EAN) enclosed between glass plates. 15N NMR spectra demonstrated preferential orientation of the principal axes of the nitrate anions perpendicular to the normal of the glass surface. Therefore, isotropic ionic liquid EAN, when placed within a micrometer-spaced enclosure, forms an ordered phase, which is similar to a liquid crystal. The peculiarity of this phase is that the cations do not have a predominant orientation. Other features of this phase that are typical for liquid crystal phases are the changed local and translational dynamics in comparison with the isotropic state and slow transformation occurring under the action of an external magnetic field. [ABSTRACT FROM AUTHOR]

Published
2023
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results