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Grote, F., Lyubartsev, A., Dvinskikh, S., Rinwa, V. & Holmbäck, J. (2023). Phase equilibrium, dynamics and rheology of phospholipid-ethanol mixtures: a combined molecular dynamics, NMR and viscometry study. Physical Chemistry, Chemical Physics - PCCP, 25(23), 15905-15915
Open this publication in new window or tab >>Phase equilibrium, dynamics and rheology of phospholipid-ethanol mixtures: a combined molecular dynamics, NMR and viscometry study
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2023 (English)In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 25, no 23, p. 15905-15915Article in journal (Refereed) Published
Abstract [en]

Binary mixtures of ethanol and phospholipids DOPC and DOPE have been investigated in a composition range relevant for topical drug delivery applications. This was done using a combined computer simulation and experimental approach where molecular dynamics simulations of ethanol-lipid mixtures with different compositions were performed. Several key properties including diffusion coefficients, longitudinal relaxation times, and shear viscosity were computed. In addition, diffusion coefficients, viscosities and NMR longitudinal relaxation times were measured experimentally for comparison and in order to validate the results from simulation. Diffusion coefficients and relaxation times obtained from simulations are in good agreement with results from NMR and computed viscosities are in reasonable agreement with viscometry experiments indicating that the simulations provide a realistic description of the ethanol-phospholipid mixtures. Structural changes in the simulated systems were investigated using an analysis based on radial distribution functions. This showed that the structure of ethanol-DOPC mixtures remains essentially unchanged in the investigated concentration range while ethanol-DOPE mixtures undergo structural rearrangements with the tendency for forming small aggregates on the 100 ns time scale consisting of less than 10 lipids. Although our simulations and experiments indicate that no larger aggregates form, they also show that DOPE has stronger aggregation tendency than DOPC. This highlights the importance of the character of the lipid headgroup for lipid aggregation in ethanol and gives new insights into phase equilibrium, dynamics and rheology that could be valuable for the development of advanced topical drug delivery formulations.

Place, publisher, year, edition, pages
Royal Society of Chemistry (RSC), 2023
National Category
Physical Chemistry
Identifiers
urn:nbn:se:kth:diva-333004 (URN)10.1039/d3cp00425b (DOI)000999450700001 ()37260055 (PubMedID)2-s2.0-85162089775 (Scopus ID)
Note

QC 20230725

Available from: 2023-07-25 Created: 2023-07-25 Last updated: 2023-09-06Bibliographically approved
Subbotina, E., Ram, F., Dvinskikh, S., Berglund, L. & Olsen, P. (2022). Aqueous synthesis of highly functional, hydrophobic, and chemically recyclable cellulose nanomaterials through oxime ligation. Nature Communications, 13(1), Article ID 6924.
Open this publication in new window or tab >>Aqueous synthesis of highly functional, hydrophobic, and chemically recyclable cellulose nanomaterials through oxime ligation
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2022 (English)In: Nature Communications, E-ISSN 2041-1723, Vol. 13, no 1, article id 6924Article in journal (Refereed) Published
Abstract [en]

Cellulose nanofibril (CNF) materials are candidates for the sustainable development of high mechanical performance nanomaterials. Due to inherent hydrophilicity and limited functionality range, most applications require chemical modification of CNF. However, targeted transformations directly on CNF are cumbersome due to the propensity of CNF to aggregate in non-aqueous solvents at high concentrations, complicating the choice of suitable reagents and requiring tedious separations of the final product. This work addresses this challenge by developing a general, entirely water-based, and experimentally simple methodology for functionalizing CNF, providing aliphatic, allylic, propargylic, azobenzylic, and substituted benzylic functional groups. The first step is NaIO4 oxidation to dialdehyde-CNF in the wet cake state, followed by oxime ligation with O-substituted hydroxylamines. The increased hydrolytic stability of oximes removes the need for reductive stabilization as often required for the analogous imines where aldehyde groups react with amines in water. Overall, the process provides a tailored degree of nanofibril functionalization (2-4.5 mmol/g) with the possible reversible detachment of the functionality under mildly acidic conditions, resulting in the reformation of dialdehyde CNF. The modified CNF materials were assessed for potential applications in green electronics and triboelectric nanogenerators. Water is a standing challenge in the chemical modification of cellulose nanofibrils. Here, authors employ oxime-ligation to solve this by direct covalent chemistry on dialdehyde-CNF in water and assess the material for potential applications in green electronics and triboelectric nanogenerators.

