Mutual- and Self-Diffusion Coefficients of a Semiflexible Polymer in Solution

Mutual- and self-diffusion coefficients of a semiflexible polymer, cellulose tris(phenyl carbamate) (CTC), in tetrahydrofuran were measured by dynamic light scattering and pulsed field gradient NMR, respectively, as functions of the polymer concentration and molecular weight. The mutual-diffusion coefficient after elimination of the effects of thermodynamic force and solvent back flow agrees with the self-diffusion coefficient for a low molecular weight CTC fraction with the number of Kuhn’s statistical segments N=1.8 up to high concentrations, but they disagree for a higher molecular weight CTC fraction with N=4.7 at the highest concentration investigated. The mutual diffusion coefficients for CTC fractions with N ranging from 1.8 to 10.6 after elimination of the above two effects were also compared with the fuzzy cylinder theory for the self-diffusion coefficient. Disagreements start at lower concentration for larger N, which form in a contrast with good agreements for a more stiff polymer, poly(n-hexyl isocyanate), previously studied.