Novel Polynorbornenes for Gas Separation Membranes

Saudi Arabia produces approximately half of its domestic electricity from natural gas.  With nearly 300 trillion standard cubic feet in proven natural gas reserves, a small fraction of those reserves has low BTU content.  Gas separation membranes have the potential to help monetize these low BTU content reserves, but there are still challenges with membrane technologies for these applications.  To address these challenges, a systematic series of novel polynorbornenes with varying substituents were synthesized.  Structural evidence via NMR and FTIR demonstrate the role that substituent endo-exo isomerism has on resulting polymeric microstructure, yield, and permeation properties.  Substitution also enables covalent crosslinking via tunable sol-gel routes that helps to stabilize the membranes.  This talk will describe how X-ray diffraction has been used to provide a unique perspective into the porosity and crosslinking of these materials and to demonstrate that pendant substitution can be a successful technique to increase intermolecular spacing, a paradigm for further improving selectivities.  Finally, both pure and mixed gas permeation studies have revealed that substitution can double gas separation selectivities compared to unmodified polynorbornene while retaining high gas permeabilities, further demonstrating the promise of these novel membranes for gas separation applications.