Synthesis of fluoroalkyl‐modified polyester and its application in improving the hydrophobicity and oleophobicity of cured polyester coatings

Abstract

ABSTRACTThe fluoroalkyl‐modified polyester (PE‐Fn) was synthesized by the reaction of polyester resin (PE) and fluorinated isocyanate, and the structure of the synthesized product was characterized by proton nuclear magnetic resonance (1H‐NMR) and fluorine nuclear magnetic resonance (19F‐NMR). The water and oil wettability of the cured PE coatings with PE‐Fn as additives was investigated by contact angle meter. The results showed that the introduction of an extremely low concentration of PE‐Fn into PE led to the increase in contact angle of water and diiodomethane on cured PE coatings, and the decrease in the surface free energy. The X‐ray photoelectron spectroscopic (XPS) analysis showed that the F/C molar ratio in the outer few nanometers was significantly higher than that in the bulk, indicating that the fluoroalkyl groups in PE‐Fn had enriched on the coating surface. It was also found that longer fluoroalkyl groups and fluoroalkyl groups with CF3 at its end had the higher tendency to aggregate on the coating surface. The topological structures of the cured coatings were recorded by an atomic force microscope under tapping mode and the results revealed that there was a strong surface segregation of fluorinated species. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39812.