Chemically tethered functionalized graphene oxide based novel sulfonated polyimide composite for polymer electrolyte membrane

Novel sulfonated diamine (NSDA) having pendant sulfonic acid group was synthesized. Polycondensation reaction of this NSDA, dianhydride, and graphene oxide (GO) yielded sulfonated imidized graphene oxide (SIGO). Sulfonated imidized graphene oxide(SIGO) along with NSDA, 4,4′-oxydianiline (ODA) and 1,4,5,8-naphthalene tetracarboxylic dianhydride dianhydride(NTDA) were used for the preparation of polymer electrolyte membranes (PEMs). High temperature proton conduction due to the hydrophobic- hydrophilic phase separation resulted from the incorporation of SIGO. 2.28 meq/g of ion exchange capacity (IEC), 11.18 × 10⁻² S/cm of proton conductivity at room temperature and bound water of worth 5.1% between temperature ranges of 100 °C to 150 °C were exhibited by NSPI/3 wt%SIGO composite membrane. Maximum power density of 74.9 mWcm⁻² was achieved at 70 °C by NSPI/ 3% SIGO in single cell direct methanol fuel cell test. All these results make these composite membranes suitable candidate to be used as PEM.