Effects of oxidized cellulose nanocrystals on the structure and mechanical properties of regenerated collagen fibers

Abstract The mechanical properties of regenerated collagen composite materials are of significant importance for promoting its diverse applications. However, the efficient strategy reported so far for enhancing the mechanical properties of regenerated collagen fibers remains limited. Herein, the oxidized cellulose nanocrystals (oCNCs) were successfully prepared in aqueous media by oxidation of the hydroxyl groups on the surface of cellulose nanocrystals (CNCs) using ammonium persulfate (APS) as an oxidant, and collagen composite fibers were prepared by introducing oCNCs into the collagen matrix via the dry-jet wet spinning technique. The morphology, structures and properties of prepared collagen composite fibers were carefully investigated. These results indicated that oCNCs and CNCs can induce collagen microfibril orientation during the formation process of fibers and protect the possibility of their interactions with collagen molecules. Compared with CNCs, oCNCs offered higher levels of enhancing efficiency and the as-prepared collagen/oCNCs composite fibers exhibited extraordinary improvements in both the tensile strength and toughness with only a 0.05 wt% oCNCs loading. The reason for this improvement is that the hydroxyl groups and carboxyl groups of oCNCs can form stronger hydrogen bonds and electrostatic interactions with collagen molecules, resulting in the synergistic enhancement of the tensile strength, toughness and thermal stability of collagen composite fibers. This work provides an efficient and facile method to achieve collagen composite fibers with high mechanical properties for their broad applications.