Carboxylated PIM‐1 incorporating sulfonated graphene oxide effectively improves the ion transport properties of the membrane

Abstract

This study explores the ion transport properties of self‐microporous polymers by introducing a novel combination of carboxylated PIM‐1 with sulfonated graphene oxide (SGO) to fabricate membranes. The resulting membranes exhibit enhanced structural stability, hydrophilicity, and ion exchange capacity (IEC) compared with the original carboxylated PIM‐1 (CPIM‐1), while preserving the subnanoporous structure. However, it was observed that excessive SGO loading leads to a detrimental “blocking effect” that compromises various membrane properties. Through electrically driven ion transport tests in a 0.01 M NaCl solution, it is demonstrated that a moderate amount of SGO effectively enhances membrane conductivity from 46.96 μS m−1 (for carboxylated PIM‐1 membranes without SGO) to 56.55 μS m−1. Additionally, the membranes exhibit selective sieving of cations and anions. The presence of small‐sized ion channels and the electrostatic repulsion generated by the abundant carboxyl and sulfonic acid groups significantly hinder Cl− transport. Consequently, the Na+/Cl− migration ratio (t+/t−) reaches 98 at a concentration ratio of 10:1 on both sides of the membrane, surpassing the value of 3.74 observed for the pure CPIM‐1 membrane. This investigation provides valuable insights for the practical application of easily prepared, processable, and cost‐effective hydrophilic self‐contained microporous polymer membranes in ion transport applications.