Addition of low concentrations of an ionic liquid to a base oil reduces friction over multiple length scales: a combined nano- and macrotribology investigation

During machining, the cutting fluids play an essential role in cooling and lubrication. In order to reduce the friction forces, the excessive amount of the cutting fluids are generally used. This, in turn, leads to wastage of the cutting fluids which results in a serious impact on the environment, health and cost of production. Therefore, the judicious use of lubricants is the foremost concern in the manufacturing industry. In order to mitigate these drawbacks, various alternatives have been developed in the last decade. In the present paper, ionic liquids have been proved as favourable sustainable alternative additives in the base oil. The effect of alkyl chain length of ionic liquids with base oil on the thermo-physical and tribological characteristics of cutting fluids including viscosity, wettability, anticorrosion behaviour, thermal stability, and coefficient of friction have been analysed. In the present study, pyrrolidinium and hexafluoro-phosphate (PF6) have been used as cation and anion, respectively, with rice bran oil as base oil. The five different ionic liquids have been dispersed in base oil by 1.0 wt%. It has been found that longer alkyl chain length showed the favourable results as compared to the shorter one. Results indicated that ionic liquid based cutting fluid attained ample enhanced thermophysical and tribological properties as compared to the neat rice bran oil. There has been 5.08% and 4.29% improvement in viscosity and thermal conductivity for IL4 + RBO in comparison to neat RBO. In addition, the wettability, coefficient of friction, and wear volume have been reduced by 20.34%, 53.79% and 57.87% correspondingly.

Download Full-text

Effect of Ionicity of Three Protic Ionic Liquids as Neat Lubricants and Lubricant Additives to a Biolubricant

Coatings ◽

10.3390/coatings9110713 ◽

2019 ◽

Vol 9 (11) ◽

pp. 713 ◽

Cited By ~ 5

Author(s):

Hong Guo ◽

Angela Rina Adukure ◽

Patricia Iglesias

Keyword(s):

Ionic Liquid ◽

Ionic Liquids ◽

Friction And Wear ◽

Cost Effective ◽

Lubricant Additive ◽

Lubricant Additives ◽

Environmental Damage ◽

Protic Ionic Liquids ◽

Protic Ionic Liquid ◽

Wear Process

Friction and wear of sliding surfaces are responsible for important energy losses and negative environmental effects. The use of environmentally friendly and cost-effective protic ionic liquids as neat lubricants and lubricant additives has the potential to increase the efficiency and durability of mechanical components without increasing the environmental damage. In this work, three halogen-free protic ionic liquids with increasing extent of ionicity, 2-hydroxyethylammonium 2-ethylhexanoate, 2-hydroxymethylammonium 2-ethylhexancate, and 2-hydroxydimethylammonium 2-ethylhexanoate, were synthesized and studied as neat lubricants and additives to a biodegradable oil in a steel–steel contact. The results show that the use of any protic ionic liquid as a neat lubricant or lubricant additive reduced friction and wear with respect to the biodegradable oil. The ionic liquid with the lowest ionicity reached the highest wear reduction. The one possessing the highest ionicity presented the poorest friction and wear behaviors as a neat lubricant, probably due to the more ionic nature of this liquid, which promoted tribocorrosion reactions on the steel surface. This ionic liquid performed better as an additive, showing that a small addition of this liquid in a biodegradable oil is enough to form protective layers on steel surfaces. However, it is not enough to accelerate the wear process with detrimental tribocorrosion reactions.

