Effect of Sulfonic Groups Concentration on IEC Properties in New Fluorinated Copolyamides

Abstract

Seven aromatic polyamides and copolyamides were synthesized from two different aromatic diamines: 4,4′-(Hexafluoroisopropylidene)bis(p-phenyleneoxy)dianiline (HFDA) and 2,4-Aminobenzenesulfonic acid (DABS). The synthesis was carried out by polycondensation using isophthaloyl dichloride (1SO). The effect of an increasing molar concentration of the sulfonated groups, from DABS, in the copolymer properties was evaluated. Inherent viscosity tests were carried out to estimate molecular weights. Mechanical tests were carried out under tension, maximum strength ( σ max), Young’s modulus (E), and elongation at break (εmax) to determine their mechanical properties. Tests for water sorption and ion exchange capacity (IEC) were carried out. Proton conductivity was measured using electrochemical impedance spectroscopy (EIS). The results indicate that as the degree of sulfonation increase, the greater the proton conductivity. The results obtained showed conductivity values lower than the commercial membrane Nafion 115 of 0.0065 S cm−1. The membrane from copolyamide HFDA/DABS/1S0-70/30 with 30 mol DABS obtained the best IEC, with a value of 0.747 mmol g−1 that resulted in a conductivity of 2.7018 × 10−4 S cm−1, lower than the data reported for the commercial membrane Nafion 115. According to the results obtained, we can suggest that further developments increasing IEC will render membranes based on aromatic polyamides that are suitable for their use in PEM fuel cells.

Humidity effect on the transport properties of per‐fluorinated sulfonic acid/PTFE proton exchange membranes: Positron annihilation study

“…In addition, the F‐14100 membrane with an IEC of 0.71 meq/g has the largest strain, indicating that this membrane has the most flexibility while the mechanical properties of the remaining membranes (F‐1050&F‐950) are good enough for electrodialysis applications in all circumstances. These results are compatible with the data of Pali‐Casanova et al 43 …”

“…Many vital parameters can be achieved using the tensile test, such as the elastic modulus that can be investigated by studying the first region at the stress–strain curve and its slope equal to Young's modulus. Figure 4 shows the stress and strain diagram, for F‐950, F‐1050, F‐14100 membranes and evidently, as the sulfonation degree of these membranes (i.e., IEC) increased, the ultimate tensile stress of the membranes decreased and the tensile strain increased 43 as listed in Table 2. Moreover, incrementing the IEC prompts increasing of WU then, at that point, the mechanical stability diminishes 38 .…”

Synthesis, Characterization, and Proton Conductivity of Muconic Acid-Based Polyamides Bearing Sulfonated Moieties

“…It can be seen that the lowest inherent viscosity is that of the MUFASA34 polymer, indicating that the chain size of this polymer is smaller than that of the other polymers. The ηinh values obtained are in the range of other synthetic polymers [34,35]. The ηinh values of the DABS-containing polyamides are very similar to each other, whereas the ηinh values of the DASDA-containing polyamides decrease as the DS increases; it is likely that the higher amount of DASDA in the The density, ρ, of the new polyamide membranes was determined by the flotation method using ethanol as the liquid, at room temperature.…”

Síntesis y caracterización de poli(metil metacrilato-co-sulfopropil metacrilato) para su aplicación como membranas de intercambio protónico

“…Un procedimiento importante para producir polímeros conductores de protones ha sido post-sulfonar materiales termoplásticos aromáticos. Comúnmente, los grupos Brazilian Journal of Development, Curitiba, v.9, n.7, p. 23057-23076, jul., 2023 sulfónicos son adheridos usando ácido sulfúrico fumante o ácido cloro sulfónico al grupo arilo contenido en la cadena principal del polímero seguido de un proceso de sustitución electrofílica aromática (Pali-Casanova et al, 2019). La cadena principal hidrofóbica mejora las propiedades físicas, mientras que los grupos sulfónicos proveen la conductividad iónica.…”