Enhancement of Proton Transport in an Oriented Polypeptide Thin Film

Abstract

Proton transport properties of a partially protonated poly(aspartic acid)/sodium polyaspartate (P-Asp) were investigated. A remarkable enhancement of proton conductivity has been achieved in the thin film. Proton conductivity of 60-nm-thick thin film prepared on MgO(100) substrate was 3.4 × 10(-3) S cm(-1) at 298 K. The electrical conductivity of the oriented thin film was 1 order of magnitude higher than the bulk specimen, and the activation energies for the proton conductivity were 0.34 eV for the oriented thin film and 0.65 eV for the pelletized sample, respectively. This enhancement of the proton transport is attributable to the highly oriented structure on MgO(100) substrate. This result proposes great potential for a new strategy to produce a highly proton-conductive material using the concept of an oriented thin film structure without strong acid groups.

In-plane oriented highly ordered lamellar structure formation of poly(N-dodecylacrylamide) induced by humid annealing

“…Furthermore, the amide I peaks are sensitive to the hydrogen bonding conformation. 27 The amide I peak is located at 1642 cm À1 for the lamellar structured lm. The peak regions show that the amide bond has an a-helix or random-coil structure with a random hydrogen-bonded network.…”

“…The peak regions show that the amide bond has an a-helix or random-coil structure with a random hydrogen-bonded network. 27 Although it is difficult to ascertain which structure is formed, the random hydrogen-bonded structure could be dominant in the planar lamellar structure.…”

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

“…However, thin films of partially protonated poly(aspartic acid)/sodium polyaspartate (P-Asp) showed proton conduction inside of the thin film and exhibited anisotropic proton conduction between in-plane and out-of-plane directions of the thin film [87]. The mobile carrier was determined as a proton by checking H/D isotope effects and the open circuit potential [88]. The P-Asp thin films showed a molecularly oriented structure of amide groups, as portrayed in Figure 3(c).…”

Effect of Casting Solvent on Interfacial Molecular Structure and Proton Transport Characteristics of Sulfonated Polyimide Thin Films

“…[5][6][7][8][9][10][11][12][13] The confinements in thin films induce preferred chain packings and molecular orientations along the in-plane or out-of-plane direction from a substrate plane by self-assembly, which exhibits the highly organized ion-conducting channels that possibly lead to the change of transport characteristics. [14][15][16][17][18][19] Therefore, the organized structure has attracted considerable interest for high proton conduction in thin films.…”