Metal-organic frameworks (MOFs) have emerged as an attractive new platform of crystalline porous materials that have metal ions or clusters bridged by organic ligands.  Although not yet used industrially at broad scale, the structural versatility and tunable pore systems render MOFs as preferred filler materials in polymers for the production of gas-separation MOF-polymer mixed matrix membranes (MMMs).    One of the challenges in commissioning polymer/MMMs for industrial gas separations is plasticization that swells the polymer matrix by highly soluble species at high pressures, resulting in a loss of selectivity. Since most realistic feeds are pressurized, commercial gas separation membranes are required to maintain stable polymer chain mobility and free volume under high transmembrane pressures in order to deliver uncompromised separation efficiency.  In this talk, the engineering of MOF crystal morphology will be discussed as a novel solution to addressing membrane plasticization at high feed gas pressures. The branched MOF crystals are found to effectively suppress polymer matrix swelling with stable CO<sub>2 </sub>permeability at high pressures (&gt;700 psi) for a MMM with branched MOF crystals as fillers.  Our further studies indicate that this MOF crystal branching strategy may serve as a generalized approach to counteracting plasticization in MOF-polymer MMMs for gas separations.<br/>

MOF crystal branching: Novel solution to counteracting plasticization in MOF-polymer mixed-matrix membranes

2019 Fall National Meeting

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