Characterization of water in bacterial cellulose using dielectric spectroscopy and electron microscopy

Artikel i vetenskaplig tidskrift, 2007

It is shown that only 10% of the 99 wt% water present in bacterial cellulose (BC) gels, produced by Acetobacter xylinum, behave like free bulk water; the majority of the water mols. in the gels is more or less tightly bound to the cellulose. The magnitude of the diffusion coeffs. of ions transported in the water phase of the BC gels as well as the information contained in freeze fracture transmission electron microscopic images of the gel structures indicates that the bulk-like water is confined in "lakes" rather than forming a continuous phase throughout the gel. Water desorption isotherms suggest that these "lakes" decrease in size with increasing oxygen concn. used during the biosynthesis process of the gels.