Cellulose Nanocrystals: Chemistry, Self-Assembly, and Applications

The hydrogen-bonding network and molecular orientation in cellulose vary widely that gives rise to cellulose polymorphs or allomorphs, depending on the respective source, method of extraction, or treatment. Microcrystalline cellulose (MCC) offers a significant opportunity for multiple uses in pharmaceutical industry as a tablet binder, in food applications as a texturizing agent and fat replacer, and also, as an additive in paper and composites applications. The main process for the isolation of cellulose nanocrystal (CN) from cellulose fibers is based on acid hydrolysis. The sulfuric and hydrochloric acids have been extensively used for CN preparation, but phosphoric and hydrobromic acids have also been employed for such purposes. The cellulose nanocrystal generated from hydrochloric acid hydrolysis and then treated with sulfuric acid solution has the same particle size as those directly obtained from sulfuric acid hydrolysis.