Preparation and characterization of proton exchange membrane based on SPSEBS/PSU blends for fuel cell applications Perumal Bhavani, Dharmalingam Sangeetha * Department of Chemistry, Anna University Chennai, Sardar Patel Road, Chennai 600025, Tamil Nadu, India article info Article history: Received 30 September 2010 Received in revised form 2 March 2011 Accepted 11 March 2011 Available online 16 April 2011 Keywords: PSU SPSEBS Blend Sulfonation abstract Proton-conducting polymer membranes are used as an electrolyte in the so-called proton exchange membrane fuel cells. Commercially available membranes are perfluosulfonic acid polymers, a class of high-cost ionomers. This paper examines the potential of polymer blends, namely those of sulfonated polystyrene ethylene butylene polystyrene (SPSEBS) and polysulfone (PSU), in the proton exchange membrane application. SPSEBS/PSU blends were prepared by solvent evaporation method. SPSEBS membranes exhibited good conductivity, flexibility and chemical stability while they had poor mechanical stability. In an effort to improve the mechanical properties of SPSEBS while maintaining the initial conductivity, it was incorporated with PSU. The obtained membranes were characterized in terms of conductivity, ionic exchange capacity and water uptake. Blend membranes were studied by FTIR spectroscopy and X-ray diffraction. The morphology of the membranes was studied by scanning electron microscope (SEM). Thermal stability of the membranes was studied by TGA and DSC. Mechanical strength was studied by UTM. This paper presents results of recent investigations to develop an opti- mized in-house membrane electrode assembly (MEA) preparation technique combining catalyst ink spraying and assembly hot pressing. Easy steps were chosen in this preparation technique in order to simplify the method, aiming at cost reduction. The influence of MEA fabrication parameters like elec- trode pressing or annealing on the performance of hydrogen fuel cells was studied by single cell measurements with H 2 /O 2 operation. Carbon cloth was used as a gas diffusion layer (GDL) and the composition of electrode inks was optimized with regard to most favorable fuel cell performance. Commercial E-TEK catalyst was used on the anode and cathode with Pt loadings of 0.125 and 0.37 mg/ cm 2 , respectively. The MEA with best performance delivered approximately 0.50 W/cm 2 , at room temperature. The methanol permeability and selectivity showed a strong influence on DMFC performance. Crown Copyright Ó 2011 Published by Elsevier Ltd. All rights reserved. 1. Introduction A fuel cell is an electrochemical energy conversion device that combines a fuel (hydrogen, natural gas, methanol, gasoline, etc) and an oxidant (air or oxygen) and converts a fraction of their chemical energy into electrical energy. Polymer electrolyte membrane is one of the key components for polymer electrolyte membrane fuel cell (PEMFC) and direct methanol fuel cell (DMFC) [1]. Configuration of DMFC is almost same as that of PEMFC, except for using different species of feeding fuel and catalyst. The perfor- mance of DMFC system is known to be lower than PEMFC due to poor catalyst [2]. Nafion, a perfluorosulfonic acid, is the commercially available electrolyte membrane, which is widely used in PEMFCs due to its excellent proton conductivity in the order of 10 1 S/cm and good mechanical stability [3]. Though it possesses several advantages, it still has some disadvantages such as high cost (w700$ per sq. ft), permeability of methanol through membrane in DMFCs and fluo- rine content which is not eco-friendly. In order to over come these disadvantages many research works are being carried out on hydrocarbon membranes like polysulfone, polystyrene [4], poly- ether ether ketones [5], polyvinylidine fluoride [6], polyethylene oxide and polypropylene oxide [7]. One of the hydrocarbon based electrolyte membrane is sul- phonated polystyrene ethylene butylene polystyrene (SPSEBS). It possesses good conductivity in the order of 10 1 S/cm but compared to Nafion, its mechanical stability is low [8]. But in respect of improving the mechanical stability of SPSEBS, no work * Corresponding author. Tel.: þ91 (0) 44 22358656. E-mail address: sangeetha@annauniv.edu (D. Sangeetha). Contents lists available at ScienceDirect Energy journal homepage: www.elsevier.com/locate/energy 0360-5442/$ e see front matter Crown Copyright Ó 2011 Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.energy.2011.03.033 Energy 36 (2011) 3360e3369