pyromellitic acid dianhydride. The hydrophilic arms were formed by polyoxyethylene and hydrophobic ones either by perfluoro- or by alkyl chains. The adsorption monolayers (Gibbs monolayers) were studied by surfacepressure (π) measurements as a function of time for different surfactant concentrations. For the spread monolayers (Langmuir monolayers), the measurements of the surfacepressure (π) versus