Task-Specific Ionic Liquids and Deep Eutectic Solvents for Lubrication Nanotechnology

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Picolinium‐based hydrophobic ionic liquids as additives to PEG200 to lubricate steel‐silicon contacts

Publication . Donato, Mariana T.; Caetano, Fernando J. P.; Colaco, Rogério; Branco, Luís C.; Saramago, Benilde

New ionic liquids (ILs) based on picolinium, [C6-x-pic][TfO] where x=2, 3 and 4, were successfully synthesized using microwave process. The performance of these ILs as additives to model lubricant oil PEG200 was evaluated and compared with that of other ILs sharing the same hydrophobic anion, using the tribological pair steel sphere/Si surface. [C6-4-pic][TfO] was the most efficient additive, which may be attributed to the symmetry of the cation leading to an ordered adsorbed layer.

2020-05-26Journal article

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Improving the lubrication of silicon surfaces using ionic liquids as oil additives: the effect of sulfur-based functional groups

Publication . Antunes, Mónica; Donato, Mariana T.; Paz, Victória; Caetano, Fernando J. P.; Santos, Luís; Colaco, Rogério; Branco, Luís C.; Saramago, Benilde

The performance of micro/nanoelectromechanical systems (MEMS/NEMS) relies on efficient lubrication. In the present work, new sulfur-based organic salts were tested as additives in a polyethylene glycol to lubricate silicon surfaces used in the manufacture of MEMS/NEMS. Seven salts were tested: 1-butylsulfonic-3-methylimidazolium triflate [(C4SO3H)MIM][TfO], thiamine triflate [Thiamine][TfO]2, 1-ethyl-3-methylimidazolium camphorsulfonate [C2MIM][CSA] [isomers (R) and (S)], 1,3-dimethylpiridinium methylsulfate [C1-3pic][MeSO4], methylimidazolium methanesulfonate [HMIM][MeSO3], and tetramethylguanidine methanesulfonate [TMG][MeSO3]. A nanotribometer was used to determine the friction coefficients using steel spheres as counter bodies. Excellent tribological properties were achieved with the additives containing the anions [MeSO4]− and [MeSO3]−. The films formed on the Si substrates were studied by FTIR, ellipsometry and AFM. A mixed lubrication mechanism was proposed where additive adsorption avoids contact between sliding surfaces.

2020-05-14Journal article

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