title: Gas Separation Membranes Derived from High-Performance Immiscible Polymer Blends Compatibilized with Small Molecules.
abstract: 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.
authors.affiliation: The University of Texas at Dallas , Department of Chemistry and Biochemistry, 800 West Campbell Road, Richardson, Texas 75080, United States.
authors.forename: Nimanka P
authors.initials: NP
authors.lastname: Panapitiya
authors.affiliation: The University of Texas at Dallas , Department of Chemistry and Biochemistry, 800 West Campbell Road, Richardson, Texas 75080, United States.
authors.forename: Sumudu N
authors.initials: SN
authors.lastname: Wijenayake
authors.affiliation: The University of Texas at Dallas , Department of Chemistry and Biochemistry, 800 West Campbell Road, Richardson, Texas 75080, United States.
authors.forename: Do D
authors.initials: do D
authors.lastname: Nguyen
authors.affiliation: The University of Texas at Dallas , Department of Chemistry and Biochemistry, 800 West Campbell Road, Richardson, Texas 75080, United States.
authors.forename: Yu
authors.initials: Y
authors.lastname: Huang
authors.affiliation: The University of Texas at Dallas , Department of Chemistry and Biochemistry, 800 West Campbell Road, Richardson, Texas 75080, United States.
authors.forename: Inga H
authors.initials: IH
authors.lastname: Musselman
authors.affiliation: The University of Texas at Dallas , Department of Chemistry and Biochemistry, 800 West Campbell Road, Richardson, Texas 75080, United States.
authors.forename: Kenneth J
authors.initials: KJ
authors.lastname: Balkus
authors.affiliation: The University of Texas at Dallas , Department of Chemistry and Biochemistry, 800 West Campbell Road, Richardson, Texas 75080, United States.
authors.forename: John P
authors.initials: JP
authors.lastname: Ferraris
keywords: compatibilizers; gas separations; immiscible polymer blends; membrane microstructure; small molecules