Studies of Surface Segregation and Surface Properties of N-Pentylperfluorooctaneamide End-Capped Semicrystalline Poly(butylene isophthalate) Films

The surface segregation behavior of a series of N-pentyl-perfluorooctaneamide end-capped semicrystalline poly(butylene isophthalate) films (FPBI) was investigated in this work by differential scanning calorimetry, fluorine analysis, contact angle measurements based on axisymmetric drop shape analysis-profile, angle-resolved X-ray photoelectron spectroscopy, ellipsometry and tapping-mode atomic force microscopy (AFM). The fluorine content of the FPBI varied from 0% to 9.14 wt %. AFM measurements indicated a pin-like topography of the FPBI films. The density of pin-like peaks increased with the increase of the fluorine content, indicating that FPBI chains were well organized in the way that the perfluorinated groups oriented toward the film surface. The high hydrophobicity and oleophobicity together with a high fluorine content in the surface region confirmed that the pin-like peaks were due to aggregates of polymer chains with perfluoroalkyl segments. The F/C atomic ratio at the topmost surface was as high as 0.68 and the CF(3)/CF(2) ratio increased significantly from the inner bulk to the film surface.