Toward highly ionic polyelectrolyte membrane: Synthesis, characterization, membrane performance and theoretical studies of PVDF-g-PAN/PAMPS hybrid membranes

• Published in: Materials today communications 2024-08, Vol.40, p.110232, Article 110232
• Main Authors: Abu-Saied, M.A., El Desouky, Eman.A., Rafea, M. Abdel, Abusaif, Moustafa S.
• Format: Article
• Language: English
• Subjects: Conductivity; Electrophilicity index (ω); ELUMO; Energy band gap; Polyelectrolyte membranes; PVDF-g-PAN; Thermal stability
• ISSN: 2352-4928; 2352-4928
• DOI: 10.1016/j.mtcomm.2024.110232

Novel highly ionic polyvinylidene fluoride (PVDF) membranes grafted with an acrylonitrile monomer to yield the target (PVDF-g-PAN) via radical polymerization and then blended with the amphiphilic copolymer poly (2-acrylamido-2-methyl-1-Propane sulfonic acid (PAMPS) via physical interactions (PVDF-g-PAN)/(PAMPS), were designed and constructed. The new functional groups obtained (fluoride, nitrile, and sulfonic functions) were confirmed via FTIR analysis, and the prepared membranes were characterized using SEM, TGA, tensile strength, water contact angle, and mechanical stability instruments. The essential characteristics of the polyelectrolyte membranes, including the IEC, ionic conductivity, methanol permeability, thermal stability, and high mechanical qualities, were examined. It was discovered that, the oxidative stability of the modified membrane (P3) with a high concentration of conductive PAMPS affected the percentage of weight loss (5.25 %) at the end of 24 h. In addition, the water absorption capacity increased with increasing in the concentration of PAMPS. Similarly, the highly concentrated PAMPS modified membranes (P3) have an ionic exchange capacity and proton conductivity equal to IEC= 1.93 meq/g, which is greater than that of the Nafion membrane by 0.91 meq/g. Furthermore, appropriate DFT theoretical studies such as EHOMO, ELUMO, energy band gap and dipole moment (µ) were thoroughly examined and employed to validate the highly ionic system. It was found that, the energy band gap of PVDF-g-PAN/PAMPS was 5.19 eV, which is lower than that of the grafted polymer value (7.17 eV), confirming that the electrons are transferred readily from the HOMO level to the LUMO level. In addition, the dipole moment of the PVDF-g-PAN/PAMPS was 7.10 Debye, which is greater than the dipole moment value of the grafted polymer (2.07 Debye), indicating the highly ionic character of the hybrid polymer. Finally, the promising results obtained demonstrated favorable film-forming and structural properties, making it a promising option for polyelectrolyte membranes. It also has the added advantage of being cost-effective and can be applied in many electrochemical applications. [Display omitted] •Novel PVDF-g-PAN/PAMPS was synthesized by grafting polymerization and then blending process.•Grafting with acrylonitrile significantly improved the mechanical properties, while incorporating PAMPS enhanced the IEC and conductivity of the prepared membranes.•The resulting membranes de