Solution Properties of Amylose Tris(Phenylcarbamate): Local Conformation and Chain Stiffness in 1,4-Dioxane and 2-Ethoxyethanol

Abstract

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.

Solvent‐dependent conformation of a regioselective amylose carbamate: Amylose‐2‐acetyl‐3,6‐bis(phenylcarbamate)

“…The latter value is 12% smaller than that at the wavelength used for light scattering (436 nm). Similar wavelength dependence was also found for other polymer solvent systems22 including amylose carbamate derivatives 10, 11, 12, 16…”

“…Procedures including optically clean and calibration of the photometer were described in Ref. 10. Vertically polarized incident light of 436 nm wavelength was used and the reduced scattering intensities R θ , Hv and R θ , Uv was measured with or without analyzer in the horizontal direction, respectively, in a scattering angle θ ranging from 22.5° to 150°.…”

“…See Refs. 10 and21 for experimental details and data analysis, respectively. The partial specific volume and ∂ n /∂ c at the used wavelength (675 nm) were determined to be 0.715 and 0.125 cm 3 g −1 , respectively, for AAPC in DIOX at 25°C.…”

“…Dilute solution properties have been thus studied for amylose tris(phenylcarbamate) (ATPC) and amylose tris( n ‐butylcarbamate) (ATBC), for which the chemical structures are illustrated in Figure 1. We found that both λ −1 and h significantly depend on the side group and solvents, and furthermore, the intramolecular hydrogen bond (H‐bond) between CO and NH groups plays an important role in the high chain stiffness 10–12. As seen from infrared adsorption, about 50% polar groups are, however, still free in tetrahydrofuran (THF) and 1,4‐dioxane (DIOX) even when the polymer has high stiffness, suggesting that such residual polar sites do not contribute to the chain stiffness.…”

Enantioseparation using amylose esters as chiral stationary phases for high-performance liquid chromatography

“…This may be because the amylose derivatives probably have a more labile structure than cellulose derivatives. 26 This indicates that the polymer chain of amylose ester 1a can be influenced by even a small perturbation from outside, making it difficult to have a regular structure, which is important for polymer-based CSPs to show chiral recognition ability. 4 The CSPs 1b, 1c and 2 also showed almost no recognition ability.…”