Place, publisher, year, edition, pages
Springer Nature, 2022
National Category
Materials Chemistry
Identifiers
urn:nbn:se:kth:diva-322308 (URN)10.1038/s41467-022-34697-5 (DOI)000883836600043 ()36376337 (PubMedID)2-s2.0-85141950119 (Scopus ID)
Note

QC 20221212

Available from: 2022-12-12 Created: 2022-12-12 Last updated: 2023-03-28Bibliographically approved
Majhi, D., Dai, J. & Dvinskikh, S. (2022). Insights into cation-anion hydrogen bonding in mesogenic ionic liquids: an NMR study. Physical Chemistry, Chemical Physics - PCCP, 24(38), 23532-23539
Open this publication in new window or tab >>Insights into cation-anion hydrogen bonding in mesogenic ionic liquids: an NMR study
2022 (English)In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 24, no 38, p. 23532-23539Article in journal (Refereed) Published
Abstract [en]

The hydrogen-bonding interaction is studied in imidazolium-based mesogenic ionic liquids in their isotropic, smectic, and solid phases and in a nanoconfined state by proton solid-state nuclear magnetic resonance (NMR). In the smectic phase, the more basic anions form stronger hydrogen bonds. A small decrease of H-bonding in the mesophase with respect to that in the isotropic phase is associated with the presence of a layered assembly with high orientational order and limited conformational freedom. Hydrogen bond strength is not sensitive to the cation structural modification as long as the aprotic nature of the material is preserved. The strong cation-anion hydrogen bonding observed in the smectic phases provides direct support for the presence of ionic sublayers which form in ionic liquid crystals regardless of the location and alignment of the charged group in the cation, particularly irrespective of whether the charged group occupies a terminal or central position in the cation structure. A comparison of the results obtained in isotropic, liquid-crystalline, and solid states shows that in the bulk materials the dynamic state of ions ranging from high reorientational and translational freedom to partial orientation and positional order to full immobilization, respectively, has no strong impact on the cation-anion hydrogen bond strength. On the other hand, nanoconfinement of ionic liquid crystals led to hydrogen bond disruption due to competing interactions of anions with a solid interface. 

Place, publisher, year, edition, pages
Royal Society of Chemistry (RSC), 2022
Keywords
Bond strength (materials), Crystal structure, Ionic liquids, Ionic strength, Negative ions, Nuclear magnetic resonance, Phase interfaces, Positive ions, Cation-anions, Charged groups, Hydrogen bond strength, Hydrogen bonding interactions, Imidazolium-based, Ionic liquid crystals, Isotropic phasis, Mesogenics, Nuclear magnetic resonance studies, Smectic phase, Hydrogen bonds
National Category
Physical Chemistry
Identifiers
urn:nbn:se:kth:diva-328123 (URN)10.1039/d2cp03188d (DOI)000857436300001 ()36129074 (PubMedID)2-s2.0-85139342555 (Scopus ID)
Note

QC 20230602

Available from: 2023-06-02 Created: 2023-06-02 Last updated: 2023-06-02Bibliographically approved
Majhi, D. & Dvinskikh, S. (2021). Ion conformation and orientational order in a dicationic ionic liquid crystal studied by solid-state nuclear magnetic resonance spectroscopy. Scientific Reports, 11(1), Article ID 5985.
Open this publication in new window or tab >>Ion conformation and orientational order in a dicationic ionic liquid crystal studied by solid-state nuclear magnetic resonance spectroscopy
2021 (English)In: Scientific Reports, E-ISSN 2045-2322, Vol. 11, no 1, article id 5985Article in journal (Refereed) Published
Abstract [en]

Ionic liquids crystals belong to a special class of ionic liquids that exhibit thermotropic liquid-crystalline behavior. Recently, dicationic ionic liquid crystals have been reported with a cation containing two single-charged ions covalently linked by a spacer. In ionic liquid crystals, electrostatic and hydrogen bonding interactions in ionic sublayer and van der Waals interaction in hydrophobic domains are the main forces contributing to the mesophase stabilization and determining the molecular orientational order and conformation. How these properties in dicationic materials are compared to those in conventional monocationic analogs? We address this question using a combination of advanced NMR methods and DFT analysis. Dicationic salt 3,3 '-(1,6-hexanediyl)bis(1-dodecylimidazolium)dibromide was studied. Local bond order parameters of flexible alkyl side chains, linker chain, and alignment of rigid polar groups were analyzed. The dynamic spacer effectively "decouples" the motion of two ionic moieties. Hence, local order and alignment in dicationic mesophase were similar to those in analogous single-chain monocationic salts. Bond order parameters in the side chains in the dicationic smectic phase were found consistently lower compared to double-chain monocationic analogs, suggesting decreasing contribution of van der Waals forces. Overall dication reorientation in the smectic phase was characterized by low values of orientational order parameter S. With increased interaction energy in the polar domain the layered structure is stabilized despite less ordered dications. The results emphasized the trends in the orientational order in ionic liquid crystals and contributed to a better understanding of interparticle interactions driving smectic assembly in this and analogous ionic mesogens.

