Molecular layers of a polymer at the free water surface : microscopy at the Brewster angle

Abstract

A recently developed microscope, allowing the visualization of monolayers at liquid surfaces without the addition of fluorescent molecules, is used to study molecular layers of a polymer, poly(dimethylsiloxane), on water. Coexistence of domains of different surface density is observed, both at low concentrations and at concentrations above collapse. Small isolated domains are circular ; characteristic relaxation times for a deformed domain are measured. These relaxation times, coupled with the very low surface viscosities previously measured, suggest very low line tensions (∼10-13 N). Small changes in experimental conditions can result in the destabilization of domain borders.