High-yield nanocellulose from supramolecular chemistry-driven delignified softwood

In this study, nanocellulose (NC) was produced via ultrasonication of supramolecular chemistry-driven delignified softwood with thymol and methanesulfonic acid-based solvent. Supramolecular chemistry-driven delignification could be performed under very mild conditions (40 °C-60 °C for 1-5 min), allowing the production of cellulosic pulp (CP) with low lignin content to take place with very low energy consumption. Due to the mild conditions, CP with good optical properties (high whiteness) was obtained. In the best cases, CP could be completely disintegrated into its nanosized constituents during ultrasonication. Regarding the mass of original wood, at maximum, half of the mass could be converted into NC, demonstrating good material effectiveness, particularly when considering extremely mild delignification conditions. Based on morphology analysis, NC consisted of elemental fibrils with lengths ranging from short, cellulose nanocrystal-like particles to elongated, cellulose nanofiber-type fibrils. Owing to these morphological properties, NC suspensions exhibited high transparency and relatively high viscosity compared with commercial cellulose nanocrystals. Furthermore, NC exerted excellent reinforcement effect on polyvinyl alcohol films. Therefore, supramolecular chemistry-driven delignification is a highly potential green treatment method for producing CP with low lignin content to be easily converted to as quality bio-based nanomaterial.