Download Full-text

Friction and Wear Properties of Halogen-Free and Halogen-Containing Ionic Liquids Used As Neat Lubricants, Lubricant Additives and Thin Lubricant Layers

Volume 10: 2017 ASME International Power Transmission and Gearing Conference ◽

10.1115/detc2017-67971 ◽

2017 ◽

Author(s):

Hong Guo ◽

Rui Liu ◽

Alfonso Fuentes-Aznar ◽

Patricia Iglesias Victoria

Keyword(s):

Ionic Liquid ◽

Ionic Liquids ◽

Friction And Wear ◽

Mineral Oil ◽

Surface Interactions ◽

Lubricant Additives ◽

Wear Properties ◽

Sem Images ◽

Wear Reduction ◽

Halogen Free

The lubricating ability of one halogen-free and one halogen-containing phosphonium-based ionic liquids are investigated as neat lubricants, lubricant additives and thin lubricant layers in steel-steel contact. The use of the ionic liquids in any of the three lubricating methods reduced friction and wear compared to a base mineral oil. The halogen-free ionic liquid outperformed the halogen-containing ionic liquid in the three methods of lubrication. The highest friction and wear reduction were obtained when ionic liquids were used as neat lubricants. Under this condition, friction reductions of 37.21% and 25.73 %, and wear reduction of 47.12% and 41.18% compared to the based mineral oil were obtained for the halogen-free and halogen-containing ionic liquids respectively. The wear mechanisms and surface interactions are discussed in terms of ionic liquid-metal surface interactions from optical and SEM images and EDS analysis.

Download Full-text

Competitive Adsorption of Ionic Liquids Versus Friction Modifier and Anti-Wear Additive at Solid/Lubricant Interface—Speciation with Vibrational Sum Frequency Generation Spectroscopy

Lubricants ◽

10.3390/lubricants8110098 ◽

2020 ◽

Vol 8 (11) ◽

pp. 98

Author(s):

Dien Ngo ◽

Xin He ◽

Huimin Luo ◽

Jun Qu ◽

Seong H. Kim

Keyword(s):

Ionic Liquids ◽

Competitive Adsorption ◽

Silica Surface ◽

Sum Frequency Generation ◽

Lubricant Additives ◽

Solid Base ◽

Friction Modifier ◽

Base Oil ◽

Sum Frequency ◽

Frequency Generation

A modern lubricant contains various additives with different functionalities and the interactions or reactions between these additives could induce synergistic or antagonistic effects in tribological performance. In this study, sum frequency generation (SFG) spectroscopy was used to investigate competitive adsorption of lubricant additives at a solid/base oil interface. A silica substrate was used as a model solid surface. The lubricant additives studied here included two oil-soluble ionic liquids (ILs, [N888H][DEHP] and [P8888][DEHP]), an antiwear additive (secondary ZDDP), an organic friction modifier (OFM), and a dispersant (PIBSI). Our results showed that for mixtures of ZDDP and IL in a base oil (PAO4), the silica surface is dominated by the IL molecules. In the cases of base oils containing OFM and IL, the silica/lubricant interface is dominated by OFM over [N888H][DEHP], while it is preferentially occupied by [P8888][DEHP] over OFM. The presence of PIBSI in the mixture of PAO4 and IL leads to the formation of a mixed surface layer at the silica surface with PIBSI as a major component. The SFG results in this investigation provide fundamental insights that are helpful to design the formulation of new lubricant additives of desired properties.

Download Full-text

Estimating Antiwear Properties of Ionic Liquids as Lubricant Additives Using a QSTR Model

Journal of Tribology ◽

10.1115/1.4043904 ◽

2019 ◽

Vol 141 (9) ◽

Cited By ~ 2

Author(s):

Ze Song ◽

Tao Chen ◽

Tingting Wang ◽

Zhan Wang ◽

Xinlei Gao

Keyword(s):

Ionic Liquids ◽

Influencing Factor ◽

Three Dimensional ◽

Predictive Ability ◽

Lubricant Additives ◽

Wear Scar Diameter ◽

Base Oil ◽

Hartree Fock ◽

Antiwear Properties ◽

Quantum Parameters

The antiwear properties of ionic liquids (ILs) as lubricant additives were studied with polyethylene glycol (PEG) used as the lubricant base oil. The quantum parameters of the ILs were calculated using a Hartree–Fock ab initio method. Correlation between the scale of the wear scar diameter and quantum parameters of the ILs was studied by multiple linear regression (MLR) analysis. A quantitative structure tribo-ability relationship (QSTR) model was built with a good fitting effect and predictive ability. The results show that the entropy of the ILs is the main descriptor affecting the antiwear performance of the lubricant system. To improve the antiwear performance of the lubricants, the entropy of the system should be decreased, reducing the system randomness and increasing the system regularity. A major influencing factor on the entropy of a system is the intra- and intermolecular hydrogen bonds present. Therefore, enhanced antiwear properties of lubricants could be achieved with a three-dimensional netlike structure of lubricant formed by hydrogen bonding.

