Sulfonation of PEEK-WC polymer via chloro-sulfonic acid for potential PEM fuel cell applications

The preparation and characterization of thin dense sulfonated poly ether ether ketone with cardo group (PEEK WC) membranes for proton exchange membrane fuel cell (PEMFC) applications are described The sulfonation of PEEK WC polymer was realized via chloro sulfonic acid and different kinds of membrane samples were prepared with a sulfonation degree ranging from 67 to 99% The degree of sulfonaton homogeneity and thickness significantly affect both the membrane transport properties and the electrochemical performances The dense character of the membranes was confirmed by SEM analysis Proton conductivity measurements were carried out in a temperature range from 30 to 80 degrees C and at 100% of relative humidity reaching 5 40x10(-3) S/cm(-1) as best value at 80 degrees C and with a sulfonation degree (DS) of 99% At the same conditions a water uptake of 17% was achieved DSC and TGA characterizations were used in order to determine the thermal stability of the membranes confirming a T-g ranging between 206 and 216 C depending on the DS whereas FT IR yielded indication about intermolecular interactions and water uptake at various sulfonation degrees (C) 2010 Professor T Nejat Veziroglu Published by Elsevier Ltd All rights reserved