Optimizing the Production of Bacterial Cellulose Nanofibers and Nanocrystals Through Strategic Fiber Pretreatment

Bacterial cellulose (BC) has unique properties such as high tensile strength, high crystallinity, and high purity. The fiber length of BC causes different attributes. Therefore, the degradation of BC has been studied extensively. In this study, the fibers of BC were rearranged via a DMAc-LiCl solvent and BC was degraded in the wet state. Two different degradation methods were applied: milling with liquid nitrogen and autoclave treatment. The degraded BCs were characterized by FTIR, TEM, AFM, TGA, and XRD. The solvent helps to align the fibers, making them more crystalline. The degraded BCs had a lower crystalline ratio than untreated BC, due to increased hydrogen bonding during degradation in the wet state. Degradation with an autoclave produced two different degraded BCs: nanofibrils and spherical nanocrystals, with and without solvent pretreatment, respectively. The nanofibril lengths were between 312 and 700 nm depending on the applied method, and the spherical nanocrystal size was 56 nm. The rearrangement via solvent causes an important difference in the degradation of BC. Nanofibrils and nanocrystals can be obtained, depending on the rearrangement of fibers before the degradation process.