1KTH Royal Institute of Technology, Stockholm, Sweden
2University of New South Wales, Sydney, Australia
3Ecole Centrale de Lyon, Lyon, France
Tribological additives and lubricants are some of the less glamorous applications of ionic liquids, but they are of interest due to their tuneability and also due to the possibility of controlling the surface composition using an applied field. Much work remains to understand the interfacial properties of these liquids and their corresponding frictional behavior. Of particular interest are ionic liquids with orthoborate based anions, which avoid the issue of fluorination – however relatively little is known about their properties otherwise.
Quartz crystal microbalance, Vibrational sum frequency spectroscopy and neutron reflectance have been applied at isolated interfaces, whereas confined properties have been studied using AFM and Surface Forces (ATLAS). In both cases applied electric fields are applied and the electroresponsiveness measured. The role of water is also addressed, and found to be important in this context. A brief summary of conclusions will be presented.
Watanabe, S.; Pilkington, G. A.; Oleshkevych, A.; Pedraz, P.; Radiom, M.; Welbourn, R.; Glavatskih, S.; Rutland, M. W., Interfacial structuring of non-halogenated imidazolium ionic liquids at charged surfaces: effect of alkyl chain length. Phys Chem Chem Phys 2020,22 (16), 8450-8460.
Pilkington, G. A.; Welbourn, R.; Oleshkevych, A.; Watanabe, S.; Pedraz, P.; Radiom, M.; Glavatskih, S.; Rutland, M. W., Effect of water on the electroresponsive structuring and friction in dilute and concentrated ionic liquid lubricant mixtures. Phys Chem Chem Phys 2020, 22 (48), 28191-28201.
Pilkington, G. A.; Oleshkevych, A.; Pedraz, P.; Watanabe, S.; Radiom, M.; Reddy, A. B.; Vorobiev, A.; Glavatskih, S.; Rutland, M. W., Electroresponsive structuring and friction of a non-halogenated ionic liquid in a polar solvent: effect of concentration. Phys Chem Chem Phys 2020, 22 (34), 19162-19171.
Shah, F.U., A. Holmgren, M.W. Rutland, S. Glavatskih, and O.N. Antzutkin, Interfacial Behavior of Orthoborate Ionic Liquids at Inorganic Oxide Surfaces Probed by NMR, IR, and Raman Spectroscopy. The Journal of Physical Chemistry C, 2018. 122(34): p. 19687-19698.
Hjalmarsson, N.; Bergendal, E.; Wang, Y. L.; Munavirov, B.; Wallinder, D.; Glavatskih, S.; Aastrup, T.; Atkin, R.; Furo, I.; Rutland, M. W., Electro-Responsive Surface Composition and Kinetics of an Ionic Liquid in a Polar Oil. Langmuir 2019, 35 (48), 15692-15700.
Radiom, M., P. Pedraz, G. Pilkington, P. Rohlmann, S. Glavatskih, and M.W. Rutland, Anomalous Interfacial Structuring of a Non-Halogenated Ionic Liquid : Effect of Substrate and Temperature. Colloids and Interfaces, 2018. 2(4).
Pilkington, G.A., K. Harris, E. Bergendal, A.B. Reddy, G.K. Pålsson, A. Vorobiev, O.N. Antzutkin, S. Glavatskih, and M.W. Rutland, Electro-responsivity of ionic liquid boundary layers in a polar solvent revealed by neutron reflectance. Journal of Chemical Physics, 2018. 148(19).