Properties of bacterial cellulose transparent film regenerated from dimethylacetamide-LiCl solution

Abstract

Excellent transparent films were prepared from bacterial cellulose (BC) sheets by solubilization of its defibrillated freeze-dried specimens in a solvent of dimethylacetamide (DMAc) containing 8.0% (w/w) lithium chloride (LiCl), and their properties were compared with those of the native BC. Fibrillar structure of the native BC disappeared after dissolution, and the film formed after dissolution also loose this structure. Occurence of structural transformation from crystalline to amorphous state was also evidenced by X-ray diffraction, solid state cross polarization/magic angle spinning 13C-NMR and attenuated total reflectance–Fourier transform infrared spectroscopic analyses. In addition, excellent 3D uniform structure of the transparent BC film was further evidenced by X-ray micro computed tomography. Plastic-like characteristic was enhanced by film formation after dissolving the BC specimens in the DMAc–LiCl solution as shown by changing mechanical properties, a slight decrease in tensile strength (67.2 to 59.6 MPa) and breaking stress (67.2 to 58.4 MPa) but significant increase in elongation at break from 3.4 to 10.5%, and improvement of work of fracture from 5.8 to 21.2 kJ/m2. Copyright © 2016 John Wiley & Sons, Ltd.