Preparation of super-hydrophobic cotton fabrics with the controllable roughening fiber surface by carbene polymerization grafting

Abstract

Superhydrophobic cotton fabrics were successfully prepared by grafting modification of cotton fabrics through carbene polymer induced crystallization and self-assembly. The structures and properties of grafted polymer crystals on the surface of cotton fabrics were examined by scanning electron microscopy (SEM), fourier transform infrared spectroscopy (FT-IR) and nuclear magnetic resonance spectroscopy (NMR). The surface grafting positions with diazo active groups were pre-constructed on the fibers. The 3,3,4,4,5,5,6,6,6-nonfluorohexyl diazoacetate (Hex(C4F9)DA) and 3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyl diazoacetate (Oct(C6F13)DA) were synthesized as precursors followed by carbene grafting to fiber. Under different reaction conditions, the polymer crystallized on the fiber surface and produced different morphologies such as solid rods, hollow rods, and spheres. The surface morphology was controllable by changing the medium, reaction time and kinetic conditions. When 3,3,4,4,5,5,6,6,6-nonfluorohexyl diazoacetate (Hex(C4F9)DA) was used as the precursor and tetrahydrofuran (THF) as the solvent, the grafted cotton fabric exhibited excellent hydrophobic properties with a water contact angle of 152°. When 3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyl diazoacetate (Oct(C6F13)DA) was used as the grafting precursor, THF or THF/EtOH mixed solvent was used as the reaction medium, the contact angle of the as-prepared cotton fabric to water was measured to be 151° and 154°, respectively. During the carbene grafting polymerization, the solvent has a significant influence on the morphology of the grafted polymer. The WCA and EDS results suggest that the synergistic effect between the rough structure of the grafted cotton fabric surface and the low surface energy of fluorine element made the fabric super-hydrophobic.