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Bergendal E, Rutland MW. Unveiling Texture and Topography of Fatty Acid Langmuir Films: Domain Stability and Isotherm Analysis. Langmuir 2024; 40:10468-10476. [PMID: 38713000 DOI: 10.1021/acs.langmuir.3c03501] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2024]
Abstract
3D texturing by self-assembly at the air-water interface has recently been proposed. The hypothesis of this work is that, if this is true, such domain formation should be inferable directly from pressure-area isotherms and be thermodynamically stable. Monolayers of branched fatty acid mixtures with straight chain analogues and their stability are thus studied using a combination of pressure-area isotherms, thermodynamic analysis, in situ Brewster angle microscopy, and atomic force microscopy of both LB-deposited and drop-cast films on silicon wafers. Isotherms reflecting the behavior of monodisperse 3D domains are shown to be independent of compression rate and display long-term stability. Gibbs analysis further confirms the thermodynamic rather than kinetic origin of such novel species by revealing that deviations from ideal mixing can be explained only a priori by differences in the topography of the water surface, thus also indirectly confirming the self-assembly deformation of the water interface. The intrinsic self-assembly curvature and miscibility of the two fatty acids is confirmed by drop-casting, which also provides a rapid, tunable thin-film preparation approach. Finally, the longevity of the nanostructured films is extraordinary, the long-range order of the deposited films increases with equilibration time at the water interface, and the integrity of the nanopatterns remains intact on the scale of years.
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Affiliation(s)
- Erik Bergendal
- Department of Chemistry, School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, Teknikringen 30, Stockholm SE-100 44, Sweden
| | - Mark W Rutland
- Department of Chemistry, School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, Teknikringen 30, Stockholm SE-100 44, Sweden
- RISE Research Institutes of Sweden, Chemistry, Materials and Surfaces, Box 5607, Stockholm SE-114 86, Sweden
- School of Chemistry, University of New South Wales, Sydney, New South Wales 2052, Australia
- Laboratoire de Tribologie et Dynamique des Systèmes, École Centrale de Lyon, Ecully Cedex 69134, France
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2
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Li S, Hammond OS, Nelson A, de Campo L, Moir M, Recsei C, Shimpi MR, Glavatskih S, Pilkington GA, Mudring AV, Rutland MW. Anion Architecture Controls Structure and Electroresponsivity of Anhalogenous Ionic Liquids in a Sustainable Fluid. J Phys Chem B 2024; 128:4231-4242. [PMID: 38639329 DOI: 10.1021/acs.jpcb.3c08189] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/20/2024]
Abstract
Three nonhalogenated ionic liquids (ILs) dissolved in 2-ethylhexyl laurate (2-EHL), a biodegradable oil, are investigated in terms of their bulk and electro-interfacial nanoscale structures using small-angle neutron scattering (SANS) and neutron reflectivity (NR). The ILs share the same trihexyl(tetradecyl)phosphonium ([P6,6,6,14]+) cation paired with different anions, bis(mandelato)borate ([BMB]-), bis(oxalato)borate ([BOB]-), and bis(salicylato)borate ([BScB]-). SANS shows a high aspect ratio tubular self-assembly structure characterized by an IL core of alternating cations and anions with a 2-EHL-rich shell or corona in the bulk, the geometry of which depends upon the anion structure and concentration. NR also reveals a solvent-rich interfacial corona layer. Their electro-responsive behavior, pertaining to the structuring and composition of the interfacial layers, is also influenced by the anion identity. [P6,6,6,14][BOB] exhibits distinct electroresponsiveness to applied potentials, suggesting an ion exchange behavior from cation-dominated to anion-rich. Conversely, [P6,6,6,14][BMB] and [P6,6,6,14][BScB] demonstrate minimal electroresponses across all studied potentials, related to their different dissociative and diffusive behavior. A mixed system is dominated by the least soluble IL but exhibits an increase in disorder. This work reveals the subtlety of anion architecture in tuning bulk and electro-interfacial properties, offering valuable molecular insights for deploying nonhalogenated ILs as additives in biodegradable lubricants and supercapacitors.
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Affiliation(s)
- Sichao Li
- Division of Surface and Corrosion Science, School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, Stockholm SE-100 44, Sweden
| | - Oliver S Hammond
- Department of Materials and Environmental Chemistry, Stockholm University, Stockholm SE-114 18, Sweden
- intelligent Advanced Materials, Department of Biological & Chemical Engineering and iNANO, Aarhus University, Aarhus C 8000, Denmark
| | - Andrew Nelson
- Australian Centre for Neutron Scattering, ANSTO, Lucas Heights, New South Wales 2234, Australia
| | - Liliana de Campo
- Australian Centre for Neutron Scattering, ANSTO, Lucas Heights, New South Wales 2234, Australia
| | - Michael Moir
- National Deuteration Facility, ANSTO, Lucas Heights, New South Wales 2234, Australia
| | - Carl Recsei
- National Deuteration Facility, ANSTO, Lucas Heights, New South Wales 2234, Australia
| | - Manishkumar R Shimpi
- Department of Materials and Environmental Chemistry, Stockholm University, Stockholm SE-114 18, Sweden
- Chemistry of Interfaces, Department of Civil and Environmental Engineering, Luleå University of Technology, Luleå SE-97187, Sweden
| | - Sergei Glavatskih
- System and Component Design, Department of Engineering Design, KTH Royal Institute of Technology, Stockholm SE-100 44, Sweden
- School of Chemistry, University of New South Wales, Sydney, New South Wales 2052, Australia
- Department of Electromechanical, Systems and Metal Engineering, Ghent University, Ghent B-9052, Belgium
| | - Georgia A Pilkington
- Division of Surface and Corrosion Science, School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, Stockholm SE-100 44, Sweden
| | - Anja-Verena Mudring
- Department of Materials and Environmental Chemistry, Stockholm University, Stockholm SE-114 18, Sweden
- intelligent Advanced Materials, Department of Biological & Chemical Engineering and iNANO, Aarhus University, Aarhus C 8000, Denmark
- Department of Physics, Umeå University, Umeå SE-901 87, Sweden
| | - Mark W Rutland
- Division of Surface and Corrosion Science, School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, Stockholm SE-100 44, Sweden
- School of Chemistry, University of New South Wales, Sydney, New South Wales 2052, Australia
- Bioeconomy and Health Department Materials and Surface Design, RISE Research Institutes of Sweden, Stockholm SE-114 28, Sweden
- Laboratoire de Tribologie et Dynamique des Systèmes, École Centrale de Lyon, Ecully Cedex 69134, France
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3
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Hammond O, Morris DC, Bousrez G, Li S, de Campo L, Recsei C, Moir M, Glavatskih S, Rutland MW, Mudring AV. Small-Angle Neutron Scattering Insights into 2-Ethylhexyl Laurate: A Remarkable Bioester. ACS Sustain Chem Eng 2024; 12:1816-1821. [PMID: 38333201 PMCID: PMC10848283 DOI: 10.1021/acssuschemeng.3c04736] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/28/2023] [Revised: 11/17/2023] [Accepted: 11/17/2023] [Indexed: 02/10/2024]
Abstract
Commercial (protiated) samples of the "green" and biodegradable bioester 2-ethylhexyl laurate (2-EHL) were mixed with D-2-EHL synthesized by hydrothermal deuteration, with the mixtures demonstrating bulk structuring in small-angle neutron scattering measurements. Analysis in a polymer scattering framework yielded a radius of gyration (Rg) of 6.5 Å and a Kuhn length (alternatively described as the persistence length or average segment length) of 11.2 Å. Samples of 2-EHL dispersed in acetonitrile formed self-assembled structures exceeding the molecular dimensions of the 2-EHL, with a mean aggregation number (Nagg) of 3.5 ± 0.2 molecules across the tested concentrations. We therefore present structural evidence that this ester can function as a nonionic (co)surfactant. The available surfactant-like conformations appear to enable performance beyond the low calculated hydrophilic-lipophilic balance value of 2.9. Overall, our data offer an explanation for 2-EHL's interfacial adsorption properties via self-assembly, resulting in strong emolliency and lubricity for this sustainable ester-based bio-oil.
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Affiliation(s)
- Oliver
S. Hammond
- Department
of Biological and Chemical Engineering and iNANO, Aarhus University, Aarhus
C 8000, Denmark
- Department
of Materials and Environmental Chemistry, Stockholm University, Stockholm 114 18, Sweden
| | - Daniel C. Morris
- School
of Chemical Engineering, University of New
South Wales, Sydney 2052, Australia
| | - Guillaume Bousrez
- Department
of Biological and Chemical Engineering and iNANO, Aarhus University, Aarhus
C 8000, Denmark
- Department
of Materials and Environmental Chemistry, Stockholm University, Stockholm 114 18, Sweden
| | - Sichao Li
- Division
of Surface and Corrosion Science, School of Engineering Sciences in
Chemistry, Biotechnology and Health, KTH
Royal Institute of Technology, Stockholm 100 44, Sweden
| | - Liliana de Campo
- Australian
Centre for Neutron Scattering, ANSTO, Lucas Heights, New South Wales 2234, Australia
| | - Carl Recsei
- National
Deuteration Facility, ANSTO, Lucas
Heights, New South Wales 2234, Australia
| | - Michael Moir
- National
Deuteration Facility, ANSTO, Lucas
Heights, New South Wales 2234, Australia
| | - Sergei Glavatskih
- Department
of Engineering Design, KTH Royal Institute
of Technology, Stockholm 100 44, Sweden
- Department
of Electromechanical, Systems and Metal Engineering, Ghent University, Ghent 9052, Belgium
- School
of Chemistry, University of New South Wales, Sydney 2052, Australia
| | - Mark W. Rutland
- Division
of Surface and Corrosion Science, School of Engineering Sciences in
Chemistry, Biotechnology and Health, KTH
Royal Institute of Technology, Stockholm 100 44, Sweden
- School
of Chemistry, University of New South Wales, Sydney 2052, Australia
- Laboratoire
de Tribologie et Dynamique des Systèmes, École Central
de Lyon, Lyon 69130, France
| | - Anja-Verena Mudring
- Department
of Biological and Chemical Engineering and iNANO, Aarhus University, Aarhus
C 8000, Denmark
- Department
of Materials and Environmental Chemistry, Stockholm University, Stockholm 114 18, Sweden
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Li S, Pilkington GA, Mehler F, Hammond OS, Boudier A, Vorobiev A, Glavatskih S, Rutland MW. Tuneable interphase transitions in ionic liquid/carrier systems via voltage control. J Colloid Interface Sci 2023; 652:1240-1249. [PMID: 37657223 DOI: 10.1016/j.jcis.2023.08.111] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2023] [Revised: 08/09/2023] [Accepted: 08/18/2023] [Indexed: 09/03/2023]
Abstract
The structure and interaction of ionic liquids (ILs) influence their interfacial composition, and their arrangement (i.e., electric double-layer (EDL) structure), can be controlled by an electric field. Here, we employed a quartz crystal microbalance (QCM) to study the electrical response of two non-halogenated phosphonium orthoborate ILs, dissolved in a polar solvent at the interface. The response is influenced by the applied voltage, the structure of the ions, and the solvent polarizability. One IL showed anomalous electro-responsivity, suggesting a self-assembly bilayer structure of the IL cation at the gold interface, which transitions to a typical EDL structure at higher positive potential. Neutron reflectivity (NR) confirmed this interfacial structuring and compositional changes at the electrified gold surface. A cation-dominated self-assembly structure is observed for negative and neutral voltages, which abruptly transitions to an anion-rich interfacial layer at positive voltages. An interphase transition explains the electro-responsive behaviour of self-assembling IL/carrier systems, pertinent for ILs in advanced tribological and electrochemical contexts.
