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Hjalmarsson, N., Bergendal, E., Wang, Y.-L., Munavirov, B., Wallinder, D., Glavatskih, S., . . . Rutland, M. W. (2019). Electro-Responsive Surface Composition and Kinetics of an Ionic Liquid in a Polar Oil. Langmuir, 35(48), 15692-15700
Åpne denne publikasjonen i ny fane eller vindu >>Electro-Responsive Surface Composition and Kinetics of an Ionic Liquid in a Polar Oil
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2019 (engelsk)Inngår i: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 35, nr 48, s. 15692-15700Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

The quartz crystal microbalance (QCM) has been used to study how the interfacial layer of an ionic liquid dissolved in a polar oil at low weight percentages responds to changes in applied potential. The changes in surface composition at the QCM gold surface depend on both the magnitude and sign of the applied potential. The time-resolved response indicates that the relaxation kinetics are limited by the diffusion of ions in the interfacial region and not in the bulk, since there is no concentration dependence. The measured mass changes cannot be explained only in terms of simple ion exchange; the relative molecular volumes of the ions and the density changes in response to ion exclusion must be considered. The relaxation behavior of the potential between the electrodes upon disconnecting the applied potential is more complex than that observed for pure ionic liquids, but a measure of the surface charge can be extracted from the exponential decay when the rapid initial potential drop is accounted for. The adsorbed film at the gold surface consists predominantly of ionic liquid despite the low concentration, which is unsurprising given the surtactant-like structures of (some of) the ionic liquid ions. Changes in response to potential correspond to changes in the relative numbers of cations and anions, rather than a change in the oil composition. No evidence for an electric field induced change in viscosity is observed. This work shows conclusively that electric potentials can be used to control the surface composition, even in an oil-based system, and paves the way for other ion solvent studies.

sted, utgiver, år, opplag, sider
American Chemical Society (ACS), 2019
Emneord
Double-Layer, Antiwear Performance, Friction, Nanotribology, Interface, Additives, Solvents, Nanostructure, Capacitance, Lubricants
HSV kategori
Identifikatorer
urn:nbn:se:kth:diva-266194 (URN)10.1021/acs.langmuir.9b02119 (DOI)000500838500027 ()31581771 (PubMedID)2-s2.0-85073873461 (Scopus ID)
Merknad

QC 2020013

Tilgjengelig fra: 2020-01-13 Laget: 2020-01-13 Sist oppdatert: 2020-01-13bibliografisk kontrollert
Abreu, B., Rocha, J., Ferreira Fernandes, R. M., Regev, O., Furo, I. & Marques, E. F. (2019). Gemini surfactants as efficient dispersants of multiwalled carbon nanotubes: Interplay of molecular parameters on nanotube dispersibility and debundling. Journal of Colloid and Interface Science, 547, 69-77
Åpne denne publikasjonen i ny fane eller vindu >>Gemini surfactants as efficient dispersants of multiwalled carbon nanotubes: Interplay of molecular parameters on nanotube dispersibility and debundling
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2019 (engelsk)Inngår i: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 547, s. 69-77Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

Surfactants have been widely employed to debundle, disperse and stabilize carbon nanotubes in aqueous solvents. Yet, a thorough understanding of the dispersing mechanisms at molecular level is still warranted. Herein, we investigated the influence of the molecular structure of gemini surfactants on the dispersibility of multiwalled carbon nanotubes (MWNTs). We used dicationic n-s-n gemini surfactants, varying n and s, the number of alkyl tail and alkyl spacer carbons, respectively; for comparisons, single-tailed surfactant homologues were also studied. Detailed curves of dispersed MWNT concentration vs. surfactant concentration were obtained through a stringently controlled experimental procedure, allowing for molecular insight. The gemini are found to be much more efficient dispersants than their single-tailed homologues, i.e. lower surfactant concentration is needed to attain the maximum dispersed MWNT concentration. In general, the spacer length has a comparatively higher influence on the dispersing efficiency than the tail length. Further, scanning electron microscopy imaging shows a sizeable degree of MWNT debundling by the gemini surfactants in the obtained dispersions. Our observations also point to an adsorption process that does not entail the formation of micelle-like aggregates on the nanotube surface, but rather coverage by individual molecules, among which the ones that seem to be able to adapt best to the nanotube surface provide the highest efficiency. These studies are relevant for the rational design and choice of optimal dispersants for carbon nanomaterials and other similarly water-insoluble materials.

