Proton Transport Property of Nafion Thin Films on MgO(100) with Anisotropic Molecular Structure

Nagao, Yuki

doi:10.1380/ejssnt.2012.114

Cited by 14 publications

(26 citation statements)

References 18 publications

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“…This discussion of main-chain orientation can be supported by the work of another research group [64]. Figure 2(g-j) presents the film thickness dependence of the in-plane proton conductivity on quartz [37], MgO [35,36], sputtered Pt [37], and sputtered Au [36] surfaces. All proton conductivities showed lower values than those of a commercially available Nafion membrane [35,65,66].…”

Section: Introductionmentioning

confidence: 55%

“…Our group reported the highly oriented structure of Nafion thin films on SiO x [34], MgO [35,36], sputtered Pt [37], and sputtered Au [36] surfaces by infrared p-polarized multiple-angle incidence resolution spectrometry (pMAIRS), which was developed by Hasegawa and co-workers [38][39][40], as presented in Figure 2(a-d). IR pMAIRS offers the molecular orientation for each functional group to various functional materials such as derivatives of polythiophene [41,42], porphyrin [43], pentacene [44], fullerene [45], naphthalene diimide [46], phthalimide [47], azulene [48], metal-oxide nanowire [49], polymer brushes [50], and polyimide [51].…”

Section: Introductionmentioning

confidence: 99%

“…Figure 2(g-j) presents the film thickness dependence of the in-plane proton conductivity on quartz [37], MgO [35,36], sputtered Pt [37], and sputtered Au [36] surfaces. All proton conductivities showed lower values than those of a commercially available Nafion membrane [35,65,66]. This lower proton conductivity is a widely reported result [33,[67][68][69][70].…”

Section: Introductionmentioning

confidence: 99%

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Progress on highly proton-conductive polymer thin films with organized structure and molecularly oriented structure

Nagao

2020

Science and Technology of Advanced Materials

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Several current topics are introduced in this review, with particular attention to highly protonconductive polymer thin films with organized structure and molecularly oriented structure. Organized structure and molecularly oriented structure are anticipated as more promising approaches than conventional less-molecular-ordered structure to elucidate mechanisms of high proton conduction and control proton conduction. This review introduces related polymer materials and molecular design using lyotropic liquid crystals and hydrogen bond networks for high proton conduction. It also outlines the use of substrate surfaces and external fields, such as pressure and centrifugal force, for organizing structures and molecularly oriented structures.

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Section: Introductionmentioning

confidence: 55%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Progress on highly proton-conductive polymer thin films with organized structure and molecularly oriented structure

Nagao

2020

Science and Technology of Advanced Materials

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“…The empirically determined condition on a single example induces confusion that the angle set can commonly be employed for some substrates. Nagao studied 12,13 a functionalized polymer thin film prepared on some substrates using the IR pMAIRS technique with an angle set of six angles from 8 to 38 in 6 steps (38 ¼ 8 þ 6 Â 5), which readily revealed chemically new insights. Since the angle set for calibrating MAIRS was determined on a single sample, however, the optimization does not look over a wide variety of substrates with various refractive indices.…”

Section: Introductionmentioning

confidence: 99%

Optimal Experimental Condition of IR pMAIRS Calibrated by Using an Optically Isotropic Thin Film Exhibiting the Berreman Effect

et al. 2016

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Infrared (IR) p-polarized multiple-angle incidence resolution spectrometry (pMAIRS) is a useful spectroscopic tool for revealing the molecular anisotropic structure in a thin film, which is used for the molecular orientation analysis of many functionalized organic thin films. Infrared pMAIRS provides both in-plane (IP) and out-of-plane (OP) vibrational mode spectra, which are influenced by the choice of the angles of incidence, i.e., angle set. To obtain quantitatively reliable pMAIRS spectra, therefore, the optimal angle set must be revealed. In a former study, an optimization study was carried out on a silicon substrate by using the band intensity ratio of the IP and OP spectra of highly oriented molecules in a thin film, which has a problem that the optimized results cannot be used for another substrate. In the present study, a totally new idea using an optically isotropic thin film as a standard sample is proposed to comprehensively explore the optimal angle set on various substrates: the band shift due to the Berreman effect of a strongly absorbing compound is used, instead of the band intensity. This new approach makes the pMAIRS calibration for various substrates a much easier task. With the optimal angle set, the molecular orientation angle in the film calculated by the pMAIRS spectra is also found to be reliable quantitatively. This technique opens a user-friendly way to a reliable molecular orientation analysis in an ultrathin film using IR pMAIRS.