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Affiliation(s)
- Sichao Li
- Division of Surface and Corrosion Science, School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, SE-100 44 Stockholm, Sweden
| | - Georgia A Pilkington
- Division of Surface and Corrosion Science, School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, SE-100 44 Stockholm, Sweden
| | - Filip Mehler
- Division of Surface and Corrosion Science, School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, SE-100 44 Stockholm, Sweden
| | - Oliver S Hammond
- Department of Materials and Environmental Chemistry, Stockholm University, SE-114 18 Stockholm, Sweden; Department of Biological and Chemical Engineering, Aarhus University, Aarhus C 8000 Denmark
| | - Anthony Boudier
- Department of Materials and Environmental Chemistry, Stockholm University, SE-114 18 Stockholm, Sweden
| | - Alexei Vorobiev
- Department of Physics and Astronomy, Division of Materials Physics, Uppsala University, SE-751 20 Uppsala, Sweden
| | - Sergei Glavatskih
- System and Component Design, Department of Engineering Design, KTH Royal Institute of Technology, SE-100 44 Stockholm, Sweden; School of Chemistry, University of New South Wales, Sydney, NSW 2052, Australia; Department of Electromechanical, Systems and Metal Engineering, Ghent University, B-9052 Ghent, Belgium
| | - Mark W Rutland
- Division of Surface and Corrosion Science, School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, SE-100 44 Stockholm, Sweden; School of Chemistry, University of New South Wales, Sydney, NSW 2052, Australia; Bioeconomy and Health Department Materials and Surface Design, RISE Research Institutes of Sweden, SE-114 28 Stockholm, Sweden; Laboratoire de Tribologie et Dynamique des Systèmes, École Centrale de Lyon, 69134 Ecully Cedex, France.
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5
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Hammond OS, Bousrez G, Mehler F, Li S, Shimpi MR, Doutch J, Cavalcanti L, Glavatskih S, Antzutkin ON, Rutland MW, Mudring AV. Molecular Architecture Effects on Bulk Nanostructure in Bis(Orthoborate) Ionic Liquids. Small 2023; 19:e2300912. [PMID: 37395635 DOI: 10.1002/smll.202300912] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Revised: 04/11/2023] [Indexed: 07/04/2023]
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 L3 spongelike phases when the alkyl chains are longer than C6 (hexyl). L3 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.
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Affiliation(s)
- Oliver S Hammond
- Department of Materials and Environmental Chemistry, Stockholm University, Stockholm, SE-114 18, Sweden
- Department of Biological and Chemical Engineering and iNANO, Aarhus University, Aarhus C, 8000, Denmark
| | - Guillaume Bousrez
- Department of Materials and Environmental Chemistry, Stockholm University, Stockholm, SE-114 18, Sweden
- Department of Biological and Chemical Engineering and iNANO, Aarhus University, Aarhus C, 8000, Denmark
| | - Filip Mehler
- Division of Surface and Corrosion Science, School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, Stockholm, SE-100 40, Sweden
| | - Sichao Li
- Division of Surface and Corrosion Science, School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, Stockholm, SE-100 40, Sweden
| | - Manishkumar R Shimpi
- Department of Materials and Environmental Chemistry, Stockholm University, Stockholm, SE-114 18, Sweden
- Chemistry of Interfaces, Luleå University of Technology, Luleå, SE-971 87, Sweden
| | - James Doutch
- ISIS Neutron & Muon Source, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell-Oxford, OX11 0QX, UK
| | - Leide Cavalcanti
- ISIS Neutron & Muon Source, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell-Oxford, OX11 0QX, UK
| | - Sergei Glavatskih
- Department of Engineering Design, KTH Royal Institute of Technology, Stockholm, SE-10044, Sweden
- School of Chemistry, University of New South Wales, Sydney, 2052, Australia
- Department of Electromechanical, Systems and Metal Engineering, Ghent University, Ghent, B-9052, Belgium
| | - Oleg N Antzutkin
- Chemistry of Interfaces, Luleå University of Technology, Luleå, SE-971 87, Sweden
| | - Mark W Rutland
- Division of Surface and Corrosion Science, School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, Stockholm, SE-100 40, Sweden
- School of Chemistry, University of New South Wales, Sydney, 2052, Australia
- Bioeconomy and Health Department Materials and Surface Design, RISE Research Institutes of Sweden, Stockholm, SE-114 86, Sweden
- Laboratoire de Tribologie et Dynamique des Systèmes, École Centrale de Lyon, Lyon, 69130, France
| | - Anja-Verena Mudring
- Department of Materials and Environmental Chemistry, Stockholm University, Stockholm, SE-114 18, Sweden
- Department of Biological and Chemical Engineering and iNANO, Aarhus University, Aarhus C, 8000, Denmark
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Sun K, Shoaib T, Rutland MW, Beller J, Do C, Espinosa-Marzal RM. Insight into the assembly of lipid-hyaluronan complexes in osteoarthritic conditions. Biointerphases 2023; 18:021005. [PMID: 37041102 DOI: 10.1116/6.0002502] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/13/2023] Open
Abstract
Interactions between molecules in the synovial fluid and the cartilage surface may play a vital role in the formation of adsorbed films that contribute to the low friction of cartilage boundary lubrication. Osteoarthritis (OA) is the most common degenerative joint disease. Previous studies have shown that in OA-diseased joints, hyaluronan (HA) not only breaks down resulting in a much lower molecular weight (MW), but also its concentration is reduced ten times. Here, we have investigated the structural changes of lipid-HA complexes as a function of HA concentration and MW to simulate the physiologically relevant conditions that exist in healthy and diseased joints. Small angle neutron scattering and dynamic light scattering were used to determine the structure of HA-lipid vesicles in bulk solution, while a combination of atomic force microscopy and quartz crystal microbalance was applied to study their assembly on a gold surface. We infer a significant influence of both MW and HA concentrations on the structure of HA-lipid complexes in bulk and assembled on a gold surface. Our results suggest that low MW HA cannot form an amorphous layer on the gold surface, which is expected to negatively impact the mechanical integrity and longevity of the boundary layer and could contribute to the increased wear of the cartilage that has been reported in joints diseased with OA.
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Affiliation(s)
- Kangdi Sun
- Materials Science and Engineering Department, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801
| | - Tooba Shoaib
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830
| | - Mark W Rutland
- KTH Royal Institute of Technology, Department of Chemistry, Stockholm SE-100 44, Sweden; School of Chemistry, University of New South Wales, Sydney 2052, Australia; Laboratoire de Tribologie et Dynamique des Systèmes, École Centrale de Lyon, Lyon 69130, France; and Bioeconomy and Health, Materials and Surface Design, RISE Research Institutes of Sweden, Stockholm, Sweden
| | | | - Changwoo Do
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830
| | - Rosa M Espinosa-Marzal
- Materials Science and Engineering Department, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801
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7
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Reddy AB, Pilkington GA, Rutland MW, Glavatskih S. Tribotronic control of an ionic boundary layer in operando extends the limits of lubrication. Sci Rep 2022; 12:20479. [DOI: 10.1038/s41598-022-22504-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2022] [Accepted: 10/17/2022] [Indexed: 11/29/2022] Open
Abstract
AbstractThe effect of electric potential on the lubrication of a non-halogenated phosphonium orthoborate ionic liquid used as an additive in a biodegradable oil was studied. An in-house tribotronic system was built around an instrument designed to measure lubricant film thickness between a rolling steel ball and a rotating silica-coated glass disc. The application of an electric field between the steel ball and a set of customized counter-electrodes clearly induced changes in the thickness of the lubricant film: a marked decrease at negative potentials and an increase at positive potentials. Complementary neutron reflectivity studies demonstrated the intrinsic electroresponsivity of the adsorbate: this was performed on a gold-coated silicon block and made possible in the same lubricant system by deuterating the oil. The results indicate that the anions, acting as anchors for the adsorbed film on the steel surface, are instrumental in the formation of thick and robust lubricating ionic boundary films. The application of a high positive potential, outside the electrochemical window, resulted in an enormous boost to film thickness, implicating the formation of ionic multi-layers and demonstrating the plausibility of remote control of failing contacts in inaccessible machinery, such as offshore wind and wave power installations.
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Munavirov B, Black JJ, Shah FU, Leckner J, Rutland MW, Harper JB, Glavatskih S. The effect of anion architecture on the lubrication chemistry of phosphonium orthoborate ionic liquids. Sci Rep 2021; 11:24021. [PMID: 34912003 PMCID: PMC8674318 DOI: 10.1038/s41598-021-02763-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Accepted: 11/23/2021] [Indexed: 11/26/2022] Open
Abstract
Phosphonium ionic liquids with orthoborate anions have been studied in terms of their interfacial film formation, both physisorbed and sacrificial from chemical breakdown, in sheared contacts of varying harshness. The halogen-free anion architecture was varied through (i) the heteronuclear ring size, (ii) the hybridisation of the constituent atoms, and (iii) the addition of aryl functionalities. Time of Flight-Secondary Ion Mass Spectrometry analysis revealed the extent of sacrificial tribofilm formation allowing the relative stability of the ionic liquids under tribological conditions to be determined and their breakdown mechanisms to be compared to simple thermal decomposition. Overall, ionic liquids outperformed reference oils as lubricants; in some cases, sacrificial films were formed (with anion breakdown a necessary precursor to phosphonium cation decomposition) while in other cases, a protective, self-assembly lubricant layer or hybrid film was formed. The salicylate-based anion was the most chemically stable and decomposed only slightly even under the harshest conditions. It was further found that surface topography influenced the degree of breakdown through enhanced material transport and replenishment. This work thus unveils the relationship between ionic liquid composition and structure, and the ensuing inter- and intra-molecular interactions and chemical stability, and demonstrates the intrinsic tuneability of an ionic liquid lubrication technology.
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Affiliation(s)
- Bulat Munavirov
- System and Component Design, KTH Royal Institute of Technology, 100 44, Stockholm, Sweden
| | - Jeffrey J Black
- School of Chemistry, University of New South Wales, UNSW Sydney, Sydney, NSW, 2052, Australia
| | - Faiz Ullah Shah
- Chemistry of Interfaces, Luleå University of Technology, 97 187, Luleå, Sweden
| | - Johan Leckner
- Axel Christiernsson International AB, 44911, Nol, Sweden
| | - Mark W Rutland
- School of Chemistry, University of New South Wales, UNSW Sydney, Sydney, NSW, 2052, Australia.
