Anion exchange membrane with a novel quaternized ammonium containing long ether substituent

• Published in: Journal of membrane science 2019-07, Vol.581, p.293-302
• Main Authors: Qaisrani, Naeem Akhtar, Ma, Lingling, Liu, Jiafei, Hussain, Manzoor, Li, Lv, Li, Panyue, Gong, Shoutao, Zhang, Fengxiang, He, Gaohong
• Format: Article
• Language: English
• Subjects: 4-(dimethylamino)butyraldehyde diethyl acetal; Alkaline stability; Anion exchange membrane; Conductivity; LUMO energy
• ISSN: 0376-7388; 1873-3123
• DOI: 10.1016/j.memsci.2019.03.054

The anion exchange membranes (AEM) is one of the key components for alkaline electrolyte membrane fuel cells. However, poor alkaline stability and conductivity of the membrane greatly hinders its practical application. Herein, we report a novel 4-(dimethylamino)butyraldehyde diethyl acetal (DABDA) quaternized polysulfone AEM, or PSf-DABDA, which shows improved conductivity and alkaline stability due to the better hydrophilicity and the electron donating effect imparted by the long alkyl substituent with two ether-containing moieties in the cation structure. Its room temperature conductivity reaches 21 mS/cm while that of trimethylamine (TMA)- and dimethylbutylamine (DMBA) quaternized AEMs with comparable ion exchange capacity (IEC) is 11.8 and 13.2 mS/cm, respectively. When treated 150 h in 1 M NaOH at 60 °C, the PSf-DABDA membrane experiences a slight conductivity decrease of 5% while the PSf-TMA and PSf-DMBA membranes with a comparable IEC suffer a more serious conductivity decay of 19 and 13.5%, respectively. The better alkali stability of PSf-DABDA over its counterparts is further confirmed by a density functional theoretical study and a structural characterization before and after the alkali treatment. Our work demonstrates the advantage of the DABDA cation by both experimental and computational study; it presents a new possibility of improving AEM conductivity and stability. [Display omitted] •Anion exchange membranes with a novel cation containing long ether substituent were prepared.•The method was facile and more environmentally benign than some traditional ones.•The membrane showed an improved room temperature conductivity of 21 mS/cm.•95% conductivity was retained after 150 h alkali treatment at 60 °C.•Advantage of the cation structure was confirmed by density functional theory.