Characterization of the structures and dynamics of phosphoric acid doped benzimidazole mixtures: a molecular dynamics study

• Published in: Journal of molecular modeling Vol. 19; no. 1; pp. 109 - 118
• Main Authors: More, Minal, Pahari, Swagata, Roy, Sudip, Venkatnathan, Arun
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer-Verlag 2013
• Subjects: Characterization and Evaluation of Materials; Chemistry; Chemistry and Materials Science; Computer Appl. in Life Sciences; Computer Applications in Chemistry; Molecular Medicine; Original Paper; Theoretical and Computational Chemistry; Molecular dynamics; Radial distribution functions; Diffusion coefficient; Hydrogen bond
• ISSN: 1610-2940; 0948-5023
• DOI: 10.1007/s00894-012-1519-8

Benzimidazole-based polymer membranes like poly(2,5-benzimidazole) (ABPBI) doped with phosphoric acid (PA) are electrolytes that exhibit high proton conductivity in fuel cells at elevated temperatures. The benzimidazole (BI) moiety is an important constituent of these membranes, so the present work was performed in order to achieve a molecular understanding of the BI–PA interactions in the presence of varying levels of the PA dopant, using classical molecular dynamics (MD) simulations. The various hydrogen-bonding interactions, as characterized based on structural properties and hydrogen-bond lifetime calculations, show that both BI and PA molecules exhibit dual proton-acceptor/donor functionality. An examination of diffusion coefficients showed that the diffusion of BI decreases with increasing PA uptake, whereas the diffusion of PA slightly increases. The hydrogen-bond lifetime calculations pointed to the existence of competitive hydrogen bonding between various sites in BI and PA. Figure Structure and dynamics of phosphoric acid doped benzimidazole mixtures