HYDRODYNAMICS OF DOMAIN SIZE EQUILIBRATION IN MONOLAYERS

Coexisting thermodynamic phases of lipid molecules at the air-water in terface often exhibit microscopically observable domains with a variet y of sizes and shapes. The size and shape equilibration of these domai ns generally involve fluid flow in the monolayer as well as in the aqu eous subphase. The present work treats the problem of the rate of size equilibration of a circular solid domain surrounded by a liquid compo sed of the same substance. The pressure at large distances from the do main is maintained constant, so that there is monolayer flow toward or away from the central domain. The central domain accordingly increase s or decreases in size until a state of stable or metastable equilibri um is reached. Calculated rates of domain size change are discussed in terms of different experimental conditions, including applied electri c fields.