Abstract

Cellulose nanofiber films (CNFF), were treated via a welding process using ionic liquids (ILs). Acid-base conjugated ILs derived from 1,5-diazabicyclo[4.3.0]non-5-ene [DBN] and 1-ethyl-3-methylimidazolium acetate ([emim][OAc]) were utilized. The removal efficiency of ILs from welded CNFF was assessed using liquid-state nuclear magnetic resonance (NMR) spectroscopy and Fourier transform infrared spectroscopy (FTIR). The mechanical and physical properties of CNFF indicated surface plasticization of CNFF, which improved transparency. Upon treatment, the average CNFF toughness increased by 27 % and the films reached a Young modulus of ~5.8GPa. These first attempts for IL ‘welding’ show promise to tune bio-based films surfaces, expanding the scope of properties for the production of new bio-based materials in a green chemistry context. The results of this work are highly relevant to the fabrication of CNFFs using ionic liquids and related solvents