Place, publisher, year, edition, pages
NATURE RESEARCH, 2021
National Category
Physical Chemistry
Identifiers
urn:nbn:se:kth:diva-292490 (URN)10.1038/s41598-021-85021-y (DOI)000630512100009 ()33727569 (PubMedID)2-s2.0-85102718329 (Scopus ID)
Note

QC 20210412

Available from: 2021-04-12 Created: 2021-04-12 Last updated: 2022-09-15Bibliographically approved
Majhi, D., Kharkov, B. B. & Dvinskikh, S. (2021). Sign determination of dipolar couplings in liquid crystals by off-magic-angle sample spinning. Chemical Physics Letters, 781, Article ID 138997.
Open this publication in new window or tab >>Sign determination of dipolar couplings in liquid crystals by off-magic-angle sample spinning
2021 (English)In: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 781, article id 138997Article in journal (Refereed) Published
Abstract [en]

Dipolar NMR spectroscopy is a powerful analytical tool to study structural and dynamic properties of rigid and soft solids at the molecular level. While magnitudes of dipolar couplings can be determined from spectral splittings, signs of the constants are unavailable. A method to determine the signs of the dipolar couplings in liquid crystals is presented. Sign information is directly obtained from one-dimensional NMR spectra in samples spinning at an angle slightly misset from the magic angle. The approach is used to develop an experimental strategy for sign-sensitive measurements of heteronuclear dipolar couplings in anisotropic soft materials.

Place, publisher, year, edition, pages
Elsevier BV, 2021
Keywords
Solid-state NMR, Magic-angle spinning, Dipolar couplings, Soft matter, Liquid crystals
National Category
Physical Chemistry
Identifiers
urn:nbn:se:kth:diva-303531 (URN)10.1016/j.cplett.2021.138997 (DOI)000703480400004 ()2-s2.0-85113922556 (Scopus ID)
Note

QC 20211026

Available from: 2021-10-26 Created: 2021-10-26 Last updated: 2022-06-25Bibliographically approved
Majhi, D., Komolkin, A. V. & Dvinskikh, S. (2020). NMR Spectroscopic Studies of Cation Dynamics in Symmetrically-Substituted Imidazolium-Based Ionic Liquid Crystals. International Journal of Molecular Sciences, 21(14), Article ID 5024.
Open this publication in new window or tab >>NMR Spectroscopic Studies of Cation Dynamics in Symmetrically-Substituted Imidazolium-Based Ionic Liquid Crystals
2020 (English)In: International Journal of Molecular Sciences, ISSN 1661-6596, E-ISSN 1422-0067, Vol. 21, no 14, article id 5024Article in journal (Refereed) Published
Abstract [en]

Ionic liquid crystals (ILCs) present a new class of non-molecular soft materials with a unique combination of high ionic conductivity and anisotropy of physicochemical properties. Symmetrically-substituted long-chain imidazolium-based mesogenic ionic liquids exhibiting a smectic liquid crystalline phase were investigated by solid state NMR spectroscopy and computational methods. The aim of the study was to reveal the correlation between cation size and structure, local dynamics, and orientational order in the layered mesophase. The obtained experimental data are consistent with the model of a rod-shaped cation with the two chains aligned in opposite directions outward from the imidazolium core. The alignment of the core plane to the phase director and the restricted conformations of the chain segments were determined and compared to those in single-chain counterparts. The orientational order parameterS similar to 0.5-0.6 of double-chain ionic liquid crystals is higher than that of corresponding single-chain analogues. This is compatible with the enhanced contribution of van der Waals forces to the stabilization of smectic layers. Increased orientational order for the material with Br(-)counterions, which exhibit a smaller ionic radius and higher ability to form hydrogen bonds as compared to that of BF4-, also indicated a non-negligible influence of electrostatic and hydrogen bonding interactions. The enhanced rod-shape character and higher orientational order of symmetrically-substituted ILCs can offer additional opportunities in the design of self-assembling non-molecular materials.

