  Plasma treatment of polymer films results in their electrical charging, which
in turn gives rise to an increase in their surface energy. The process results
in pronounced hydrophilization of the polymer surfaces. A phenomenological
theory relating the change in the apparent contact angle of charged solids to
the surface density of the electrical charge is introduced. Partial wetting,
inherent for polymer films, becomes possible until the threshold surface
density of the electrical charge is gained. The predictions of the theory are
illustrated by plasma-treated polymer films and inflatable latex balloons.
Deflating the plasma treated latex balloons resulted in an essential increase
in the surface charge density of the latex. This increase switched the wetting
regime from partial to complete wetting. The kinetics of hydrophobic recovery
follows the kinetics of the electrical charge leakage from the surfaces of the
plasma treated polymers. The characteristic time of the surface charge leakage
coincides with the time scale of the decay of the electret response of plasma
treated polymer films.
