Surface self-assembly of fluorosurfactants during film formation of MMA/nBA colloidal dispersions

These studies focus on the behavior of fluorosurfactants (FS) containing hydrophobic and ionic entities in the presence of methyl methacrylate/n-butyl acrylate (MMA/nBA) colloidal dispersions stabilized by sodium dodecyl sulfate (SDS). The presence of FS significantly not only alters the mobility of SDS in MMA/nBA films, but their hydrophobic and ionic nature results in self-assembly near the film-air (F-A) interface leading to different surface morphologies. Spherical islands and rodlike morphologies are formed which diminish the kinetic coefficient of friction of films by at least 3 orders of magnitude, and the presence of dual hydrophobic tails and an anionic head appears to have the largest effect on the surface friction. Using internal reflection IR imaging, these studies show that structural and chemical features of FS are directly related to their ability to migrate to the F-A interface and self-assemble to form specific morphological features. While the anionic nature of FS allows for SDS migration to the F-A interface and the formation of stable domains across the surface, intermolecular cohesion of nonionic FS allows for the formation of rodlike structures due to inability to form mixed micelles with SDS. These studies also establish the relationship between surface morphologies, kinetic coefficient of friction, and structural features of surfactants in the complex environments.