Place, publisher, year, edition, pages
MDPI, 2020
Keywords
ionic liquids, liquid crystals, ionic liquid crystals, molecular orientational order, NMR spectroscopy
National Category
Physical Chemistry
Identifiers
urn:nbn:se:kth:diva-279185 (URN)10.3390/ijms21145024 (DOI)000554083100001 ()32708674 (PubMedID)2-s2.0-85088012942 (Scopus ID)
Note

QC 20200909

Available from: 2020-09-09 Created: 2020-09-09 Last updated: 2022-06-25Bibliographically approved
Dvinskikh, S. V. (2020). Nuclear magnetic resonance studies of translational diffusion in thermotropic ionic liquid crystals. Liquid crystals (Print), 47(13), 1975-1985
Open this publication in new window or tab >>Nuclear magnetic resonance studies of translational diffusion in thermotropic ionic liquid crystals
2020 (English)In: Liquid crystals (Print), ISSN 0267-8292, E-ISSN 1366-5855, Vol. 47, no 13, p. 1975-1985Article in journal (Refereed) Published
Abstract [en]

The NMR methodologies employed for investigating translational diffusion in anisotropic fluids and the results of their applications to ionic liquid crystals are reviewed. Experiments on ionic liquid crystals are preferably performed using oriented samples and require magnetic field gradients in orthogonal directions. Diffusion experiments in anisotropic systems with broad NMR lines are performed using line narrowing techniques and by application of strong static or pulsed field gradients for efficient gradient encoding/decoding of the spatial locations of molecules. Self-diffusion studies on various thermotropic ion-conductive materials exhibiting smectic, cubic, and columnar phases have been reported. Diffusion rates and anisotropy characterise the translational dynamics of ions in nanostructures and reflect the molecular ordering and ion pairing/dissociation processes. Distinct diffusion behaviours were observed for cations and anions. The knowledge of molecular mobility in ionic liquid crystals is important for the understanding their dynamic properties and is, therefore, valuable for the development of anisotropic soft materials for ion transport.

Place, publisher, year, edition, pages
Taylor & Francis, 2020
Keywords
Ionic liquid crystals, smectic, columnar, cubic, anisotropic translational diffusion, pulsed-field-gradient NMR
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-257649 (URN)10.1080/02678292.2019.1647569 (DOI)000480073900001 ()2-s2.0-85070233730 (Scopus ID)
Note

QC 20190905

Available from: 2019-09-05 Created: 2019-09-05 Last updated: 2024-03-15Bibliographically approved
Majhi, D., Dai, J., Komolkin, A. V. & Dvinskikh, S. V. (2020). Understanding ionic mesophase stabilization by hydration: a solid-state NMR study. Physical Chemistry, Chemical Physics - PCCP, 22(24), 13408-13417
Open this publication in new window or tab >>Understanding ionic mesophase stabilization by hydration: a solid-state NMR study
2020 (English)In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 22, no 24, p. 13408-13417Article in journal (Refereed) Published
Abstract [en]

The correlation between the water contribution to hydrogen bonding within ionic sublayer, mesophase order parameter, and ion translational self-diffusion in the layered ionic liquid crystalline phase is investigated. Changes in hydrogen bonding, conformational and translational dynamics, and orientational order upon hydration were followed by solid-state NMR combined with density functional theory (DFT) analysis. We observed that the smectic mesophase of monohydrated imidazolium-based ionic liquids, which was stabilized in a wider temperature range compared to that of anhydrous materials, counterintuitively exhibited a lower orientational order of organic cations. Thus the role of anisotropic alignment of cations and contribution of dispersion forces in the mesophase stability decreased upon hydration. The local dynamics of cations is controlled by the alignment of the bulky methyl-imidazolium ring, experiencing strong electrostatic and H-bond interactions in the ionic sublayer. Anisotropy of translational diffusion increased in the hydrated samples, thus supporting the layer-stabilizing effect of water. The effect of decreasing molecular order is outweighed by the contribution of water hydrogen bonding to the overall interaction energy within the ionic sublayer.

