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

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

• Auteur / Autrice : Vincent Pradines
• Direction : Véronique Pimienta
• Type : Thèse de doctorat
• Discipline(s) : Chimie macromoléculaire et supramoléculaire
• Date : Soutenance en 2006
• Etablissement(s) : Toulouse 3

Mots clés

Mots clés contrôlés

Adsorption

Méthodes ab initio (chimie quantique)

Instabilités hydrodynamiques

Mots clés libres

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

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.