Preparation and applications of wettability-controlled fluoroalkyl end-capped oligomer/cellulose nanofiber composites

Abstract

Sol-gel reaction of two fluoroalkyl end-capped vinyltrimethoxysilane oligomer [RF-(CH2CHSi(OMe)3) n-RF; RF = CF(CF3)OC3F7; n = 2, 3: RF-(VM) n-RF] in the presence of cellulose nanofiber (CNF) under non-catalytic conditions was found to provide the corresponding fluorinated oligomeric silica/CNF composites [RF-(VM-SiO3/2) n-RF/CNF]. The obtained composites were applied to the surface modification of glass to give a good oleophobic/superhydrophobic characteristic on the composite surface due to the fabrication of the roughness architecture. The RF-(VM-SiO3/2) n-RF/CNF composites were also applied to the surface modification of poly(ethylene terephthalate) [PET] fabric swatch, affording a superoleophilic/superhydrophobic characteristic on the modified fabric surface. Modified PET fabric swatch thus obtained was applicable to not only the separation membrane to separate the mixture of oil/water but also the perfect adsorption of oil droplets spread on water interface. In addition, we have prepared the RF-(VM-SiO3/2) n-RF/CNF composites films by casting homogeneous aqueous methanol solutions containing the corresponding composites. Pristine CNF film afforded the superoleophilic property on the surface; however, it was demonstrated that the obtained transparent colorless CNF composite films can supply highly oleophobic characteristic on the surface.