(542b) Effect of Polymer Composition on Performance for Benzyl Norbornene Based Anion Exchange Membranes

Anion exchange membranes (AEMs) are a material of growing interest for use as polymer electrolytes in hydrogen-based fuel cells and electrolyzers. Vinyl addition polynorbornenes have been examined as the polymer backbone for AEMs since they form mechanically robust free-standing films and typically have glass transition temperatures above 200°C, making them similar to engineering thermoplastics like polysulfones and poly(para-phenylene oxide). In addition, norbornene monomers can be polymerized via a living chain-growth polymerization mechanism, enabling control over polymer architecture (e.g., block, statistical and star). Polymers prepared from 5-hexyl-2-norbornene and 5-(4-bromobutyl)norbornene were prepared previously and converted into ammonium and phosphonium AEMs. In this talk, discussions of alternative monomers for copolymerization will be discussed. Specifically, the copolymerization kinetics of 5-benzyl-2-norbornene and 5-(4-bromobutyl)-norbornene will be presented, and how this change influences monomer enchainment relative to prior work. Conversion of the copolymer to an ammonium through a substitution of the bromoalkyl group with trimethylamine led to an AEM with an impressive ^-OH conductivity of 116 ± 15 mS/cm at 80°C. To our knowledge, this is the highest conductivity for a non-crosslinked polynorbornene AEM to date. Further characterization of these materials using small angle x-ray scattering and transmission electron microscopy will be discussed, and preliminary exploration in fuel cell devices will be discussed if time remains.