Nanoscale building blocks for the development of novel proton exchange membrane fuel cells

We propose a new type of sulfonated aromatic polyarylenes as candidate building blocks for proton exchange membranes. Density functional theory calculations and ab initio molecular dynamics simulations suggest that desulfonation is limited at high temperatures, owing to the strong aryl-SO3H bond induced by the electron-deficient aromatic ring, and that the proposed polymers exhibit good thermomechanical stability due to the robust aromatic main-chain repeating unit. Simulations also emphasize the importance of the Grotthuss-type mechanism, with interconversion between Eigen (H9O4+) and Zundel cations (H5O2+) as limiting structures, for the hydrated proton transport in the vicinity of the sulfonic acid groups.