SURFACE-ACTIVITY OF PERFLUORODECANOYL END-CAPPED POLY(ETHYLENE OXIDE)AND ASSOCIATED ADSORPTION BEHAVIOR TO THE AIR-WATER-INTERFACE

The structure and adsorption kinetics of poly(ethylene oxide) end-capp ed with perfluorodecanoyl groups either at one or both ends have been characterized. These nearly monodisperse polymers with molecular weigh ts in the range of 400-16 K g/mol are effective nonionic surfactants w ith very high surface activity. For aqueous solutions with concentrati ons in the range of 2-8 mg/ml, surface tensions determined by the drop -volume method are as low as 13.6- 18.0 mN/m at 20 degrees C. At high surface coverage, close-packed PEO chains with one end capped form a b rush-like structure at the interface. Polarized infrared reflectance s pectroscopy showed that perfluoroalkyl groups were nearly perpendicula r to the air-water interface. The molecular area per chain was 30-32 A ngstrom(2) for poly(ethylene oxide) capped only at one end and 36-40 A ngstrom(2) for poly(ethylene oxide) with both ends capped. Only 22% of poly(ethylene oxide) chains with both ends capped form loops at the i nterface, while the remaining chains form an extended structure at hig h surface coverage. (C) 1998 Elsevier Science Ltd. All rights reserved .