(708g) Enhanced Growth of Metal Organic Frameworks On Polymer Fiber Mats Using Atomic Layer Deposition

Immobilization of metal organic frameworks (MOFs) promotes the application to hazardous gas adsorption, membrane separation, catalytic coating and sensors. However, conventional MOF synthesis methods are not easily adapted to MOF-polymer composite materials.  Previous reports of MOFs in or on polymer fibers led to composites with low MOF mass fraction or limited accessible MOF surface area. By depositing an Al₂O₃ thin film via atomic layer deposition (ALD), we modified the surface of non-woven polypropylene (PP) fiber mats to facilitate the nucleation of HKUST-1 [Cu₃(BTC)₂]. Using solvothermal MOF synthesis, ALD-coated PP substrates showed good uniform MOF growth with high coverage (as observed by SEM), whereas similar fiber substrates without ALD led to poor growth and non-uniform coverage. The MOF growth on ALD-coated fibers produced a mass gain of 388% and BET surface area of MOF-PP samples was up to 798 m²/g. Considering the mass of the MOF only, this corresponded to 1046 m²/g for the MOF surface area on the fibers, representing good quality of HKUST-1 without activation. The MOF crystals were found to be strongly attached to the fibers, with ~90% of the MOF mass withstanding a high-rate gas-flow adhesion test. Breakthrough tests showed dynamic loading of ammonia was up to 4.9 mol/kg on MOF-PP samples with ALD. We will discuss how ALD thickness affects MOF growth and the application of this technique to other polymer materials.