Langmuir films of (alpha-amino) phosphorus amphiphiles on various ion-containing subphases.
Monolayers of amphiphilic (alpha-amino)phosphonocarboxylic and (alpha-amino)phosphonic acids have been formed by adsorption at the air/water interface. The influence of both the ionic strength and the pH of the subphase on the stability and compactness of the monolayers have been studied. The stability and the compactness of the Langmuir films are enhanced by introduction of metallic ions such as Ca(2+) or Mg(2+) in the subphases. These effects are more pronounced with Ca(2+). These metal ions can form dimeric complexes with the phosphorus moieties of the surfactant polar heads and therefore bring the amphiphiles closer. For the less hydrophobic derivative, complexation with Ca(2+) or Mg(2+) is required to ensure the formation of a stable monomolecular film. For both phosphonocarboxylic and phosphonic compounds, models have been proposed to represent the complexation phenomenon at the air/water interface.
Al-Ali
Fatima
F
Laboratoire des Interactions Moléculaires et Réactivité Chimique et Photochimique (UMR CNRS 5623), Université Paul Sabatier, Bât. IIR1, 118, route de Narbonne, 31062 Toulouse Cedex 04, France.
Déjugnat
Christophe
C
Etemad-Moghadam
Guita
G
Rico-Lattes
Isabelle
I