Supplementary data

Deposition of the Monodispersed Pt Nanodots on a Substrate by using the Pt Nanoparticle-containing Dendrimer Micelle Aqueous Solution

Isao Hirano, Takane Imaoka, Kimihisa Yamamoto*

Chemical Resources Laboratory, Tokyo Institute of Technology,

4259 Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa, 226-8503, Japan

* Corresponding author. Email:

Estimation of the CMC of BMN in each buffer aqueous solution.

When surfactants of over the CMC are dissolved in an aqueous solution, not only the sphere micelles, but also the stick-like micelles or plate-like micelles are prepared. The sizes and structures of these micelles are much larger and more complicated than those of the sphere-like micelles [17]. Such giant micelles including two more molecules of DPAG4 may be eventually prepared. Furthermore, it is difficult to deposit single molecular Pt dots on the substrate then case of using such DPAG4-BMN micelles. In this study, we attempted to prepare DPAG4-BMN micelles using BMN aqueous solution of each CMC in some aqueous buffer solutions. In general, the CMC of every surfactant is estimated from the surface tension change as follows. The surface tension changes significantly with the concentration of the surfactant before the concentration reaches the CMC. When the concentration reaches the CMC, the surface tension is constant or slightly lower. This turning point denotes the CMC of the surfactant [17]. Surface tensions of all BMN aqueous solutions were measured by the pendant drop technique using Dropmaster 800, Kyowa Interface Science Co., Ltd [25]. Some concentrations of the BMN aqueous solution were prepared in an aqueous buffer solution such as sodium phosphate SP (PH6.86), THAM/ HCl (PH8.3) or (N-(2-acetoamido)-2-aminoethanesulphonic acid (ACES) / tetrametylanmoniumhydroxide (TMAH)) (PH7.7). Fig.S1 shows the relationship between the BMN concentration in an aqueous buffer solution and the surface tension. The surface tension slightly decreased over 5mM of the BMN concentration in all the aqueous buffer solutions. Based on this result, we determined the CMC of BMN aqueous solution to be 5mM.

Preparation of the micelle between DPAG4 and BMN of CMC (M-DPAG4-BMN).

Using these buffer aqueous solutions at CMC, M-DPAG4-BMN was prepared as mentioned in the Experimental Section. These UV-vis absorptions and the colors of the solutions showed that the M-DPAG4-BMN aqueous solution in both THAM/HCl and ACES/TMAH was almost same to that dissolved in SP. (Fig.S2) Therefore, we employed THAM/HCl as the metal free buffer in the preparation of M-BMN-DPAG4-14Pt.

XPS of BMN and M-BMN-DPAG4.

A strong peak around 69.0eV was detected by XPS of the solids of both BMN and M-BMN-DPAG4 on the HOPG. This peak corresponds to Br in the bromide compounds. (Fig.S3)

Observation of the surface of the bare HOPG before and after the UV-ozone treatment by STM.

References

[17] J. N. Israelachvili, Intermolecular and Surface Forces, second ed; Academic Press, New York 1992.

[25] C. E. Stauffer, J. Phys. Chem. 69 (1965) 1933.

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