sted, utgiver, år, opplag, sider
ACADEMIC PRESS INC ELSEVIER SCIENCE, 2019
Emneord
Gemini surfactant, Carbon nanotube, Exfoliation, Dispersion efficiency, Molecular structure, Spacer length, Tail length, Adsorption, Hydrophobicity
HSV kategori
Identifikatorer
urn:nbn:se:kth:diva-252363 (URN)10.1016/j.jcis.2019.03.082 (DOI)000466826600007 ()30939346 (PubMedID)2-s2.0-85063650726 (Scopus ID)
Merknad

QC 20190718

Tilgjengelig fra: 2019-07-18 Laget: 2019-07-18 Sist oppdatert: 2019-07-18bibliografisk kontrollert
Chen, P., Terenzi, C., Furo, I., Berglund, L. & Wohlert, J. (2019). Heterogeneous dynamics in cellulose from molecular dynamics simulations. Paper presented at National Meeting of the American-Chemical-Society (ACS), MAR 31-APR 04, 2019, Orlando, FL. Abstracts of Papers of the American Chemical Society, 257
Åpne denne publikasjonen i ny fane eller vindu >>Heterogeneous dynamics in cellulose from molecular dynamics simulations
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2019 (engelsk)Inngår i: Abstracts of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 257Artikkel i tidsskrift, Meeting abstract (Annet vitenskapelig) Published
sted, utgiver, år, opplag, sider
AMER CHEMICAL SOC, 2019
HSV kategori
Identifikatorer
urn:nbn:se:kth:diva-257590 (URN)000478860502701 ()
Konferanse
National Meeting of the American-Chemical-Society (ACS), MAR 31-APR 04, 2019, Orlando, FL
Merknad

QC 20190919

Tilgjengelig fra: 2019-09-19 Laget: 2019-09-19 Sist oppdatert: 2019-10-15bibliografisk kontrollert
Chaudhary, H., Ferreira Fernandes, R. M., Gowda, V., Claessens, M. M. A., Furo, I. & Lendel, C. (2019). Intrinsically disordered protein as carbon nanotube dispersant: How dynamic interactions lead to excellent colloidal stability. Journal of Colloid and Interface Science, 556, 172-179
Åpne denne publikasjonen i ny fane eller vindu >>Intrinsically disordered protein as carbon nanotube dispersant: How dynamic interactions lead to excellent colloidal stability
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2019 (engelsk)Inngår i: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 556, s. 172-179Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

The rich pool of protein conformations combined with the dimensions and properties of carbon nanotubes create new possibilities in functional materials and nanomedicine. Here, the intrinsically disordered protein α-synuclein is explored as a dispersant of single-walled carbon nanotubes (SWNTs) in water. We use a range of spectroscopic methods to quantify the amount of dispersed SWNT and to elucidate the binding mode of α-synuclein to SWNT. The dispersion ability of α-synuclein is good even with mild sonication and the obtained dispersion is very stable over time. The whole polypeptide chain is involved in the interaction accompanied by a fraction of the chain changing into a helical structure upon binding. Similar to other dispersants, we observe that only a small fraction (15–20%) of α-synuclein is adsorbed on the SWNT surface with an average residence time below 10 ms

sted, utgiver, år, opplag, sider
Academic Press, 2019
HSV kategori
Identifikatorer
urn:nbn:se:kth:diva-258234 (URN)10.1016/j.jcis.2019.08.050 (DOI)000491301300018 ()31445446 (PubMedID)2-s2.0-85070901886 (Scopus ID)
Merknad

QC 20191014

Tilgjengelig fra: 2019-09-10 Laget: 2019-09-10 Sist oppdatert: 2020-03-09bibliografisk kontrollert
Gao, J., Yang, W., El-Zohry, A. M., Prajapati, G. K., Fang, Y., Dai, J., . . . Kloo, L. (2019). Light-induced electrolyte improvement in cobalt tris(bipyridine)-mediated dye-sensitized solar cells. Journal of Materials Chemistry A, 7(33), 19495-19505
Åpne denne publikasjonen i ny fane eller vindu >>Light-induced electrolyte improvement in cobalt tris(bipyridine)-mediated dye-sensitized solar cells
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2019 (engelsk)Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 7, nr 33, s. 19495-19505Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

