Journal of Physical Chemistry B, Vol.102, No.37, 7210-7215, 1998
Scanning polarization force microscopy study of the condensation and wetting properties of glycerol on mica
The condensation of glycerol on mica surfaces in ambient air was studied with scanning polarization force microscopy (SPFM). Two different wetting regimes were found that depend on the state of the surface. On freshly cleaved mica, glycerol condenses, forming flat films. The films expand until a uniform layer is formed. The first molecular layer of glycerol was found to be more strongly bound to the surface than were subsequent layers, On contaminated mica (after 2 h of exposure to air) droplets in the shape of spherical caps form that partially wet the substrate. The droplets grow indefinitely in the saturated vapor. The contact angle of droplets with heights <20 nm was found to deviate from the macroscopic value found in large drops. The results are discussed in the context of the long-range forces in the liquid film.