Hubei Engineering & Technology Research Center for Functional Materials from Biomass, School of Chemistry and Material Science, Hubei Engineering University, Xiaogan, Hubei 432000, China; School of Materials Science and Engineering, Hubei University, Wuhan, Hubei 430062, China.
Department of Fashion and Design, Lee Ming Institute of Technology, New Taipei City 243, Taiwan, China.
Carbohydr Polym. 2019 Jun 1;213:320-328. doi: 10.1016/j.carbpol.2018.12.059. Epub 2018 Dec 19.
Utilization of chitosan as the host polymer of anion exchange membranes (AEMs) can avoid the carcinogenic chloromethylation step which is indispensable for aromatic polymers during their quaternization process. To further improve the ionic conductivity and mechanical stability, a hydroxide ion conductor (layered double hydroxides, LDHs) was intercalated by glycine betaine and then incorporated to quaternized chitosan and polyvinyl alcohol mixed matrix to prepare AEMs. Due to intercalated organic ions, the LDHs can be homogeneously dispersed in the matrix, thus promoting the load transfer from the matrix to stiff LDHs. The tensile strength and elongation of the composite membrane (5% intercalated LDHs content) are 23.6 MPa and 51.4% which are 71% and 44% respectively higher than those of the pure QCS/PVA membrane. Moreover, the hydroxide ion conductor (LDHs) and the intercalated quaternary ammonium groups could act as new OH conductive sites and further enhance the ionic conductivity. The membrane with 5 wt.% intercalated LDHs loading shows ionic conductivity of ˜35.7 mS cm (80 °C) and peak power density of 97.8 mW cm which are respectively 42% and ˜50% higher than those of the pure membrane. Furthermore, better alkaline stability was also proved in the composite system, and the ionic conductivity of the composite membrane can retain 70% (only 49% for the pure membrane) even after immersing in a 1 M KOH for 168 h.
壳聚糖可用作阴离子交换膜（AEMs）的主体聚合物，可避免在季铵化过程中芳香聚合物不可缺少的致癌氯甲基化步骤。为了进一步提高离子电导率和机械稳定性，将层状双氢氧化物（LDHs）通过甘氨酸甜菜碱插层，然后掺入季铵化壳聚糖和聚乙烯醇混合基质中，制备 AEMs。由于插层的有机离子，LDHs 可以均匀分散在基质中，从而促进从基质到刚性 LDHs 的负载转移。复合膜（5%插层 LDHs 含量）的拉伸强度和伸长率分别为 23.6 MPa 和 51.4%，分别比纯 QCS/PVA 膜提高了 71%和 44%。此外，氢氧化物导体（LDHs）和插层的季铵基团可以作为新的 OH 导电位点，进一步提高离子电导率。负载 5wt.%插层 LDHs 的膜在 80°C 时的离子电导率约为 35.7 mS cm，峰值功率密度为 97.8 mW cm，分别比纯膜提高了 42%和约 50%。此外，在复合体系中也证明了更好的碱性稳定性，即使在 1 M KOH 中浸泡 168 小时后，复合膜的离子电导率仍能保留 70%（纯膜仅为 49%）。
