| dc.description.abstract | Polymerized ionic liquid (PIL) block copolymers can be used as solid-state membranes in alkaline fuel cells (AFCs) to extend AFC lifetime performance. Combining the multiple block chemistries synergizes the individual properties of each chemistry into one polymer membrane, forming a high-ion-conducting, chemically stable, mechanically-strong, water insoluble, free-standing film. Moreover, PIL block copolymers can exhibit an array of nanostructured morphologies, which can affect the ion conductivity of the polymer (a key property that is proportional to AFC power output). Previously, only PIL diblock copolymers with limited morphologies and properties have been synthesized for the AFC. In this work, a PIL triblock terpolymer was synthesized providing more chemistries, more morphologies, and a wider property window.
First, a diblock copolymer poly(styrene-b-vinylbenzyl chloride) [poly(S-b-VBC)] was synthesized via reversible addition-fragmentation chain-transfer (RAFT) polymerization and the effect of chain transfer agent, and monomer and initiator concentrations were investigated at a small scale (ca. 1 g). Once the optimum conditions were determined at a small scale, poly(S-b-VBC) synthesis was successfully scaled-up to a larger scale (ca. 50 g) with narrow dispersity and well-defined molecular weight. Poly(S-b-VBC) was further chain extended using 4-octylstyrene and subsequently functionalized with N-methylpyrrolidine to obtain a PIL triblock terpolymer, poly(styrene-b-vinylbenzyl methylpyrrolidinium chloride-b-octylstyrene) [poly(S-b-VBMPyr-Cl-b-OS)]. Preliminary studies were performed on this PIL triblock terpolymer to study the thermal properties (glass transition temperature and degradation temperature) and morphology. Further studies on this PIL triblock terpolymer at various compositions will allow for the exploration of a broader range of membrane properties and therefore the ability to tailor AFC performance. | en |
