Author: Richard Espiritu (University of the Philippines) - Interest in hydrogen energy as a solution in achieving green energy self-sufficiency has increased significantly. This study explores the development of a cost-efficient, effective, and scalable cellulose acetate-based material for use as an anion exchange membrane (AEM) in fuel cell applications. Specifically, the combination of cellulose acetate (CA) and polyepichlorohydrin (PECH) crosslinked with 1,4-diazabicyclo[2.2.2]octane (DABCO) was investigated. The factors examined are blend ratios, DABCO crosslinking mole ratio (RD/P), and trimethyl amine (TMA) functionalization time. FTIR confirmed successful crosslinking of PECH with DABCO and functionalization with TMA while SEM revealed a well-defined CA-PECH phase. Thermogravimetric analysis demonstrated that the AEM maintained thermal stability under typical operational conditions. For a 50:50 blend (CA:PECH wt%), crosslinking with DABCO resulted in a 38% increase in tensile strength (TS) and a 9% increase in elongation at break (Eb). Varying the blend ratio revealed that higher CA content improved TS (32 MPa and 15 MPa for 60:40 and 25:75 blend, respectively), while the strain rate increased significantly for the higher PECH content. However, RD/P greater than 0.75 produce AEM with decreased mechanical stability. Extending the functionalization time from 3 to 13 days decreased TS by at least 50%, expectedly showing inverse relationship of water uptake (WU) with TS. The p5050-0.75-13 membrane exhibited the best hydrophysical properties, with an ion-exchange capacity (IEC) of 1.32 mmol/g, WU of 83%, and an average degree of swelling (DSAve) of 40%. The ionic conductivity of CA/PECH membranes with 50:50 wt% and RD/P of 0.5 peaked at 51.12 mS/cm (60⁰C). Accelerated stability test in 1M KOH showed insignificant degradation, indicating promising chemical stability. Lastly, single cell H2/O2 fuel cell test for current density and peak power density measurement were performed.