- Division of Surface and Corrosion Science, KTH Royal Institute of Technology, 100 44, Stockholm, Sweden.
- Surfaces, Processes and Formulation, RISE Research Institutes of Sweden, 100 44, Stockholm, Sweden.
| | - Jason B Harper
- School of Chemistry, University of New South Wales, UNSW Sydney, Sydney, NSW, 2052, Australia.
| | - Sergei Glavatskih
- System and Component Design, KTH Royal Institute of Technology, 100 44, Stockholm, Sweden.
- School of Chemistry, University of New South Wales, UNSW Sydney, Sydney, NSW, 2052, Australia.
- Department of Electromechanical, Systems and Metal Engineering, Ghent University, 9052, Ghent, Belgium.
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9
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Skedung L, Collier ES, Harris KL, Rutland MW, Applebaum M, Greaves AJ, Luengo GS. A Curly Q: Is Frizz a Matter of Friction? Perception 2021; 50:728-732. [PMID: 34152243 DOI: 10.1177/03010066211024442] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The oft discussed and fretted over environmental influences on hair have led to a popular consensus which suggests that elevated temperature and humidity lead to frizzier, wilder hair. However, few attempts at actually quantifying these effects have been made. Although frizziness is usually perceived visually, here the influence of variations in temperature and humidity on the tactile perception and friction of curly and straight hair were investigated. It is shown that changes in humidity may disproportionately affect perceived frizziness of curly hair by touch due to concurrent changes in the tactile friction.
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Affiliation(s)
- Lisa Skedung
- L'Oréal Research and Innovation, Aulnay sous Bois, France
| | | | - Kathryn L Harris
- 388792RISE Research Institutes of Sweden AB, Sweden.,L'Oréal Research and Innovation, Aulnay sous Bois, France
| | - Mark W Rutland
- KTH Royal Institute of Technology, Sweden; 388792RISE Research Institutes of Sweden AB, Sweden.,L'Oréal Research and Innovation, Aulnay sous Bois, France
| | - Mara Applebaum
- L'Oréal Research and Innovation, Clark, New Jersey, United States.,L'Oréal Research and Innovation, Aulnay sous Bois, France
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Bergendal E, Gutfreund P, Pilkington GA, Campbell RA, Müller-Buschbaum P, Holt SA, Rutland MW. Tuneable interfacial surfactant aggregates mimic lyotropic phases and facilitate large scale nanopatterning. Nanoscale 2021; 13:371-379. [PMID: 33351024 DOI: 10.1039/d0nr06621d] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
It is shown that the air-liquid interface can be made to display the same rich curvature phenomena as common lyotropic liquid crystal systems. Through mixing an insoluble, naturally occurring, branched fatty acid, with an unbranched fatty acid of the same length, systematic variation in the packing constraints at the air-water interface could be obtained. The combination of atomic force microscopy and neutron reflectometry is used to demonstrate that the water surface exhibits significant tuneable topography. By systematic variation of the two fatty acid proportions, ordered arrays of monodisperse spherical caps, cylindrical sections, and a mesh phase are all observed, as well as the expected lamellar structure. The tuneable deformability of the air-water interface permits this hitherto unexplored topological diversity, which is analogous to the phase elaboration displayed by amphiphiles in solution. It offers a wealth of novel possibilities for the tailoring of nanostructure.
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Affiliation(s)
- Erik Bergendal
- Department of Chemistry, KTH Royal Institute of Technology, School of Engineering Sciences in Chemistry, Biotechnology and Health, Drottning Kristinas väg 51, 100 44, Stockholm, Sweden.
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Pilkington GA, Welbourn R, Oleshkevych A, Watanabe S, Pedraz P, Radiom M, Glavatskih S, Rutland MW. Effect of water on the electroresponsive structuring and friction in dilute and concentrated ionic liquid lubricant mixtures. Phys Chem Chem Phys 2020; 22:28191-28201. [PMID: 33295339 DOI: 10.1039/d0cp05110a] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The effect of water on the electroactive structuring of a tribologically relevant ionic liquid (IL) when dispersed in a polar solvent has been investigated at a gold electrode interface using neutron reflectivity (NR). For all solutions studied, the addition of small amounts of water led to clear changes in electroactive structuring of the IL at the electrode interface, which was largely determined by the bulk IL concentration. At a dilute IL concentration, the presence of water gave rise to a swollen interfacial structuring, which exhibited a greater degree of electroresponsivity with applied potential compared to an equivalent dry solution. Conversely, for a concentrated IL solution, the presence of water led to an overall thinning of the interfacial region and a crowding-like structuring, within which the composition of the inner layer IL layers varied systematically with applied potential. Complementary nanotribotronic atomic force microscopy (AFM) measurements performed for the same IL concentration, in dry and ambient conditions, show that the presence of water reduces the lubricity of the IL boundary layers. However, consistent with the observed changes in the IL layers observed by NR, reversible and systematic control of the friction coefficient with applied potential was still achievable. Combined, these measurements provide valuable insight into the implications of water on the interfacial properties of ILs at electrified interfaces, which inevitably will determine their applicability in tribotronic and electrochemical contexts.
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Affiliation(s)
- Georgia A Pilkington
- Division of Surface and Corrosion Science, School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, SE-100 44 Stockholm, Sweden.
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12
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Pilkington GA, Oleshkevych A, Pedraz P, Watanabe S, Radiom M, Reddy AB, Vorobiev A, Glavatskih S, Rutland MW. Electroresponsive structuring and friction of a non-halogenated ionic liquid in a polar solvent: effect of concentration. Phys Chem Chem Phys 2020; 22:19162-19171. [PMID: 32812565 DOI: 10.1039/d0cp02736g] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Neutron reflectivity (NR) measurements have been employed to study the interfacial structuring and composition of electroresponsive boundary layers formed by an ionic liquid (IL) lubricant at an electrified gold interface when dispersed in a polar solvent. The results reveal that both the composition and extent of the IL boundary layers intricately depend on the bulk IL concentration and the applied surface potential. At the lowest concentration (5% w/w), a preferential adsorption of the IL cation at the gold electrode is observed, which hinders the ability to electro-induce changes in the boundary layers. In contrast, at higher IL bulk concentrations (10 and 20% w/w), the NR results reveal a significantly larger concentration of the IL ions at the gold interface that exhibit significantly greater electroresponsivity, with clear changes in the layer composition and layer thickness observed for different potentials. In complementary atomic force microscopy (AFM) measurements on an electrified gold surface, such IL boundary layers are demonstrated to provide excellent friction reduction and electroactive friction (known as tribotronics). In agreement with the NR results obtained, clear concentration effects are also observed. Together such results provide valuable molecular insight into the electroactive structuring of ILs in solvent mixtures, as well as provide mechanistic understanding of their tribotronic behaviours.
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Affiliation(s)
- Georgia A Pilkington
- Division of Surface and Corrosion Science, School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, SE-100 44 Stockholm, Sweden.
| | - Anna Oleshkevych
- Division of Surface and Corrosion Science, School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, SE-100 44 Stockholm, Sweden.
| | - Patricia Pedraz
- Division of Surface and Corrosion Science, School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, SE-100 44 Stockholm, Sweden.
| | - Seiya Watanabe
- Division of Surface and Corrosion Science, School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, SE-100 44 Stockholm, Sweden.
| | - Milad Radiom
- Division of Surface and Corrosion Science, School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, SE-100 44 Stockholm, Sweden.
| | - Akepati Bhaskar Reddy
- System and Component Design, Department of Machine Design, KTH Royal Institute of Technology, SE-100 44 Stockholm, Sweden
| | - Alexei Vorobiev
- Department of Physics and Astronomy, Division of Materials Physics, Uppsala University, Uppsala, Sweden
| | - Sergei Glavatskih
- System and Component Design, Department of Machine Design, KTH Royal Institute of Technology, SE-100 44 Stockholm, Sweden and Department of Electromechanical, Systems and Metal Engineering, Ghent University, B-9052 Ghent, Belgium
| | - Mark W Rutland
- Division of Surface and Corrosion Science, School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, SE-100 44 Stockholm, Sweden. and Surfaces, Processes and Formulation, RISE Research Institutes of Sweden, SE-100 44 Stockholm, Sweden
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13
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Bergendal E, Campbell RA, Pilkington GA, Müller-Buschbaum P, Rutland MW. 3D texturing of the air-water interface by biomimetic self-assembly. Nanoscale Horiz 2020; 5:839-846. [PMID: 32364200 DOI: 10.1039/c9nh00722a] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
A simple, insoluble monolayer of fatty acid is shown to induce 3D nanotexturing of the air-water interface. This advance has been achieved through the study of monolayers of a methyl-branched long chain fatty acid, analogous to those found on the surface of hair and wool, directly at the air-water interface. Specular neutron reflectometry combined with AFM probing of deposited monolayers shows pronounced 3D surface domains, which are absent for unbranched analogues and are attributed to hydrocarbon packing constraints. The resulting surface topographies of the water far exceed the height perturbation that can be explained by the presence of capillary waves of a free liquid surface. These have hitherto been considered the only source of perturbation of the flatness of a planar water interface under gravity in the absence of topographical features from the presence of extended, globular or particulate matter. This amounts to a paradigm shift in the study of interfacial films and opens the possibility of 3D texturing of the air-water interface.
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Affiliation(s)
- Erik Bergendal
- KTH Royal Institute of Technology, School of Engineering Sciences in Chemistry, Biotechnology and Health, Department of Chemistry, Drottning Kristinas väg 51, 10044 Stockholm, Sweden.
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14
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Li H, Choi YS, Rutland MW, Atkin R. Nanotribology of hydrogels with similar stiffness but different polymer and crosslinker concentrations. J Colloid Interface Sci 2020; 563:347-353. [PMID: 31887698 DOI: 10.1016/j.jcis.2019.12.045] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Revised: 12/02/2019] [Accepted: 12/12/2019] [Indexed: 11/26/2022]
Abstract
HYPOTHESIS The stiffness has been found to regulate hydrogel performances and applications. However, the key interfacial properties of hydrogels, like friction and adhesion are not controlled by the stiffness, but are altered by the structure and composition of hydrogels, like polymer volume fraction and crosslinking degree. EXPERIMENTS Colloidal probe atomic force microscopy has been use to investigate the relationship between tribological properties (friction and adhesion) and composition of hydrogels with similar stiffness, but different polymer volume fractions and crosslinking degrees. FINDINGS The interfacial normal and lateral (friction) forces of hydrogels are not directly correlated to the stiffness, but altered by the hydrogel structure and composition. For normal force measurements, the adhesion increases with polymer volume fraction but decreases with crosslinking degree. For lateral force measurements, friction increases with polymer volume fraction, but decreases with crosslinking degree. In the low normal force regime, friction is mainly adhesion-controlled and increases significantly with the adhesion and polymer volume fraction. In the high normal force regime, friction is predominantly load-controlled and shows slow increase with normal force.
