Enhanced oxidation stability and proton conductivity of sulfonated poly(arylene ether ketone sulfone)s via embedment of surface-modified ceria nanoparticles

Sulfonated poly(arylene ether ketone sulfone)s (SPAEKS) were prepared by polycondensation reaction as polymer matrix. Dopamine hydrochloride was sulfonated and then modified onto the surface of the ceria (CeO2) nanoparticles. The sulfonated dopamine ceria (SPD@CeO2) was added to the polymer matrix as an inorganic nanofiller to prepare a series of composite membranes. The structure and morphology of modified inorganic nanoparticles and membranes were characterized and analyzed by means of SEM, 1H NMR, PXRD and FTIR. Among all the composite membranes obtained, S-SPD@CeO2-2 (the quality of the SPD@CeO2 percentage was 2%) had the most outstanding comprehensive performance. Oxidative stability of S-SPD@CeO2-2 reached 95.33% due to the free radical scavenging effect of CeO2. At 80 °C, 100% relative humidity (RH), the proton conductivity of S-SPD@CeO2-2 was 218.93 mS cm−1. Meanwhile, this membrane also had good mechanical property (Young's modulus was 1332.59 MPa) and dimensional stability (swelling ratio was 34.34% at 80 °C). Besides, the maximum power density and open circuit voltage (OCV) of S-SPD@CeO2-2 membranes reached 445.48 mW cm−2 and 0.917 V. Both of the above results were better than pure membranes (304.45 mW cm−2 and 0.872 V). Comprehensive the above data, S-SPD@CeO2-2 had considerable potential for application as fuel cell diaphragm.