scholarly journals Ionic Liquid Crystals in Tribology

Lubricants ◽  
2019 ◽  
Vol 7 (9) ◽  
pp. 72 ◽  
Author(s):  
M.D. Avilés ◽  
C. Sánchez ◽  
R. Pamies ◽  
J. Sanes ◽  
M.D. Bermúdez
Keyword(s):  
Molecular Structure ◽  
Ionic Liquid ◽  
Ionic Liquids ◽  
Liquid Crystals ◽  
Tribological Performance ◽  
Wear Rates ◽  
Fatty Acid Derivatives ◽  
Potential Applications ◽  
Ionic Liquid Crystals ◽  
Definition Of

The present work intends to provide a brief account of the most recent advances in the use of ionic liquid crystals (ILCs) in the field of tribology, that is, the development of new lubricants with the ability to reduce the coefficients of friction and the wear rates of materials under sliding conditions. After a definition of ILCs and their relationship with neutral liquid crystals (LCs) and ionic liquids (ILs), the review will be focused on the influence of molecular structure and composition on the tribological performance, the combination with base oils, surfactants or water, and the different sliding configuration and potential applications. The main mechanisms proposed in order to justify the lubricating ability of ILCs will be analyzed. Special emphasis will be made for recent results obtained for fatty acid derivatives due to their renewable and environmentally friendly nature.

scholarly journals Low temperature glass/crystal transition in ionic liquids determined by H-bond vs. coulombic strength

2020 ◽  
Vol 22 (36) ◽  
pp. 20524-20530
Author(s):  
Carlos López-Bueno ◽  
Marius R. Bittermann ◽  
Bruno Dacuña-Mariño ◽  
Antonio Luis Llamas-Saiz ◽  
María del Carmen Giménez-López ◽  
...  
Keyword(s):  
Ionic Liquid ◽  
Ionic Liquids ◽  
Solar Cells ◽  
Liquid Crystals ◽  
Low Temperature ◽  
Ionic Conductors ◽  
Potential Applications ◽  
Crystal Transition ◽  
Ionic Liquid Crystals ◽  
Glass Crystal

Self-assembled ionic liquid crystals are anisotropic ionic conductors, with potential applications in areas as important as solar cells, battery electrolytes and catalysis. We show that the type of crystal formed depend on the strength of H-bonds.

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

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Debashis Majhi ◽  
Sergey V. Dvinskikh
Keyword(s):  
Ionic Liquid ◽  
Ionic Liquids ◽  
Liquid Crystals ◽  
Bond Order ◽  
Van Der Waals ◽  
Orientational Order ◽  
Smectic Phase ◽  
Side Chains ◽  
Dicationic Ionic Liquid ◽  
Ionic Liquid Crystals

AbstractIonic 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.

scholarly journals Designing Functional Polyoxometalate-Based Ionic Liquid Crystals and Ionic Liquids

2019 ◽  
Vol 2020 (3) ◽  
pp. 228-247 ◽  
Author(s):  
Yohan Martinetto ◽  
Bruce Pégot ◽  
Catherine Roch-Marchal ◽  
Betty Cottyn-Boitte ◽  
Sébastien Floquet
Keyword(s):  
Ionic Liquid ◽  
Ionic Liquids ◽  
Liquid Crystals ◽  
Ionic Liquid Crystals

scholarly journals 2D assemblies of ionic liquid crystals based on imidazolium moieties: formation of ion-conductive layers

2015 ◽  
Vol 39 (6) ◽  
pp. 4471-4477 ◽  
Author(s):  
Junji Sakuda ◽  
Masafumi Yoshio ◽  
Takahiro Ichikawa ◽  
Hiroyuki Ohno ◽  
Takashi Kato
Keyword(s):  
Ionic Liquid ◽  
Ionic Liquids ◽  
Liquid Crystals ◽  
Ionic Conductivity ◽  
Imidazolium Ionic Liquids ◽  
Ionic Liquid Crystals

Organization of imidazolium ionic liquids into 2D ion-conductive pathways enhances the ionic conductivity of the imidazolium-based ionic liquid crystals.

Ionic liquids and ionic liquid crystals of vinyl functionalized imidazolium salts

2011 ◽  
Vol 21 (6) ◽  
pp. 1866-1873 ◽  
Author(s):  
Shih-Ci Luo ◽  
Shaowen Sun ◽  
Amol R. Deorukhkar ◽  
Jung-Tang Lu ◽  
Amitabha Bhattacharyya ◽  
...  
Keyword(s):  
Ionic Liquid ◽  
Ionic Liquids ◽  
Liquid Crystals ◽  
Imidazolium Salts ◽  
Ionic Liquid Crystals

scholarly journals Fatty Acid-Derived Ionic Liquid Lubricant. Protic Ionic Liquid Crystals as Protic Ionic Liquid Additives

Coatings ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 710 ◽  
Author(s):  
María-Dolores Avilés ◽  
Ramón Pamies ◽  
José Sanes ◽  
Francisco-José Carrión ◽  
María-Dolores Bermúdez
Keyword(s):  
Ionic Liquid ◽  
Ionic Liquids ◽  
Liquid Crystal ◽  
Fatty Acid ◽  
Liquid Crystals ◽  
Water Evaporation ◽  
Protic Ionic Liquid ◽  
X Ray ◽  
Sliding Surfaces ◽  
Ionic Liquid Crystals

Fatty acids are natural products which have been studied as green lubricants. Ionic liquids are considered efficient friction reducing and wear preventing lubricants and lubricant additives. Fatty acid-derived ionic liquids have shown potential as neat lubricant and additives. Protic ionic liquid crystals (PILCs) are protic ionic liquids (PILs) where cations and anions form ordered mesophases that show liquid crystalline behavior. The adsorption of carboxylate units on sliding surfaces can enhance the lubricant performance. Ionic liquid crystal lubricants with longer alkyl chains can separate sliding surfaces more efficiently. However, they are usually solid at room temperature and, when used as additives in water, transitions to high friction coefficients and wear rates, with tribocorrosion processes occur when water evaporation takes place at the interface. In order to avoid these inconveniences, in the present work, a protic ammonium palmitate (DPA) ionic liquid crystal has been added in 1 wt.% proportion to a short chain citrate ionic liquid (DCi) with the same protic ammonium cation. A spin coated layer of (DCi + DPA) was deposited on AISI316L steel surface before the sliding test against sapphire ball. Synergy between DCi PIL and DPA PILC additive reduces friction coefficient and wear rate, without tribocorrosion processes, as shown by scanning electron microscopy (SEM)/energy dispersive X-ray microanalysis (EDX) and X-ray photoelectron spectroscopy (XPS) results.

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