2000 Fiscal Year Final Research Report Summary
Structure and Dynamics in Physical Gels of Biopolymers
| Project/Area Number |
11450360
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| Research Category |
Grant-in-Aid for Scientific Research (B).
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
高分子構造・物性(含繊維)
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| Research Institution | HOKKAIDO UNIVERSITY |
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Principal Investigator |
TSUTSUMI Akihiro Hokkaido Univ., Grad.School of Eng., Prof., 大学院・工学研究科, 教授 (80000884)
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| Co-Investigator(Kenkyū-buntansha) |
ISHII Fumiaki Hokkaido Univ., Grad.School of Eng., Inst., 大学院・工学研究科, 助手 (30001308)
HIRAOKI Toshifumi Hokkaido Univ., Grad.School of Eng., Ass.Prof., 大学院・工学研究科, 助教授 (10125346)
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| Project Period (FY) |
1999 – 2000
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| Keywords | Physical gel / Sol-gel transition / Polysaccharides / Polypeptides / Dynamics / Metal ions / NMR / ESR |
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| Research Abstract |
Dynamical properties of the physical gel have been investigated on (l) polysaccharides-water systems and (2) rod-like polypeptides-organic solvent systems by means of ^<13>C-NMR, ESR and DSC (Differential Scanning Calorimetry) measurements.
(1) Effects of the addition of divalent metal cations on the gelation of the alginic acid and gellan gum aqueous solutions have been investigated using the paramagnetic metal ion Mn^<2+>. Remarkable broadening of signals from carboxyl group and nearby carbons were observed in the ^<13>C-NMR spectra for both polysaccharides, indicating that divalent metal cations selectively attached to carboxyl group and undergo the rapid chemical exchange to surrounding water molecules. ESR spectra of Mn^<2+> in aqueous solution of polysaccharides showed a considerable intensity loss and line shape change. Spectral simulation indicated that there exist three states of Mn^<2+>, free one in the free water, weakly restricted one in the water nearby carboxyl groups, and
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strongly restricted one attached to carboxyl groups. With increasing Mn^<2+> concentration, solutions varied from the sol to the viscous sol and then to the stable gel due to the formation of the molecular aggregation and the cross-linking. It was found that relative ratios of Mn^<2+> in three states vary in each solution state and have definite relations to the polymer concentrations.
(2) Anisotropic dinamics of rod-like polypeptides in the gel has been investigated using polymer-end spin-labeled poly(γ-benzyl L-glutamate)(PBLG) and poly (L-leucine)(PLL) in organic solvents by means of the ESR measurements. In benzene solutions of these polymers, fairly large values of order parameters were obtained in the gel, reflecting the strong molecular association. Similar results were obtained for PBLG in the benzylalcohol solution. ^2H-NMR relaxation of the deuterated solvents showed that solvents undergo two order of magnitude slower motion in the cross-linked region than in pure solvent. Addition of PBLG more than 1% wt into the PLL-benzene solution hindered the gelation and reduced the order parameter. After the long time annealing at high temperatures below 100℃, the stable gel again appeared. These phenomena gave the information about the anisotropic structure of the composite gels composed of polymers having side chains with different polar groups. Less
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Research Products
(24 results)
