Ultrafine Nanofibers

Ultrafine nanofibers are nanofibers with typical fiber diameters ranging from 1 to about 10 nm. They can be fabricated by using a variety of techniques, such as self-assembly, electrospinning, or chemical catalysis. A novel technology has been developed to fabricate ultrafine polysaccharide nanofibers (e.g., ultrafine cellulose nanofibers) by using a combination of chemical and mechanical treatments on natural resources, such as wood, cotton, and crab/shrimp shell (chitin) (Ma et al. 2011). The fiber diameter of the achieved ultrafine nanofibers was 5–15 nm with various fiber lengths of a few hundred nanometers to a few microns. The chemical treatment, typically, is a selective oxidation of C6-hydroxyl groups in cellulose with the TEMPO/NaBr/NaClO aqueous system. After oxidation, a mechanical treatment, such as grind, sonication, or/and homogenization, is applied to defibrillate the fiber bundles. Therefore, ultrafine cellulose nanofibers with nominal fiber diameters of 5–15 nm in...