著者

Karthik KRISHNAN Tomoaki YAMADA Hiroko IWATSUKI Mitsuo HARA Shusaku NAGANO Kazuya OTSUBO Osami SAKATA Akihiko FUJIWARA Hiroshi KITAGAWA Yuki NAGAO

出版者

公益社団法人 電気化学会

雑誌

Electrochemistry (ISSN:13443542)

巻号頁・発行日

vol.82, no.10, pp.865-869, 2014-10-05 (Released:2014-10-05)

参考文献数

36

被引用文献数

1 11

---

The organized structure and proton transport property in sulfonated polyimide (SPI) thin film have been studied, much less is known at the interfacial charge transport during confinement of such materials. The proton conductivity of SPI thin film is correlated well with the highly oriented polymer structures as determined by infrared (IR) p-polarized multiple-angle incidence resolution spectrometry (p-MAIRS) and in situ RH dependent synchrotron grazing incidence X-ray diffraction (GI-XRD). The high proton conductivity of 2.8 × 10−1 S cm−1 at 80°C and 90% RH was achieved in the highly oriented SPI thin film. In contrast, the bulk SPI showed the drop of conductivity value at high relative humidity region, which is due to the significant structural disorder accompanied by the strong interaction between the sulfonic acid side chains and water molecules.

著者

Yuki Nagao

出版者

The Chemical Society of Japan

雑誌

Chemistry Letters (ISSN:03667022)

巻号頁・発行日

vol.42, no.5, pp.468-470, 2013-05-05 (Released:2013-05-05)

参考文献数

22

被引用文献数

6

---

Three oligo[(1,2-propanediamine)-alt-(oxalic acid)] thin films were prepared on SiO2, R-plane sapphire, and MgO(100) substrates, and their proton conductivities were investigated. Conductivity depended on the substrate and varied from 4 × 10−3 to 1 × 10−4 S cm−1 under the same conditions (80% relative humidity and 298 K). The thin films between the R-plane (1102) sapphire and MgO(100) substrates showed different molecular oriented structures. The thin film on the sapphire substrate, which shows higher proton conductivity, has a structure oriented parallel to the substrate. The molecular orientation in the thin film could be correlated with the proton-transport properties.

著者

Yuki Nagao

出版者

公益社団法人 日本表面科学会

雑誌

e-Journal of Surface Science and Nanotechnology (ISSN:13480391)

巻号頁・発行日

vol.10, pp.229-233, 2012-06-16 (Released:2012-06-16)

参考文献数

28

被引用文献数

1 5

---

In this study, contact angle measurements and an infrared p-polarized multiple-angle incidence resolution spectrometry (p-MAIRS) technique were performed on MgO(100) and quartz substrates. The contact angle and IR spectra of the in-plane and out-of-plane vibration modes depended on the cleaning methods. The surface of the as-received substrates was contaminated in MgO(100) and quartz substrates. As determined by contact angle and p-MAIR spectra analysis, plasma treatment resulted in a relatively clean and superhydrophilic surface under atmospheric conditions. [DOI: 10.1380/ejssnt.2012.229]

著者

Athchaya SUWANSOONTORN Katsuhiro YAMAMOTO Shusaku NAGANO Jun MATSUI Yuki NAGAO

出版者

The Electrochemical Society of Japan

雑誌

Electrochemistry (ISSN:13443542)

巻号頁・発行日

pp.21-00042, (Released:2021-05-21)

参考文献数

47

被引用文献数

2

---

Investigation of interfacial proton transport is necessary to elucidate biological systems. As commonly found in biomaterials, the carboxylic acid group was proven to act as a proton-conducting group. This study investigated the influence of carboxylic acid concentration on both interfacial and internal proton transport. Several styrene-based polymers containing the carboxylic acid group were synthesized. The amount of carboxylic acid group in the polymer chain was varied to explore the effects of weak acid concentration on polymer thin films’ electrical properties. The IR p-polarized multiple-angle incidence resolution spectrometry (pMAIR) spectra show the higher ratio of the free carboxylic acid groups rather than cyclic dimers in polymers with a higher concentration of carboxylic acid group, facilitating the more hydrogen bonding networks in films. The water uptake results reveal the similar number of adsorbed water molecules per carboxylic acid group in all thin films. Remarkably, polymer thin films with high carboxylic acid concentration provide internal proton conduction because of the relative increase in the amount of the free carboxylic acid group. In contrast, interfacial proton conduction was found in low carboxylic acid concentration polymers because of the relatively large amount of cyclic dimer carboxylic acid group and poor amount of free carboxylic acid group. This study provides insight into interfacial proton transport behavior according to the weak acid concentration, which might explain proton transport in biological systems.

著者

Yuki Nagao

出版者

The Japan Society of Vacuum and Surface Science

雑誌

e-Journal of Surface Science and Nanotechnology (ISSN:13480391)

巻号頁・発行日

vol.10, pp.114-116, 2012-04-21 (Released:2012-04-21)

参考文献数

17

被引用文献数

11 11

---

To investigate the proton transport properties of the Nafion thin films on MgO(100) substrates, impedance measurements of the 60 and 400 nm thick thin films were carried out. The proton conductivity of two thin films were quite lower values compared to that of the commercial Nafion membrane, and the thickness dependence of the proton conductivity was also observed. To investigate in-plane and out-of-plane molecular vibrations in an identical 400 nm thick film of Nafion on the MgO(100) substrate, an infrared p-polarized multiple-angle incidence resolution spectrometry (p-MAIRS) technique was carried out. The in-plane spectrum showed well-known spectrum, however, the out-of-plane spectrum was quite different compared to the in-plane spectrum. The largely different shapes of the spectra clearly indicate that the 400 nm thick film of Nafion has an anisotropic molecular structure. [DOI: 10.1380/ejssnt.2012.114]