実験報告書様式（一般利用課題・成果公開利用）（ ※本報告書は英語で記述してください。ただし、産業利用課題として採択されている方は日本語で記述していただいても結構です。 ）MLF Experimental Report

提出日 Date of Report
September 18 (2014)

課題番号 Project No.

装置責任者 Name of responsible person

2014A0206

Toshiya Otomo

実験課題名 Title of experiment
Hierarchical structures in a mixture of water / organic solvent /antagonistic salt
実験責任者名 Name of principal investigator

装置名 Name of Instrument/（BL No.）BL 21
実施日 Date of Experiment
May 16 to May 18 (2014)

Koichiro Sadakane
所属 Affiliation
Ritsumeikan University

試料、実験方法、利用の結果得られた主なデータ、考察、結論等を、記述して下さい。（適宜、図表添付のこと）
Please report your samples, experimental method and results, discussion and conclusions. Please add figures andtables for better explanation.
1. 試料 Name of sample(s) and chemical formula, or compositions including physical form.
(1) Deuterium Oxide (D2O)(2) Deuterium Oxide (D2O) + 3-methylpyridine (C6H7N) + NaBPh4 (C24H20BNa), NaBPh4 = 0 ～ 200 mM

2. 実験方法及び結果 （実験がうまくいかなかった場合、その理由を記述してください。）
Experimental method and results.

If you failed to conduct experiment as planned, please describe reasons.

2-1 The background of this research
The aim of this research is to observe the hierarchical structures in a mixture of water / organic solvent /antagonistic salt with a scale of 1 Å to 100 Å.
So far, we investigated the effect of an antagonistic salt, which is composed of hydrophilic cation andhydrophobic anion, on a mixture of water and organic solvent. For example, a lamellar structure with a scale of100 Å was observed in a mixture of water / 3-methylpyridine / NaBPh4 by small-angle neutron scattering (SANS)
measurement although no surfactant is contained (KS, et al., 2009). Such an experimental observation can beunderstood in the framework of the theory proposed by Onuki and Kitamura (A. Onuki and H. Kitamura, 2008).
In their model, hydrophilic and hydrophobic ions can be adsorbed to the interface between water and organicsolvent. These ions reduce the interfacial tension between the solvents, and mesoscopic structures are induced.
Therefore, it is assumed that pairs of hydrophilic cation (Na+) and hydrophobic anion (BPh4-) play roles of
surface-active agent in a mixture of water and 3-methylpyridine. However, the details of how a salt-inducedordered structure is formed are not understood completely.
In this study, we observed the distribution of D2O, 3-methylpyridine, Na+, and BPh4- by means of HighIntensity Total Diffractometer at BL21 (NOVA) to clarify the driving force of the ordered structure in the mixture.
2-2 Experiments
D2O (99.9% purity, Pure Chemical Industries), 3-methylpyridine-d7 (deuterated 3-methylpyridine, 98% purity,12. 実験方法及び結果（つづき） Experimental method and results (continued)
Cambridge IsotopeAldrich), and NaBPh4 (sodium tetraphenylborate, 99.5% purity, DOJINDO) were mixed

without further purification. The volume fraction of 3-methylpyridine, φ3MP = V3MP/(Vwater + V3MP + Vsalt), was set
at 0.09, 0.10, 0.12, and 0.13 (Vwater, V3MP, and Vsalt denote the volumes of D2O, 3-methylpyridine-d7, andNaBPh4, respectively). The concentration of NaBPh4 in the mixture, Csalt, was varied between 0 mmol/L and 200mmol/L. The neutron diffraction measurements were performed at BL21, NOVA. The samples were kept intitanium–vanadium cells with a diameter of 6 mm. The sample temperature was controlled between 303 K and333 K with an accuracy of ± 0.1 K. The observed data were corrected for transmission, background scattering,and the sample thickness to obtain absolute intensities. Then, the pair correlation function, g(r), was also
evaluated.
2-3 Results
Figure 1 (a) shows the diffraction data (I(Q) vs Q) for a mixture of D2O / 3-methylpyridine-d7 / NaBPh4.
Several peaks, which reflect the distribution of D2O, 3-methylpyridine-7, Na+, and BPh4-, are confirmed. Using
these data, we also evaluated the pair-correlation function, g(r) (see Fig. 1 (b)). Now we are discussing how tointerpret these results with our collaborator, Professor. Kameda in Yamagata University.

Figure 1: (a) The neutron diffraction profile (I(Q) vs Q) for the mixture D2O / 3-methylpyridine-d7 /NaBPh4.Here, X and Y denote the molar fraction of 3-methylpyridine-d7 and NaBPh4, respectively. (b) The
pare-correlation function, g(r) for the same mixtures as Fig. 1 (a).
2