Scanning Electric Potential Microscopy Imaging of Polymer Latex Films: Detection of Supramolecular Domains with Nonuniform Electrical Characteristics

Scanning electric potential microscopy (SEPM) together with noncontact AFM images were obtained from the surfaces of two latex films:  the first is a self-arrayed poly(styrene-co-hydroxyethyl methacrylate) macrocrystal, while the other is a thin film formed by coagulation of polystyrene particles at the latex liquid surface, under exposure to chloroform vapor. In both cases, large electric potential differences are detected by the microscope probe between adjacent domains in the films. Domains with positive or negative potentials reach a few hundred nanometers in size. These dielectric films are thus mosaics of electrically charged domains, and their electroneutrality is only observed at the macroscopic level.