1,2,3-Triazolium vs 1,2,4-triazolium quaternized poly (2, 6-dimethyl-1, 4-phenylene oxide) (PPO) anion exchange membranes (AEMs): A molecular dynamics (MD) study

Abstract

This work investigates AEMs prepared from Poly (2, 6-dimethyl-1, 4-Phenylene Oxide) (PPO) quaternized with 1,2,3-triazolium and 1,2,4-triazolium, using molecular dynamics (MD) simulations to compare and evaluate their hydroxide transport and their stability against hydroxide degradation at different hydration levels. Hydroxide diffusivity (DOH) at λ = 6 is 0.69 × 10−10 m2/s, and 0.23 × 10−10 m2/s, at λ = 9 is 0.97 × 10−10 m2/s, and 0.67 × 10−10 m2/s and at λ = 12 is 1.85 × 10−10 m2/s, and 1.69 × 10−10 m2/s for 1,2,3-triPPO and 1,2,4-triPPO, respectively. At lower hydration levels (λ = 6 and λ = 9), 1,2,4-triPPO is stable against hydroxide degradation. However, at higher hydration levels, 1,2,3-triPPO has fewer hydroxide ions around the cationic group due to the hydroxide ions being solvated by the water, making it harder for the hydroxide ions to approach the cationic group at higher hydration levels, which means 1,2,3-triPPO is stable against hydroxide degradation.