| Project/Area Number |
11440205
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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 |
機能・物性・材料
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| Research Institution | Osaka University |
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Principal Investigator |
SHIKATA Toshiyuki Osaka University, Graduate School of Science, Associate Professor, 大学院・理学研究科, 助教授 (10178858)
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| Co-Investigator(Kenkyū-buntansha) |
HASHIDZUME Akihito Osaka University, Graduate School of Science, Research Associate, 大学院・理学研究科, 助手 (70294147)
MORISHIMA Yotaro Osaka University, Graduate School of Science, Professor, 大学院・理学研究科, 教授 (70028249)
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| Project Period (FY) |
1999 – 2000
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| Project Status |
Completed (Fiscal Year 2000)
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| Budget Amount *help |
¥14,600,000 (Direct Cost: ¥14,600,000)
Fiscal Year 2000: ¥4,600,000 (Direct Cost: ¥4,600,000)
Fiscal Year 1999: ¥10,000,000 (Direct Cost: ¥10,000,000)
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| Keywords | Surfactant / Spherical Micelle / Threadlike Micelle / Dielectric Relaxation / Rotational Relaxation / Ion Pair / Diffusion / Fluorescence Anisotropy Relaxation / 四電極測定法 / 誘起電気双極子 / 永久電気双極子 |
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| Research Abstract |
Relaxation behavior in the frequency range from 1 M to 20 GHz was investigated using a dielectric relaxation technique for aqueous cetyltrimethylammonium bromide (CTAB) solutions. In spherical micelles formed in the aqueous CTAB solutions, dielectric relaxation was found at around 1ns attributed to the rotation relaxation of ion pairs between CTA^+ and Br^_. The separation between the centers of CTA^+ and Br^_ ions estimated from the value of dielectric relaxation strength reasonably well agrees with that from the value of the average occupied area for a head group of CTA^+ in micelles. Dielectric relaxation behavior for aqueous dodecyldimethylamineoxide (DDAO) solutions was also examined in the same frequency range changing pH value by adding an aqueous hydrogen bromide (HBr) solution. Because DDAO molecules were protonated to become cationic (surfactant) molecules by the added HBr, dielectric relaxation behavior for the aqueous DDAO solutions was remarkably changed with the degree of protonation (α) controlled by the HBr addition. The aqueous DDAO solutions exhibited dielectric relaxation at around 0.1 ns attributed to the rotational of a dipole moment due to a coordination chemical bond between nitrogen and oxygen atoms in the head group of DDAO molecules at α = 0. However, another dielectric relaxation mode was found at around 1 ns when α> 0. The strength of the slow dielectric relaxation mode remarkably increased with the value of α. This implies that the slow relaxation mode is attributed to the rotation of ion pairs formed between a protonated DDAO cation and a Br^_ aion.
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