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Affiliation(s)
- Hua Li
- School of Molecular Sciences, The University of Western Australia, 35 Stirling Highway, Perth, WA 6009, Australia; Centre for Microscopy, Characterisation and Analysis, The University of Western Australia, Perth, WA 6009, Australia.
| | - Yu Suk Choi
- School of Human Sciences, The University of Western Australia, 35 Stirling Highway, Perth, WA 6009, Australia
| | - Mark W Rutland
- School of Chemical Science and Engineering, KTH Royal Institute of Technology, SE100 44, Sweden; Surfaces, Processes and Formulation, RISE Research Institutes of Sweden, SE114 86 Stockholm, Sweden
| | - Rob Atkin
- School of Molecular Sciences, The University of Western Australia, 35 Stirling Highway, Perth, WA 6009, Australia
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15
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Watanabe S, Pilkington GA, Oleshkevych A, Pedraz P, Radiom M, Welbourn R, Glavatskih S, Rutland MW. Interfacial structuring of non-halogenated imidazolium ionic liquids at charged surfaces: effect of alkyl chain length. Phys Chem Chem Phys 2020; 22:8450-8460. [DOI: 10.1039/d0cp00360c] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Control of the interfacial structures of ionic liquids (ILs) at charged interfaces is important to many of their applications, including in energy storage solutions, sensors and advanced lubrication technologies utilising electric fields.
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Affiliation(s)
- Seiya Watanabe
- Division of Surface and Corrosion Science
- School of Engineering Sciences in Chemistry
- Biotechnology and Health
- KTH Royal Institute of Technology
- SE-100 44 Stockholm
| | - Georgia A. Pilkington
- Division of Surface and Corrosion Science
- School of Engineering Sciences in Chemistry
- Biotechnology and Health
- KTH Royal Institute of Technology
- SE-100 44 Stockholm
| | - Anna Oleshkevych
- Division of Surface and Corrosion Science
- School of Engineering Sciences in Chemistry
- Biotechnology and Health
- KTH Royal Institute of Technology
- SE-100 44 Stockholm
| | - Patricia Pedraz
- Division of Surface and Corrosion Science
- School of Engineering Sciences in Chemistry
- Biotechnology and Health
- KTH Royal Institute of Technology
- SE-100 44 Stockholm
| | - Milad Radiom
- Division of Surface and Corrosion Science
- School of Engineering Sciences in Chemistry
- Biotechnology and Health
- KTH Royal Institute of Technology
- SE-100 44 Stockholm
| | - Rebecca Welbourn
- ISIS Neutron & Muon Source
- Rutherford Appleton Laboratory
- STFC
- Didcot
- UK
| | - Sergei Glavatskih
- System and Component Design
- Department of Machine Design
- KTH Royal Institute of Technology
- SE-100 44 Stockholm
- Sweden
| | - Mark W. Rutland
- Division of Surface and Corrosion Science
- School of Engineering Sciences in Chemistry
- Biotechnology and Health
- KTH Royal Institute of Technology
- SE-100 44 Stockholm
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16
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Hjalmarsson N, Bergendal E, Wang YL, Munavirov B, Wallinder D, Glavatskih S, Aastrup T, Atkin R, Furó I, Rutland MW. Electro-Responsive Surface Composition and Kinetics of an Ionic Liquid in a Polar Oil. Langmuir 2019; 35:15692-15700. [PMID: 31581771 DOI: 10.1021/acs.langmuir.9b02119] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
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.
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Affiliation(s)
| | | | | | | | | | - Sergei Glavatskih
- Department of Electrical Energy, Metals, Mechanical Constructions and Systems , Ghent University , B-9000 , Ghent , Belgium
| | | | - Rob Atkin
- School of Molecular Sciences , University of Western Australia , 6009 Perth , Australia
| | | | - Mark W Rutland
- Surfaces, Processes and Formulation , RISE Research Institutes of Sweden , SE-50115 Stockholm , Sweden
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17
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Pilkington GA, Harris K, Bergendal E, Reddy AB, Palsson GK, Vorobiev A, Antzutkin ON, Glavatskih S, Rutland MW. Electro-responsivity of ionic liquid boundary layers in a polar solvent revealed by neutron reflectance. J Chem Phys 2018; 148:193806. [DOI: 10.1063/1.5001551] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Affiliation(s)
- Georgia A. Pilkington
- Surface and Corrosion Science, Department of Chemistry, KTH Royal Institute of Technology, Stockholm, Sweden
| | - Kathryn Harris
- System and Component Design, Department of Machine Design, KTH Royal Institute of Technology, Stockholm, Sweden
| | - Erik Bergendal
- Surface and Corrosion Science, Department of Chemistry, KTH Royal Institute of Technology, Stockholm, Sweden
| | - Akepati Bhaskar Reddy
- System and Component Design, Department of Machine Design, KTH Royal Institute of Technology, Stockholm, Sweden
| | - Gunnar K. Palsson
- Department of Physics and Astronomy, Division of Materials Physics, Uppsala University, Uppsala, Sweden
| | - Alexei Vorobiev
- Department of Physics and Astronomy, Division of Materials Physics, Uppsala University, Uppsala, Sweden
| | | | - Sergei Glavatskih
- System and Component Design, Department of Machine Design, KTH Royal Institute of Technology, Stockholm, Sweden
- Department of Electrical Energy, Systems and Automation, Ghent University, Ghent, Belgium
| | - Mark W. Rutland
- Surface and Corrosion Science, Department of Chemistry, KTH Royal Institute of Technology, Stockholm, Sweden
- Surfaces, Processes and Formulation, RISE Research Institutes of Sweden, Stockholm, Sweden
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18
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Besharat Z, Ghadami Yazdi M, Wakeham D, Johnson M, Rutland MW, Göthelid M, Grönbeck H. Se-C Cleavage of Hexane Selenol at Steps on Au(111). Langmuir 2018; 34:2630-2636. [PMID: 29405715 DOI: 10.1021/acs.langmuir.7b03713] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Selenols are considered as an alternative to thiols in self-assembled monolayers, but the Se-C bond is one limiting factor for their usefulness. In this study, we address the stability of the Se-C bond by a combined experimental and theoretical investigation of gas-phase-deposited hexane selenol (CH3(CH2)5SeH) on Au(111) using photoelectron spectroscopy, scanning tunneling microscopy, and density functional theory (DFT). Experimentally, we find that initial adsorption leaves atomic Se on the surface without any carbon left on the surface, whereas further adsorption generates a saturated selenolate layer. The Se 3d component from atomic Se appears at 0.85 eV lower binding energy than the selenolate-related component. DFT calculations show that the most stable structure of selenols on Au(111) is in the form of RSe-Au-SeR complexes adsorbed on the unreconstructed Au(111) surface. This is similar to thiols on Au(111). Calculated Se 3d core-level shifts between elemental Se and selenolate in this structure nicely reproduce the experimentally recorded shifts. Dissociation of RSeH and subsequent formation of RH are found to proceed with high barriers on defect-free Au(111) terraces, with the highest barrier for scissoring R-Se. However, at steps, these barriers are considerably lower, allowing for Se-C bond breaking and hexane desorption, leaving elemental Se at the surface. Hexane is formed by replacing the Se-C bond with a H-C bond by using the hydrogen liberated from the selenol to selenolate transformation.
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Affiliation(s)
- Zahra Besharat
- Material Physics, MNF, SCI, KTH Royal Institute of Technology , Stockholm SE-164 40, Sweden
- Department of Chemistry, Division of Surface and Corrosion Science, KTH Royal Institute of Technology , Stockholm SE-100 44, Sweden
| | - Milad Ghadami Yazdi
- Material Physics, MNF, SCI, KTH Royal Institute of Technology , Stockholm SE-164 40, Sweden
| | - Deborah Wakeham
- Department of Chemistry, Division of Surface and Corrosion Science, KTH Royal Institute of Technology , Stockholm SE-100 44, Sweden
| | - Magnus Johnson
- Department of Chemistry, Division of Surface and Corrosion Science, KTH Royal Institute of Technology , Stockholm SE-100 44, Sweden
| | - Mark W Rutland
- Department of Chemistry, Division of Surface and Corrosion Science, KTH Royal Institute of Technology , Stockholm SE-100 44, Sweden
- Chemistry, Materials and Surfaces, SP Technical Research Institute of Sweden , Box 5607, Stockholm SE-114 86, Sweden
| | - Mats Göthelid
- Material Physics, MNF, SCI, KTH Royal Institute of Technology , Stockholm SE-164 40, Sweden
| | - Henrik Grönbeck
- Department of Physics and Competence Centre for Catalysis, Chalmers University of Technology , Göteborg SE-412 96, Sweden
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19
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Badal Tejedor M, Pazesh S, Nordgren N, Schuleit M, Rutland MW, Alderborn G, Millqvist-Fureby A. Milling induced amorphisation and recrystallization of α-lactose monohydrate. Int J Pharm 2018; 537:140-147. [DOI: 10.1016/j.ijpharm.2017.12.021] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2017] [Revised: 12/06/2017] [Accepted: 12/09/2017] [Indexed: 11/28/2022]
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20
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Badal Tejedor M, Nordgren N, Schuleit M, Millqvist-Fureby A, Rutland MW. AFM Colloidal Probe Measurements Implicate Capillary Condensation in Punch-Particle Surface Interactions during Tableting. Langmuir 2017; 33:13180-13188. [PMID: 29048171 DOI: 10.1021/acs.langmuir.7b02189] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Adhesion of the powders to the punches is a common issue during tableting. This phenomenon is known as sticking and affects the quality of the manufactured tablets. Defective tablets increase the cost of the manufacturing process. Thus, the ability to predict the tableting performance of the formulation blend before the process is scaled-up is important. The adhesive propensity of the powder to the tableting tools is mostly governed by the surface-surface adhesive interactions. Atomic force microscopy (AFM) colloidal probe is a surface characterization technique that allows the measurement of the adhesive interactions between two materials of interest. In this study, AFM steel colloidal probe measurements were performed on ibuprofen, MCC (microcrystalline cellulose), α-lactose monohydrate, and spray-dried lactose particles as an approach to modeling the punch-particle surface interactions during tableting. The excipients (lactose and MCC) showed constant, small, attractive, and adhesive forces toward the steel surface after a repeated number of contacts. In comparison, ibuprofen displayed a much larger attractive and adhesive interaction increasing over time both in magnitude and in jump-in/jump-out separation distance. The type of interaction acting on the excipient-steel interface can be related to a van der Waals force, which is relatively weak and short-ranged. By contrast, the ibuprofen-steel interaction is described by a capillary force profile. Even though ibuprofen is not highly hydrophilic, the relatively smooth surfaces of the crystals allow "contact flooding" upon contact with the steel probe. Capillary forces increase because of the "harvesting" of moisture-due to the fast condensation kinetics-leaving a residual condensate that contributes to increase the interaction force after each consecutive contact. Local asperity contacts on the more hydrophilic surface of the excipients prevent the flooding of the contact zone, and there is no such adhesive effect under the same ambient conditions. The markedly different behavior detected by force measurements clearly shows the sticky and nonsticky propensity of the materials and allows a mechanistic description.
