Highly Cationized and Porous Hyper-cross-linked Polymer Nanospheres for Composite Anion Exchange Membranes
Tong Huang, Junfeng Zhang, Xin Liu, Jiandang Xue, Haifei Jiang, Yanxiong Ren, Xiaoyu Qiu, Yan Yin, Zhongyi Jiang, Michael D. Guiver
Abstract
Hyper-cross-linked polymer (HCP), a category of porous organic materials (POMs), is exploited as an anion conducting membrane via a highly cationized and porous quaternized ammonium triptycene-based HCP in the form of <100 nm nanospheres (QTP-HCP-NS) for the first time. The material possesses a high ion density of 3.65 mmol g–1 as well as a high Brunauer–Emmett–Teller (BET) surface area of 706 m2 g–1. Anion exchange membranes (AEMs) are prepared by mixing different loadings of QTP-HCP-NS with quaternized poly(phenylene oxide) (QPPO) and compared with a compressed QTP-HCP pellet. Owing to the high ion density and high water sorption, which results in abundant ion conduction channels in QTP-HCP, the ion conductivity of the composite AEMs is enhanced by 79.5% compared with the unfilled QPPO membrane and by 677% compared with a compressed QTP-HCP pellet. In addition, lower dimensional swelling and higher tensile strength are achieved for the composite AEMs. Aggregation and the resulting interfacial defects of QTP-HCP-NS are found in the composite AEM at a high loading and in the comparative compressed pellet, causing a significant reduction in ion conduction and mechanical properties.