Physical properties of silk fibroin/cellulose blend films regenerated from the hydrophilic ionic liquid

In this work, silk fibroin/cellulose (SF/CE) blend films were regenerated from hydrophilic ionic liquid, 1-butyl-3-methylimidazolium chloride (BmimCl). The structure of the blend films was characterised by Fourier transform infrared spectroscopy (FTIR). The thermal and mechanical properties and the surface morphology of the blend films were also investigated. In addition, moisture content, swelling index, total water absorption and film weight loss were measured. The results indicate that with the introduction of CE, the interactions between SF and CE in the blend films induced the conformation transition of SF from random coil form or silk I to β-sheet structure. At the same time, the physical properties of the blend films were improved. When the ratio of SF to CE is 25:75, the stronger interactions in the matrices contribute to the higher tensile strength, higher thermal stability and higher water stability. However, the blend film with half CE illustrates higher elongation at break, a more homogeneous surface and higher miscibility.