Lithium-ion-free tris(2,2 '-bipyridine) Co(ii/iii)-mediated electrolytes have previously been proposed for long-term stable dye-sensitized solar cells (DSSCs). Such redox systems also offer an impressive DSSC performance improvement under light soaking exposure, manifested by an increase in photocurrent and fill factor without the expense of decreasing photovoltage. Kinetic studies show that charge transfer and ion diffusion at the electrode/electrolyte interface are improved due to the light exposure. Control experiments reveal that the light effect is unambiguously associated with electrolyte components, [Co(bpy)(3)](3+) and the Lewis-base additive tert-butylpyridine (TBP). Electrochemical and spectroscopic investigation of the [Co(bpy)(3)](3+)/TBP mixtures points out that the presence of TBP, which retards the electrolyte diffusion, however causes an irreversible redox reaction of [Co(bpy)(3)](3+) upon light exposure that improves the overall conductivity. This discovery not only provides a new strategy to mitigate the typical J(sc)-V-oc trade-off in Co(ii/iii)-mediated DSSCs but also highlights the importance of investigating the photochemistry of a photoelectrochemical system.

sted, utgiver, år, opplag, sider
ROYAL SOC CHEMISTRY, 2019
HSV kategori
Identifikatorer
urn:nbn:se:kth:diva-259417 (URN)10.1039/c9ta07198a (DOI)000482139000027 ()2-s2.0-85071187004 (Scopus ID)
Merknad

QC 20190924

Tilgjengelig fra: 2019-09-24 Laget: 2019-09-24 Sist oppdatert: 2019-09-24bibliografisk kontrollert
Rohlmann, P., Munavirov, B., Furo, I., Antzutkin, O., Rutland, M. W. & Glavatskih, S. (2019). Non-halogenated Ionic Liquid Dramatically Enhances Tribological Performance of Biodegradable Oils. Frontiers in Chemistry, 7, Article ID 98.
Åpne denne publikasjonen i ny fane eller vindu >>Non-halogenated Ionic Liquid Dramatically Enhances Tribological Performance of Biodegradable Oils
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2019 (engelsk)Inngår i: Frontiers in Chemistry, E-ISSN 2296-2646, Vol. 7, artikkel-id 98Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

It is demonstrated that a phosphonium orthoborate ionic liquid may serve as a wear reducing additive in biodegradable oils at steel-steel surfaces in the boundary lubrication regime. Tribological tests were performed in a bail-on-three plate configuration. A set of surface characterization techniques-SEM/EDS, FIB and white light interferometry were used to characterize surfaces following the tribotests and to observe the formation of any tribofilms. B-11 NMR was used to follow changes in the composition of the ionic-liquid-oil blends and to identify boron-containing decomposition products after the tribotests. The ionic liquid reduces the wear of steel surfaces by up to 92% compared to the neat oil at 90 degrees C; it is shown that the reduction in wear can be correlated with the formation of boron enriched patches in the boundary films.

sted, utgiver, år, opplag, sider
FRONTIERS MEDIA SA, 2019
Emneord
biodegradable oil, ionic liquid, wear, friction, boundary lubrication, NMR
HSV kategori
Identifikatorer
urn:nbn:se:kth:diva-246253 (URN)10.3389/fchem.2019.00098 (DOI)000459858200001 ()2-s2.0-85068538860 (Scopus ID)
Merknad

QC 20190401

Tilgjengelig fra: 2019-04-01 Laget: 2019-04-01 Sist oppdatert: 2019-10-04bibliografisk kontrollert
Niga, P., Hansson-Mille, P. M., Swerin, A., Claesson, P. M., Schoelkopf, J., Gane, P. A. C., . . . Johnson, C. M. (2019). Propofol adsorption at the air/water interface: a combined vibrational sum frequency spectroscopy, nuclear magnetic resonance and neutron reflectometry study. Soft Matter, 15(1), 38-46
Åpne denne publikasjonen i ny fane eller vindu >>Propofol adsorption at the air/water interface: a combined vibrational sum frequency spectroscopy, nuclear magnetic resonance and neutron reflectometry study
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2019 (engelsk)Inngår i: Soft Matter, ISSN 1744-683X, E-ISSN 1744-6848, Vol. 15, nr 1, s. 38-46Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

