Isolation and surface modification of cellulose nanocrystals from sugarcane bagasse waste: From a micro- to a nano-scale view

Highlights: • Isolation of cellulose nanocrystals (CNCs) from sugarcane bagasse (SCB). • X-ray microtomography to study the morphology of SCB is reported for the first time. • Methodology to functionalize CNCs following the principles of green chemistry. • Tailoring the dispersion of CNCs in water and chloroform through surface modification. • Use of CNCs as reinforcing agent in polymer nanocomposites is shown to be suitable. This work presents the isolation and functionalization of cellulose nanocrystals (CNCs) extracted from sugarcane bagasse (SCB). CNCs were obtained by acid hydrolysis of bleached bagasse pulp and functionalized with adipic acid. The results showed that unmodified CNCs exhibit both a high crystallinity index and a significant aspect ratio. Surface modification with adipic acid decreases the nanocrystal dimensions due to removal of the amorphous region between the crystalline domains and also changes the electrostatic repulsion and hydrophilic affinity of CNCs. Unmodified CNCs offer potential applications as reinforcing phase in hydrophilic polymeric matrices, while modified CNCs interact better with hydrophobic matrices. The use of CNCs as reinforcement in polymer nanocomposites expands the application of this renewable material and increases its added value, providing nonenergy-based markets for the main biomass of the sugarcane industry.