Propriétés tensioactives de phosphobétaïnes neutres à distance intercharge modulée Surfactant Properties of Neutral Phosphobetaines with a Modulated Intercharge Distance

Abstract

Une famille de phosphobétaïnes neutres (I) à caractères structuraux variés - chaînes lipophiles R = C12H25 et C18H37; distances intercharges définies par un nombre de groupe méthylène n entre têtes polaires (2 A family of neutral amphiphilic phosphobetaines (I), with R = C12H25 or C18H37, with 2 < n < 6, and with R3 -ethoxy and phenyl, was investigated in pseudo-ternary-phase diagrams as new surfactants. In all cases, microemulsions are depicted with the occurrence of Winsor type systems, WI, WII and WIll. Remarkable variations in the diagrams are observed with molecular structural changes of zwitterionic amphiphiles. Interionic distances effects are obtained in the WI and WIll phases, suggesting a polar head surface change, while the HLB factor implies the appearance of differently ordered structures. The nature of the substituent covalently bonded on phosphorus can be used as a molecular probe to check the hydrophilicity of amphionics. Analyses of phases behaviors under various salinity and temperature conditions are also described, and attempts are made to rationalize these variations through the molecular parameters of the surfactants. On the basis of these results, an analysis can be made to optimize the structural parameters of surfactants for use as additives in tertiary oil-recovery processes.