1997 Fiscal Year Final Research Report Summary
Precise Analyzes of Low Frequency Motions of Polymers by Advanced Solid-State NMR Spectroscopy
| Project/Area Number |
08455453
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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 | KYOTO UNIVERSITY |
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Principal Investigator |
HORII Fumitaka Kyoto University, Institute for Chemical Research, Professor, 化学研究所, 教授 (70124758)
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| Co-Investigator(Kenkyū-buntansha) |
HIRAI Asako Kyoto University, Institute for Chemical Research, Associate Instructor, 化学研究所, 教務職員 (20156623)
KAJI Hironori Kyoto University, Institute for Chemical Research, Instructor, 化学研究所, 助手 (30263148)
TSUNASHIMA Yoshisuke Kyoto University, Institute for Chemical Research, Associate Professor, 化学研究所, 助教授 (30089130)
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| Project Period (FY) |
1996 – 1997
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| Keywords | Solid-State NMR / Glassy polymera / Molecular Motion / Two-Dimensional NMR / Chemical Shift Anisotropy / Relaxation Processes |
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| Research Abstract |
In order to clarify the low frequency motion of polymers at awide rangeof temperature including the glass transition region by advanced solid-state NMR spectroscpy, we have developed one-and two-dimensional NMR tochniques and established methods of the spectral analyzes by using phenoxy resins with a lower T_g as a model polymer.
In CP/MAS ^<13>C NMR spectra, it has been found that the gamma-relaxation process can observed as changes in spectra from doublets to singlets for the phenylene CH carbons. The detailed analysis of this process by the two-site exchange model has determined the exchange frequencies at different temperatures. In contrast, the alpha-relaxation process is recognized as remarkable motional broadening/motional narrowing for most of resonance lines, leading to the determination of frequencies of the molecular motions associated with these changes in linewidth. Moreover, new analytical methods of two-dimensional exchange ^<13>C CP/MAS spectra in the alpha-and gamma-rel
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axation processes have been proposed to characterize slower molecular motions that are not detectable by one-dimensional methods above described.
To further determine the modes of molecular motions in the alpha-and gamma-relaxation processes, we have developed two-dimensional switching angle sample spinning (SASS) or two-dimensional magic angle turning (MAT) method for the precise measurements of chemical shift anisotropy (CSA) of the phenylene carbons. The CSA spectra thus obtained have been successfully analyzed in terms of the 2-site of 8-site exchange model for the gamma-or alpha-relaxation process, respectively. As for the aliphatic CH and CH_2 carbons, we have tried to measure spectra reflecting the ^1H-^<13>C dipolar interaction by using two-dimensional SASS method. Unfortunately, such measurements have been found to be unsuccessful because the RF power is not enough for the two-dimensional measurements. Since the improvement of tha SASS prove has been very recently performed, we believe that the analyzing method for the ^1H-^<13>C dipolar spectra will be also established in near future. Less
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Research Products
(2 results)
