Preparation and properties of halloysite nanotubes/waterborne polyurethane fluorinated composite film

The halloysite nanotubes/waterborne polyurethane (HNTs/WPU) composite film was synthesized by both in-situ polymerization and surface fluorination method. The effects of the content of amine-modified halloysite nanotubes(AHNTs) and the modification of fluoroalkylsilane(FAS) on the properties of AHNTs/WPU composite film were also investigated. The results show that the mechanical properties and thermal resistance of the AHNTs/WPU composite film increase first and then decrease with the increase of the mass ratio of AHNTs to WPU, and the hydrophobicity improve. When the mass ratio of AHNTs to WPU is 1.5%, the AHNTs/WPU composite film has better comprehensive properties. The tensile strength of the AHNTs/WPU composite film increases by 50% and the elongation at break increases by 35%; the initial thermal degradation temperature (T_d5) increases by 9℃ comparing with pure WPU. The water absorption ratio of the AHNTs/WPU composite film decreases to 5.8%, the water contact angle increases to 95.1°. After fluorination of the AHNTs/WPU composite film, the water contact angle of the composite film is 114.5°. The AHNTs/WPU composite film shows hydrophobicity. The surface fluorination treatment has significant effect on the mechanical properties and water absorption ratio of the AHNTs/WPU composite film.