Solution properties of celluloses from different biological origins in LiCl - DMAc

Differences in the solution properties of cellulose in 8% LiCl · DMAc (dimethyl acetamide) were investigated using celluloses from different origins. The latter included plants (dissolving pulp (DP), cotton linters (CC), and kraft pulp), bacteria (Acetobacter xylinum, BC), and marine animals (tunicin from Halocynthia). The celluloses from plants and bacteria formed LiCl · DMAc solutions that were isotropic and anisotropic, respectively; and the animal cellulose was insoluble. The weight average molecular weights, M_w, of DP, CC and BC were found to be 98.2 × 10⁴, 170 × 10⁴ and 192 × 10⁴, respectively. The solution viscosities were proportional to c^α (c; polymer concentration) in the dilute and semi-dilute regions, where the exponent α was 1 for all samples in the dilute region; in the semi-dilute region, it was 4 for the DP and CC solutions and 3 for the BC solution. Molecular weight differences were compensated by plotting the viscosity against cM_w or c[η] (where [η] is the limiting viscosity number). The difference in viscosity behavior at elevated solution concentration indicates that the cellulose molecules from DP and CC behave as flexible polymer chains and those of BC as rod-like ones. These results suggest that differences in molecular structure and properties exist between celluloses from different sources, and that these differences relate to the mechanism or the type of the intermolecular interaction between the celluloses of plants (DP and CC) and those of bacteria (BC).