Fabrication and performance study of a zwitterionic polyimide antifouling ultrafiltration membrane

In this paper, the new aromatic zwitterionic polyimide (PI) copolymer was synthesized by a one-pot polymerization reaction and used to prepare a fouling-resistant ultrafiltration membrane. The obtained polymer was thoroughly characterized by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) and exhibited excellent thermal stability. Meanwhile, the zwitterionic PI membrane was compared to the reference PI membrane to determine changes in hydrophilicity, performance and antifouling properties. The results displayed that the surface hydrophilicity, pure water flux and protein solution permeation of the zwitterionic PI membrane were remarkably higher than those of the reference PI membrane. The cycle ultrafiltration experiment for protein solution revealed that nonspecific protein adsorption, especially irreversible protein adsorption, for the zwitterionic PI membrane was significantly reduced, suggesting superior antifouling performance. In sum, the zwitterionic PI is employed as the polymer-based membrane material, resulting in the ultrafiltration membrane with long-term performance stability.