Water/Vapor Assisted Fabrication of Large‐Area Superprotonic Conductive Covalent Organic Framework Membranes
Niaz Ali Khan, Mengying Luo, Xinlin Zha, Chandra S. Azad, Jing Lü, Jiahui Chen, Chunyang Fan, Ata Ur Rahman, Mark A. Olson, Zhongyi Jiang, Dong Wang
Abstract
Abstract Fabrication of large‐area ionic covalent organic framework membranes (iCOMs) remains a grand challenge. Herein, the authors report the liquid water and water vapor‐assisted fabrication of large‐area superprotonic conductive iCOMs. A mixed monomer solution containing 1,3,5‐triformylphloroglucinol (TFP) in 1,4‐dioxane and p‐diaminobenzenesulfonic acid (DABA) in water is first polymerized to obtain a pristine membrane which subsequently underwent crystallization process in mixed vapors containing water vapor. During the polymerization stage, water played a role of a diluting agent, weakening the Coulombic repulsion between sulfonic acid groups. During the crystallization stage, water vapor played a role of a structure‐directing agent to facilitate the formation of highly crystalline, large‐area iCOMs. The resulting membranes achieved a proton conductivity value of 0.76 S cm −1 at 90 °C under 100% relative humidity, which is among the highest ever reported. Using liquid water and water vapor as versatile additives open a novel avenue to the fabrication of large‐area membranes from covalent organic frameworks and other kinds of crystalline organic framework materials.