Forces measured in a swollen lyotropic lamellar mesophase confined between solid surfaces

Abstract

The measured force as a function of separation between two mica surfaces immersed in a swollen lyotropic lamellar mesophase (interlamellar spacing 25–30 nm) is an oscillatory function of distance superimposed on a background attraction. The periodicity of the oscillations matches the bulk layer spacing at large surface separations, but it decreases at smaller separations, suggesting that the interlayer repulsion is due to fluctuations of the interfaces. The solid walls reduce these fluctuations, leading to a negative disjoining pressure.