Electrostatic pressure and line tension in a Langmuir monolayer.

Abstract

We present a Brewster angle microscopy study of the domains of liquid condensed phase $({L}_{2})$ in the liquid expanded phase $({L}_{1})$ in a Langmuir monolayer of a long-chain fatty acid. A strong deformation of the domains is observed when they are close to each other, indicating the presence of long-range repulsive dipolar interactions between them. The line tension of the ${L}_{1}{/L}_{2}$ interface is deduced from the balance between the line tension and the electrostatic forces. The latter were deduced from surface potential measurements.