SURFACE CHEMICAL-PROPERTIES OF HOMOLOGS AND ANALOGS OF LYSOPHOSPHATIDYLCHOLINE AND LYSOPHOSPHATIDYLETHANOLAMINE IN WATER

Equilibrium surface tension versus concentration curves for aqueous so lutions of homologs of lysophosphatidylcholine (lysoPC) and lysophosph atidylethanolamine (lysoPE) and two analogs of lysoPC, that is, alkylp hosphoryl-choline and partially fluorinated lysoPC were measured by th e Wilhelmy plate method using a ground-glass plate. From these measure ments the critical micelle concentration (cmc), the molecular area in saturated adsorption, the standard chemical potential of adsorption fr om the infinitely dilute solution to the saturated adsorption surface, and the standard chemical potential of micellization were obtained fo r each lipid. Further, the measurements of the free energy of formatio n of black film, the steady-state fluorescence anisotropy in the non-p olar region of black film and the rate of growth of black film were pe rformed separately for single foam films of the above lipids, together with the measurement of foam stability. By comparing these surface ch emical properties among the respective lysophospholipids, the differen ce in foam stability between lysoPC and lysoPE is discussed in terms o f these static and dynamic properties of solution surfaces and single foam films. (C) 1997 Elsevier Science Ireland Ltd.