ABSTRACT:The temperature and molecular weight dependencies of the intrinsic viscosity [] were investigated for cellulose tris(phenyl carbamate) (CTC) in tetrahydrofuran (THF). By the analysis of the [] 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 À20 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. [DOI 10.1295/polymj.38.226] KEY WORDS Cellulose Derivative / Intrinsic Viscosity / Persistence Length / Broken Wormlike Chain / Local Conformation / Helicity of polymer chains plays important roles in chain rigidity, liquid crystallinity, and chiral discrimination. Recently, several synthetic polymers have been found to take more or less regular helical conformations in solution, and extensive arguments have been made on the relationship among their chemical structure, helicity, chain rigidity, liquid crystallinity, and cholesteric structure. Many review articles deal with recent advances in this subject. [1][2][3][4][5] Cellulose derivatives are known as semiflexible polymers exhibiting liquid crystallinity 6,7 and important materials in chiral chromatography.8 These features imply helical nature in the cellulosic chain. Conformations of cellulose derivatives in solution were studied both experimentally and theoretically for a long time. However, as mentioned in a previous paper, 9 their conformational analysis was not an easy task because both chain stiffness and excluded volume effect must be taken into account simultaneously due to their intermediate chain rigidity. Only recent literature provides proper analyses for the conformation of cellulosic chains 9,10 and also for solution properties (e.g., liquid crystallinity, 11 viscosity, 12 and diffusivity 13 ) based on the properly analyzed conformation. On the other hand, theoretical studies on the conformation of the cellulosic chain were carried out by Brant et al.14-17 in 1970s, who made an extensive conformational energy analysis and found two energetically stable conformations implying left-handed 3/1 and 2/1 helices for the cellulosic chain. However, the characteristic ratio C 1 and its temperature dependence estimated from their conformational energy did not satisfactorily agree with experimental results for cellulose derivatives. 15,16 The disagreement was argued occasionally afterward, 17,18 but satisfactory explanation has not been made yet. Thus, the local conformation of the cellulosic chain is still unclear.In this study, we have revisited...