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论文类型：期刊论文

发表时间：2014-08-21

发表刊物：JOURNAL OF MATERIALS CHEMISTRY A

收录刊物：SCIE、EI、Scopus

卷号：2

期号：31

页面范围：12222-12231

ISSN号：2050-7488

摘要：Poly(ether ether ketone) (PEEK) with multiple quaternary ammonium groups on pendent side chains is synthesized through the chloromethylation di-quaternization route, using bi-functional 1,4-diazabicyclo [2,2,2] octane (DABCO) as quaternization reagent. The materials are made into tough and transparent anion exchange membranes (AEMs) by solvent casting. The purpose is to promote efficient hydroxide ion conductive channels, which are particularly important and challenging to improve hydroxide conductivity of AEMs due to the inherently low mobility of hydroxide ions. Transmission electron microscopy (TEM) images show ionic clusters of bigger size scattering in the di-quaternized membranes compared with the mono-quaternized membranes. Given similar ion exchange capacities (IECs), the di-quaternized membranes exhibit much higher values of effective hydroxide ion mobility (similar to 3.5 x 10(-4) cm(2) s(-1) V-1) than the mono-quaternized membranes (similar to 1.7 x 10(-4) cm(2) s(-1) V-1). The structure of multiple quaternary ammonium groups on the pendent side chain promotes hydrophilic-hydrophobic micro-phase separation and efficient hydroxide ion conductive channels in the membranes. As a result, hydroxide conductivity of the di-quaternized membranes is about 2 to 3 fold higher than that of the mono-quaternized membranes with similar IEC, exhibiting a high value of about 35.3 mS cm(-1) at 25 degrees C. At a certain IEC, the di-quaternized membranes have fewer pendent side chains on the polymer backbone, which also benefits the mechanical and chemical stabilities of the AEMs.