We demonstrate the use of the atomic force microscope (AFM) for studying perfluoropolyether polymer liquid films as thin as sim;20 Aring;. With the AFM we are able to measure three distinct properties of the liquid film: (1) its thickness when the thickness of liquid on the AFM tip is taken into account, (2) the meniscus force acting on the AFM tip as a function of depth into the liquid film, and (3) the topography of the liquid/air interface. All three of these measurements can be done with a very high lateral resolution, sim;1000 Aring;, demonstrating the unique capability of AFM for studying liquid films. With AFM we have observed several interesting properties of these polymeric liquid films. First films thinner than sim;300 Aring; are fairly uniformly distributed, while films thicker than sim;300 Aring; slowly dewet the surface. Second, by measuring the meniscus radius of liquid in a micron sized hole on the surface, we can determine the disjoining pressure in a thin liquid film.
展开▼
