Ionic Liquid Crystals in Tribology

Avilés, M.A.; Sánchez, Cristián G.; Pamies, Ramón; Sanes, J.; Bermúdez,

doi:10.3390/lubricants7090072

Cited by 21 publications

(10 citation statements)

References 39 publications

(48 reference statements)

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“…Bei For-K schungsarbeiten, die sich mit der Untersuchung der makroskopischen Reibung beschäftigen, stehen Additive zur Optimierung von Wasser als Schmierstoff im Fokus. Dazu werden in wissenschaftlichen Arbeiten MoS2 Nanopartikel [22], CuO-beschichtete Nanopartikel [23], geschichtete Doppelhydroxid-Nanoplättchen [24], fluoriertes Graphen [25], Lithiumsalz und nichtionische Tenside [26], oxidierte aus Holz stammende Nanokohlenstoffe [27], Pflanzenextrakte [3] und ILCs [28] diskutiert. Es wurde herausgefunden, dass das Einlaufverhalten zum Erreichen extrem niedriger Reibung einen entscheidenden Einfluss bei der Verwendung einer wässrigen Mischung mit Schwefelsäure und Glycerin hat [29].…”

Section: Stand Der Wissenschaftunclassified

Entwicklung von galvanisch gekoppelten Gleitlagern zur Reduzierung von Reibung und Verschleiß

Amann

Chen

Baur

et al. 2020

Forsch Ingenieurwes

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Zusammenfassung Durch Reibung und Verschleiß werden weltweit Gesamtkosten von 250 Mrd. €/Jahr verursacht und 8120 MtCO2-Emissionen freigesetzt. Die aktuellen Herausforderungen bestehen darin, die Vorteile ultraniedriger Reibung, der verschleißlosen Gleit- und Reibungskontrolle sowie der wasserbasierten Schmierung hinsichtlich Energie- und Ressourceneffizienz für technische Anwendungen zu nutzen. An dieser Problematik, der Steigerung der Energieeffizienz und Nachhaltigkeit, setzt diese Arbeit an. Vorarbeiten haben gezeigt, dass mit speziellen mesogenen Flüssigkeiten Superlubrizität (µ < 0,005) realisiert werden kann. In dieser Arbeit sollen neben der anwendungsnahen Prüfung dieser mesogenen Fluide auch die Eigenschaften von Wasser als Schmierstoff durch Additivierung mit komplexen Fluiden (ionischen Flüssigkeiten, lyotroper Flüssigkristall) und Einbringung eines elektrochemischen Schutzes durch galvanische Kopplung verbessert werden. Durch die Zugabe der komplexen Fluide in Wasser wurden Reibung- und Verschleiß in Modellreibversuchen verbessert. Gleitlagerversuche mit dem mesogenen Schmierstoff zeigen bei galvanisch induziertem Oberflächenpotenzial, durch Kopplung des Stahllagers mit Kupfer, eine Reibwertreduzierung um 60 % und eine Verschleißreduktion um 40 % im Vergleich zu einem Referenzöl.

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Section: Stand Der Wissenschaftunclassified

Entwicklung von galvanisch gekoppelten Gleitlagern zur Reduzierung von Reibung und Verschleiß

Amann

Chen

Baur

et al. 2020

Forsch Ingenieurwes

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“…Some dicationic ionic liquids (DILs) are more thermally stable than those based on monocationic units 5 , 12 . Imidazolium based DILCs have found growing applications in areas varying from biochemistry and biology 13 – 15 to electrochemistry 16 and electro-optics 17 to tribology 18 . Recent studies have demonstrated that dicationic ILs not only show favorable physicochemical properties 19 but are also significantly different in their dynamic behaviour 20 as compared to conventional monocationic analogs.…”

Section: Introductionmentioning

confidence: 99%

Ion conformation and orientational order in a dicationic ionic liquid crystal studied by solid-state nuclear magnetic resonance spectroscopy

Majhi

Dvinskikh

2021

Sci Rep

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

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“…Investigations into complex fluids with anisotropic properties, e.g., mesogenic fluids, ionic liquids and ionic liquid crystals, have shown their potential for friction reduction [28,29]. Liquid crystals (LCs) are a further substance class of additives which have been shown to improve friction and optimize water as a lubricant.…”

Section: Introductionmentioning

confidence: 99%

“…LCs have already been intensively investigated as pure lubricants [31] and as additives in mineral oils [32,33] and water [34,35]. A new field of research is currently opening up in the field of ionic liquid crystals (ILCs) [29], also in combination with water [36,37]. It is assumed that the resulting ultralow friction and wear are ascribed to their specific molecular interactions and orientation in the shear flow [38].…”

Section: Introductionmentioning

confidence: 99%

Macroscopic Friction Studies of Alkylglucopyranosides as Additives for Water-Based Lubricants

et al. 2020

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Water-based lubricants might become an interesting alternative to conventional oil-based lubricants and help to reduce wear as well as improve the energy efficiency of transport processes. Since pure water is generally a rather poor lubricant due to its low viscosity and corrosiveness, it must be tribologically optimized with suitable additives. Here, we study the friction behavior of alkyl glucopyranosides (AGPs) with varying lengths of the alkyl chain. Sliding experiments show that a significant reduction in the coefficient of friction compared to that of pure water is observed. The extent of friction reduction depends strongly on the concentration and on the shearing conditions. It is assumed that the low coefficients of friction are due to the ability of AGPs to form liquid crystalline phases with an ordered structure in the friction gap. Furthermore, the interaction of the AGPs with the surface forms a wear protection layer (boundary lubrication). The friction properties of the water-based system are compared to those of a conventional, mineral oil-based lubricant.

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Ionic Liquid Crystals in Tribology

Cited by 21 publications

References 39 publications

Entwicklung von galvanisch gekoppelten Gleitlagern zur Reduzierung von Reibung und Verschleiß

Entwicklung von galvanisch gekoppelten Gleitlagern zur Reduzierung von Reibung und Verschleiß

Ion conformation and orientational order in a dicationic ionic liquid crystal studied by solid-state nuclear magnetic resonance spectroscopy

Macroscopic Friction Studies of Alkylglucopyranosides as Additives for Water-Based Lubricants

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