Sulfonated poly(ether-ether-ketone) polymer membranes for fuel cells

In the work, sulfonated poly(ether-ether-ketone) (SPEEK) ionomers were synthesized using an original (submitted for patent) and simple method. The resulting membranes were tested to determine parameters that are important for the use of this material in fuel cells (water absorption, sulfonation degree, conductivity, etc.). The thermo-gravimetric analysis has shown a good thermal stability in the range from RT to 200-220 °C, and two characteristic regions of weight loss - 7.4% at ∼140 °C (reversible water loss) and 10.3% at 200-220 °C (due to polymer degradation when cross-linked polymer chains permanently break down and their SO₃H-groups are lost). The conductivity values obtained by the through-plane measurements of SPEEK membranes were 12 mS/cm at RT and 23 mS/cm at 80 °C.