Dimensional and hydrodynamic properties of cellulose tris(alkylcarbamate)s in solution: Side chain dependent conformation in tetrahydrofuran

We prepared cellulose tris(ethylcarbamate) (CTEC), cellulose tris(n-butylcarbamate) (CTBC), and cellulose tris(n-octadecylcarbamate) (CTODC) samples with different molecular weight to determine their conformational properties in dilute solution. Weight average molar masses Mw, z-average mean-square radii of gyration z, particle scattering functions P(q), and intrinsic viscosities [η] of the CTEC, CTBC, and CTODC samples in tetrahydrofuran (THF) at 25℃ were determined by size exclusion chromatography equipped with multi-angle light scattering detectors (SEC-MALS), small angle X-ray scattering (SAXS), and viscometry. Infrared (IR) absorption measurements were also made to observe intramolecular hydrogen bonding between C=O and NH groups. The obtained z, P(q), and [η] data were analyzed in terms of the wormlike chain model to determine the Kuhn segment length (stiffness parameter, or twice of the persistence length) λ-1 and the helix pitch (rise) per residue h. While CTBC has the highest chain stiffness in the three cellulose derivatives as in the case of the corresponding amylose derivatives, the difference in the wormlike chain parameters is less significant for the cellulose alkylcarbamate derivatives. Indeed, intramolecular hydrogen bonding of CTEC, CTBC, and CTODC is weaker and fewer than that for the corresponding amylose derivatives owing to the main chain linkage, α or β