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Affiliation(s)
- Maria Badal Tejedor
- RISE Bioscience and Materials, RISE Research Institutes of Sweden , Box 5607, SE-114 86 Stockholm, Sweden
- Division of Surface and Corrosion Science, KTH Royal Institute of Technology , Drottning Kristinas väg 51, SE-100 44 Stockholm, Sweden
| | - Niklas Nordgren
- RISE Bioscience and Materials, RISE Research Institutes of Sweden , Box 5607, SE-114 86 Stockholm, Sweden
| | - Michael Schuleit
- Novartis Pharma AG, GDC, Novartis Institutes for Biomedical Research , Novartis Campus, 4056 Basel, Switzerland
| | - Anna Millqvist-Fureby
- RISE Bioscience and Materials, RISE Research Institutes of Sweden , Box 5607, SE-114 86 Stockholm, Sweden
| | - Mark W Rutland
- RISE Bioscience and Materials, RISE Research Institutes of Sweden , Box 5607, SE-114 86 Stockholm, Sweden
- Division of Surface and Corrosion Science, KTH Royal Institute of Technology , Drottning Kristinas väg 51, SE-100 44 Stockholm, Sweden
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21
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Filippov A, Gnezdilov OI, Hjalmarsson N, Antzutkin ON, Glavatskih S, Furó I, Rutland MW. Acceleration of diffusion in ethylammonium nitrate ionic liquid confined between parallel glass plates. Phys Chem Chem Phys 2017; 19:25853-25858. [PMID: 28932828 DOI: 10.1039/c7cp01772c] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Diffusion of EAN confined between polar glass plates separated by a few micrometers is higher by a factor of ca. 2 as compared to bulk values. Formation of a new phase, different to the bulk, was suggested.
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Affiliation(s)
- Andrei Filippov
- Chemistry of Interfaces, Luleå University of Technology, SE-97187 Luleå, Sweden. and Institute of Physics, Kazan Federal University, 420008 Kazan, Russia
| | - Oleg I Gnezdilov
- Institute of Physics, Kazan Federal University, 420008 Kazan, Russia
| | - Nicklas Hjalmarsson
- Surface and Corrosion Science, KTH Royal Institute of Technology, SE-10044 Stockholm, Sweden
| | - Oleg N Antzutkin
- Chemistry of Interfaces, Luleå University of Technology, SE-97187 Luleå, Sweden.
| | - Sergei Glavatskih
- System and Component Design, KTH Royal Institute of Technology, SE-10044 Stockholm, Sweden and Department of Mechanical Construction and Production, Ghent University, B-9000 Ghent, Belgium
| | - István Furó
- Applied Physical Chemistry, KTH Royal Institute of Technology, SE-10044 Stockholm, Sweden
| | - Mark W Rutland
- Surface and Corrosion Science, KTH Royal Institute of Technology, SE-10044 Stockholm, Sweden and RISE Technical Research Institute of Sweden, Chemistry Materials and Surfaces, Box 5607, SE-11486 Stockholm, Sweden
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Abstract
It is an honour to be charged with providing the concluding remarks for a Faraday Discussion. As many have remarked before, it is nonetheless a prodigious task, and what follows is necessarily a personal, and probably perverse, view of a watershed event in the Chemical Physics of Electroactive materials. The spirit of the conference was captured in a single sentence during the meeting itself."It is the nexus between rheology, electrochemistry, colloid science and energy storage". The current scientific climate is increasingly dominated by a limited number of global challenges, and there is thus a tendency for research to resemble a football match played by 6 year olds, where everyone on the field chases the (funding) ball instead of playing to their "discipline". It is thus reassuring to see how the application of rigorous chemical physics is leading to ingenious new solutions for both energy storage and harvesting, via, for example, nanoactuation, electrowetting, ionic materials and nanoplasmonics. In fact, the same language of chemical physics allows seamless transition between applications as diverse as mechano-electric energy generation, active moisture transport and plasmonic shutters - even the origins of life were addressed in the context of electro-autocatalysis!
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Affiliation(s)
- Mark W Rutland
- KTH Royal Institute of Technology, Surface and Corrosion Science, Drottning Kristinas väg 51, Stockholm 10044, Sweden. and RISE Research Institutes of Sweden AB, Chemistry Materials and Surfaces, Drottning Kristinas väg 45, Stockholm 11486, Sweden
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23
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Abstract
Atomic force microscopy (AFM) has been used to investigate the potential dependent boundary layer friction at solvate ionic liquid (SIL)-highly ordered pyrolytic graphite (HOPG) and SIL-Au(111) interfaces. Friction trace and retrace loops of lithium tetraglyme bis(trifluoromethylsulfonyl)amide (Li(G4) TFSI) at HOPG present clearer stick-slip events at negative potentials than at positive potentials, indicating that a Li+ cation layer adsorbed to the HOPG lattice at negative potentials which enhances stick-slip events. The boundary layer friction data for Li(G4) TFSI shows that at HOPG, friction forces at all potentials are low. The TFSI- anion rich boundary layer at positive potentials is more lubricating than the Li+ cation rich boundary layer at negative potentials. These results suggest that boundary layers at all potentials are smooth and energy is predominantly dissipated via stick-slip events. In contrast, friction at Au(111) for Li(G4) TFSI is significantly higher at positive potentials than at negative potentials, which is comparable to that at HOPG at the same potential. The similarity of boundary layer friction at negatively charged HOPG and Au(111) surfaces indicates that the boundary layer compositions are similar and rich in Li+ cations for both surfaces at negative potentials. However, at Au(111), the TFSI- rich boundary layer is less lubricating than the Li+ rich boundary layer, which implies that anion reorientations rather than stick-slip events are the predominant energy dissipation pathways. This is confirmed by the boundary friction of Li(G4) NO3 at Au(111), which shows similar friction to Li(G4) TFSI at negative potentials due to the same cation rich boundary layer composition, but even higher friction at positive potentials, due to higher energy dissipation in the NO3- rich boundary layer.
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Affiliation(s)
- Hua Li
- Priority Research Centre for Advanced Fluids and Interfaces, The University of Newcastle, Callaghan, NSW 2308, Australia.
| | - Mark W Rutland
- School of Chemical Science and Engineering, KTH Royal Institute of Technology, SE100 44 Sweden and Chemistry, Materials and Surfaces, SP Technical Research Institute of Sweden, SE114 86 Sweden
| | - Masayoshi Watanabe
- Department of Chemistry and Biotechnology, Yokohama National University, Yokohama 240-8501, Japan
| | - Rob Atkin
- Priority Research Centre for Advanced Fluids and Interfaces, The University of Newcastle, Callaghan, NSW 2308, Australia.
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24
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Badal Tejedor M, Nordgren N, Schuleit M, Pazesh S, Alderborn G, Millqvist-Fureby A, Rutland MW. Determination of Interfacial Amorphicity in Functional Powders. Langmuir 2017; 33:920-926. [PMID: 28045271 DOI: 10.1021/acs.langmuir.6b03969] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The nature of the surfaces of particles of pharmaceutical ingredients, food powders, and polymers is a determining factor for their performance in for example tableting, powder handling, or mixing. Changes on the surface structure of the material will impact the flow properties, dissolution rate, and tabletability of the powder blend. For crystalline materials, surface amorphization is a phenomenon which is known to impact performance. Since it is important to measure and control the level of amorphicity, several characterization techniques are available to determine the bulk amorphous content of a processed material. The possibility of characterizing the degree of amorphicity at the surface, for example by studying the mechanical properties of the particles' surface at the nanoscale, is currently only offered by atomic force microscopy (AFM). The AFM PeakForce QNM technique has been used to measure the variation in energy dissipation (eV) at the surface of the particles which sheds light on the mechanical changes occurring as a result of amorphization or recrystallization events. Two novel approaches for the characterization of amorphicity are presented here. First, since particles are heterogeneous, we present a methodology to present the results of extensive QNM analysis of multiple particles in a coherent and easily interpreted manner, by studying cumulative distributions of dissipation data with respect to a threshold value which can be used to distinguish the crystalline and amorphous states. To exemplify the approach, which is generally applicable to any material, reference materials of purely crystalline α-lactose monohydrate and completely amorphous spray dried lactose particles were compared to a partially amorphized α-lactose monohydrate sample. Dissipation data are compared to evaluations of the lactose samples with conventional AFM and SEM showing significant topographical differences. Finally, the recrystallization of the surface amorphous regions in response to humidity was followed by studying the dissipation response of a well-defined surface region over time, which confirms both that dissipation measurement is a useful measure of surface amorphicity and that significant recrystallization occurs at the surface in response to humidity.
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Affiliation(s)
- Maria Badal Tejedor
- SP Chemistry, Materials and Surfaces, SP Technical Research Institute of Sweden , Box 5607, SE-114 86 Stockholm, Sweden
- Division of Surface and Corrosion Science, KTH Royal Institute of Technology , Drottning Kristinas väg 51, SE-100 44 Stockholm, Sweden
| | - Niklas Nordgren
- SP Chemistry, Materials and Surfaces, SP Technical Research Institute of Sweden , Box 5607, SE-114 86 Stockholm, Sweden
| | - Michael Schuleit
- Novartis Institutes for Biomedical Research, GDC, Novartis Pharma AG , Novartis Campus, 4002 Basel, Switzerland
| | - Samaneh Pazesh
- Department of Pharmacy, Uppsala University , Uppsala, Sweden
| | - Göran Alderborn
- Department of Pharmacy, Uppsala University , Uppsala, Sweden
| | - Anna Millqvist-Fureby
- SP Chemistry, Materials and Surfaces, SP Technical Research Institute of Sweden , Box 5607, SE-114 86 Stockholm, Sweden
| | - Mark W Rutland
- SP Chemistry, Materials and Surfaces, SP Technical Research Institute of Sweden , Box 5607, SE-114 86 Stockholm, Sweden
- Division of Surface and Corrosion Science, KTH Royal Institute of Technology , Drottning Kristinas väg 51, SE-100 44 Stockholm, Sweden
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25
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Gebbie MA, Smith AM, Dobbs HA, Lee AA, Warr GG, Banquy X, Valtiner M, Rutland MW, Israelachvili JN, Perkin S, Atkin R. Long range electrostatic forces in ionic liquids. Chem Commun (Camb) 2017; 53:1214-1224. [DOI: 10.1039/c6cc08820a] [Citation(s) in RCA: 231] [Impact Index Per Article: 33.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Experimental evidence for long range surface forces in ionic liquids is collated and examined, key outstanding questions are identified, and possible mechanisms underpinning these long range forces are explored.
