Addition-type alkoxysilyl-substituted polynorbornenes for post-combustion carbon dioxide separations

The separation of CO2 from N-2 using polymeric membranes has proven a particularly challenging task. One promising class of polymers for this application is alkoxysilyl-substituted vinyl-added polynorbornenes (VAPNBs), which are high Tg materials that often exhibit notable CO2/N-2 separation performance. This performance is believed to arise from their anomalous behavior in which they display high levels of solubility selectivity, a trait more commonly encountered in rubbery polymers than high Tg glassy materials. Though this trait has been documented in literature, no systematic investigations have been reported that probe the relationship between alkoxysilyl-substituted VAPNB structure and their resultant gas separation behavior. Therefore, we herein describe the synthesis and evaluation of three sets of alkoxysilyl-substituted VAPNBs that are designed to probe distinct facets of their structure-transport relationships. This includes investigations into the effect that alkoxysilyl branching, chain length, and carbon linker length have on CO2/N-2 permeability, solubility, and diffusivity.