Séminaire de Marija Bester-Rogac (Univ. of Ljubljana) :
Ionic liquids in water : from simple electrolytes to surfactants
le mardi 18 juin 2019 à 13h, bibliothèque de PHENIX, couloir 32-42, 2ème étage.
Résumé
It is known, that the bulk and interfacial structures of pure ionic liquids (ILs) exhibit exceptional diversity so in the nature of ions as well as in the organization of these ions in the liquid phase [1, 2]. By increasing the alkyl cationic side-chain length even the transition from the known spatially heterogeneous structure to a liquid crystal-like phase was observed [3]. However, the growing number of reviews dealing with the physico-chemical properties of ILs in their pure state has been extended to investigations of their mixtures with molecular co-solvents.
In this seminar first it will be shown, that ILs in solutions can serve as excellent model (electrolyte) systems. It turned out, that the association of imidazolium based ILs – as model 1,1-electrolytes – in water is weak, but evidently dependent on the molecular structure (alkyl chain length), which also strongly affects the mobility of imidazolium cations [4]. According to experimental and computational results, hydrophobic hydration of the side chain on the imidazolium ring is most responsible for structure making/breaking properties of investigated imidazolium salts [5].
Next, ionic liquids with long alkyl chains will be discussed. They behave similar to conventional surfactants forming aggregates in water [6,7], but due to the possible variations in the chain length and counter-ions they are extremely appropriate for studying ion and isomer effects on self-assembly processes in solutions.
In addition, the isotherm titration calorimetry (ITC) will be represented shortly as one of the most powerful techniques for the thermodynamic characterization of aggregation processes in solutions.
References
[1] T. L. Greaves, C. J. Drummond. Chem. Rev., 115 (2015) 11379.
[2] R-Hayes, G. G. Warr, R. Atkin. Chem. Rev., 115 (2015) 6357.
[3] Y. Ji, R. Shi, Y. Wang, G. Saielli. J. Phys. Chem. B, 117 (2013) 1104.
[4] M. Bešter-Rogač, M.V. Fedotova, S.E. Kruchinin, M. Klähn. Phys. Chem. Chem. Phys., 18 (2016) 28594.
[5] R. Tomaš, A. Tot, J. Kuhar, M. Bešter-Rogač. J. Mol. Liq., 2018, 254, 267–271.
[6] B. Šarac, Ž. Medoš, A. Cognigni, K. Bica, L.-J. Chen, M. Bešter-Rogač. Colloid Surf. A, 532 (2017) 609.
[7] I. Čobanov, B. Šarac, Ž. Medoš, M. Vraneš, S. Gadžurić, N. Zec, M. Bešter-Rogač, J. Mol. Liquids, 271, (2018) 437.
