LOCAL MECHANICAL-PROPERTIES OF MONOMOLECULAR FILMS ON WATER MEASURED WITH A CAPILLARY WAVE PROBE

The distribution of local mechanical properties in monolayers spread on water has been measured for the first time by means of a capillary wave probe. Under a uniaxial compression, strong inhomogeneity and anisotropy of the surface pressure were found in films known for their stiffness. Stiff films can also have sharp edges at essentially zero pressure delineating a continuous monolayer sheet against a bare water surface. The boundary is visible with the capillary wave probe because of the large elastic modulus of the monolayer. These findings should be taken into account in interpreting the pressure-area relationship of stiff monolayers as well as in making the strategy for fabricating high-quality Langmuir-Blodgett films from these monolayers. © 1990, American Chemical Society. All rights reserved.