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Park, J.; Enomoto, Kazuyuki; Yamashita, Takashi*; Takagi, Yasuyuki*; Todaka, Katsunori*; Maekawa, Yasunari
Journal of Membrane Science, 438, p.1 - 7, 2013/07
Times Cited Count:15 Percentile:43.24(Engineering, Chemical)Alicyclic polyimides (APIs) were successfully applied to radiation-induced graft polymerization for developing polymer electrolyte membranes for fuel cells. The grafting into fully aromatized polyimide barely proceeded (grafting degrees (GDs) of less than 5%), whereas that of styrene into the API films proceeded with styrene GDs of up to 70%. In combination of electron spin resonance measurements and ultraviolet-visible (UV-VIS) spectroscopy, the radical species was identified as a long-lived intermediate and 10% of the radicals were consumed as grafting initiators. The moderate reaction conditions allowed for selective sulfonation on the polystyrene grafts, and not on the API substrates, to give API-based polymer electrolyte membranes (PEMs) with ion exchange capacities (IEC) of 1.7-2.8 mmol/g. The PEMs exhibited appropriate proton conductivity and low water uptake, together with excellent mechanical properties, compared with conventional PEMs such as Nafion.
Park, J.*; Enomoto, Kazuyuki; Yamashita, Takashi*; Takagi, Yasuyuki*; Todaka, Katsunori*; Maekawa, Yasunari
Journal of Photopolymer Science and Technology, 22(3), p.285 - 287, 2009/08
Times Cited Count:0 Percentile:0.01(Polymer Science)Alicyclic Polyimide (A-PI) films were utilized as a substrate of radiation-induced polymerization to prepare PEM for fuel cells. We successfully prepared the A-PI- PEM by radiation-induced grafting of styrene into A-PI films and subsequent sulfonation. The obtained A-PI-PEM has higher ion conductivity and mechanical and thermal properties, compared with conventional PEM (Nafion). Furthermore, the long-lived intermediates in irradiated A-PI films were observed in the UV-VIS spectra. In comparison with the decay profile of ESR spectra of irradiated A-PI films, the initiation radicals (600, 420 nm) and radical anion (720 nm) can be characterized in terms of the graft polymerization mechanism of A-PI films.