PROTON TRANSPORT THROUGH POLYETHYLENE-TETRAFLUOROETHYLENE-COPOLYMER-BASED MEMBRANE CONTAINING SULFONIC-ACID GROUP PREPARED BY RIGP

A novel sulfonic acid (SO3H) group containing membrane (SH membrane) w as prepared by grafting glycidyl methacrylate onto an ethylene-tetrafl uoroethylene copolymer film with subsequent sulfonation. The graft cha ins introduced on the SH membrane form a flexible brush-type structure capable of binding water molecules (30% more than Nafion 117 membrane ) and transporting protons. Proton conductivity of the SH membrane was evaluated as a function of SO3H group density. The SH membrane with t he SO3H group conversion of 97% and the thickness of 70 mu m had speci fic resistivity of 24 Omega cm at 303 K, which was comparable to that of Nafion 117 membrane. A uniform distribution of the SO3H group acros s the SH membrane was verified using an electron probe x-ray microanal yzer.