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Affiliation(s)
- Matthew A. Gebbie
- Geballe Laboratory for Advanced Materials
- Stanford University
- Stanford
- USA
| | - Alexander M. Smith
- Department of Chemistry
- Physical & Theoretical Chemistry Laboratory
- University of Oxford
- Oxford
- UK
| | - Howard A. Dobbs
- Department of Chemical Engineering
- University of California
- Santa Barbara
- UK
| | - Alpha A. Lee
- School of Engineering and Applied Sciences
- Harvard University
- Cambridge
- USA
| | - Gregory G. Warr
- School of Chemistry
- F11
- The University of Sydney
- NSW 2006
- Australia
| | - Xavier Banquy
- Faculty of Pharmacy
- Universite de Montreal
- Montreal
- Canada
| | - Markus Valtiner
- Interface Chemistry and Surface Engineering
- Max Planck Institut fur Eisenforschung GmbH
- Dusseldorf
- Germany
| | - Mark W. Rutland
- Surface and Corrosion Science
- KTH Royal Institute of Technology
- SE-10044 Stockholm
- Sweden
- SP Chemistry Materials and Surfaces
| | | | - Susan Perkin
- Department of Chemistry
- Physical & Theoretical Chemistry Laboratory
- University of Oxford
- Oxford
- UK
| | - Rob Atkin
- Priority Research Centre for Advanced Fluid Interfaces
- Newcastle Institute for Energy and Resources
- The University of Newcastle
- Australia
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26
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Besharat Z, Wakeham D, Johnson CM, Luengo GS, Greaves A, Odnevall Wallinder I, Göthelid M, Rutland MW. Mixed monolayers of alkane thiols with polar terminal group on gold: Investigation of structure dependent surface properties. J Colloid Interface Sci 2016; 484:279-290. [DOI: 10.1016/j.jcis.2016.08.053] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Revised: 08/19/2016] [Accepted: 08/19/2016] [Indexed: 10/21/2022]
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27
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Nyström L, Álvarez-Asencio R, Frenning G, Saunders BR, Rutland MW, Malmsten M. Electrostatic Swelling Transitions in Surface-Bound Microgels. ACS Appl Mater Interfaces 2016; 8:27129-27139. [PMID: 27644921 DOI: 10.1021/acsami.6b09751] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Herein, electrostatic swelling transitions of poly(ethyl acrylate-co-methacrylic acid) microgels covalently bound to silica surfaces are investigated. Confined at a solid surface, microgel swelling is anisotropically hindered and the structure is flattened to an extent dictated by pH and microgel composition. Microgel deformation under applied load is also shown to depend on microgel charge density, with the highest deformation observed at intermediate charge densities. Two modes of microgel deformation under load were observed, one elastic and one viscoelastic, related to polymer strand deformation and displacement of trapped water, respectively. Results on polymer strand dynamics reveal that the microgels are highly dynamic, as the number of strand-tip interaction points increases 4-fold during a 10 s contact time. Furthermore, finite element modeling captures these effects qualitatively and shows that stress propagation in the microgel network decays locally at the rim of contact with a solid interface or close to the tip probe. Taken together, the results demonstrate a delicate interplay between the surface and microgel which determines the structure and nanomechanical properties of the latter and needs to be controlled in applications of systems such as pH-responsive surface coatings in biomaterials.
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Affiliation(s)
- Lina Nyström
- Department of Pharmacy, Uppsala University , P.O. Box 580, SE-752 32 Uppsala, Sweden
| | - Rubén Álvarez-Asencio
- Department of Surface and Corrosion Science, School of Chemical Science and Engineering, KTH Royal Institute of Technology , SE-100 44 Stockholm, Sweden
- Institute for Advanced Studies, IMDEA Nanoscience , 28049 Madrid, Spain
| | - Göran Frenning
- Department of Pharmacy, Uppsala University , P.O. Box 580, SE-752 32 Uppsala, Sweden
| | - Brian R Saunders
- School of Materials, The University of Manchester , MSS Tower, Manchester M13 9PL, United Kingdom
| | - Mark W Rutland
- Department of Surface and Corrosion Science, School of Chemical Science and Engineering, KTH Royal Institute of Technology , SE-100 44 Stockholm, Sweden
- SP Technical Research Institute of Sweden, SP Chemistry, Materials and Surfaces , SE-114 86 Stockholm, Sweden
| | - Martin Malmsten
- Department of Pharmacy, Uppsala University , P.O. Box 580, SE-752 32 Uppsala, Sweden
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28
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Abstract
Atomic force microscopy has been used to study the effect of temperature on normal forces and friction for the room temperature ionic liquid (IL) ethylammonium nitrate (EAN), confined between mica and a silica colloid probe at 25 °C, 50 °C, and 80 °C. Force curves revealed a strong fluid dynamic influence at room temperature, which was greatly reduced at elevated temperatures due to the reduced liquid viscosity. A fluid dynamic analysis reveals that bulk viscosity is manifested at large separation but that EAN displays a nonzero slip, indicating a region of different viscosity near the surface. At high temperatures, the reduction in fluid dynamic force reveals step-like force curves, similar to those found at room temperature using much lower scan rates. The ionic liquid boundary layer remains adsorbed to the solid surface even at high temperature, which provides a mechanism for lubrication when fluid dynamic lubrication is strongly reduced. The friction data reveals a decrease in absolute friction force with increasing temperature, which is associated with increased thermal motion and reduced viscosity of the near surface layers but, consistent with the normal force data, boundary layer lubrication was unaffected. The implications for ILs as lubricants are discussed in terms of the behaviour of this well characterised system.
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Affiliation(s)
- Nicklas Hjalmarsson
- Surface and Corrosion Science, KTH Royal Institute of Technology, SE-10044 Stockholm, Sweden.
| | - Rob Atkin
- Priority Research Centre for Advanced Fluids and Interfaces, The University of Newcastle, Callaghan, NSW 2308, Australia
| | - Mark W Rutland
- Surface and Corrosion Science, KTH Royal Institute of Technology, SE-10044 Stockholm, Sweden. and Chemistry, Materials and Surfaces, SP Technical Research Institute Sweden, SE-11428 Stockholm, Sweden
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29
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Ploss MA, Rutland MW, Glavatskih S. Influence of electric potential on the apparent viscosity of an ionic liquid: facts and artifacts. Phys Chem Chem Phys 2016; 18:26609-26615. [PMID: 27711405 DOI: 10.1039/c6cp02846b] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
According to recent findings, the steady shear viscosity of the ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([Emim][Tf2N]) decreases significantly under the influence of electric potential. This implies a causal connection between nanoscale ordering at the electrified interface and a macroscopic change of transport properties. To study this phenomenon in more detail, we reproduced the above-mentioned measurements; however, we find no evidence that the viscosity of [Emim][Tf2N] is a function of electric potential. Additionally, our results show that steady shear measurements can lead to artifacts that, at first glance, may appear to be potential-induced changes in viscosity. We demonstrate that the artifacts result from a sliding electrical contact at the working electrode of the electrochemical cell and we suggest to consider our findings for future viscosity measurements of ionic liquids.
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Affiliation(s)
- Moritz A Ploss
- System and Component Design, KTH Royal Institute of Technology, SE-100 44 Stockholm, Sweden
| | - Mark W Rutland
- Surface and Corrosion Science, KTH Royal Institute of Technology, SE-100 44 Stockholm, Sweden. and Chemistry, Materials and Surfaces, Box 5607, SE-114 86 Stockholm, Sweden
| | - Sergei Glavatskih
- System and Component Design, KTH Royal Institute of Technology, SE-100 44 Stockholm, Sweden and Mechanical Construction and Production, Ghent University, B-9000 Ghent, Belgium
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30
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Benselfelt T, Cranston ED, Ondaral S, Johansson E, Brumer H, Rutland MW, Wågberg L. Adsorption of Xyloglucan onto Cellulose Surfaces of Different Morphologies: An Entropy-Driven Process. Biomacromolecules 2016; 17:2801-11. [DOI: 10.1021/acs.biomac.6b00561] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Tobias Benselfelt
- Department
of Fibre and Polymer Technology and Wallenberg Wood Science Center, KTH Royal Institute of Technology, 100 44 Stockholm, Sweden
| | - Emily D. Cranston
- Department
of Chemical Engineering, McMaster University, Hamilton, Ontario L8S 4L7, Canada
| | - Sedat Ondaral
- Department
of Pulp and Paper Technology, Karadeniz Technical University, 61080 Trabzon, Turkey
| | | | - Harry Brumer
- The
Michael Smith Laboratories and the Department of Chemistry, The University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
| | - Mark W. Rutland
- Surface and
Corrosion Science, KTH Royal Institute of Technology, 100 44 Stockholm, Sweden
| | - Lars Wågberg
- Department
of Fibre and Polymer Technology and Wallenberg Wood Science Center, KTH Royal Institute of Technology, 100 44 Stockholm, Sweden
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31
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Nyström L, Nordström R, Bramhill J, Saunders BR, Álvarez-Asencio R, Rutland MW, Malmsten M. Factors Affecting Peptide Interactions with Surface-Bound Microgels. Biomacromolecules 2016; 17:669-78. [DOI: 10.1021/acs.biomac.5b01616] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Lina Nyström
- Department
of Pharmacy, Uppsala University, P.O. Box 580, SE-752 32 Uppsala, Sweden
| | - Randi Nordström
- Department
of Pharmacy, Uppsala University, P.O. Box 580, SE-752 32 Uppsala, Sweden
| | - Jane Bramhill
- School
of Materials, The University of Manchester, MSS Tower, Manchester, M13 9PL, United Kingdom
| | - Brian R. Saunders
- School
of Materials, The University of Manchester, MSS Tower, Manchester, M13 9PL, United Kingdom
| | - Rubén Álvarez-Asencio
- Department
of Surface and Corrosion Science, School of Chemical Science and Engineering, KTH Royal Institute of Technology, SE-100 44 Stockholm, Sweden
- Institute
for Advanced Studies, IMDEA Nanoscience, 28049 Madrid, Spain
| | - Mark W. Rutland
- Department
of Surface and Corrosion Science, School of Chemical Science and Engineering, KTH Royal Institute of Technology, SE-100 44 Stockholm, Sweden
- SP Technical Research Institute of Sweden, SP Chemistry,
Materials and Surfaces, SE-114
86 Stockholm, Sweden
| | - Martin Malmsten
- Department
of Pharmacy, Uppsala University, P.O. Box 580, SE-752 32 Uppsala, Sweden
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32
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Li H, Somers AE, Howlett PC, Rutland MW, Forsyth M, Atkin R. Addition of low concentrations of an ionic liquid to a base oil reduces friction over multiple length scales: a combined nano- and macrotribology investigation. Phys Chem Chem Phys 2016; 18:6541-7. [DOI: 10.1039/c5cp07061a] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The efficacy of ionic liquids (ILs) as lubricant additives to a model base oil has been probed at the nanoscale and macroscale as a function of IL concentration using the same materials.
