PROPERTIES OF HYDROPHOBIC POLYMER MELTS TETHERED TO THE WATER-SURFACEAS DETERMINED WITH IN-SITU X-RAY REFLECTIVITY

Insoluble monolayers of hydrophobic polymers with low glass transition temperature (perfluoropolyethers, polyisoprenes) and a single ionic h ead group (carboxylic acid, sulfonate) have been characterized at the air/water interface via X-ray reflectivity measurements. The films are considerably thicker (30-420 Angstrom) than conventional Langmuir mon olayers of low molecular weight substances or polymers with surface ac tive repeat units. The thickness is inversely proportional to the area per head group and is in accordance with a model assuming a solvent-f ree hydrophobic layer of the same density as the bulk material.