Download Full-text

Understanding the thermal decomposition mechanism of a halogen-free chelated orthoborate-based ionic liquid: a combined computational and experimental study

Physical Chemistry Chemical Physics ◽

10.1039/c6cp03191a ◽

2016 ◽

Vol 18 (32) ◽

pp. 22458-22466 ◽

Cited By ~ 6

Author(s):

M. Golets ◽

M. R. Shimpi ◽

Y.-L. Wang ◽

O. N. Antzutkin ◽

S. Glavatskih ◽

...

Keyword(s):

Experimental Study ◽

Thermal Decomposition ◽

Ionic Liquid ◽

Ionic Liquids ◽

Physicochemical Properties ◽

Vapour Pressure ◽

Lubricant Additives ◽

Thermal Decomposition Mechanism ◽

Halogen Free ◽

Significant Attention

In the last few decades, ionic liquids (ILs) have gained significant attention as lubricants and lubricant additives due to their polar nature, low vapour pressure and tunable physicochemical properties.

Download Full-text

Mapping the “Extra Solvent Power, ESP” of Ionic Liquids for Monomers, Polymers and Globular Nanoparticles

10.26434/chemrxiv.5384293.v1 ◽

2017 ◽

Author(s):

Jose A. Pomposo

Keyword(s):

Ionic Liquid ◽

Ionic Liquids ◽

Linear Polymers ◽

Green Solvents ◽

Ionic Polymers ◽

First Time ◽

Solvent Power

Understanding the miscibility behavior of ionic liquid (IL) / monomer, IL / polymer and IL / nanoparticle mixtures is critical for the use of ILs as green solvents in polymerization processes, and to rationalize recent observations concerning the superior solubility of some proteins in ILs when compared to standard solvents. In this work, the most relevant results obtained in terms of a three-component Flory-Huggins theory concerning the “Extra Solvent Power, ESP” of ILs when compared to traditional non-ionic solvents for monomeric solutes (case I), linear polymers (case II) and globular nanoparticles (case III) are presented. Moreover, useful ESP maps are drawn for the first time for IL mixtures corresponding to case I, II and III. Finally, a potential pathway to improve the miscibility of non-ionic polymers in ILs is also proposed.

Download Full-text

Dynamics of Ion Locking in Doubly Polymerized Ionic Liquids

10.26434/chemrxiv.13239059.v1 ◽

2020 ◽

Author(s):

Swati Arora ◽

Julisa Rozon ◽

Jennifer Laaser

Keyword(s):

Dielectric Constant ◽

Ionic Liquid ◽

Ionic Liquids ◽

Ion Pairs ◽

Polymer Chains ◽

Ion Motion ◽

Charged Species ◽

Broadband Dielectric Spectroscopy ◽

Covalently Linked ◽

Insight Into

<div>In this work, we investigate the dynamics of ion motion in “doubly-polymerized” ionic liquids (DPILs) in which both charged species of an ionic liquid are covalently linked to the same polymer chains. Broadband dielectric spectroscopy is used to characterize these materials over a broad frequency and temperature range, and their behavior is compared to that of conventional “singly-polymerized” ionic liquids (SPILs) in which only one of the charged species is attached to the polymer chains. Polymerization of the DPIL decreases the bulk ionic conductivity by four orders of magnitude relative to both SPILs. The timescales for local ionic rearrangement are similarly found to be approximately four orders of magnitude slower in the DPILs than in the SPILs, and the DPILs also have a lower static dielectric constant. These results suggest that copolymerization of the ionic monomers affects ion motion on both the bulk and the local scales, with ion pairs serving to form strong physical crosslinks between the polymer chains. This study provides quantitative insight into the energetics and timescales of ion motion that drive the phenomenon of “ion locking” currently under investigation for new classes of organic electronics.</div>

Download Full-text

Ionic Liquid Assisted Synthesis of Some 2-Aminobenzenethiols

Letters in Organic Chemistry ◽

10.2174/1570178615666181011114454 ◽

2019 ◽

Vol 16 (7) ◽

pp. 550-555

Author(s):

Dinesh K. Jangid ◽

Keshav L. Ameta ◽

Surbhi Dhadda ◽

Anjali Guleria ◽

Prakash G. Goswami ◽

...