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“…An earlier study by the author revealed that the proton conductivity of Nafion thin film (400 nm) is much less than that of a commercial membrane. 3 In the thin film, sulfonic acid groups are highly oriented and mutually isolated from each other, producing poor conductive channel formation. Therefore, the proton-conductivegroup orientation is important to improve proton conductivity.…”

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confidence: 99%

Substrate Dependence of the Proton Transport and Oriented Structure in Oligo[(1,2-propanediamine)-alt-(oxalic acid)] Thin Films

Nagao

2013

Chemistry Letters

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Three oligo[(1,2-propanediamine)-alt-(oxalic acid)] thin films were prepared on SiO 2 , R-plane sapphire, and MgO(100) substrates, and their proton conductivities were investigated. Conductivity depended on the substrate and varied from 4 © 10 ¹3 to 1 © 10 ¹4 S cm ¹1 under the same conditions (80% relative humidity and 298 K). The thin films between the Rplane (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.The design of highly proton-conductive solid electrolytes is necessary for many applications in the field of solid-state ionics. One fundamental method to create highly proton-conductive material is chemical modification by strong acid groups.1 When using chemical modification such as sulfonation, the resultant chemical stability and mechanical strength are often unfavorable. However, excellent proton conductivity is exhibited. Because of this tradeoff between proton conductivity and mechanical strength and chemical stability, a new method to produce a highly proton-conductive material has been sought for a long time.In a Nafion membrane, protons are known to be transported through nanochannels made of sulfonic acid groups and water clusters, a point that has been discussed intensively in the literature.2 Nanochannels are created by phase separation with the amphiphilic character of Nafion. For a Nafion membrane, the high proton conductivity is known to result from phase separation. An earlier study by the author revealed that the proton conductivity of Nafion thin film (400 nm) is much less than that of a commercial membrane. 3 In the thin film, sulfonic acid groups are highly oriented and mutually isolated from each other, producing poor conductive channel formation. Therefore, the proton-conductivegroup orientation is important to improve proton conductivity.A recent report has described anomalous proton conductivity by thin films based on oligomeric amides. 4 Thin films (ca. 200 nm) of oligomers on SiO 2 substrate exhibit about 10-fold higher proton conductivity than pelletized material (thickness ca. 0.5 mm). Although the reason for this enhancement in proton conduction remains unknown, application of this phenomenon shows promise as a new strategy to produce highly proton-conductive materials. Our group previously reported that this origin for the proton-conductivity enhancement by thin film can result from structural effects such as molecular orientation by thin film on the substrate. This report explains the substrate dependence of the proton-transport property in thin films, which had different molecular-oriented structure.Proton-conductive oligomeric amide (oligo[(1,2-propanediamine)-alt-(oxalic acid)]) was synthesized as described elsewhere.4 Details related to synthesis and characterization of the oligomeric amide are presented ...

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Proton Transport Property of Nafion Thin Films on MgO(100) with Anisotropic Molecular Structure

Cited by 14 publications

References 18 publications

Progress on highly proton-conductive polymer thin films with organized structure and molecularly oriented structure

Progress on highly proton-conductive polymer thin films with organized structure and molecularly oriented structure

Optimal Experimental Condition of IR pMAIRS Calibrated by Using an Optically Isotropic Thin Film Exhibiting the Berreman Effect

Substrate Dependence of the Proton Transport and Oriented Structure in Oligo[(1,2-propanediamine)-alt-(oxalic acid)] Thin Films

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