title: Change of the persistence lengths in the conformational transitions of pullulan- and amylose-tricarbanilates.
abstract: With raising temperature in the domain of 20 to 60 degrees C, the intrinsic viscosity [eta] for pullulan-tricarbanilate PTC and amylose-tricarbanilate ATC in solutions was found to decrease, indicating that they exhibited thermal-induced conformational transition from expanded form to compact form. The persistence length P(l) of the chains, evaluated with small-angle X-ray scattering, has also decreased as the temperature is raised and, moreover, it significantly depended on the solvents employed, where as P(l) of pullulan, having no carbanilate groups, has exhibited neither temperature- nor solvent-dependence. The temperature dependence of [eta] for PTC and ATC was well elucidated in terms of the temperature-dependent P(l) with the wormlike chain model. From these results, it is suggested that intramolecular hydrogen bonds would be formed between carbanilate groups neighboring along the backbone chain, but they are gradually and cooperatively collapsed as the temperature is raised, inducing the conformational transition.
authors.affiliation: Department of Applied Chemistry, Graduate School of Engineering, Nagoya University, Nagoya 464-8603, Japan. ymuroga@apchem.nagoya-u.ac.jp
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Muroga
authors.forename: Kentaro
authors.initials: K
authors.lastname: Hayashi
authors.forename: Mitsuhiro
authors.initials: M
authors.lastname: Fukunaga
authors.forename: Tadaya
authors.initials: T
authors.lastname: Kato
authors.forename: Shigeru
authors.initials: S
authors.lastname: Shimizu
authors.forename: Kimio
authors.initials: K
authors.lastname: Kurita
mesh_terms: D000688:Amylose / Q000737:chemistry*; D002219:Carbamates / Q000737:chemistry*; D005936:Glucans / Q000737:chemistry*; D008968:Molecular Conformation; D014783:Viscosity
chemical_list: D002219:Carbamates; D005936:Glucans; C009109:pullulan; D000688:Amylose; C059692:phenylcarbamic acid