PERFLUOROPOLYETHERS TETHERED TO THE AIR-WATER-INTERFACE

The surface pressure/area isotherms of the perfluoropolyethers (PFPEs) 1 (F-(-(CF2)3O-)n-(CF2)2-X) and 2 (X-CF2-O-(-((CF2)2O)0.4-(CF2O)0.6-)n-CF2-X), with the end groups X = -CF3, -CH2OH, or -COOH, have been determined on water. 1-CF3 and 2-CF3 are not surface active. The collapse pressure is lower for the hydroxy- than for the carboxy-terminated polymers. Below collapse, the isotherm shapes are independent of the nature of the hydrophilic head groups. The isotherms of the polymers with two head groups are more expanded than those of polymers with only one head. Films of 1-COOH can be transferred to glass substrates by the Langmuir-Blodgett technique.