Cellulose tricarbanilate

Vo and Zugenmaier (105) determined the pitch of cellulose tricarbanilate (CTC, D.P. = 100) in 2-pentanone and methyl ethyl ketone (MEK) and ethyl cellulose (EC) in glacial acetic acid as a function of temperature, concentration, solvent, and degree of polymerization. The pitch of the helicoidal structure of CTC/MEK and CTC/2-pentanone is right-handed but EC in glacial acetic acid is left-handed. This is the first report that the substituent will influence the sense of the cholesteric superhelicoidal structure. 

Fig. 3.5. Reduced stored free energy FB vs. reduced shear rate for a fraction of cellulose tricarbanilate in benzophenone (7 77). Mol. wt. 720,000, concentration 0.1 wt. per cent, measurement temperatures (o-) 55°, (- ) 65°, (f ) 80°, (o) 95°...

At this point it seems of interest to include a graph obtained on a quite different polymer, viz. cellulose tricarbanilate. Results from a series of ten sharp fractions of this polymer will be discussed in Chapter 5 in connection with the limits of validity of the present theory. In Fig. 3.5 a double logarithmic plot of FR vs. is given for a molecular weight of 720000. This figure refers to a 0.1 wt. per cent solution in benzophenone. It appears that the temperature reduction is perfect. Moreover, the JeR-value for fiN smaller than one is very close to the JeR value obtained from Figure 3.1 for anionic polystyrenes in bromo-benzene. As in the case of Fig. 3.1, pN is calculated from zero shear viscosity. The correspondence of Figs. 3.1 and 3.5 shows that also the molecules of cellulose tricarbanilate behave like flexible linear chain molecules. For more details on this subject reference is made to Chapter 5. 

Fig. 5.7. Ratio of Maxwell-constant to intrinsic viscosity as a function of molecular weight for fractions of cellulose tricarbanilate in benzophenone at the two indicated temperatures according to Janeschitz-Kriegl and Burchard (172)...

Fig. 5.8. Cotangent of the doubled extinction angle (corrected for solvent birefringence) vs. reduced shear rate f s for a series of cellulose tricarbanilate fractions in benzophenone at 55° C (772). Broken and dotted lines are explained in the text. Hatched area indicates location of experimental results on anionic polystyrenes. Molecular weights of cellulose tricarbanilate fractions () 27000, (f) 38000, (A) 57000, (a) 90000, (o) 152,000, ( ) 280,000, (o) 500,000, ( ) 720,000 and...

One remark must be made As the molecules of cellulose tricarbanilate possess such a large persistence length, the Gaussian range is only reached at considerable molecular weights, where reduced shear rate exceeds the value one. This value has been found to be critical with respect to... 

Fig. 5.9. Comparison of extinction angle curves of high molecular weight fractions of polystyrene and cellulose tricarbanilate, using linear scales and reduced shear rate For data on polystyrene Taps. No. 5 and solvents see Table 3.2. (n) Taps. No. 5 in methyl (4-bromo-phenyl carbinol) at 18° C (theta-temperature), (V) the same at 50° C, (o) Taps. No. 5 in monobromo benzene at 25° C, ( ) cellulose tricarbanilate M = 720,000 in benzophenone at 55° C (jy = 4.70 cps) and (a) at...

An important point in the discussion of internal friction is the fact that results, which were obtained on the dilute solutions of a series of cellulose tricarbanilate fractions in benzophenone, are all amenable to a perfect temperature reduction according to the principles of Chapter 3 (cf. Fig. 3.5 and ref. 171). 

For these measurements, temperature has been varied between 55 and 110° C. In this temperature range, the solvent viscosity changes by a factor three 4.7 to 1.5 cps). It is very improbable that a noticeable internal friction factor would change just by the same factor. Moreover, as has already been pointed out at the end of Section 5.2.2, the curves obtained by plotting cot2 c vs reduced shear stress fjN are practically coinciding for dilute solutions of cellulose tricarbanilate fractions with M S 500,000 and for anionic polystyrenes. So one can conclude that the internal friction of the thermodynamically stiff molecules of cellulose tricarbanilate must be rather low. 

