Anion exchange membrane from polyvinyl alcohol functionalized with quaternary ammonium groups via alkyl spacers
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Anion exchange membranes (AEMs) functionalized with quaternary ammonium groups are prepared from polyvinyl alcohol for alkaline polymer electrolyte fuel cell (APEFC) application. A series of AEMs were synthesized by direct quaternization of PVA using flexible alkyl spacer as charge carrier added in different weight percentages. These membranes were further cross-linked chemically and thermally before evaluating their ionic conductivity and ion exchange capacity. The interaction of alkyl spacer group with the polymer backbone was confirmed by FT-IR spectroscopy. XRD pattern reveals that the introduction of quaternary ammonium group disrupts the crystalline structure of polymer, increasing its amorphous phase thereby enhancing the conductivity. The QPVA membrane with 15 wt% of alkyl spacer exhibited an improved conductivity of 0.0057 S cm−1 at 40 °C in comparison with other ratios. The cell polarization data for the optimized QPVA membrane was studied at 40 °C with varying ionomer amount. The alkaline stability and cell durability for the optimized QPVA membrane were evaluated for 300 and 25 h, respectively.
KeywordsFuel cells Alkyl spacers Morphology Alkaline stability QPVA
The financial support from Council of Scientific and Industrial Research (CSIR) Govt. of India, under CSIR Young Scientist Award Project (Grant No.DU-MLP-0090), is gratefully acknowledged. The authors thank technical officer Mrs. Bhagyalakshmi from CSIR-CECRI-Karaikudi for helping us with AFM imaging. The authors also thank the Director, CSIR-Central Electrochemical Research Institute and Scientist-In-Charge, CECRI Madras Unit for their suggestions and support.