A comprehensive review on cellulose nanocrystals and cellulose nanofibers: Pretreatment, preparation, and characterization

Abstract Crafting ecological materials from green resources is posing a significant challenge for the researchers and scientists around the globe and has resulted in the development of nanocellulose materials, which has paved the way for enriching the basic knowledge and many opportunities on developing bio‐based materials. This has augmented the utilization of carbohydrate‐based organic materials and successfully replacing conventional nonrenewable materials. Cellulose nanomaterials (CNMs) belonging to the newer emerging field of nanomaterials are finding increasing interest among the investigators owing to their environmentally sustainable characteristics like biodegradability, biocompatibility, and potential availability in abundance at a cheaper price. The present review article intends to provide a detailed insight about the advancements and various challenges postured in the field of cellulose nanocrystals (CNCs) and cellulose nanofibers (CNFs). The article further discusses about different cellulose fiber extraction sources and their methods, purification processes employed, various sample preparation and drying techniques used for CNCs and CNFs. The article also outlines the various characterization methods practiced for scrutinizing CNCs and CNFs when used in polymer matrix composites. Finally, the benefits of using the CNMs in several potential applications such as paper, oil and gas industries, food packaging and structural sectors, conductive ink and water purification areas, medical and printed electronic fields are highlighted in this extensively reviewed article.