Water-based Preparation of ZIF-8/Polyurethane Membranes

In order to extend application field and improve processability of crystalline metal-organic frameworks (MOFs), recently MOF/polymer hybrid membranes have been actively studied. Such membranes are generally prepared from polymer solutions and MOF particles. In this research, we chose zeolitic imidazolate framework-8 (ZIF-8), one of MOF families, and attempted to prepare ZIF-8/polymer hybrid membranes without using any organic solvent. In order to improve dispersibility of ZIF-8 particles, ZIF-8 was prepared from an aqueous solution containing Zn2+, 2-methylimidazole and polystyrene sulfonate (PSS). Through dispersion of PSS@ZIF-8 particles along with a dispersing agent into a polyurethane (PU) emulsion and casting on a polystyrene substrate, transparent ZIF-8/PU membranes were successfully prepared (PSS@ZIF-8 content: maximum 41 wt%), and characterized with respect to their tensile properties and water uptakes.