Imaging of Features on Surfaces by Condensation Figures

Abstract

Condensation of a vapor to a liquid on a cold surface that is not wet completely by this liquid leads to the formation of an array of droplets. If the surface is heterogeneous in its physical properties (especially its interfacial free energy), the patterns of these arrays reflect this heterogeneity. The distribution of droplets of water (condensation figures or CFs) observed by optical microscopy on a surface can be correlated with the molecular structure of that surface. The substrates used to investigate the formation and morphology of the CFs were patterned, self-assembled monolayers of different alkanethiolates on gold and of alkyl siloxanes on glass. Analysis of CFs is a valuable nondestructive technique for characterizing heterogeneities in surfaces.