Figure 1 shows the chemical structures of the BP-SPES and FL-SPES. Both SPESs were divided into hydrophilic and hydrophobic domains. Compared to BP-SPES composed of a flat linear structure (Fig. 1a), the quaternary carbon and bulky ring structure of the cardo polymer cause structural rigidity in FL-SPES by significantly restraining the rotational motion of the polymer bonds leading to relative steric hindrance21,23. The rigidity enables FL-SPES to have a large free volume in the hydrophobic domain, which is advantageous for gas permeation, whereas the steric structure limits the degree of swelling in the hydrophilic domain (Fig. 1b)19,20,21,23.Figure 1Chemical structures of the (a) BP-SPES composed of a flat linear structure and (b) FL-SPES composed of a steric structure.Hydrocarbon-based electrolyte polymers typically require significantly higher amounts of sulfonic acid…
Fuel cell performance improvement via the steric effect of a hydrocarbon-based binder for cathode in proton exchange membrane fuel cells
