Electrochimica Acta 50 (2004) 589–593 Proton conducting semi-IPN based on Nafion and crosslinked poly(AMPS) for direct methanol fuel cell Ki-Yun Cho a , Ho-Young Jung a , Seung-Shik Shin a , Nam-Soon Choi a , Shi-Joon Sung a , Jung-Ki Park a,∗ , Jong-Ho Choi b , Kyung-Won Park b , Yung-Eun Sung b a Department of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology, 373-1, Guseong-Dong, Yuseung-Gu, Daejon 305-701, Republic of Korea b Department of Materials Science and Engineering, Kwangju Institute of Science and Technology, Gwangju 500-712, Republic of Korea Received 2 June 2003; received in revised form 29 March 2004; accepted 29 March 2004 Available online 20 August 2004 Abstract For direct methanol fuel cell, the proton conducting membrane based on semi-interpenetrating polymer networks (IPNs) of Nafion and crosslinked poly(AMPS) was prepared and characterized. The modification of Nafion with crosslinked poly(AMPS) such as hydrocarbon polymer changed the state of water in membranes. Without a significant increase of the membrane resistance, the semi-IPNs demonstrated a reduction of the methanol permeability, comparing to the native Nafion. And the maximum power density of AMPS60 increased as much as 22.2% compared with Nafion. © 2004 Elsevier Ltd. All rights reserved. Keywords: Direct methanol fuel cell; Polymer electrolyte membrane; Semi-IPNs; Methanol permeability; Cell performance 1. Introduction The direct methanol fuel cell (DMFC) is a promising power source. However, there are two main points that should be addressed to achieve the high efficiency with DMFC. First is the development of highly active anode catalysts coupled with a suitable anode structure for the direct methanol oxi- dation [1,2]. Second is the prevention of methanol crossover from anode to cathode through the polymer electrolyte mem- brane (PEM) [3]. Methanol crossover wastes fuel, and also causes performance losses at the cathode due to the consump- tion of oxygen and catalyst poisoning. If these problems can be effectively addressed, it is possible that the DMFC will be adopted in a wide range of application. A number of different approaches have been taken to mit- igate the effects of methanol crossover in DMFC, including the change of operational parameters, the use of different ∗ Corresponding author. Tel.: +82 42 8693925; fax: +82 42 8693910. E-mail address: pjk@mail.kaist.ac.kr (J.-K. Park). cathode catalysts and cell designs, and the development of polymer membranes less permeable to methanol. But, sig- nificant research efforts to decrease methanol crossover have focused on the improvement of polymer electrolyte mem- brane [4–6]. In particular, a number of different composite membrane structures in conventional PEM have been proposed. One patent described the lamination of ionomer layers of different equivalent weight (EW) [7]. The non-ion exchange polymer supported layers, the laminated structures with Pd or Pt foils of nanometer thickness, and the layer of plasma polymer- ized hexane, have also been used to partially block methanol crossover [8–10]. This paper focused on the modification of commercial Nafion membranes by impregnating them with poly(2- acrylamido-2-methyl-1-propanesulphonic acid-co-1,6-hexa- nediol propoxylate diacrylate-co-ethyl methacrylate) which is called by crosslinked poly(AMPS)) by in situ polymeriza- tion, to decrease the methanol permeability, while maintain- ing their high proton conductivity. 0013-4686/$ – see front matter © 2004 Elsevier Ltd. All rights reserved. doi:10.1016/j.electacta.2004.03.062