The radius of gyration 〈S 2 〉 1/2 , hydrodynamic radius RH, intrinsic viscosity [η], and second virial coefficient A2 for cellulose tris(phenyl carbamate) (CTC) in tetrahydrofuran (THF) at 25 °C were determined in a wide range of molecular weights, 1.91 × 10 4 to 392 × 10 4 , by static and dynamic light scattering and viscometry. Furthermore, the osmotic compressibility ∂c/∂Π for isotropic THF solutions of CTC samples was measured at 25 °C by static light scattering over wide ranges of the polymer concentration. Data of 〈S 2 〉 1/2 , RH, and [η] were analyzed by the established quasi-two parameter theory for the wormlike chain model to determine the molar mass ML per unit contour length and the persistence length q. On the other hand, results of A2 and ∂c/∂Π were analyzed on the basis of the scaled particle theory for wormlike spherocylinders combined with the quasi-two parameter theory for A2 to estimate the hard-core diameter d0 and strength δ of the soft dispersion force of the CTC chain in THF. The value of ML [)1040 ((70) nm -1 ] estimated is consistent with the 3 /2 helical conformation of CTC in the crystal of the CTC-methyl ethyl ketone complex, while the hard-core diameter d0 [)1.4 ((0.1) nm] is slightly smaller than the interchain spacing ()1.66 nm) of CTC in the same crystal. The value of q [)10.5 ((1) nm] for CTC is comparable to literature values of q for some other cellulose derivatives reported so far.

ABSTRACT: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 ¼ 1:8 up to high concentrations, but they disagree for a higher molecular weight CTC fraction with N ¼ 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. [DOI 10.1295/polymj.37.65] KEY WORDS Mutual-Diffusion Coefficient / Self-Diffusion Coefficient / Dynamic Light Scattering / Pulsed Field Gradient NMR / Semiflexible Polymer / Cellulose Derivative / There are two kinds of translational diffusion coefficients for binary solution systems: the mutual-diffusion coefficient D m and the self-diffusion coefficient D s .1-3 The conventional concentration gradient method provides the former diffusion coefficient. Dynamic light scattering is a more convenient method to determine D m , where the concentration gradient is generated by thermal fluctuation. On the other hand, a certain solute molecule is labeled, and the Brownian motion of the labeled molecule (the tracer) is monitored by some method to measure the latter diffusion coefficient D s . Forced Rayleigh scattering, fluorescence recovery after photobleaching, pulsed field gradient NMR, and so on belong to techniques to measure D s .3,4 These two diffusion coefficients are identical at infinite dilution, but they often exhibit opposite concentration dependencies.The mutual and self diffusions occur under different experimental conditions. While the solution is thermodynamically homogeneous during the measurement of D s , the concentration gradient is necessary to measure D m . The concentration gradient provides a thermodynamic force to make a macroscopic flow of the solute at a finite concentration, and the solute flow is accompanied by the solvent back flow to maintain the constant density of the solution. The thermodynamic force and the solvent back flow discriminate D m from D s , and the two effects may be eliminated by use of the following equation:where M, c, and " v v are the molecular weight, the mass concentration, and the partial specific volume of the solute, respectively, RT is the gas constant multiplied by the absolute temperature, and Å is the osmotic pressure. The effects of the thermodynamic force and the solvent back flow are taken into account by the...

We have synthesized a new series of fluorinated liquid crystalline napthalenes having fluorinated naphthalene moiety at the end of molecule and compared the properties to the previously presented naphthalenes with a similar chemical structure. The new fluorinated liquid crystalline naphthalene with calculated smaller molecular volume shows lower rotational viscosity. Moreover, the naphthalene with calculated larger dipole moment shows larger dielectric anisotropy.