Propofol is an amphiphilic small molecule that strongly influences the function of cell membranes, yet data regarding interfacial properties of propofol remain scarce. Here we consider propofol adsorption at the air/water interface as elucidated by means of vibrational sum frequency spectroscopy (VSFS), neutron reflectometry (NR), and surface tensiometry. VSFS data show that propofol adsorbed at the air/ water interface interacts with water strongly in terms of hydrogen bonding and weakly in the proximity of the hydrocarbon parts of the molecule. In the concentration range studied there is almost no change in the orientation adopted at the interface. Data from NR show that propofol forms a dense monolayer with a thickness of 8.4 angstrom and a limiting area per molecule of 40 angstrom(2), close to the value extracted from surface tensiometry. The possibility that islands or multilayers of propofol form at the air/water interface is therefore excluded as long as the solubility limit is not exceeded. Additionally, measurements of the 1H NMR chemical shifts demonstrate that propofol does not form dimers or multimers in bulk water up to the solubility limit.

sted, utgiver, år, opplag, sider
ROYAL SOC CHEMISTRY, 2019
HSV kategori
Identifikatorer
urn:nbn:se:kth:diva-241311 (URN)10.1039/c8sm01677a (DOI)000454838800015 ()30516226 (PubMedID)2-s2.0-85058894693 (Scopus ID)
Merknad

QC 20190125

Tilgjengelig fra: 2019-01-25 Laget: 2019-01-25 Sist oppdatert: 2019-12-20bibliografisk kontrollert
Chen, P., Terenzi, C., Furo, I., Berglund, L. & Wohlert, J. (2019). Quantifying Localized Macromolecular Dynamics within Hydrated Cellulose Fibril Aggregates. Macromolecules, 52(19), 7278-7288
Åpne denne publikasjonen i ny fane eller vindu >>Quantifying Localized Macromolecular Dynamics within Hydrated Cellulose Fibril Aggregates
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2019 (engelsk)Inngår i: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835, Vol. 52, nr 19, s. 7278-7288Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

Molecular dynamics (MD) simulations of C-13 NMR longitudinal relaxation (T-1) distributions were recently established as a powerful tool for characterizing moisture adsorption in natural amorphous polymers. Here, such computational-experimental synergy is demonstrated in a system with intrinsically high structural heterogeneity, namely crystalline cellulose nanofibrils (CNFs) in highly hydrated aggregated state. In such a system, structure-function properties on the nanoscale remain largely uncovered by experimental means alone. In this work, broadly polydispersed experimental C-13 NMR T-1 distributions could be successfully reproduced in simulations and, for the first time, were decomposed into contributions from distinct molecular sources within the aggregated CNFs, namely, (i) the core and (ii) the less-accessible and accessible surface regions of the CNFs. Furthermore, within the surface groups structurally different sites such as (iii) residues with different hydroxymethyl orientations and (iv) center and origin chains could be discerned based on their distinct molecular dynamics. The MD simulations unravel a direct correlation between dynamical and structural heterogeneity at an atomistic-level resolution that cannot be accessed by NMR experiments. The proposed approach holds the potential to enable quantitative interpretation of NMR data from a range of multicomponent high-performance nanocomposites with significantly heterogeneous macromolecular structure.

sted, utgiver, år, opplag, sider
AMER CHEMICAL SOC, 2019
HSV kategori
Identifikatorer
urn:nbn:se:kth:diva-262947 (URN)10.1021/acs.macromol.9b00472 (DOI)000489678400017 ()2-s2.0-85072991639 (Scopus ID)
Merknad

QC 20191104

Tilgjengelig fra: 2019-11-04 Laget: 2019-11-04 Sist oppdatert: 2019-11-04bibliografisk kontrollert
Ferreira Fernandes, R. M., Dai, J., Regev, O., Marques, E. F. & Furo, I. (2018). Block Copolymers as Dispersants for Single-Walled Carbon Nanotubes: Modes of Surface Attachment and Role of Block Polydispersity. Langmuir, 34(45), 13672-13679
Åpne denne publikasjonen i ny fane eller vindu >>Block Copolymers as Dispersants for Single-Walled Carbon Nanotubes: Modes of Surface Attachment and Role of Block Polydispersity
Vise andre…
2018 (engelsk)Inngår i: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 34, nr 45, s. 13672-13679Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

