DELAYED APPEARANCE OF THE LIQUID-CONDENSED PHASE IN 1-OCTADECANOL FILMS ON LEVITATED WATERDROPS

We have observed dramatic delays in the formation of the liquid-condensed phase of 1-octadecanol thin films on the surface of levitated water drops as the drops evaporate into a flowing gas stream. When the aqueous substrate starts with more than 1.0X10(-4) M EU(3+) (EDTA), the liquid-condensed phase of 1-octadecanol appears, as expected, at a surface concentration equivalent to one monolayer. As we reduce the initial EU(3+) (EDTA) content, higher and higher surface concentrations of 1-octadecanol are reached prior to the appearance of the liquid-condensed phase. At initial concentrations of EU(3+) (EDTA) below similar to 4.0X10(-7) M, the average surface concentration at the liquid-condensed phase change exceeds ten monolayers. Light-scattering data attest to the presence of small, <400 nm radius, 1-octadecanol particles initially dispersed throughout the substrate. We demonstrate that these particles are collected by the shrinking drop surface with minimal diffusion of the particles to the surface.