Keyword(s):

Ionic Liquid ◽

Ionic Liquids ◽

Comparative Study ◽

Maximum Yield ◽

Efficient Synthesis ◽

Target Molecules ◽

Presence And Absence

Ionic Liquid assisted efficient synthesis of some 2-aminobenzenethiols has been reported using three different Ionic Liquids (ILs) namely methylimidazolium tetrafluoroborate [MIM]+[BF4]−, methylimidazolium chloride [MIM]+[Cl]− and methylimidazolium nitrate [MIM]+[NO3]−. A comparative study has been carried out for the synthesis of target molecules in the presence and absence of IL, leading to conclusion that maximum yield has been observed with [MIM]+[BF4]−.

Download Full-text

Dispersive Liquid-Liquid Microextraction Based on Ionic Liquid and Spectrophotometric Determination of Bilirubin in Biological Samples

Current Analytical Chemistry ◽

10.2174/1573411015666190212123437 ◽

2020 ◽

Vol 16 (5) ◽

pp. 652-659

Author(s):

Asiye A. Avan ◽

Hayati Filik

Keyword(s):

Ionic Liquid ◽

Ionic Liquids ◽

Biological Samples ◽

Urine Samples ◽

Spectrophotometric Detection ◽

Full Color ◽

Dispersive Liquid Liquid Microextraction ◽

Urine And Serum ◽

Liquid Microextraction

Background: An Ionic Liquid-based based Dispersive Liquid-Liquid Microextraction (IL-DLLME) method was not applied to preconcentration and determination of bilirubin. Ionic Liquids (ILs) are new chemical compounds. In recent years, Ionic Liquids (ILs) have been employed as alternative solvents to toxic organic solvents. Due to these perfect properties, ILs have already been applied in many analytical extraction processes, presenting high extraction yield and selectivity for analytes. Methods: In this study, IL-DLLME was applied to biological samples (urine and serum) for the spectrophotometric detection of bilirubin. For bilirubin analysis, the full-color development was based on the reaction with periodate in the presence of hydrochloric acid. The high affinity of bilirubin for the ionic liquid phase gave extraction percentages above 98% in 0.3 M HCl solution. Results: Several IL-extraction parameters were optimized and room temperature ionic liquid 1-butyl- 1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide and ethanol were used as extraction and disperser solution. The linear range was found in the range of 0.5-6.0 μM (0.3-3.5 μg mL-1) and the limits of detection of the proposed method was 0.5 μM (0.3 μg mL-1). The proposed method was applied for the preconcentration and separation of trace bilirubin in real urine samples. Also, the recoveries for bilirubin in spiked biological samples (urine and serum) were found to be acceptable, between 95-102%. Conclusion: The proposed IL-DLLMEapproach was employed for the enrichment and determination of trace levels of bilirubin in urine samples using NaIO4 as an oxidizing agent and Uv-vis spectrophotometric detection. The periodate oxidation of bilirubin is rapid, effective, selective, and simple to perform. The method contains only HCl, NaOI4, and an anionic surfactant. The method may be useful for economizing in the consumption of reagents in bilirubin determining. The IL-DLLMEmethod ensures a high yield and has a low toxicity no skin sensitization, no mutagenicity and no ecotoxicity in an aquatic environment since only very low quantities of an IL is required. For full-color formation, no any extra auxiliary reagents are required. Besides, the IL-DLLME technique uses a low-cost instrument such as Uv-vis which is present in most of the medical laboratories.

Download Full-text