Light and small-angle X-ray scattering, sedimentation equilibrium, viscosity, circular dichroism, and infrared absorption measurements have been made on 1,4-dioxane (DIOX) and 2-ethoxyethanol (2EE) solutions of seven amylose tris(phenylcarbamate) samples ranging in molecular weight from 2 Â 10 4 to 3 Â 10 6 . Analyses of gyration radius, scattering function, and intrinsic viscosity data in terms of the wormlike chain model yield Kuhn segment lengths of 22 AE 2 nm and 16 AE 2 nm in DIOX and 2EE, respectively, and a contour length per residue of 0:33 AE 0:02 nm in both, showing that the amylose derivative chain has high stiffness and a contour length slightly shorter than the known value 0.37-0.40 nm for amylosetriesters in the crystalline state. These results are consistent with the intramolecular hydrogen bonding between the C=O and NH groups of the neighbor repeating units detected by infrared absorption and also with the locally regular (or helical) conformation indicated by circular dichroism.

The z-average mean-square radius of gyration S(2)(z), the particle scattering function P(k), the second virial coefficient, and the intrinsic viscosity [eta] have been determined for amylose tris(phenylcarbamate) (ATPC) in methyl acetate (MEA) at 25 degrees C, in ethyl acetate (EA) at 33 degrees C, and in 4-methyl-2-pentanone (MIBK) at 25 degrees C by light and small-angle X-ray scattering and viscometry as functions of the weight-average molecular weight in a range from 2 x 10(4) to 3 x 10(6). The first two solvents attain the theta state, whereas the last one is a good solvent for the amylose derivative. Analysis of the S(2)(z), P(k), and [eta] data based on the wormlike chain yields h (the contour length or helix pitch per repeating unit) = 0.37 +/- 0.02 and lambda(-1) (the Kuhn segment length) = 15 +/- 2 nm in MEA, h = 0.39 +/- 0.02 and lambda(-1) = 17 +/- 2 nm in EA, and h = 0.42 +/- 0.02 nm and lambda(-1) = 24 +/- 2 nm in MIBK. These h values, comparable with the helix pitches (0.37-0.40 nm) per residue of amylose triesters in the crystalline state, are somewhat larger than the previously determined h of 0.33 +/- 0.02 nm for ATPC in 1,4-dioxane and 2-ethoxyethanol, in which intramolecular hydrogen bonds are formed between the C==O and NH groups of the neighbor repeating units. The slightly extended helices of ATPC in the ketone and ester solvents are most likely due to the replacement of those hydrogen bonds by intermolecular hydrogen bonds between the NH groups of the polymer and the carbonyl groups of the solvent.

Five amylose tris(3,5-dimethylphenylcarbamate) (ADMPC) samples ranging in weightaverage molecular weight Mw from 1.7  10 4 to 3.4  10 5 were studied by light and small-angle X-ray scattering, sedimentation equilibrium, and viscometry in methyl acetate (MEA), 2-butanone (MEK), and 4-methyl-2-pentanone (MIBK) at 25 °C. Seven amylose tris(phenylcarbamate) (ATPC) samples whose Mw ranges between 2  10 4 and 3  10 6 were also investigated in MEK at 25 °C. The radii of gyration, particle scattering functions, and intrinsic viscosities determined as a function of Mw were analyzed in terms of the cylindrical wormlike chain model mainly to determine the Kuhn segment length  -1 and the contour length h (or the helix pitch) per residue. While the obtained h values (0.36 -0.38 nm) of ADMPC are quite insensitive to the solvents, the  -1 value is not only 1.5 -3 times larger than that of ATPC in the corresponding solvent, but also significantly increases with an increase of the molar volume of the solvent and it reaches 73 nm in MIBK, which is the highest value for previously investigated phenylcarbamate derivatives of polysaccharides. This high stiffness is most likely due to the steric hindrance of the solvent molecules H-bonding with the NH groups of the polymer.

Six amylose-2-acetyl-3,6-bis(phenylcarbamate) (AAPC) samples ranging in weight-average molar mass M(w) from 1.8 × 10(4) g mol(-1) to 1.1 × 10(6) g mol(-1) have been prepared from enzymatically synthesized amylose samples. Static light scattering, small-angle X-ray scattering, sedimentation equilibrium, and viscosity measurements were made for the samples in 1,4-dioxane (DIOX), 2-ethoxyethanol (2EE), and 2-butanone (MEK) all at 25°C to determine particle scattering functions, z-average radii of gyration, intrinsic viscosities, as well as M(w). The data were analyzed in terms of the wormlike cylinder model mainly to yield the helix pitch per residue h and the Kuhn segment length λ(-1), which corresponds to twice of the persistence length. The latter parameters (λ(-1)) in 2EE (11 nm) and MEK (12 nm) are quite smaller than those for amylose tris(phenylcarbamate) (ATPC) in the same solvent (16 nm in 2EE and 18 nm in MEK) whereas those for AAPC (21 nm) and ATPC (22 nm) in DIOX are essentially the same as each other. This indicates that the chain stiffness of AAPC is more strongly influenced by the solvents since the number of intramolecular H-bonds of AAPC is more changeable than that for ATPC.