Topography of thin teflon layers and induced orientation of nematic liquidcrystals

It has recently been shown that teflon (PTFE) films can be used as orientat ion layers to align liquid crystal molecules. In this paper we study the in fluence of the deposition parameters (pressure, speed and temperature) on t he layer morphology given by both optical and atomic force microscopy. In a ddition, we have measured the surface pretilt angle induced on nematics by these films. It turns out that teflon gives a small pretilt, of the order o f 0.3 degrees, at the surface. Although the topography of the deposited lay er is seen to vary, the characteristic nematic textures do not vary with a variation of the deposition parameters.