Phospholipid monolayers at the hydrocarbon-electrolyte interface. The interrelation of film potential and film pressure

Abstract

Measurements of surface pressure and of surface potential are reported for films of distearoyl phosphatidylcholine (density range: 0.15–2.65 · 10 18 molecules/m 2) spread at the interface between 2,2,4-trimethylpentane and 100 mM NaCl. Low density behavior of the surface pressure is explained using classical virial theory. The behavior of the surface potential is qualitatively explained for all densities in terms of the dipole moments associated with the carboxyl groups and headgroups of the phosphatidylcholine.