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ORIGINAL PAPER

Polymer grafted GO/sulfonated copolyimide proton exchange nanocomposite membrane: as a polymer electrolyte membranes fuel cell Leila Ahmadian-Alam 1 & Mahdi Teymoori 1 & Hossein Mahdavi 1 Received: 28 July 2019 / Accepted: 21 February 2020 # The Polymer Society, Taipei 2020

Abstract Attaining a high performance proton exchange membrane as a suitable replacement for Nafion is one of the research priorities of fuel cell research. In this regard, we synthesized a copolyimide consisting of sulfonic acid substituents filled with different content of GO grafted sulfonated poly (urea-co-urethane) via in situ condensation polymerization. All nanocomposites showed a significant increase in thermal, mechanical properties, ion exchange capacity (IEC), water uptake (WU) and proton conductivity by incorporation of the modified GO nanosheets and the best results were found for membrane containing 1 wt% modified GO loading. The nanocomposite membrane with 1 wt% modified GO nanosheets exhibits 0.73 meq g−1 IEC and 7.3 mS cm−1 proton conductivity at room temperature. A single fuel cell test of this membrane demonstrates a maximum power density of 26.30 mW cm−2 at 0.26 V. Keywords Polymer electrolyte fuel cells . GO nanosheets . Nanocomposite membrane . Sulfonated copolyimide

Introduction Nowadays, environmental safety considerations and risk of greenhouse gases emission are the most important global issues and challenges facing contemporary humans. Reducing the consumption of fossil fuels as the potential carbon producers has been proposed by many theorists as a key current way to alleviate these concerns. The use of renewable sources especially fuel cell technology as a promising option in addressing these challenges is the most prominent approach that has drawn a lot of attention in developed and also developing countries [1, 2]. Due to provide clean and efficient energy, as well as the availability of different fuel cells, this technology has grown significantly in recent decades [3]. Among different fuel cells, polymer electrolyte membrane fuel cells (PEMFCs) have been proposed for portable electronics, automotive, stationary and residential due to their high power conversion, quick start up, low operation temperature, simplicity

* Hossein Mahdavi [email protected] 1

School of Chemistry, College of Science, University of Tehran, P.O. Box 14155-6455, Tehran, Iran

and low cost [4]. Polymer electrolyte membrane (PEM) is a key part of PEMFCs which supplies long durability and high performance of PEMFCs [5, 6]. Nafion membrane has a good potential for use as a PEM in PEMFCs, however, the aliphatic structure and high cost of this polymer limit its application, especially at high temperature due to decreasing conductivity and stability [7, 8]. In PEM field, various kind of polymers with aliphatic and aromatic sequences were investigated for possible use as main matrices of electrolyte in PEMFCs, including perfluorinated [9, 10] and nonfluorinated polymers [11–15]. Despite having high proton conductivity, a