Local conformation of the cellulosic chain in solution

The temperature and molecular weight dependencies of the intrinsic viscosity [eta] were investigated for cellulose tris(phenyl carbamate) (CTC) in tetrahydrofuran (THF). By the analysis of the [eta] data in terms of the wormlike cylinder model, the persistence length q of CTC was determined as a function of the temperature. With decreasing the temperature from 25 to -20 degrees C, q increases from 10.5 to 13.7 nm. This temperature dependence of q was successfully explained by the broken wormlike chain model, where each glucose residue in the cellulosic chain is assumed to take left-handed 3/1 or 2/1 helical state and occasionally a kink state generated by a glucosidic bridge angle fluctuation. While the torsional fluctuation in each glucosidic bond is considerably small, there are two energetically favored helical (3/1 and 2/1) states, so that the cellulosic chain may not be regarded as a regular helix in solution.