Proton Conductivity of Oligomeric Poly[(1,2-Propanediamine)-alt-(Oxalic Acid) Thin Films on Al2O3 Substrates

2017

Langmuir

Self Cite

Highly proton conductive polymers have long attracted the attention of researchers for use in energy conversion, sensors, catalysts, and other applications. From the viewpoint of the scientific history of the creation of highly proton conductive polymers, one fundamental approach is based on the strategy of phase-segregated structures with strong acid groups. This Feature Article presents a new approach to enhancing the proton conductivity of the polymer thin films using an interface that can modify the degrees of freedom for a polymer structure through interaction between the substrate surface and polymers. I introduce suppressed proton conductivity into Nafion thin films and then specifically examine the enhancement in proton conductivity by the molecular orientation of the polymers. As the last topic, a highly proton conductive organized polyimide thin film is demonstrated using the lyotropic liquid-crystal property. Both molecular ordering and the in-plane oriented structure can enhance proton conductivity. Moreover, the optical domain and degree of molecular ordering derived from the molecular weight can contribute strongly to the proton transport property.

Section: ■ Introductionmentioning

confidence: 95%

Proton-Conductivity Enhancement in Polymer Thin Films

2017

Langmuir

Self Cite

“…Results showed that proton conductivity is changed by molecular orientation of the polymer according to an interaction between the substrate and the polymer interface [21,22]. In 2008, the first report was made of a study in which the proton conductivity of oligo[(1,2-propanediamine)-alt-(oxalic acid)] thin films was improved by the molecular orientation [23][24][25]. As the oriented structure of other research groups, Tamura and Kawakami presented composite membranes containing uniaxially aligned sulfonated polyimide nanofibers by an electrospinning process (Figure 1(f)) [26].…”

Section: Introductionmentioning

confidence: 99%

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

Science and Technology of Advanced Materials

2020

Self Cite

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.

“…They found that ion domains flattened along the in-plane direction and ordered along the thickness direction from the results of small angle X-ray scattering measurements. Recently, anomalous proton conductivity through the synthesis of thin films of proton-conductive oligomeric amides and polypeptide has been reported [2][3][4][5]. These proton conductivities are dependent on the thickness of the thin film, and the maximum proton conductivity of the thin film exhibits a value 10 times higher than that of the pelletized sample.…”

Section: Introductionmentioning

confidence: 99%

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

e-J. Surf. Sci. Nanotechnol.

2012

Self Cite

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.