Influence of silk fibroin content on cellulose blend film using LiBr solution

Abstract

Cellulose–silk fibroin (CSF) films were prepared by blending cellulose and silk fibroin (SF) in different ratios (10:0, 10:3, 10:6, 10:9, and 10:12 wt%) in 60% LiBr aqueous solution. All of the blend films were transparent, and their coloration gradually increased with increasing SF content. Interestingly, cross-sections of all of the tested films were observed by scanning electron microscopy and exhibited similar morphologies. The silk II structure was not well developed in the CSF; however, regenerated SF affected the crystal structure of the cellulose and formed intermolecular hydrogen bonds with cellulose. EDS mapping showed that cellulose and silk in the film were distributed uniformly. The mechanical properties of the dry-state film was greatly improved with the addition of an appropriate amount of SF. In contrast with the dry-state films, the films in the wet state exhibited smaller tensile strengths and E-modulus as SF content increased; however, the elongation values were higher than those in the dry-state films.