Synthesis of PEMs based on alicyclic polyimide by radiation-graft polymerization

Park, J.*; Enomoto, Kazuyuki; Yamashita, Takashi*; Maekawa, Yasunari

We prepared the polymer electrolyte membranes (PEMs) consisting of poly(styrenesulfonic acid) graft chains onto alicyclic polyimide (PI) films using radiation induced-graft polymerization and subsequent sulfonation with a chloro-sulfonic acid solution. The graft polymerization were proceeded with grafting degrees of 070%. Sulfonation degrees gradually increased and reached at near a quantitative yeild, indicating the selective sulfonation to the polystyrene graft chains. The PI-based PEMs showed the highest proton conductivity of 0.26 S/cm with water uptake lower than 100%. We could clearly demonstrate that a series of sulfonated polyimide ionomers for PEMs can be synthesized by radiation-graft polymerization of alicyclic polyimide.