A systematic study was carried out on Nafion^® 112 membranes to evaluate the effects of different electric field strengths on the structural and electrical properties of the membranes. The membranes were subjected to different electric field strengths (0, 40, 80, and 140 MV/m) at a temperature of 90 °C. Proton conductivity was measured using an LCR meter, revealing that conductivity values varied with the electric field strengths, with the optimal conductivity observed at 40 MV/m. Positron annihilation lifetime (PAL) spectroscopy provided insights into the free volume structure of the membranes, showing an exponential increase in the hole volume size as the electric field strength increased. It was also found that the positronium intensity of the Nafion^® 112 membranes was influenced by their degree of crystallinity, which decreased with higher electric field strengths. This indicates complex interactions between structural changes and the effects of the electric field. Dielectric studies of the membranes were characterized over a frequency range of 50 Hz to 5 MHz, demonstrating adherence to Jonscher’s law. The Jonscher’s power law’s s-parameter values increased with the electric field strength, suggesting a transition from a hopping conduction mechanism to more organized ionic transport. Overall, the study emphasizes the relationship between the free volume, crystallinity, and macroscopic characteristics, such as ionic conductivity. The study highlights the potential to adjust membrane performance by varying the electric field.

This study examines the influence of relative humidity (RH) on the physicochemical and electrochemical characteristic of perfluorinated sulfonic acid/PTFE-based polymer electrolyte membranes (PEMs) under varying ion exchange capacity (IEC) condition’s. Three commercial membranes Fumapem® F-950, F-1050, and F-14100 exhibiting IECs of 1.05, 0.95, and 0.71 meq/g, respectively, were systematically evaluated to understand their dielectric heavier across a RH range of 0–80%. Proton conductivity was measured using AC impedance spectroscopy, while DC conductivity was derived from Nyquist plots. Dielectric constant and loss tangent were analyzed to study charge relaxation and polarization behavior. Stress-strain curves were used to extract mechanical parameters such as toughness, resilience, elongation at break, Young's modulus, and also tensile strength. Dynamic mechanical analysis (DMA) provided insight into the temperature-dependent viscoelastic properties and glass transition temperature (Tg) of each membrane. Results show that increasing IEC enhances proton conductivity (and water uptake, but reduces mechanical stability. Dielectric analysis revealed strong dependence on both RH and IEC, with relaxation processes indicating mixed ionic conduction mechanisms. A strong correlation was observed between IEC and dynamic response, suggesting a trade-off between ionic transport efficiency and mechanical integrity. By balancing hydration, conductivity, and structural resilience under practical circumstances.