Solution Properties of Cellulose Tris(phenyl carbamate). 1. Characterization of the Conformation and Intermolecular Interaction

Abstract

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.

Local Conformation of the Cellulosic Chain in Solution

“…[22][23][24][25][26] The values of k 0 are normal, indicating no aggregation of CTC in THF upon cooling. Figure 2 plots [] vs. M w double-logarithmically of CTC in THF at 0 and À25 C as well as the previous results at 25 C. 9 The molecular weight dependencies of [] become slightly stronger with lowering temperature. Figure 3 plots the second virial coefficient A 2 for fraction F11 against temperature.…”

“…Previously, 9 [] data of CTC in THF at 25 C were analyzed by using the theory of Yamakawa, Fujii, and Yoshizaki for the wormlike cylinder model [27][28][29] combined with the quasi-two-parameter theory [29][30][31] for the intramolecular excluded-volume effect to obtain the following wormlike-cylinder parameters: the persistence length q ¼ 10: 5 nm, the molar mass per unit contour length M L ¼ 1110 nm À1 , the cylinder diameter d ¼ 2:2 nm, and the strength of the excludedvolume B ¼ 1:8 nm. The M L value in THF is close to that expected for the energetically stable conformation of the cellulosic chain.…”

“…references cited in ref 9). Figure 4 contains some literature data 10,22 for CTC in THF and dioxane by a diamond and triangles.…”

“…Four CTC fractions prepared in previous studies 9,11 were chosen for viscosity measurements. Table I lists the weight-average molecular weight M w and the ratio of the weight-to number-average molecular weight y To whom correspondence should be addressed (Tel: +81-6-6850-5461, Fax: +81-6-6850-5461, E-mail: tsato@chem.sci.osaka-u.ac.jp).…”

“…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.…”