Alternative Preparation of Metal Organic Framework-Polyelectrolyte Composites for Anion Exchange Applications

Abstract

Metal organic frameworks (MOFs) have continued to receive attention because of flexibility in their designs leading to a large number of uniformly ordered structures which possess high surface area and high porosities. They have shown significant performance in many separation applications including ion-exchange. Therefore, in a bid to exploit the versatility of MOFs and harness their advantages with those of polyelectrolytes for ion-exchange processes, we have prepared MOF-polyelectrolyte composites for ion-exchange applications [1, 2]. The functionalities of the polyelectrolyte guests in the host MOFs are freely exposed to the solution consequently allowing a more efficient ion exchange than in the conventional resins where the ion-exchange functionalities are hidden within the polymeric beads.In an earlier work, [1], an anion exchange MOF-polymer composite was prepared and functionalized under conditions of high pH and involving lengthy steps. This procedure disfavors MOFs that are unstable in strong alkaline medium. In the present study, we have prepared another anion exchange MOF-polymer composite under mild conditions by using a simpler approach. The preliminary results from the HNMR, FTIR, thermal degradation and nitrogen gas sorption tests indicate successful insertion of the polyelectrolyte within the cavities of the MOF. The XRD also confirms that the crystalline structure of MOF is retained after the polymerization.References[1] J. Am. Chem. Soc., 2014, 136 (20), 7209-12.[2] Chem. Mater., 2015, 27 (10), 3601–3608