Structure-property relationship of poly(2,6-dimethyl-1,4-phenylene oxide) anion exchange membranes with pendant sterically crowded quaternary ammoniums

New block poly(ether sulfone) based anion exchange membranes with rigid side-chains and high-density quaternary ammonium groups for fuel cell application

“…† It is clear that with the increase in temperature, the relaxation of polymer chains is evident and the water absorption capacity increases, leading to enhanced dimensional changes. Moreover, a relatively smaller dimensional swelling was obtained, for the membranes bPES(x/y)-Q than the reported ones, 35,36 indicating their dimensional stability. The smaller dimensional swelling ratio of bPES(x/y)-Q could be attributed to the rigid side-chains of the structure.…”

Recent progress in anion exchange membranes (AEMs) in water electrolysis: synthesis, physio-chemical analysis, properties, and applications

“…At an azidation degree of 44%, the high hygroscopic nature of isopropyl-based cations-functionalized PPO (e.g., PPO-iP-44) exhibits higher WU (192.0%) than n-propyl (141.0%) and cyclohexyl (101.0%)-based cations-functionalized PPO. 232 The PPO functionalized with identical cations and a 31% azidation level revealed lower WU values of 47.8, 38.8, and 22.6%. The hygroscopic isopropyl-based cation absorbs more water than other cations, which is what caused the higher WU to be measured.…”

“…The bulky isopropyl-graed QAs containing PPO (PPO-iP) AEMs have enriched microphase separation, conrmed through the hydrophilic (dark) and hydrophobic region (bright). 232 However, there is no such dark, and AFM images do not observe bright areas for the bulky cyclohexyl (PPO-CH) and npropyl (PPO-nP)-graed QAs containing PPO AEMs (Fig. 25b).…”

“…227 QAs-containing PPO-isopropyl AEMs showed a broad scattering peak (ionomer peak) at 1.9 nm −1 due to the growth of ionomer aggregation. 232 No ionomer peak was observed for PPO containing n-propyl and cyclohexyl AEMs (Fig. 23e).…”

Poly(phenylene oxide) Films with Hydrophilic Sulfonated Amorphous Phase and Physically Cross-Linking Hydrophobic Crystalline Phase

“…Many recent literature papers show that PPO is a choice starting polymer for ion (both cation and anion)-conducting membranes, − which have relevant roles in several energy- and environment-related fields, like e.g., batteries, fuel cells, dialysis, and electrodialysis. The choice of PPO is mainly due to its excellent thermal (glass transition temperature, T g ≈ 210 °C) and hydrolytic stability and high mechanical strength. − …”