## 3 Results and Discussion  
To validate the formation of PFAEMs via the pore-filling technique, we conducted FE-SEM analyses on both cross-sectional and surface morphologies. As depicted in Figure 4a,b, the PP substrate exhibited an asymmetric and anisotropic pore distribution. In contrast, Figure 4c-e reveal that the E3-C10 and E3-C11 PFAEMs displayed a polymer-filled PP substrate devoid of visible pores. These observations confirm the successful and complete fabrication of void-free PFAEMs using both the E3-C10 and E3-C11 combinations. The suc  
Figure 3: Schematic illustration of single cell components for AEMWE. cessful fabrication of void-free PFAEMs is significant for applications in water-electrolysis devices, where membrane integrity, ion conductivity, and no gas permeation are crucial. The observed absence of visible pores in the FE-SEM images indicates a dense and uniform membrane structure. To corroborate the successful in situ polymerization of PFAEMs, FT-IR analysis was conducted. As shown in Figure 5, the peaks corresponding to the polymerized structures of E3-C10 and E3-C11 include C-N stretching vibrations in quaternary ammonium (QA) groups at 1222 cm\({}^{-1}\) and 1221 cm\({}^{-1}\), symmetric C-H bending at 1383 cm\({}^{-1}\) and 1385 cm\({}^{-1}\), C-H scissoring vibrations at 1426 cm\({}^{-1}\) and 1427 cm\({}^{-1}\), and asymmetric C-H bending vibrations at 1489 cm\({}^{-1}\) in both samples. Additionally, C=C stretching in aromatic rings is observed at 1614 cm\({}^{-1}\) in both, while C=C stretching vibrations are identified at 1643 cm\({}^{-1}\) (E3-C10) and 1636 cm\({}^{-1}\) (E3-C11). C-H stretching vibrations are noted at 2928 cm\({}^{-1}\) in E3-C10, and at 2929 cm\({}^{-1}\) and 2969 cm\({}^{-1}\) in E3-C11. Furthermore, C-H stretching vibrations are seen at 3022 cm\({}^{-1}\) (E3-C10) and 3019 cm\({}^{-1}\) (E3-C11). The major differences between polymerized E3-C10 and E3-C11 include the C-N stretching vibration in the triazine ring at 1243 cm\({}^{-1}\) (E3-C10), C-O stretching vibrations from ester bonds at 1048 cm\({}^{-1}\) and 1089 cm\({}^{-1}\) (E3-C11), and the carbonyl (C=O) group in methacrylate esters at 1724 cm\({}^{-1}\) (E3-C11). These results confirm the successful in situ polymerization, supporting the polymer-impregnated FE-SEM images shown in Figure 4.  
C10 and C11 were chosen as cross-linkers due to their differing hydrophilic properties. C10 is slightly soluble in water and readily soluble in solvents like acetone, methanol, and tetrahydrofuran. In contrast, C11 is insoluble in water but soluble in acetone. By incorporating these cross-linkers with varying hydrophilicity into the ionomers within PP substrates, we investigated changes in the ionomers' properties. The hydrophilic nature of the cross-linker influenced the ion transport channels and the overall morphology of the ionomer, which are critical factors in determining water electrolysis performance. Figure 4: FE-SEM images of the porous PP substrate and PFAEMs: (**a**) cross-sectional view and (**b**) surface view of the PP substrate; (**c**) cross-sectional view of the E3-C10 PFAEM; (**d**) surface view of the E3-C10 PFAEM; (**e**) cross-sectional view of the E3-C11 PFAEM; (**f**) surface view of the E3-C11 PFAEM. Table 2 presents the chemical structures, and theoretical and experimental IECs of two ionomers, E3-C10 and E3-C11. The theoretical IEC represents the value calculated based on the equivalent weight of ion-exchange groups in the polymer's repeating unit, assuming complete reaction of the electrolyte and cross-linking monomers, relative to the dry weight of PFAEMs. In this study, we compared the theoretical IECs of PFAEMs incorporating the E3-C10 and E3-C11 ionomers. The results showed that E3-C10 and E3-C11 had similar IEC values of 2.20 and 2.16 meq g\({}^{-1}\), respectively. This similarity suggests that disregarding differences in their chemical structures, the two ionomers may exhibit comparable physical properties.