title: Solvent-dependent conformation of a regioselective amylose carbamate: amylose-2-acetyl-3,6-bis(phenylcarbamate).
abstract: 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.
authors.affiliation: Department of Macromolecular Science, Graduate School of Science, Osaka University, 1-1 Machikaneyama-cho, Toyonaka, Osaka 560-0043, Japan.
authors.forename: Maiko
authors.initials: M
authors.lastname: Tsuda
authors.forename: Ken
authors.initials: K
authors.lastname: Terao
authors.forename: Shinichi
authors.initials: S
authors.lastname: Kitamura
authors.forename: Takahiro
authors.initials: T
authors.lastname: Sato
mesh_terms: D000688:Amylose / Q000031:analogs & derivatives* / Q000737:chemistry*; D002219:Carbamates / Q000737:chemistry*; D006860:Hydrogen Bonding; D008968:Molecular Conformation; D048448:Phenylcarbamates / Q000737:chemistry*; D012997:Solvents / Q000737:chemistry
chemical_list: D002219:Carbamates; D048448:Phenylcarbamates; D012997:Solvents; C576290:amylose-2-acetyl-3,6-bis(phenylcarbamate); D000688:Amylose