Facile preparation of poly (2,6-dimethyl-1,4-phenylene oxide)-based anion exchange membranes with improved alkaline stability

• Published in: International journal of hydrogen energy 2019-05, Vol.44 (23), p.11877-11886
• Main Authors: Jia, Guangyao, Zhu, Zhengfang, Li, Shining, Lu, Yu, Zhu, Yuanqin
• Format: Article
• Language: English
• Subjects: Alkaline stability; Anion exchange membrane; Fuel cells; Poly(2,6-dimethyl-1,4-phenylene oxide); Quaternary ammonium
• ISSN: 0360-3199; 1879-3487
• DOI: 10.1016/j.ijhydene.2019.02.233

Traditional quaternary ammonium (QA)-type anion exchange membranes (AEMs) usually exhibit insufficient alkaline stability, which impede their practical application in fuel cells. To address this issue, a facile method for the simple and accessible preparation of QA-type AEMs with improved alkaline stability was developed in this study. A series of novel AEMs (QPPO-xx-OH) were prepared from commercially available poly (2,6-dimethyl-1,4-phenylene oxide) (PPO) and 3-(dimethylamino)-2,2-dimethyl-1-propanol, via a three-step procedure that included bromination, quaternization, and ion exchange. Scanning electron microscopy revealed that dense, uniform membranes were formed. These QPPO-xx-OH membranes exhibited moderate hydroxide conductivities with ranges of 4–15 mS/cm at 30 °C and 12–36 mS/cm at 80 °C. When tested at similar ion exchange capacity (IEC) levels, the IEC retentions of QPPO-xx-OH membranes were 16–22% higher than that of traditional PPO membranes containing benzyltriethylammonium ions, after immersed in 2 M NaOH aqueous solution at 60 °C for 480 h, and the QPPO-47-OH membrane displayed excellent alkaline stability with the IEC retention of 92% after 480 h. In addition, the QPPO-xx-OH membranes also exhibited robust mechanical properties (tensile strength up to 37.6 MPa) and good thermal stability (onset decomposition temperature up to 150 °C). This study provides a new and scalable method for the facile preparation of AEMs with improved alkaline stability. [Display omitted] •A facile method was proposed to prepare AEMs with improved alkaline stability.•QPPO-xx-OH was prepared from commercially available polymer matrix and QA precursor.•QPPO-xx-OH exhibit high alkaline stability and robust mechanical properties.