Description du sujet de thèse

Nowadays, water-ethanol solutions are used in many industrial processes as well as in fundamental research. All these observation make the appearance of déjà vu. But careful discussions with perfume industrials or spirit experts point out robust and popular beliefs, such as the over-week maturation required after the perfume mixing, or the taste-opening of distilled whiskey by a water droplet.
From a fundamental perspective, the water-ethanol system is the famous textbook example of non-ideal mixture (cf figure). Most of the macroscopic experimental observations are in favour of large-scale segregation. For example, Franks1,2 explains that the positive excess Gibbs Enthalpy (GE) of +0.3kBT “is always encountered in systems which separate” and give the example of the butanol/water mixture that exhibits two macroscopic coexisting phases with the same GE. A few papers pointed out the existence of heterogeneities,3 without exploring large space scale and slow dynamics. Half a century later, this scientific case is still unresolved.
1] Franks, F. & Ives, D. Structural Properties of Alcohol-Water Mixtures. Quarterly Reviews 20, 1 (1966).
2] Franks, F. & Desnoyers, J. Alcohol-Water Mixtures Revisited. Water Science Reviews 1, 171–232 (1985).
3] Dixit, S., et al, Molecular segregation observed in a concentrated alcohol-water solution. Nature 416, 829–832 (2002).

Contexte de travail

The PhD project will be focused on experimental techniques able to characterize both multi-scale structures and dynamics of these heterogeneities at the atomic scale (Vibrationnal and Nuclear techniques), at the molecular supramolecular scale (X-ray Scattering in house and on Synchrotron Sources), and macroscopic scales (varied light scattering techniques).
The PhD student will work in collaboration with groups in Prague (P. Stepanek), NYC (O. Gang), synchrotron SOLEIL (T. Bizien). In Rennes, the PhD Student will benefit from complementary experimental techniques (Raman, FTIR, NMR, X-ray Scattering, original optical set-up) as well as state of international leader in liquid mixture molecular dynamic (A. Ghoufi).