Sulfonated poly(arylene ether sulfone ketone) multiblock copolymers with highly sulfonated blocks. Long-term fuel...

Area of Science:

• Polymer Science
• Electrochemistry
• Materials Science

Background:

• Poly(arylene ether sulfone ketone) (SPESK) membranes are crucial for fuel cell technology.
• Assessing long-term stability under operational conditions is vital for commercialization.

Purpose of the Study:

• To evaluate the operational stability of SPESK multiblock copolymer membranes in a fuel cell environment.
• To identify degradation products and mechanisms during extended fuel cell operation.

Main Methods:

• A 2000-hour fuel cell operation test at 80 °C and 53% relative humidity.
• Monitoring electrochemical properties (cell voltage, resistance) and analyzing drain water.
• Post-test chemical structure analysis using NMR and IR spectroscopy.

Main Results:

• Minor fuel cell voltage losses and slight resistance increases were observed over 2000 hours.
• Anions like formate, acetate, and sulfate were detected in the drain water.
• NMR and IR analyses indicated degradation of the sulfonated fluorenyl group with ether linkage.

Conclusions:

• The sulfonated fluorenyl group with ether linkage is susceptible to oxidative degradation in SPESK membranes.
• This degradation produced small molecules but had minimal impact on proton conductivity, water uptake, and membrane morphology.
• SPESK membranes demonstrate reasonable stability for fuel cell applications despite minor degradation pathways.