Effects of Carboxylic Acids on Friction and Wear Reducing Properties for Alkylmethylimidazolium Derived Ionic liquids

Kamimura, Hideto; Chiba, Takeru; Watanabe, Naoko; Kubo, Tomoo; Nanao, Hidetaka; Minami, Ichiro; Mori, Shigeyuki

doi:10.2474/trol.1.40

Cited by 38 publications

(34 citation statements)

References 6 publications

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“…1. As we have reported previously, the pendulum friction test indicated that the friction coefficient of 1-alkyl-3-methylimidazolium salts decreased with an increase in the chain length of the alkyl group [12,14]. On the other hand, as shown in Fig.…”

Section: Determination Of Friction Coefficient Using Pendulum Frictiosupporting

confidence: 47%

“…Higher alkyl groups in imidazolium cations are instrumental in improving the tribological properties of a compound. Further, hydrophobic anions afford a superior thermo-oxidative stability to RT-ILs as compared to hydrophilic ones [12,14]. The thermo-oxidative stability of RT-ILs decreases with increase in the chain length of the alkyl group in an imidazolium cation [15].…”

Section: Introductionmentioning

confidence: 99%

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Tribo-Chemistry of Phosphonium-Derived Ionic Liquids

et al. 2010

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The tribological properties of room temperature ionic liquids containing tetraalkylphosphonium cations were evaluated on the basis of the chemical structure of their salts. The tribochemistry of these ionic liquids was discussed on the basis of the results of tribo-tests and surface analyses. The tribological properties of the tetraalkylphosphonium salts examined in this work were observed to be better than those of 1,3-alkylimidazolium salts. The structure of the alkyl group in the phosphonium cation also has a slight effect on the tribological properties of the salts. During a friction test carried out under lowload conditions, the phosphonium cation was oxidized to phosphate to form a boundary film. This film inhibited the reaction of the bis(trifluoromethanesulfonyl)amide anion that yielded metal fluoride on the rubbed surfaces. The combination of the phosphonium cation with a phosphate anion or thiophosphate anion resulted in a better lubricant than 1,3-alkylimidazolium bis(trifluoromethanesulfonyl)amide. The reactions of the phosphate anion and thiophosphate anion yielded a phosphate boundary film that exhibited better tribological properties than those of the fluoride boundary film.

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Section: Determination Of Friction Coefficient Using Pendulum Frictiosupporting

confidence: 47%

Section: Introductionmentioning

confidence: 99%

Tribo-Chemistry of Phosphonium-Derived Ionic Liquids

et al. 2010

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“…Zinc dialkyldithiophosphate (ZDDP) is a well-known lubricant additive and exhibites good tribological properties [18][19][20][21][22]. Fluorine-based ionic liquids exhibit superior tribological properties than ZDDP, because of the formation of tribo-films composed of FeF 2 and FeF 3 during sliding [8][9][10][11][12][13][14][15][16][17]23]. However, use of fluorine-based ionic liquids as a lubricant results in corrosion of metallic materials due to the formation of hydrogen fluoride [8,24].…”

Section: Introductionmentioning

confidence: 99%

“…They have been used as novel highperformance lubricants, because of their attractive properties, such as low vapor pressure, low volatility, high thermal stability, and high oxidation stability [4][5][6][7]. Most of the studies on ionic liquids as lubricants focus on fluorine-based ionic liquids, such as tetrafluoroborate, hexafluorophosphate, trifluoromethanesulfonate, and tris(perfluoroalkyl) trifluorophosphate [8][9][10][11][12][13][14][15][16][17]. Zinc dialkyldithiophosphate (ZDDP) is a well-known lubricant additive and exhibites good tribological properties [18][19][20][21][22].…”

Section: Introductionmentioning

confidence: 99%

Tribological Properties of Cyano-Based Ionic Liquids under Different Environments

