Effet Ouzo : Mélange, Coalescence, Répulsions Kevin Roger kevin.roger@espci.fr Bernard Cabane, Robert Botet, Bob Prud’homme, Christina Tang

Le basculement de solvant en image Diamètre (nm) PMMA + Acetone Eau

Basculement de solvant, effet Ouzo et système modèle Water Polymer solution Swollen PMMA nanoparticles PMMA Acetone

Comprendre les mécanismes ANR Limouzine : Limite Ouzo, Interprétation, Estimation

Hydrodynamique et Physico-chimie Uncoupling Polymer Solution Water Coupling

Uniform hydrodynamic domains Contrôler le mélange Homogeneous mixing : Uniform hydrodynamic domains Controlled mixing: Flux control to tune the size of the domains B.K. Johnson and R.K. Prud’homme and B. Cabane, AIChE journal, 2003

Couplage ou découplage Polymer fraction Bad Mixing 10-2 5.10-3 10-3 10-4 Good Mixing Homogeneous mixing : no more Ouzo boundary Uncoupling in good mixing conditions : opportunity to study the precipitation K. Roger*, C. Tang, R.K. Prud’homme and B. Cabane, unpublished

Synchrotron X-ray beam Suivi cinétique SAXS Synchrotron X-ray beam Fast-mixing chamber (5ms) Stop the flow Start acquisition Detector Acetone-filled Syringe (buffer) Water-filled syringe Polymer solution-filled syringe Instrument ID02, ESRF, Grenoble K. Roger*, R. Botet and B. Cabane, Langmuir, 2013

Courbes de diffusion de RX résolues en temps Porod limit Total surface time Oscillation Polydispersity Large distances Small distances

Growth through coalescence Coalescence … lente Porod limit Total Surface Invariant Total Volume Logarithmic Growth Law Rmean = a.ln(t)+b Decreasing number of droplets Growth through coalescence

The polydispersity decreases with time ! Un chemin vers des populations étroites Distributions obtained through an original inversion procedure Method in : R.Botet & B.Cabane Journal of Applied Crystallography 2012 The polydispersity decreases with time !

Contrôle par les charges de surface Adding surface charge (square dependence) OK for concentration dependence (log scale)

Un outil sensible - … Surface charge determines the size of the droplets Mean Radius decreases with the square of the surface charge Indirect method to quantify the surface charge

Air bubbles are moving to the cathode (Quincke 1861) Un vieux problème : la charge des systèmes purifiés Air bubbles are moving to the cathode (Quincke 1861) Oil droplets are moving to the cathode (Carruthers 1938)

? |μ| 20 kT pH Des observations générales Marinova et Al, Langmuir 1996 Surfactant-free conditions? OH- adsorption? Special water structuring? 20 kT |μ|

Les impuretés sont partout… The purer the oil, the less stabilizer is available The stabilizer is in the oil and is not hydroxide ions. Adding fatty acids to 99.8%-pure C16 reproduces the behavior of 99%-pure C16 K. Roger* and B. Cabane, Angewandte Chemie 2012

Et quand on s’en débarrasse… No colloidal metastability without charged end-groups PMMA-COOH particles PMMA-H particles K. Roger*, M. Eissa, A. Elaissari and B. Cabane, Langmuir 2013

Comprendre l’importance du mélange Bad Mixing Polymer fraction 10-2 5.10-3 10-3 10-4 Good Mixing Dangerous area below the binodal : no repulsions

Mélanges de polymères : l’effet Ouzo à plusieurs soluté

Mélanges de polymères : l’effet Ouzo à plusieurs soluté Mixing PMMA-COOH (M=9900) and PMMA-H (M=9800) Fraction en PMMA-COOH : x Mixing PMMA-COOH (M=9900) and PMMA-H (M=25000) Fraction en PMMA-COOH : x

Merci de votre attention Suite des festivités avec Robert Botet sète après-midi