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Affiliation(s)
- Hua Li
- Priority Research Centre for Advanced Fluids and Interfaces
- The University of Newcastle
- Callaghan
- Australia
| | | | | | - Mark W. Rutland
- School of Chemical Science and Engineering
- KTH Royal Institute of Technology
- SE100 44, Sweden
- Chemistry
- Materials and Surfaces
| | - Maria Forsyth
- Institute for Frontier Materials
- Deakin University
- Geelong
- Australia
| | - Rob Atkin
- Priority Research Centre for Advanced Fluids and Interfaces
- The University of Newcastle
- Callaghan
- Australia
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33
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Hjalmarsson N, Wallinder D, Glavatskih S, Atkin R, Aastrup T, Rutland MW. Weighing the surface charge of an ionic liquid. Nanoscale 2015; 7:16039-16045. [PMID: 26370450 DOI: 10.1039/c5nr03965g] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Electrochemical quartz crystal microbalance has been used to measure changes in the composition of the capacitive electrical double layer for 1-ethyl-3-methylimidazolium tris(pentafluoroethyl)-trifluorophosphate, an ionic liquid, in contact with a gold electrode surface as a function of potential. The mass difference between the cation and anion means that the technique can effectively "weigh" the surface charge accurately with high temporal resolution. This reveals quantitatively how changing the potential alters the ratio of cations and anions associated with the electrode surface, and thus the charge per unit area, as well as the kinetics associated with these interfacial processes. The measurements reveal that it is diffusion of co-ions into the interfacial region rather than expulsion of counterions that controls the relaxation. The measured potential dependent double layer capacitance experimentally validates recent theoretical predictions for counterion overscreening (low potentials) and crowding (high potentials) at electrode surfaces. This new capacity to quantitatively measure ion composition is critical for ionic liquid applications ranging from batteries, capacitors and electrodeposition through to boundary layer structure in tribology, and more broadly provides new insight into interfacial processes in concentrated electrolyte solutions.
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Affiliation(s)
- Nicklas Hjalmarsson
- Surface and Corrosion Science, KTH Royal Institute of Technology, SE-10044 Stockholm, Sweden
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34
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Álvarez-Asencio R, Wallqvist V, Kjellin M, Rutland MW, Camacho A, Nordgren N, Luengo GS. Nanomechanical properties of human skin and introduction of a novel hair indenter. J Mech Behav Biomed Mater 2015; 54:185-93. [PMID: 26469630 DOI: 10.1016/j.jmbbm.2015.09.014] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2015] [Revised: 09/01/2015] [Accepted: 09/14/2015] [Indexed: 11/18/2022]
Abstract
The mechanical resistance of the stratum corneum, the outermost layer of skin, to deformation has been evaluated at different length scales using Atomic Force Microscopy. Nanomechanical surface mapping was first conducted using a sharp silicon tip and revealed that Young׳s modulus of the stratum corneum varied over the surface with a mean value of about 0.4GPa. Force indentation measurements showed permanent deformation of the skin surface only at high applied loads (above 4µN). The latter effect was further demonstrated using nanomechanical imaging in which the obtained depth profiles clearly illustrate the effects of increased normal force on the elastic/plastic surface deformation. Force measurements utilizing the single hair fiber probe supported the nanoindentation results of the stratum corneum being highly elastic at the nanoscale, but revealed that the lateral scale of the deformation determines the effective elastic modulus.This result resolves the fact that the reported values in the literature vary greatly and will help to understand the biophysics of the interaction of razor cut hairs that curl back during growth and interact with the skin.
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Affiliation(s)
- Rubén Álvarez-Asencio
- KTH Royal Institute of Technology, School of Chemical Science and Engineering, Department of Chemistry, SE-100 44 Stockholm, Sweden; Institute for Advanced Studies, IMDEA Nanoscience, c/Faraday 9, Campus Cantoblanco, 28049 Madrid, Spain
| | - Viveca Wallqvist
- SP Technical Research Institute of Sweden, SP Chemistry, Materials and Surfaces, SE-114 86 Stockholm, Sweden
| | - Mikael Kjellin
- SP Technical Research Institute of Sweden, SP Chemistry, Materials and Surfaces, SE-114 86 Stockholm, Sweden
| | - Mark W Rutland
- KTH Royal Institute of Technology, School of Chemical Science and Engineering, Department of Chemistry, SE-100 44 Stockholm, Sweden; SP Technical Research Institute of Sweden, SP Chemistry, Materials and Surfaces, SE-114 86 Stockholm, Sweden
| | | | - Niklas Nordgren
- SP Technical Research Institute of Sweden, SP Chemistry, Materials and Surfaces, SE-114 86 Stockholm, Sweden.
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35
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Wang YL, Sarman S, Glavatskih S, Antzutkin ON, Rutland MW, Laaksonen A. Atomistic Insight into Tetraalkylphosphonium-Bis(oxalato)borate Ionic Liquid/Water Mixtures. I. Local Microscopic Structure. J Phys Chem B 2015; 119:5251-64. [DOI: 10.1021/acs.jpcb.5b00667] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Yong-Lei Wang
- Department
of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Sten Sarman
- Department
of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Sergei Glavatskih
- System
and Component Design, KTH Royal Institute of Technology, SE-100 44 Stockholm, Sweden
- Mechanical
Construction and Production, Ghent University, B-9000 Ghent, Belgium
| | - Oleg N. Antzutkin
- Chemistry
of Interfaces, Luleå University of Technology, SE-971 87 Luleå, Sweden
- Department
of Physics, Warwick University, CV4 7AL Coventry, United Kingdom
| | - Mark W. Rutland
- Surface and
Corrosion Science, KTH Royal Institute of Technology, SE-100 44 Stockholm, Sweden
- Chemistry,
Materials and Surfaces, SP Technical Research Institute of Sweden, SE-114
86 Stockholm, Sweden
| | - Aatto Laaksonen
- Department
of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University, SE-106 91 Stockholm, Sweden
- Stellenbosch
Institute of Advanced Study (STIAS), Wallenberg Research Centre, Stellenbosch University, Marais Street, Stellenbosch 7600, South Africa
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36
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Li H, Cooper PK, Somers AE, Rutland MW, Howlett PC, Forsyth M, Atkin R. Ionic Liquid Adsorption and Nanotribology at the Silica-Oil Interface: Hundred-Fold Dilution in Oil Lubricates as Effectively as the Pure Ionic Liquid. J Phys Chem Lett 2014; 5:4095-4099. [PMID: 26278938 DOI: 10.1021/jz5021422] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The remarkable physical properties of ionic liquids (ILs) make them potentially excellent lubricants. One of the challenges for using ILs as lubricants is their high cost. In this article, atomic force microscopy (AFM) nanotribology measurements reveal that a 1 mol % solution of IL dissolved in an oil lubricates the silica surface as effectively as the pure IL. The adsorption isotherm shows that the IL surface excess need only be approximately half of the saturation value to prevent surface contact and effectively lubricate the sliding surfaces. Using ILs in this way makes them viable for large-scale applications.
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Affiliation(s)
- Hua Li
- †Centre for Advanced Particle Processing and Transport, The University of Newcastle, Callaghan, New South Wales 2308, Australia
| | - Peter K Cooper
- †Centre for Advanced Particle Processing and Transport, The University of Newcastle, Callaghan, New South Wales 2308, Australia
| | - Anthony E Somers
- ‡ARC Centre of Excellence for Electromaterials Science, Institute for Frontier Materials, Deakin University, 221 Burwood Highway, Burwood, Victoria 3125, Australia
| | - Mark W Rutland
- §School of Chemical Science and Engineering, KTH Royal Institute of Technology, Stockholm SE100 44, Sweden
- ⊥Chemistry, Materials and Surfaces, SP Technical Research Institute of Sweden, Stockholm SE100 44, Sweden
| | - Patrick C Howlett
- ‡ARC Centre of Excellence for Electromaterials Science, Institute for Frontier Materials, Deakin University, 221 Burwood Highway, Burwood, Victoria 3125, Australia
| | - Maria Forsyth
- ‡ARC Centre of Excellence for Electromaterials Science, Institute for Frontier Materials, Deakin University, 221 Burwood Highway, Burwood, Victoria 3125, Australia
| | - Rob Atkin
- †Centre for Advanced Particle Processing and Transport, The University of Newcastle, Callaghan, New South Wales 2308, Australia
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37
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Sweeney J, Webber GB, Rutland MW, Atkin R. Effect of ion structure on nanoscale friction in protic ionic liquids. Phys Chem Chem Phys 2014; 16:16651-8. [DOI: 10.1039/c4cp02320j] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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38
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Ghalgaoui A, Shimizu R, Hosseinpour S, Alvarez-Asencio R, McKee C, Johnson CM, Rutland MW. Monolayer study by VSFS: in situ response to compression and shear in a contact. Langmuir 2014; 30:3075-3085. [PMID: 24547702 DOI: 10.1021/la4042474] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Self-assembled octadecyltrichlorosilane ((OTS), CH3(CH2)17SiCl3) layers on hydroxyl-terminated silicon oxide (SiO2) were prepared. The monolayers were characterized with atomic force microscopy (AFM) and contact angle measurements; their conformation was studied before, during, and after contact with a polymer (either PDMS or PTFE) surface using the vibrational sum frequency spectroscopy (VSFS) technique. During contact, the effect of pressure was studied for both polymer surfaces, but in the case of PTFE, the effect of shear rate on the contact was simultaneously studied. The VSFS response of the monolayers with pressure was almost entirely due to changes in the real area of contact with the polymer and therefore the Fresnel factors, whereas sliding caused disorder in the previously all-trans monolayer, as evidenced by a significant increase in the population of gauche defects.
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Affiliation(s)
- Ahmed Ghalgaoui
- KTH Royal Institute of Technology , Division of Surface and Corrosion Science, Drottning Kristinas Väg 51, SE-100 44 Stockholm, Sweden
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39
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Li H, Wood RJ, Rutland MW, Atkin R. An ionic liquid lubricant enables superlubricity to be “switched on” in situ using an electrical potential. Chem Commun (Camb) 2014; 50:4368-70. [DOI: 10.1039/c4cc00979g] [Citation(s) in RCA: 133] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
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40
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Liljeblad JFD, Tyrode E, Thormann E, Dublanchet AC, Luengo G, Magnus Johnson C, Rutland MW. Self-assembly of long chain fatty acids: effect of a methyl branch. Phys Chem Chem Phys 2014; 16:17869-82. [DOI: 10.1039/c4cp00512k] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The morphology and molecular conformation of monolayers of straight chain and methyl-branched fatty acids have been investigated by VSFS and AFM, revealing domains in the latter case, due to inverse micellar packing constraints.
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Affiliation(s)
- Jonathan F. D. Liljeblad
- School of Chemistry
- Division of Surface and Corrosion Science
- KTH Royal Institute of Technology
- SE-100 44 Stockholm, Sweden
| | - Eric Tyrode
- School of Chemistry
- Division of Surface and Corrosion Science
- KTH Royal Institute of Technology
- SE-100 44 Stockholm, Sweden
| | - Esben Thormann
- School of Chemistry
- Division of Surface and Corrosion Science
- KTH Royal Institute of Technology
- SE-100 44 Stockholm, Sweden
| | | | | | - C. Magnus Johnson
- School of Chemistry
- Division of Surface and Corrosion Science
- KTH Royal Institute of Technology
- SE-100 44 Stockholm, Sweden
| | - Mark W. Rutland
- School of Chemistry
- Division of Surface and Corrosion Science
- KTH Royal Institute of Technology
- SE-100 44 Stockholm, Sweden
- SP Technical Research Institute of Sweden
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41
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Álvarez-Asencio R, Thormann E, Rutland MW. Note: Determination of torsional spring constant of atomic force microscopy cantilevers: combining normal spring constant and classical beam theory. Rev Sci Instrum 2013; 84:096102. [PMID: 24089877 DOI: 10.1063/1.4820345] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
A technique has been developed for the calculation of torsional spring constants for AFM cantilevers based on the combination of the normal spring constant and plate/beam theory. It is easy to apply and allow the determination of torsional constants for stiff cantilevers where the thermal power spectrum is difficult to obtain due to the high resonance frequency and low signal/noise ratio. The applicability is shown to be general and this simple approach can thus be used to obtain torsional constants for any beam shaped cantilever.