When using amphiphilic polymers to exfoliate and disperse carbon nanotubes in water, the balance between the hydrophobic and hydrophilic moieties is critical and nontrivial. Here, we investigate the mode of surface attachment of a triblock copolymer, Pluronics F127, composed of a central hydrophobic polypropylene oxide block flanked by hydrophilic polyethylene oxide blocks, onto single-walled carbon nanotubes (SWNTs). Crucially, we analyze the composition in dispersant of both the as-obtained dispersion (the supernatant) and the precipitate-containing undispersed materials. For this, we combine the carefully obtained data from H-1 NMR peak intensities and self-diffusion and thermogravimetric analysis. The molecular motions behind the observed NMR features are clarified. We find that the hydrophobic blocks attach to the dispersed SWNT surface and remain significantly immobilized leading to H-1 NMR signal loss. On the other hand, the hydrophilic blocks remain highly mobile and thus readily detectable by NMR. The dispersant is shown to possess significant block polydispersity that has a large effect on dispersibility. Polymers with large hydrophobic blocks adsorb on the surface of the carbonaceous particles that precipitate, indicating that although a larger hydrophobic block is good for enhancing adsorption, it may be less effective in dispersing the tubes. A model is also proposed that consistently explains our observations in SWNT dispersions and some contradicting findings obtained previously in carbon nanohorn dispersions. Overall, our findings help elucidating the molecular picture of the dispersion process for SWNTs and are of interest when looking for more effective (i.e., well-balanced) polymeric dispersants.

sted, utgiver, år, opplag, sider
AMER CHEMICAL SOC, 2018
HSV kategori
Identifikatorer
urn:nbn:se:kth:diva-239775 (URN)10.1021/acs.langmuir.8b02658 (DOI)000450695000023 ()30335395 (PubMedID)2-s2.0-85056155151 (Scopus ID)
Merknad

QC 20190108

Tilgjengelig fra: 2019-01-08 Laget: 2019-01-08 Sist oppdatert: 2019-01-09bibliografisk kontrollert
Dai, J., Ferreira Fernandes, R. M., Regev, O., Marques, E. F. & Furo, I. (2018). Dispersing Carbon Nanotubes in Water with Amphiphiles: Dispersant Adsorption, Kinetics, and Bundle Size Distribution as Defining Factors. The Journal of Physical Chemistry C, 122(42), 24386-24393
Åpne denne publikasjonen i ny fane eller vindu >>Dispersing Carbon Nanotubes in Water with Amphiphiles: Dispersant Adsorption, Kinetics, and Bundle Size Distribution as Defining Factors
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2018 (engelsk)Inngår i: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 122, nr 42, s. 24386-24393Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

Debundling and dispersing single-walled carbon nanotubes (SWNTs) is essential for applications, but the process is not well understood. In this work, aqueous SWNT dispersions were produced by sonicating pristine SWNT powder in the presence of an amphiphilic triblock copolymer (Pluronic F127) as dispersant. Upon centrifugation, one obtains a supernatant with suspended individual tubes and thin bundles and a precipitate with large bundles (and impurities). In the supernatant, that constitutes the final dispersion, we determined the dispersed SWNT concentration by thermogravi-metric analysis (TGA) and UV-vis spectroscopy, and the dispersant concentration by NMR The fraction of dispersant adsorbed at the SWNT surface was obtained by H-1 diffusion NMR Sigmoidal dispersion curves recording the concentration of dispersed SWNTs as a function of supernatant dispersant concentration were obtained at different SWNT loadings and sonication times. As SWNT bundles are debundled into smaller and smaller ones, the essential role of the dispersant is to sufficiently quickly cover the freshly exposed surfaces created by shear forces induced during sonication. Primarily kinetic reasons are behind the need for dispersant concentrations required to reach a substantial SWNT concentration. Centrifugation sets the size threshold below which SWNT particles are retained in the dispersion and consequently determines the SWNT concentration as a function of sonication time.

sted, utgiver, år, opplag, sider
American Chemical Society (ACS), 2018
HSV kategori
Identifikatorer
urn:nbn:se:kth:diva-239095 (URN)10.1021/acs.jpcc.8b06542 (DOI)000448754300065 ()2-s2.0-85054962387 (Scopus ID)
Forskningsfinansiär
Swedish Research Council
Merknad

QC 20181121

Tilgjengelig fra: 2018-11-21 Laget: 2018-11-21 Sist oppdatert: 2019-08-20bibliografisk kontrollert
Organisasjoner
Identifikatorer
ORCID-id: ORCID iD iconorcid.org/0000-0002-0231-3970