Preparation of Chitin Nanofiber-Reinforced Cellulose Films Through Stepwise Regenerations from Individually Prepared Ion Gels

In this study, we investigated the preparation of chitin nanofiber (CNF)-reinforced cellulose films through stepwise regeneration procedures from the respective ion gels with ionic liquids. Self-assembled CNF dispersions were prepared by regeneration from the chitin ion gel with the ionic liquid, 1-allyl-3-methylimidazolium bromide, using methanol, followed by dilution with adjusted amounts of methanol. Cellulose ion gels with the ionic liquid, 1-butyl-3-methylimidazolium chloride, were then prepared, soaked in the CNF dispersions, and centrifuged to simultaneously occur regeneration of cellulose and compatibilization with the CNFs. Soxhlet extraction with methanol and subsequent drying of the resulting materials gave the CNF/cellulose composite films. The IR and SEM results of the films indicated the presence of CNFs not only on the surfaces of the films but also inside the films. Powder X-ray diffraction patterns showed the amorphous structure of the cellulose in the film. Tensile testing of the films suggested the reinforcing effect of the CNFs on the mechanical properties of the films.