Zeolite-based composite PEEK-WC membranes: gas transport and surface properties

Mixed matrix membranes (MMMs) have been prepared by using different protocols in order to improve the affinity between NaA (LTA) zeolite and a modified polyetheretherketone (PEEK-WC). A terpenic resin has been added to the polymer-zeolite slurry for enhancing the polymer chain flexibility and, consequently, its adhesion with the crystals. Coupling agents such as c-aminopropyl-diethoxymethyl silane (APDEMS) and diethanolamine (DEA) have been used to modify the zeolite surface. The instrumental analyses showed a relative efficiency of these treatments with respect to the simple dispersion of the inorganic fillers within the polymer matrix. At high zeolite concentration (30 wt%), MMMs are characterised by gas transport properties lower than neat polymer-based membrane. DEA-based treatment seems the more encouraging approach also taking into account that as the filler concentration decreases, the occurrence of defects at the interface becomes less significant.