Nanochitin preparation and its application in polymer nanocomposites: a review

Chitin is the second most abundant biopolymer on earth, next to cellulose. Due to its poor processability and tedious purification steps, chitin is an underutilized polysaccharide. Recently, scientific advancements in the field of nanotechnology have enabled the development of high-performance chitin nanomaterials. Nanochitins have great economic value as an efficient functional and reinforcement material for a wide range of industrial applications. This review article aims to explore different methods of nanochitin preparation from the main sources of chitin, like crabs and shrimps. The different chitin nanocrystal preparation methods, such as acid hydrolysis, TEMPO-mediated oxidation, and partial deacetylation, were reviewed. Similarly, the other nanochitin form, chitin nanofibers, preparation methods such as mechanical treatments, electrospinning, and self-assembly, were intensively discussed. In this case, the research outcomes on the advantages of surface modification with an appropriate reagent for ease of nanofibrillation and advanced functionality were presented. The properties of the nanochitins obtained via these methods were well addressed. Finally, this review reports recent papers on the high value-added applications of chitin nanofibers and chitin nanocrystals in polymer nanocomposites. The article also gives a proper conclusion and addresses future perspectives.