Instabilités périodiques de Marangoni en système biphasique liquide/liquide : rôle et propriétés de paires d'ions tensioactives

par Vincent Pradines

Thèse de doctorat en Chimie macromoléculaire et supramoléculaire

Sous la direction de Véronique Pimienta.

Soutenue en 2006

à Toulouse 3 .

mots clés

• Instabilités de Marangoni
• Oscillations
• Paires d'ions
• Adsorption mixte
• Calcul ab initio
• Interaction
• Hydrophobes
• Marangoni instability
• Relaxation oscillations
• Ion pairs
• Mixt adsorption
• Ab initio
• Hydrophobic interactions
• Instabilités hydrodynamiques
• Méthodes ab initio (chimie quantique)
• Adsorption

Pas de résumé disponible.

Titre traduit

Periodic Marangoni instabilities in biphasic liquid/liquid system : role and properties of tensioactive ion pairs

Résumé

Oscillations of the electrical potential and interfacial tension have been studied during mass transfer in water/dichloromethane biphasic systems: CTAB/picric acid and SDS/TAAB for which, the chain length of the tetraalkylammonium was varied (from ethyl to butyl). A detailed analysis of the signals recorded allowed us to confirm the hydrodynamic origin (Marangoni instability) of the oscillations. We have determined the physico-chemical properties of all species involved (partition and adsorption constant, molecular area, and association constant of the ion pairs). For this, measurements of the surface tension, UV/Visible spectrophotometry and mass spectrometry have been performed. For the SDS/TAAB system, we have observed increasing association of TAADS ion pairs with chain length. We have also carried out theoretical calculations (DFT, Ab-initio) to highlight a geometry supporting the hydrophobic interactions between the two ions.