Chemically modified poly(arylene ether ketone)s with pendant imidazolium groups: Anion exchange membranes for alkaline fuel cells Cao Manh Tuan, Astam K. Patra, Dukjoon Kim * School of Chemical Engineering, Sungkyunkwan University, Suwon, Gyeonggi 16419, Republic of Korea article info Article history: Received 2 October 2017 Received in revised form 29 December 2017 Accepted 10 January 2018 Available online xxx Keywords: Poly(arylene ether ketone) Imidazolium Membrane Alkaline fuel cell Conductivity abstract Anion exchange membranes (AEMs) with high stability are prepared for alkaline fuel cells using poly(arylene ether ketone)s (PAEKs) containing pendant imidazolium groups (via a direct step-growth polycondensation reaction). 1 H nuclear magnetic resonance spectros- copy ( 1 H NMR) and Fourier transform infrared (FT-IR) spectroscopy are used to analyze the chemical structure of the prepared PAEK membranes. The anion conductivity, water up- take and swelling ratio, thermal, mechanical, and chemical stability of these membranes are investigated for PAEK membranes with different 1-(3-aminopropyl)imidazole (API) molar ratios (PAEK-API-x) in details. The anion conductivity of PAEK-API-x membranes increases with increasing molar ratio of API. The membrane with API 1.5 equiv. displays the highest anion conductivity (0.0053e0.0531 S cm 1 from 30  C to 80  C). All prepared membranes show good chemical and mechanical stability as well as thermal stability up to 250  C. This high anion conductivity with good thermal, mechanical, and chemical stability of the membrane show potential advantage to meet the demands for AEMs. © 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved. Introduction As fuel cell is a safe and green energy conversion device for stationary and mobile applications, it becomes a solution for producing clean and efficient energy for the next generation. Generally, fuel cells work based on transferring ions through the electrolyte membrane between the anode and cathode. The high ionic conductivity and mechanical stability of membrane make a fuel cell a promising energy source. Improved performance and enhancing durability of electro- lyte membranes are currently areas of intense research and remain significant challenges. The ion transporting mecha- nism of the electrolyte forms many types of fuel cells such as proton exchange membrane fuel cells [1e4], alkaline fuel cells [5,6], solid oxide fuel cells [7], molten carbonate fuel cells [8], and phosphoric acid fuel cells [9]. Among them, the alkaline fuel cell is known as the most developed technology. As the liquid electrolyte-based alkaline fuel cells were operated in devices with disadvantages (limited performance and oper- ating lifetime) [10] in the beginning, they were gradually replaced by alkaline anion exchange membrane fuel cells. There are, however, still many advantages to an alkaline anion exchange membrane in a fuel cell: 1) inexpensive non- noble metal catalysts (nickel, manganese oxide, silver, and iron) are used due to the low over-potentials associated with electrochemical reactions at high pH [11], 2) undesirable fuel crossover is reduced because the direction of alkaline anion * Corresponding author. E-mail address: djkim@skku.edu (D. Kim). Available online at www.sciencedirect.com ScienceDirect journal homepage: www.elsevier.com/locate/he international journal of hydrogen energy xxx (2018) 1 e11 https://doi.org/10.1016/j.ijhydene.2018.01.059 0360-3199/© 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved. Please cite this article in press as: Tuan CM, et al., Chemically modified poly(arylene ether ketone)s with pendant imidazolium groups: Anion exchange membranes for alkaline fuel cells, International Journal of Hydrogen Energy (2018), https://doi.org/10.1016/ j.ijhydene.2018.01.059