Cellulose Nanofibers: Fabrication and Surface Functionalization Techniques

Abstract

Cellulose fibers which consist of a bundle of stretched cellulose chain molecules with cellulose fibril are the smallest structural unit of plant fiber. These elementary fibrils or nanofibers are about 2–20 nm in diameter and a few micrometers in length. Cellulose nanofiber (CNF) is the world’s most advanced bio-nanomaterial. As the cellulose is the most abundant, renewable, and sustainable biopolymer on earth, it creates low environmental impact in its production and disposal. In this chapter, the unique properties of CNFs were introduced including stiffness, biodegradability, biocompatibility, and ability to form a strong entangled nanoporous network, thermal properties, and swelling in water and water absorptivity. Different fabrication techniques including physical methods (e.g., mechanical refining), chemical methods (treatment with acids and alkalis), and biological methods (treatment with specific bacteria and enzymes) were discussed. The chemical grafting on the CNFs and deposition of nanoparticles on nanofiber surface were described. Finally, the future prospects and challenges of CNFs were presented.