The demand for cost-efficient separations requires membranes with high gas flux and high selectivity which opens the path for further improvements. Mixed matrix membranes (MMMs) made from 33.3 wt % ZIF-8 in 6FDA-durene were tested at 35 °C and 3.5 atm. At 33.3 wt % loading of ZIF-8, H 2 , N 2 , O 2 , and CH 4 gas permeabilities increased approximately 400%. Cross-linking the surface of this MMM, by reacting with ethylenediamine vapor, yielded a 10-fold increase in H 2 /CO 2 , H 2 /N 2 , and H 2 /CH 4 selectivities with respect to 6FDA-durene, preserving 55% of the H 2 permeability of 6FDA-durene. The permselective properties of the cross-linked skin of the MMM fall above the most recent permeability−selectivity trade-off lines (2008 Robeson upper bounds) for H 2 /CO 2 , H 2 /N 2 , and H 2 /CH 4 separations. To the best of our knowledge, this is the first example of a cross-linked ZIF/polymer MMM for gas separation.

An immiscible polymer blend comprised of high-performance copolyimide 6FDA-DAM:DABA(3:2) (6FDD) and polybenzimidazole (PBI) was compatibilized using 2-methylimidazole (2-MI), a commercially available small molecule. Membranes were fabricated from blends of 6FDD:PBI (50:50) with and without 2-MI for H2/CO2 separations. The membranes demonstrated a matrix-droplet type microstructure as evident with scanning electron microscopy (SEM) imaging where 6FDD is the dispersed phase and PBI is the continuous phase. In addition, membranes with 2-MI demonstrated a uniform microstructure as observed by smaller and more uniformly dispersed 6FDD domains in contrast to 6FDD:PBI (50:50) blend membranes without 2-MI. This compatibilization effect of 2-MI was attributed to interfacial localization of 2-MI that lowers the interfacial energy similar to a surfactant. Upon the incorporation of 2-MI, the H2/CO2 selectivity improved remarkably, compared to the pure blend, and surpassed the Robeson's upper bound. To our knowledge, this is the first report of the use of a small molecule to compatibilize a high-performance immiscible polymer blend. This approach could afford a novel class of membranes in which immiscible polymer blends can be compatibilized in an economical and convenient fashion.

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Carbon nanofibers (CNFs) are promising electrode materials for electrochemical double layer capacitors due to their high porosity and electrical conductivity. CNFs were prepared by electrospinning and subsequent thermal treatment of a new precursor polymer, 6FDA-durene, without the addition of pore generating agents. The conversion of precursor nanofibers into CNFs was confirmed using Raman spectroscopy. CNFs were activated and annealed, and nitrogen adsorption/desorption measurements were conducted to determine surface area and porosity. These activated/annealed CNFs were used as binderless electrodes in coin cells with an ionic liquid electrolyte. The devices displayed a specific capacitance of 128 F g, an energy density of 63.4 Wh kg (at 1 A g), and a power density of 11.0 KW kg (at 7 A g).