Magnetic field‐induced alignment of polybenzimidazole microstructures to enhance proton conduction

Abstract

Aligned polymer microstructures in the field of biomaterials, semiconductors, and ion‐conductive membranes expand steadily. Here, an alternative aligned polybenzimidazole (WM PBI) microstructures fabrication strategy based on the utilization of a weak magnetic field (0.3 T) via the solvent casting method is demonstrated. The anisotropic alignment is induced by the interaction of the π‐electron‐rich structure with the magnetic field. A ripple‐like structure was observed in the field‐emission scanning electron microscopy image for the WM PBI membrane, which depicted the successful alignment of the PBI structure toward magnetic field direction. Electrochemical studies revealed the bulk resistance of WM PBI with only 13.71 × 103 Ω compared to the unaligned PBI (WOM PBI) (63.01 × 103 Ω). WM PBI marked as the highest proton conductivity of 610.66 × 10−6 S cm−1, and it was proven that the external magnetic field does bring the impact toward the augmentation of the proton conductivity, which is useful in various future generation applications.

Study of Innovative GO/PBI Composites as Possible Proton Conducting Membranes for Electrochemical Devices

“…This observation could be interpreted by the balance of internal forces acting within the bulk of the membranes. Hydrogen bonds among the GO flakes increased their tendency to cluster, but at the same time, π-π interactions could be established among the benzimidazole rings of the polymer strands and the multiple sp 2 -hybridized domains of GO [2,20,23,46]. These two contributions could disturb the generation of planar surfaces, therefore being responsible for the coarseness visible throughout these three samples [18,35,39].…”

“…Solution casting was considered to be the method best fulfilling such requirements, although the authors had to address some critical points. For instance, several works relied on the use of N,Ndimethylacetamide (DMAc) [18,20,30,36] or N,N-dimethylformamide (DMF) [37,41,42] as organic solvents for PBI. Nevertheless, these substances are renowned for their intrinsic dangerousness toward human safety, inasmuch they are toxic and irritating.…”

“…The electron-acceptor -NH-moieties of the benzimidazoles, i.e., bicyclic groups consisting of fused benzene and imidazole rings, are able to readily tether PA to form single-phase doped proton exchange membranes (PEMs) with improved proton conductivity [4,6]. Examples of applications are nanofiltration [12,13], gas separation [14,15], flow batteries [16,17], fuel cells [11,[18][19][20], and electrolyzers [21][22][23]. Flow batteries are promising devices for stationary energy storage characterized by environmental friendliness, design flexibility, extended lifecycle, and fast response times [24].…”

Magnetic field‐aligned proton exchange membranes: A review of progress and challenges in the fuel cell applications

“…Illustration of the magnetic field treated (a) polybenzimidazole (WM PBI) and (b) graphene oxide (GO)-iron oxide (Fe 3 O 4 )/quaternized polyvinyl alcohol (PVA) membrane. Reprinted with permission from Ref [36,37]…”