Structural and rheological properties of nanocellulose with different polymorphs, nanocelluloses I and II, prepared by natural deep eutectic solvents from sugarcane bagasse

Sugarcane bagasse, a sugar industry waste, has plentiful cellulose. The present work was aimed to prepare the quality nanocellulose with different polymorphs, nanocelluloses I (NC-I) and II (NC-II) utilizing natural deep eutectic solvents (choline chloride and oxalic acid dihydrate) combined with mechanical treatment from purified cellulose (celluloses I and II), which were prepared from sugarcane bagasse, and to further compare the structural and rheological properties of NC-I and NC-II. Results showed that the yields of NC-I and NC-II were 73.66 ± 0.11 % and 75.15 ± 0.08 %, respectively. Morphology indicated that NC-I had a needle-like appearance with a length of 769.9 ± 76.4 nm and a width of 4.9 ± 1.3, while NC-II displayed a rod-like profile with a smaller size (length: 196.3 ± 50.1 nm; width: 14.9 ± 3.8 nm). Structural characterization revealed that both NC-I and NC-II had high purity, good thermal stability (>300 °C) and high crystallinity (85.5 % and 86 %, respectively). Rheological and zeta potential properties revealed that NC-I suspension had bigger shear resistance, viscoelasticity and lower zeta potential, resulting in better storage stability compared with NC-II suspension. Therefore, the NC-I and NC-II with different characteristics may have potential applications in multiple fields, such as the food, pharmaceutical, and chemical industry.