Modeling the Effect of Dimethylsulfoxide on the Energy of Interaction of Ions in Nafion-Like Membranes

Quantum chemical modeling is performed for the distancing of lithium and ammonium cations from the –O–CF2–CF2–SO$$_{3}^{ - }$$ functional group typical of Nafion-like polymer membranes in the presence of a different number of dimethylsulfoxide molecules. The cluster approach plus the B3LYP density functional and 6-31G* basis are used. It is found that cations are quite strongly bound to anions in the considered systems if the number of plasticizer molecules in them is low (n ≤ 4). Solvent molecules not incorporated in the first coordination sphere can act as polarizable dielectric layers between cations and anions upon an increase in the value of n. This allows the distance between a cation and an anion to be increased to 7–14 A with a moderate consumption of energy (∼0.3 eV).