A SLOW COLLAPSE OF A MONOLAYER SPREAD ON AN AQUEOUS SURFACE

A microscopic theoretical description of monolayer collapse is suggested: bulk-phase nucleation and growth during its slow compression. Bulk-phase nucleation at small pressures (slightly above IIC) takes place only if defects were initially present in a monolayer. A structure of growing bulk-phase nuclei is proposed. The growth of a solid bulk phase is associated with plastic deformation. The well-known discrepancy between IIC (collapse pressure) and spreading pressure is explained and estimated. It is also shown that the growth of bulk-phase nuclei in a solid monolayer leads to the plastic deformation of the surrounding monolayer. The elastic stresses around a single circular nucleus are calculated, and their contribution to IIC is found. A qualitative explanation is given to the observed facts: a convex form of nuclei and the absence of their coagulation. © 1990, American Chemical Society. All rights reserved.