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Affiliation(s)
- R Álvarez-Asencio
- Department of Surface and Corrosion Science, School of Chemical Science and Engineering, KTH Royal Institute of Technology, SE-100 44 Stockholm, Sweden
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42
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Mizuno H, Luengo GS, Rutland MW. New insight on the friction of natural fibers. Effect of sliding angle and anisotropic surface topography. Langmuir 2013; 29:5857-5862. [PMID: 23565816 DOI: 10.1021/la400468f] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
The friction anisotropy of human hair has been investigated as a function of angle using AFM fiber probe measurements to evaluate the role of cuticle alignment. It is found that friction hysteresis, the difference in friction coefficients between sliding with or against the cuticle direction, is essentially nonexistent for native human hair. For damaged human hair, however, a clear friction hysteresis is observed, which appears to be a periodic function of the angle between the fibers. The implication is that antiparallel sliding is not in itself sufficient for friction isotropy but that lifting of the cuticle edges is required. A methodology to perform friction analysis independently for trace and retrace was therefore developed, which is applicable to any type of AFM lateral force measurement. It explicitly accounts for roll, noncircular cross section, and off-axis alignment as well as baseline drift, which allows real anisotropy in the friction coefficient to be deconvoluted from these artifacts.
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Affiliation(s)
- Hiroyasu Mizuno
- Surface and Corrosion Science, School of Chemical Science and Engineering, KTH Royal Institute of Technology, Stockholm, Sweden
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43
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Nordgren N, Carlsson L, Blomberg H, Carlmark A, Malmström E, Rutland MW. Nanobiocomposite Adhesion: Role of Graft Length and Temperature in a Hybrid Biomimetic Approach. Biomacromolecules 2013; 14:1003-9. [DOI: 10.1021/bm301790b] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Niklas Nordgren
- Department of Fibre and Polymer
Technology, School of Chemical Science and Engineering, KTH Royal Institute of Technology, SE-100 44 Stockholm,
Sweden
| | - Linn Carlsson
- Department of Fibre and Polymer
Technology, School of Chemical Science and Engineering, KTH Royal Institute of Technology, SE-100 44 Stockholm,
Sweden
| | - Hanna Blomberg
- Department of Fibre and Polymer
Technology, School of Chemical Science and Engineering, KTH Royal Institute of Technology, SE-100 44 Stockholm,
Sweden
| | - Anna Carlmark
- Department of Fibre and Polymer
Technology, School of Chemical Science and Engineering, KTH Royal Institute of Technology, SE-100 44 Stockholm,
Sweden
| | - Eva Malmström
- Department of Fibre and Polymer
Technology, School of Chemical Science and Engineering, KTH Royal Institute of Technology, SE-100 44 Stockholm,
Sweden
| | - Mark W. Rutland
- Department of Chemistry,
School
of Chemical Science and Engineering, KTH Royal Institute of Technology, SE-100 44 Stockholm, Sweden
- SP Chemistry, Materials and Surfaces, SP Technical Research Institute of Sweden, SE-114 86
Stockholm, Sweden
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Li H, Rutland MW, Atkin R. Ionic liquid lubrication: influence of ion structure, surface potential and sliding velocity. Phys Chem Chem Phys 2013; 15:14616-23. [DOI: 10.1039/c3cp52638k] [Citation(s) in RCA: 126] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Elbourne A, Sweeney J, Webber GB, Wanless EJ, Warr GG, Rutland MW, Atkin R. Adsorbed and near-surface structure of ionic liquids determines nanoscale friction. Chem Commun (Camb) 2013; 49:6797-9. [DOI: 10.1039/c3cc42844c] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Skedung L, Arvidsson M, Chung JY, Stafford CM, Berglund B, Rutland MW. Feeling small: exploring the tactile perception limits. Sci Rep 2013; 3:2617. [PMID: 24030568 PMCID: PMC3771396 DOI: 10.1038/srep02617] [Citation(s) in RCA: 171] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2013] [Accepted: 08/22/2013] [Indexed: 11/25/2022] Open
Abstract
The human finger is exquisitely sensitive in perceiving different materials, but the question remains as to what length scales are capable of being distinguished in active touch. We combine material science with psychophysics to manufacture and haptically explore a series of topographically patterned surfaces of controlled wavelength, but identical chemistry. Strain-induced surface wrinkling and subsequent templating produced 16 surfaces with wrinkle wavelengths ranging from 300 nm to 90 μm and amplitudes between 7 nm and 4.5 μm. Perceived similarities of these surfaces (and two blanks) were pairwise scaled by participants, and interdistances among all stimuli were determined by individual differences scaling (INDSCAL). The tactile space thus generated and its two perceptual dimensions were directly linked to surface physical properties - the finger friction coefficient and the wrinkle wavelength. Finally, the lowest amplitude of the wrinkles so distinguished was approximately 10 nm, demonstrating that human tactile discrimination extends to the nanoscale.
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Affiliation(s)
- Lisa Skedung
- Surface and Corrosion Science, KTH Royal Institute of Technology, Drottning Kristinasväg 51, SE-100 44 Stockholm, Sweden
- Current address: Chemistry, Materials and Surfaces, SP Technical Research Institute of Sweden, Box 5607, SE-114 86 Stockholm, Sweden
| | - Martin Arvidsson
- Department of Psychology, Stockholm University, Frescati Hagväg 8, SE-106 91 Stockholm, Sweden
| | - Jun Young Chung
- Polymers Division, National Institute of Standards and Technology, Gaithersburg, Maryland, 20899, USA
- Current address: School of Engineering and Applied Sciences, Harvard University, 29 Oxford Street, Cambridge, Massachusetts 02138, USA
| | - Christopher M. Stafford
- Polymers Division, National Institute of Standards and Technology, Gaithersburg, Maryland, 20899, USA
| | - Birgitta Berglund
- Department of Psychology, Stockholm University, Frescati Hagväg 8, SE-106 91 Stockholm, Sweden
- Institute of Environmental Medicine, Karolinska Institutet, P.O. Box 210, SE-171 77 Stockholm, Sweden
| | - Mark W. Rutland
- Surface and Corrosion Science, KTH Royal Institute of Technology, Drottning Kristinasväg 51, SE-100 44 Stockholm, Sweden
- Chemistry, Materials and Surfaces, SP Technical Research Institute of Sweden, Box 5607, SE-114 86 Stockholm, Sweden
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Sweeney J, Hausen F, Hayes R, Webber GB, Endres F, Rutland MW, Bennewitz R, Atkin R. Control of nanoscale friction on gold in an ionic liquid by a potential-dependent ionic lubricant layer. Phys Rev Lett 2012; 109:155502. [PMID: 23102330 DOI: 10.1103/physrevlett.109.155502] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2012] [Indexed: 06/01/2023]
Abstract
The lubricating properties of an ionic liquid on gold surfaces can be controlled through application of an electric potential to the sliding contact. A nanotribology approach has been used to study the frictional behavior of 1-butyl-1-methylpyrrolidinium tris(pentafluoroethyl) trifluorophosphate ([Py(1,4)]FAP) confined between silica colloid probes or sharp silica tips and a Au(111) substrate using atomic force microscopy. Friction forces vary with potential because the composition of a confined ion layer between the two surfaces changes from cation-enriched (at negative potentials) to anion-enriched (at positive potentials). This offers a new approach to tuning frictional forces reversibly at the molecular level without changing the substrates, employing a self-replenishing boundary lubricant of low vapor pressure.
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Affiliation(s)
- James Sweeney
- Centre for Advanced Particle Processing and Transport, The University of Newcastle, Callaghan, NSW 2308, Australia
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Thormann E, Mizuno H, Jansson K, Hedin N, Fernández MS, Arias JL, Rutland MW, Pai RK, Bergström L. Embedded proteins and sacrificial bonds provide the strong adhesive properties of gastroliths. Nanoscale 2012; 4:3910-3916. [PMID: 22653376 DOI: 10.1039/c2nr30536d] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The adhesive properties of gastroliths from a freshwater crayfish (Cherax quadricarinatus) were quantified by colloidal probe atomic force microscopy (AFM) between heavily demineralized gastrolith microparticles and gastrolith substrates of different composition. Combined AFM and transmission electron microscopy studies demonstrated that the sequential detachment and large adhesion energies that characterise the adhesive behaviour of a native gastrolith substrate are dominated by sacrificial bonds between chitin fibres and between chitin fibres and CaCO(3). The sacrificial bonds were shown to be strongly related to the gastrolith proteins and when the majority of these proteins were removed by ethylenediaminetetraacetic acid (EDTA), the sequential detachment disappeared and the adhesive energy was reduced by more than two orders of magnitude.
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Affiliation(s)
- Esben Thormann
- KTH Royal Institute of Technology, Department of Chemistry, Surface and Corrosion Science, SE-100 44 Stockholm, Sweden
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Asencio RÁ, Cranston ED, Atkin R, Rutland MW. Ionic liquid nanotribology: stiction suppression and surface induced shear thinning. Langmuir 2012; 28:9967-9976. [PMID: 22676253 DOI: 10.1021/la3010807] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The friction and adhesion between pairs of materials (silica, alumina, and polytetrafluoroethylene) have been studied and interpreted in terms of the long-ranged interactions present. In ambient laboratory air, the interactions are dominated by van der Waals attraction and strong adhesion leading to significant frictional forces. In the presence of the ionic liquid (IL) ethylammonium nitrate (EAN) the van der Waals interaction is suppressed and the attractive/adhesive interactions which lead to "stiction" are removed, resulting in an at least a 10-fold reduction in the friction force at large applied loads. The friction coefficient for each system was determined; coefficients obtained in air were significantly larger than those obtained in the presence of EAN (which ranged between 0.1 and 0.25), and variation in the friction coefficients between systems was correlated with changes in surface roughness. As the viscosity of ILs can be relatively high, which has implications for the lubricating properties, the hydrodynamic forces between the surfaces have therefore also been studied. The linear increase in repulsive force with speed, expected from hydrodynamic interactions, is clearly observed, and these forces further inhibit the potential for stiction. Remarkably, the viscosity extracted from the data is dramatically reduced compared to the bulk value, indicative of a surface ordering effect which significantly reduces viscous losses.
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Affiliation(s)
- Rubén Álvarez Asencio
- Department of Surface and Corrosion Science, School of Chemical Science and Engineering, The Royal Institute of Technology, Stockholm, Sweden
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50
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Werzer O, Cranston ED, Warr GG, Atkin R, Rutland MW. Ionic liquid nanotribology: mica–silica interactions in ethylammonium nitrate. Phys Chem Chem Phys 2012; 14:5147-52. [DOI: 10.1039/c1cp23134k] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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