FLUORESCENCE MICROSCOPY INVESTIGATIONS OF THE DOMAIN FORMATION OF FATTY-ACID MONOLAYERS INDUCED BY POLYMERIC GEGENIONS

The monolayer behavior of long-chain fatty acids at the air/water interface on a poly(ethyleneimine)-containing subphase was investigated. The distinct influences of the polymer in the subphase on the isothermal behavior were documented: Due to the interaction with the polymeric gegenions the usually condensed fatty acid monolayers could be altered to expanded, compressible films. Their stability was also increased, as indicated by higher collapse pressures. The monolayer morphologies were studied intensively by fluorescence microscopy: The surface textures could be widely varied via the concentration of the polymeric gegenions in the subphase, the temperature, and the chain length of the fatty acid. As a result of the improved stability derived from complexation between the fatty acid monolayer and the dissolved polymer, the monolayers could be transferred, even from relative expanded states, from the air/water interface to solid substrates without damaging the original surface morphology.