Kawada

Sasaki

2018

Tribology Online

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Ionic liquids have been used as novel high-performance lubricants. However, fluorine-based ionic liquids cause corrosion of materials by the formation of FeF 2 and FeF 3 . This study focuses on cyano-based ionic liquids, as they have low corrosion tendencies owing to the absence of fluorine in their structures. However, cyano-based ionic liquids are hydrophilic, and hence, the effect of ambient conditions (e.g., atmospheric moisture) on the tribological properties needs to be investigated. This study reports the tribological properties of two types of cyano-based ionic liquids 1-ethyl-3-methylimidazolium dicyanamide and 1-ethyl-3-methylimidazolium tricyanomethane under air, vacuum, and dry air environments. Their friction coefficients were found to be dependent on the ambient condition. Both the ionic liquids exhibited low friction coefficients in vacuum. The time-of-flight secondary ion mass spectrometry results indicated that the anion was adsorbed on the worn surface under vacuum conditions, and the adsorbed anion exhibited a low friction. In dry air, the cation was adsorbed on the worn surface, and the adsorbed cation exhibited a higher friction coefficient than the adsorbed anion. In air, the cyano-based ionic liquids caused corrosion of the sliding material and exhibited a high friction coefficient, because of the absorption of moisture from air.

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“…Simple carboxylic acids improved the tribological properties of dialkylimidazorium-derived ionic liquids. 4 However, these carboxylic acids are volatile and corrosive. Based on our concept of molecular design of lubricant additives, 5 chemical modification of carboxylic acid by introduction of certain functional group was examined.…”

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confidence: 99%

Aspartic Acid-derived Wear-preventing and Friction-reducing Agents for Ionic Liquids

Minami¹,

Watanabe²,

Nanao³

et al. 2008

Chemistry Letters

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The first additives that improve the tribological properties of ionic liquids were designed. They were evaluated by a ballon-flat type tribo-test under reciprocating motion. Tetraalkylammonium and tetraalkylphosphonium salts of N-protected aspartic acid was dissolved in 1-alkyl-3-methylimidzolium bis(trifluoromethylsulfonyl)imide. They prevented wear remarkably and reduced friction considerably. The salt of N-protected glutamic acid prevented wear but did not reduce friction under the conditions we have evaluated. A new model of boundary film composed of liquid clathrate structure is proposed herein.Ionic liquids are unique fluids that possess non-flammability, non-volatility, and outstanding thermo-oxidative stability. These properties are desirable for lubricating fluids, especially for lubricants used under extreme conditions. Since ionic liquids are composed of anion and cation, variation in their structure is estimated more than one million compounds.1 The tribological properties of certain ionic liquids have been reported. 2 In our previous work, 1,3-dialkylimidazolium-derived ionic liquids were found to exhibit comparable tribological properties to the conventional synthetic lubricants such as perfluoropolyethers. 3 We also pointed out the importance of additives that improve the tribological properties of ionic liquids. However, ionic liquids are strange solvents; they hardly dissolve the conventional lubricant additives. Simple carboxylic acids improved the tribological properties of dialkylimidazorium-derived ionic liquids. 4 However, these carboxylic acids are volatile and corrosive. Based on our concept of molecular design of lubricant additives, 5 chemical modification of carboxylic acid by introduction of certain functional group was examined. Here, we wish to report molecular design of the first additives that improve anti-wear properties of ionic liquids.In our preliminary work, we found that dicarboxylic acids such as succinic and glutaric acid reduced friction of 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (BIMI-TFSI), while adipic acid did not. Solubility of these simple acids in BMIM-TFSI still remains the problem. These simple compounds are volatile and corrosive in fact, however the relation between chemical structure and the tribological properties are of interest. Recently, aspartic acid-and glutamic acid-derived ionic liquids were developed.6-8 The structural features of them are functionalized dicarboxylic acid obtained from natural resources. The ionic structure is beneficial to dissolve them into ionic liquids. Thus, we synthesized trialkylammonium and trialkylphosphonium salts of these amino acids. The free amino group was protected by benzyl or acetyl group to improve the stability. Structure of the designed additives is shown in Figure 1. Samples for the tribo-test were prepared by dissolving the additive in BIMI-TFSI at the concentration of 10 mmol kg À1 .The tribological properties were obtained using a ball-onflat type tribo-tester under reciprocating motion a...

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Effects of Carboxylic Acids on Friction and Wear Reducing Properties for Alkylmethylimidazolium Derived Ionic liquids

Cited by 38 publications

References 6 publications

Tribo-Chemistry of Phosphonium-Derived Ionic Liquids

Tribo-Chemistry of Phosphonium-Derived Ionic Liquids

Tribological Properties of Cyano-Based Ionic Liquids under Different Environments

Aspartic Acid-derived Wear-preventing and Friction-reducing Agents for Ionic Liquids

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