**4. Conclusions**

In this work, we showed that a mixture of TFA and TFAA can be used as a solvent to produce *all*-cellulose nanocomposites from microcrystalline cellulose and cellulose nanofillers (i.e., short and long nanofibers). Cellulose nanofibers were partially dissolved during the production process, increasing the content of the amorphous phase and reducing the crystallite size of cellulose. This allowed good compatibility with the cellulose matrix. The nanocellulose content affected the final

properties of the composites: keeping excellent transparency, improving mechanical properties, and relatively reducing the water permeability. These characteristics can be exploited in their potential application as food packaging films.

**Author Contributions:** Conceptualization, J.A.H.-G.; Data curation, S.G.-P.; Formal analysis, L.C., S.M., and J.A.H.-G.; Investigation, S.G.-P., G.T., A.S., and J.J.B.; Supervision, A.A. and J.A.H.-G.; Writing–original draft, S.G.-P., L.C., and J.A.H.-G.; Writing–review and editing, S.G.-P., L.C., G.T., S.M., J.J.B., A.A., and J.A.H.-G.

**Acknowledgments:** The authors would like to thank Lara Marini for her assistance with the thermal measurements.

**Conflicts of Interest:** The authors declare no conflict of interest.
