Spatial Control of Zeolitic Imidazolate Framework Growth on Flexible Substrates

The application of patterned thin film layers of metal organic frameworks onto surfaces is a matter of much interest of late with a view toward opening exciting applications for MOFs in gas sensing and catalysis. Here, the use of a plasma polymer coating technique has been employed to selectively alter the surface chemistry of a fibrous PTFE substrate to modify the in situ growth of ZIF-9 crystals over the surface, leading to the ability to control growth by promoting or inhibiting growth over desired regions on the polymer surface through the use of different coatings XPS analysis of the surface elemental composition across regularly arranged regions of plasma polymer coverage has been extensively used to determine the mechanism of action. The immobilization of metallic cations on the surface by coordination with hydroxyl and carboxyl moieties in highly oxygenated diglyme-based plasma polymer coatings are proposed as favored nucleation points for solvothermal ZIF-9 growth. In contrast, amine-containing plasma polymer coatings based on allylamine serve to inhibit ZIF-9 growth through a lack of coordinating species on the surface, leaving the cobalt salt precursor unbound to the surface.