New Strategy Based on Click Reaction for Preparation of Cross-Linked Poly(Benzimidazolium-Imide) as an Anion-Exchange Membrane with Improved Alkaline Stability

Some new anion-exchange membranes (AEMs) based on poly(benzimidazolium-imide)-containing triazolium groups were prepared. The click chemistry, as a fast and straightforward reaction, was employed to prepare triazolium groups and cross-linking simultaneously. Regarding low mechanical properties of PBIIs, cross-linked membranes with better properties were tried to be prepared. Two different crosslinked membranes with a hydrophilic cross-linker (Q-CLP1) and a hydrophobic cross-linker (Q-CLP2) were prepared. For mechanical properties, Q-CLP1 shows a higher tensile stress (15.37 MPa) due to the rigidity of the aromatic cross-linker. On the other hand, an aliphatic cross-linker in Q-CLP2 causes more fixability and tensile strain (17.5%). The sulfonated aromatic cross-linker (hydrophilic cross-linker) in Q-CLP1 increased the water uptake and the swelling ratio compared to Q-CLP2. The Q-CLP1 showed 58% WU and 17% SR, while the Q-CLP2 membrane had 27% WU and 9% SR at 30 degrees C. However, the OH- conductivity of the Q-CLP1 membrane was higher than that of the Q-CLP2 membrane (84 vs 73 mS.cm(-1) for Q-CLP2) due to the higher water absorption. This higher conductivity could not be considered as an advantage because of the lower chemical stability of the Q-CLP1 membrane for a long time. The OH- conductivities of Q-CLP1 and Q-CLP2 were equal to 37 and 46 mS.cm(-1), respectively, over 300 h at 80 degrees C.

Automated summary

New anion-exchange membranes based on poly(benzimidazolium-imide) containing triazolium groups were prepared using click chemistry for triazolium groups and cross-linking simultaneously. Two different cross-linked membranes with a hydrophilic cross-linker (Q-CLP1) and a hydrophobic cross-linker (Q-CLP2) were tested for mechanical properties. Q-CLP1 showed higher tensile stress due to the rigidity of the aromatic cross-linker, while Q-CLP2 had more fixability and tensile strain due to the aliphatic cross-linker.