Free-radical graft copolymerisation of fluorine nanocellulose surfactants

Nanocellulose surfactants (CSFs) were prepared by grafting sodium allyl sulfonate (C₃H₅NaO₃S) and trifluoroethyl methacrylate (C₆H₇F₃O₂) into nanocellulose through free-radical graft copolymerisation. The copolymerisation was carried out by one-step and two-step approaches to preparing CSF-1 and CSF-2 surfactants, respectively. The structure and properties of CSF-1 and CSF-2 were characterised by infrared spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy and surface/interfacial tension measurement. Compared with CSF-1, which was prepared with the one-step approach, a higher fluorine (F) content and a lower crystallinity degree were detected for CSF-2, which was prepared with the two-step approach. The surface tension, critical micelle concentration and oil/water interfacial tension values of the CSFs were 32·5 mN/m, 0·36 g/l and 4·8 × 10⁻² mN/m, respectively, for CSF-1 and 27·4 mN/m, 0·33 g/l, 1·9 × 10⁻² mN/m, respectively, for CSF-2. The lower surface and interfacial tensions confirmed that CSF-2 was endowed with superior surface activity and oil-displacement efficiency. Additionally, CSF-2 displayed enhanced emulsification power in comparison with CSF-1.