INVESTIGATION OF LAYERED MICRODROPLETS USING ELLIPSOMETRIC TECHNIQUES

Previously single wavelength ellipsometry has been successfully used t o study the spreading of liquid polymer microdroplets on solid substra tes. Extending that experimental approach, we present in this study th e first experiments of spatially resolved spectroscopic ellipsometry a pplied to the spreading of layered microdroplets and show that it is p ossible to recover the experimental thickness profiles of polydimethyl siloxane and squalane on hydrophilic silicon wafers. To complement the se molecular measurements, we also present new computer simulation res ults concerning the velocity field and the mass transfer during this s preading process. These results are in agreement with the predictions of the de Gennes-Cazabat model. (C) 1998 Elsevier Science S.A.