Fluorine-based surface decorated cellulose nanocrystals as potential hydrophobic and oleophobic materials

The objective of this research is to provide the first account of a simple preparation of surface fluorinated bulk cellulose nanocrystals and a characterization of their physical and chemical properties. The surface fluorinated, or polyfluorinated cellulose nanocrystals were first generated by reacting bulk cellulose with hydrochloric acid in an aqueous medium to yield cellulose nanocrystals that were subsequently purified and reacted with pentafluorobenzoyl chloride in presence of pyridine. The degree of substitution (out of a possible 3.0 hydroxyl groups/anhydroglucopyranose residue) of the polyfluorinated cellulose nanocrystals was 0.77. It was found that the dispersion of cellulose nanocrystals within an organic solvent was significantly improved following surface fluorination. Dynamic contact angle, FT-IR, NMR, TGA, DSC, XRD and XPS were used to confirm the fluorinated character of the reactant products. The polyfluorinated cellulose nanocrystals obtained and characterized demonstrated excellent hydrophobic and oleophobic properties to establish themselves as viable candidates in the consideration of a non-traditional and highly attractive conceptual paradigm for their inclusion as a nanofiller in a variety of low surface energy applications.