Influence of amine-functionalized iron titanate as filler for improving conductivity and electrochemical properties of SPEEK nanocomposite membranes

Abstract

Novel proton exchange membrane was easily prepared by incorporating amine-functionalized iron titanate (AIT) nanoparticles into sulfonated poly (ether ether ketone) (SPEEK) polymer matrix. The surface of iron titanate nanoparticles was modified by grafting (3-aminopropyl) triethoxy silane (APTES). AIT nanoparticles were uniformly dispersed within SPEEK membrane due to the good interfacial compatibility. All the membranes were characterized by Fourier transform infrared (FTIR), thermogravimetric analysis (TGA), universal test machine (UTM), field emission scanning electron microscope (FESEM) and atomic force microscopy (AFM) techniques. The resulting nanocomposite membranes exhibited improved stabilities (mechanical and oxidative) and good water retention properties. SPEEK membranes embedded with AIT nanoparticles indicated higher proton conductivity in comparison with pristine SPEEK membrane. This increase is attributed to water channeling at the polymer/nanoparticle interface and connectivity of the water channels which creates more direct pathways for proton transport. Well optimized SPEEK/AIT (2wt.%) showed 0.065Scm−1 proton conductivity, 38% water uptake and 24% swelling at 25°C. This membrane showed proton conductivity of 0.12Scm−1 and maximum power density of 204mWcm−2 at 80°C which indicates its potential application in proton exchange membrane fuel cell (PEMFC). The prepared membranes can be potential candidates for fuel cells and batteries.