## 3 Results and Discussion
However, as previously discussed, the properties of E3-C10 and E3-C11, which utilize different cross-linkers--relatively hydrophilic C10 and hydrophobic C11--could vary. The IECs of E3-C10 and E3-C11 PFAEMs were measured at 1.57 \(\pm\) 0.026 and 1.54 \(\pm\) 0.038 meq g\({}^{-1}\), respectively. As summarized in Table 2, although these measured IECs were slightly lower than the theoretical values, the trend remained consistent. Figure 6 illustrates the ion conductivity of PFAEMs containing these ionomers. PFAEMs fabricated by filling ionomers into a porous substrate have two different regions. The ionomer-filled region facilitates ion conduction, while the substrate region offers mechanical strength without contributing to ion conduction. The distinct separation between these regions promotes a physical hydrophilic-hydrophobic segregation effect. Typically, hydrophilic-hydrophobic segregation involves synthesizing polymers with significant differences in hydrophilicity between the main and side chains through multi-block or random co-polymerization. This structure enables more efficient ion conduction via ion-cluster channels within the polymer. PFAEMs adopt a strategy to enhance ion conductivity by physically forming such segregated structures. Examining the ion conductivity measurements of two ionomers with comparable theoretical and measured IECs, as shown in Figure 6, reveals that E3-C10 and E3-C11 exhibit conductivities of 98.7 \(\pm\) 7.0 and 71.1 \(\pm\) 4.0 mS cm\({}^{-1}\), respectively, deviating from the IEC trend. In other words, despite similar IEC values, the ion conductivity of the E3-C10 ionomer, utilizing the hydrophilic C10, is 38% higher than that of E3-C11, which employs the hydrophobic C11. This indicates that the aforementioned hydrophilic-hydrophobic segregation effect is more pronounced in E3-C10. The enhanced performance of E3-C10 can be attributed to its increased hydrophilicity, which facilitates better ion transport in the ionomer region. Figure 5: FT-IR spectra of the PP substrate and fabricated PFAEMs. E3-C10 and E3-C11 PFAEMs. Ensuring low hydrogen permeability in AEMs is crucial for their application in AEMWEs, as it guarantees the production of high-purity hydrogen with enhanced efficiency. In this study, we measured hydrogen permeability under fully hydrated conditions with H\({}_{2}\)/N\({}_{2}\) supplied under differential pressure, utilizing current measurement techniques. The hydrogen permeability was calculated based on crossover current, membrane thickness, and partial pressure. As depicted in Figure 7, the E3-C10 PFAEM exhibits lower hydrogen permeability compared to the E3-C11 PFAEM. This outcome is attributed to the triazine structure present in E3-C10, which effectively impedes hydrogen gas permeation, unlike the trimethylolpropane structure in E3-C11. The gas-impermeable nature of the E3-C10 structure contributes to the reduction in hydrogen permeability. Despite this difference, both E3-C10 and E3-C11 PFAEMs demonstrated exceptionally low hydrogen permeability values overall. Therefore, there are no concerns regarding the utilization of these PFAEMs in AEMWEs. \begin{table}
\begin{tabular}{c c c c c c} \hline
**Ionomer** & **Chemical Structure** & \multicolumn{2}{c}{**IEC (meq g\({}^{-1}\))**} & **Major Bonds** & **Synthesis** \\ \hline E3-C10 & \(\times\) & 2.20 & 1.57 \(\pm\) 0.026 & C-N & UV irradiation \\ E3-C11 & \(\times\) & 2.16 & 1.54 \(\pm\) 0.038 & C-OC=O & UV irradiation \\ \hline \end{tabular}
\end{table} 
Table 2: Chemical structure, theoretical, experimental IEC, major bonds, and synthesis method of the cross-linked ionomers. Figure 6: Through-plane ion conductivity of E3-C10 and E3-C11 PFAEMs in 1.0 M KOH at 60 \({}^{\circ}\)C.  
Mechanical-stability tests were conducted to investigate the effect of the structural formula of the cross-linking monomer. As shown in Figure 8a,b, the tensile strength of the PP substrate was measured at 86.94 MPa.