Improving the Mechanical Durability of Short-Side-Chain Perfluorinated Polymer Electrolyte Membranes by Annealing and Physical Reinforcement

Abstract

Physically reinforced short-side-chain perfluorinated sulfonic acid electrolyte membranes were fabricated by annealing and using a porous support. Five types of solution-cast membranes were produced from commercial perfluorinated ionomers (3M and Aquivion (AQ)) with different equivalent weights, annealed at different temperatures, and characterized in terms of ion conductivity, water uptake, and in-plane/through-plane swelling, while the effect of annealing on physical structure of membranes was evaluated by small-angle X-ray scattering and dynamic mechanical analysis. To create a reinforced composite membrane (RCM), we impregnated a polytetrafluoroethylene porous support with 3M 729 and AQ 720 electrolytes exhibiting excellent proton conductivity and water uptake. The electrolyte impregnation stability for the porous support was evaluated using a solvent resistance test, and the best performance was observed for the 3M 729 RCM annealed at 200 °C. Both annealed and nonannealed 3M 729 RCMs were used to produce membrane electrode assemblies, the durability of which was evaluated by open-circuit voltage combined wet–dry cycling tests. The nonannealed 3M 729 RCM survived 5800 cycles, while the 3M 729 RCM annealed at 200 °C survived 16 600 cycles and thus exhibited improved mechanical durability.

Performance Comparison of Proton Exchange Membrane Fuel Cells with Nafion and Aquivion Perfluorosulfonic Acids with Different Equivalent Weights as the Electrode Binders

“… 19 − 21 Also, SSC-type CCMs sustain stable running even at 110 °C while the maximum working temperature for LSC-type CCMs was 95 °C. 10 , 11 Moreover, the studies aiming to explain the PFSA morphology of SSC-PFSA as a function of EW are also carried out. 22 − 25 …”

“…The LSC-PFSA ionomers are suitable for the application under the conditions of temperature lower than 90 °C and relatively high humidity. , In 1980s, a short-side chain PFSA ionomer (SSC-PFSA) with no fluoroether group in the pendant side chain, comprising only two −CF 2 groups, was synthesized by the Dow Chemical Company . Although a significant improvement in the fuel cell performance was obtained, − the complexity of the synthesis route to the SSC monomer greatly restricted the industrial development. Subsequently, Solexis (now known as Solvay Specialty Polymers) was applied to the fluorovinylether process for the production of the SSC monomer (Aquivion) on an industrial scale .…”

“…The difference of proton exchange membranes based on LSC-PFSA and SSC-PFSA and their effect on CCM’s performance have been previously studied both ex situ and in fuel cell. It is showed that CCMs based on the Aquivion SSC-PFSA membrane exhibit higher polarization performance than the CCMs based on the Nafion LSC-PFSA membrane. − Also, SSC-type CCMs sustain stable running even at 110 °C while the maximum working temperature for LSC-type CCMs was 95 °C. , Moreover, the studies aiming to explain the PFSA morphology of SSC-PFSA as a function of EW are also carried out. − …”

Computational Design for the Damping Characteristics of Poly(ether ether ketone)

“…It is critical to understand the mechanism though which molecular structures mediate the energy dissipation performance of PEEK derivatives. The side chain modification of polymers − can improve the chemical, − biological, physical, and mechanical , properties. To improve the mechanical properties, PEEK was modified by functional groups including carboxyl groups (−COOH) and amino groups (−NH 2 ), , benzene rings (−C 6 H 5 ), methyl carboxylate (−COOHCH 3 ), and sulfonate groups (−SO 3 H). ,,, The damping characteristics of polymer materials strictly depend on the frictional energy between molecular chains that is correlated to the side chain modifications.…”

Composite Membranes Using Hydrophilized Porous Substrates for Hydrogen Based Energy Conversion

“…Since the less volume of PFSA is used compared to non-reinforced PFSA membranes, benefits can be obtained in terms of material cost [12,24,25]. To prepare reinforced composite membranes, PFSA ionomer dispersion normally in a mixed solvent of water and alcohols and poly(tetrafluoroethylene) (PTFE) porous substrate is often used due to high proton conductivity of the ionomers and polymeric compatibility with PFSA, respectively [26][27][28]. Nevertheless, the preparation process of porous PTFE-reinforced PFSA composite membranes is very difficult since not all the hydrophilic ionomer dispersions are compatible with hydrophobic PTFE porous substrates.…”