Cellulose tricarbanilate, obtained by reaction of cellulose with phenyl isocyanate - mostly in DMSO or pyridine as the solvents - has been used widely for the determination of analytical parameters of celluloses by gel permeation chromatography (GPC) in organic solvents, such as THE... 

Table 10 summarizes the parameters Kra and a of CD-solutions. With a few exceptions (CA(2.46)-DMAc, CN-acetone 78,79), cellulose tricarbanilate (CTC)-acetone and -dioxane 80-81), HEC-water 82), and EC-water 83)), a is <0.8, as for most synthetic polymer solutions 91. ... 

Woo the temperature dependence of pitch for chiral nematic polymers does not seem to follow any particular pattern. It is believed that as temperature is increased, specific interactions, e.g., hydrogen bonding, whether inter- or intramolecular or polymer-solvent interactions are destroyed. The polymer chains become more flexible and the side groups more easily relaxed, thereby changing the physical properties of the chiral nematic structure. Similarly, an increase in concentration leads to a decrease in pitch for most lyotropic cellulosic liquid crystals with the exception of cellulose tricarbanilate (CTC) in ethyl methyl ketone, 2-penta-none, or tiiethylene glycol monoether and the chlorophenyl urethane derivative in diethylene glycol monoether. ... 

Following the first observation of mesophase formation of HPC/H2O, the rheology of this system has been widely investigated. Rheological studies of other cellulosic mesophases, e.g., cellulose, ethylcellulose, and cellulose tricarbanilate, have also been reported. 

Siekmeyer, M. Zugenmaier, P. Investigations of molar mass dependence of the lyotropic liquid-crystalline system cellulose tricarbanilate/ diethylene glycol monoethyl ether. Makromol. Chem. Rapid Commun. 1987, 8 (10), 511-517. 

Siekmeyer, M. Steinmeier, H. Zugenmaier, P. Structural investigations and phase behavior of a ternary lyotropic liquid-crystalline cellulosic system cellulose tricarbanilate/3-chlorophenyl-urethane of cellulose/triethylene glycol monomethyl ether. Makromol. Chem. 1989, 190 (5), 1037-1045. 

Figure 8. Effect of nitrate and carbanilate derivatives on the calibration of CED viscosity (--------------) cellulose trinitrate ( - -j cellulose tricarbanilate.

Many cellulose derivatives form lyotropic liquid crystals in suitable solvents and several thermotropic cellulose derivatives have been reported (1-3) Cellulosic liquid crystalline systems reported prior to early 1982 have been tabulated (1). Since then, some new substituted cellulosic derivatives which form thermotropic cholesteric phases have been prepared (4), and much effort has been devoted to investigating the previously-reported systems. Anisotropic solutions of cellulose acetate and triacetate in tri-fluoroacetic acid have attracted the attention of several groups. Chiroptical properties (5,6), refractive index (7), phase boundaries (8), nuclear magnetic resonance spectra (9,10) and differential scanning calorimetry (11,12) have been reported for this system. However, trifluoroacetic acid causes degradation of cellulosic polymers this calls into question some of the physical measurements on these mesophases, because time is required for the mesophase solutions to achieve their equilibrium order. Mixtures of trifluoroacetic acid with chlorinated solvents have been employed to minimize this problem (13), and anisotropic solutions of cellulose acetate and triacetate in other solvents have been examined (14,15). The mesophase formed by (hydroxypropyl)cellulose (HPC) in water (16) is stable and easy to handle, and has thus attracted further attention (10,11,17-19), as has the thermotropic mesophase of HPC (20). Detailed studies of mesophase formation and chain rigidity for HPC in dimethyl acetamide (21) and for the benzoic acid ester of HPC in acetone and benzene (22) have been published. Anisotropic solutions of methylol cellulose in dimethyl sulfoxide (23) and of cellulose in dimethyl acetamide/ LiCl (24) were reported. Cellulose tricarbanilate in methyl ethyl ketone forms a liquid crystalline solution (25) with optical properties which are quite distinct from those of previously reported cholesteric cellulosic mesophases (26). 

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