282374 Ionic Liquid Diblock Copolymers
Polymer membranes formed from diblock copolymers have been shown to give improved CO2/N2 and CH4/N2 separations. The observed increase in selectivity is attributed to the orthogonal orientation of the cylindrical morphology relative to the membrane surface.1 While successful, these initial attempts have been based on polymers such as styrene-butadiene-styrene (SBS) which have low CO2 solubility. We have developed techniques for preparing diblock copolymers specifically designed for CO2 separation that contain ionic liquid blocks. This was accomplished using a combination of controlled radical polymerization techniques and click chemistry.2 A detailed synthesis methodology will be presented. The core synthesis centers on the polymerization of c-vinyl triazole3 monomers using free radical and reversible addition-fragmentation chain-transfer (RAFT)4 polymerizations followed by quaternization of the triazole group and ion-exchange reactions. Approaches for producing block copolymers from these pILs will be discussed, as will strategies for synthesizing, and subsequently crosslinking block copolymers to form membranes. Alternative approaches such as the direct polymerizing of c-vinyl triazolium salts, and the incorporation of ionic liquid groups unto polymer backbones using the thiol–ene reaction will also be discussed.
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