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

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 mu S m(-1) (for carboxylated PIM-1 membranes without SGO) to 56.55 mu S 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.