Place, publisher, year, edition, pages
Royal Society of Chemistry (RSC), 2020
National Category
Physical Chemistry
Identifiers
urn:nbn:se:kth:diva-278433 (URN)10.1039/d0cp01511c (DOI)000542478100005 ()32510078 (PubMedID)2-s2.0-85087095458 (Scopus ID)
Note

QC 20200716

Available from: 2020-07-16 Created: 2020-07-16 Last updated: 2024-03-15Bibliographically approved
Sophonrat, N., Sandström, L., Svanberg, R., Han, T., Dvinskikh, S., Lousada, C. M. & Yang, W. (2019). Ex Situ Catalytic Pyrolysis of a Mixture of Polyvinyl Chloride and Cellulose Using Calcium Oxide for HCl Adsorption and Catalytic Reforming of the Pyrolysis Products. Industrial & Engineering Chemistry Research, 58(31), 13960-13970
Open this publication in new window or tab >>Ex Situ Catalytic Pyrolysis of a Mixture of Polyvinyl Chloride and Cellulose Using Calcium Oxide for HCl Adsorption and Catalytic Reforming of the Pyrolysis Products
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2019 (English)In: Industrial & Engineering Chemistry Research, ISSN 0888-5885, E-ISSN 1520-5045, Vol. 58, no 31, p. 13960-13970Article in journal (Refereed) Published
Abstract [en]

In the context of chemical recycling of mixed plastics and paper, multitemperature step pyrolysis has shown good potential for the separation of oxygenated products from hydrocarbons. Here, we report results of an investigation of the first pyrolysis step at low temperature, which involves the dehydrochlorination of polyvinyl chloride (PVC) and the pyrolysis of cellulose, the main component of paper. Calcium oxide (CaO), selected for its chloride adsorption ability and its catalytic activity on biooil deoxygenation, was used for upgrading the downstream products from the pyrolysis. Additionally, we studied the performance of CaO for the simultaneous adsorption of HCl and for reforming cellulose pyrolysates in the temperature range of 300-600 degrees C with feedstock to CaO ratios of 1:0.2, 1:0.4, and 1:1. It was found that the suitable catalytic temperature for HCl and acetic acid adsorption is lower than 400 degrees C. This is due to the desorption of HCl from CaCl2 and Ca(OH)Cl in the presence of water and CO2 at 400 degrees C and higher. A larger amount of CaO resulted in a more efficient reduction of acids and the organic liquids were found to have lower amounts of oxygen. A comparison between the cases of neat and mixed feedstock showed that pyrolysis of mixed feedstock produced more water, H-2, CO, and polycyclic aromatic hydrocarbons (PAHs) when compared to the case of neat materials over CaO.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2019
National Category
Other Chemical Engineering
Identifiers
urn:nbn:se:kth:diva-257448 (URN)10.1021/acs.iecr.9b02299 (DOI)000480496100016 ()2-s2.0-85071301059 (Scopus ID)
Note

QC 20190830

Available from: 2019-08-30 Created: 2019-08-30 Last updated: 2022-12-12Bibliographically approved
Dai, J., Kharkov, B. B. & Dvinskikh, S. V. (2019). Molecular and Segmental Orientational Order in a Smectic Mesophase of a Thermotropic Ionic Liquid Crystal. Crystals, 9(1), Article ID 18.
Open this publication in new window or tab >>Molecular and Segmental Orientational Order in a Smectic Mesophase of a Thermotropic Ionic Liquid Crystal
2019 (English)In: Crystals, ISSN 2073-4352, Vol. 9, no 1, article id 18Article in journal (Refereed) Published
Abstract [en]

We investigate conformational dynamics in the smectic A phase formed by the mesogenic ionic liquid 1-tetradecyl-3-methylimidazolium nitrate. Solid-state high-resolution C-13 nuclear magnetic resonance (NMR) spectra are recorded in the sample with the mesophase director aligned in the magnetic field of the NMR spectrometer. The applied NMR method, proton encoded local field spectroscopy, delivers heteronuclear dipolar couplings of each C-13 spin to its H-1 neighbours. From the analysis of the dipolar couplings, orientational order parameters of the C-H bonds along the hydrocarbon chain were determined. The estimated value of the molecular order parameter S is significantly lower compared to that in smectic phases of conventional non-ionic liquid crystals.

Place, publisher, year, edition, pages
MDPI, 2019
Keywords
ionic liquids, liquid crystals, ionic liquid crystals, molecular orientational order, nuclear magnetic resonance
National Category
Other Physics Topics
Identifiers
urn:nbn:se:kth:diva-245954 (URN)10.3390/cryst9010018 (DOI)000458578100018 ()2-s2.0-85059389920 (Scopus ID)
Note

QC 20190311

Available from: 2019-03-11 Created: 2019-03-11 Last updated: 2024-03-15Bibliographically approved
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Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-6524-1441

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