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

Sol-gel reaction of two fluoroalkyl end-capped vinyltrimethoxysilane oligomer [R-F-(CH2CHSi(OMe)(3))(n)-R-F; R-F = CF(CF3)OC3F7;n = 2, 3: R-F-(VM)(n)-R-F] in the presence of cellulose nanofiber (CNF) under non-catalytic conditions was found to provide the corresponding fluorinated oligomeric silica/CNF composites [R-F-(VM-SiO3/2)(n)-R-F/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 R-F-(VM-SiO3/2)(n)-R-F/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 R-F-(VM-SiO3/2)(n)-R-F/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.

Automated summary

In this study, fluorinated oligomeric silica/CNF composites were prepared via sol-gel reaction, leading to surface modification of glass and PET fabric with oleophobic/superhydrophobic or superoleophilic/superhydrophobic characteristics. The modified materials exhibited excellent performance in oil-water separation and oil droplet adsorption.