Synthesis of sulfonated polyphenylsulfone as candidates for antifouling ultrafiltration membrane

Abstract This work focused on the synthesis of a series of sulfonated polyphenylsulfone (SPPSU) random copolymers with various controlled sulfonation levels by using sulfonated monomer in direct copolymerization method and the preparation of antifouling SPPSU ultrafiltration membranes via the conventional immersion precipitation phase inversion method. The chemical structures of the SPPSU copolymers were confirmed by using Fourier transform infrared spectrometer (FTIR) and their thermal properties were thoroughly characterized by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The morphologies of the SPPSU membranes were investigated by scanning electron microscopy (SEM), and the morphology changes of these resultant membranes had been detailedly explained and verified by Hansen solubility parameters (HSPs) from thermodynamic theory. In addition, the surface hydrophilicity and charged property of the SPPSU membranes were studied by water contact angle and membrane potential measurements, and the results indicated that the sulfonation of membrane material is really an effective way to enhance the hydrophilicity and negatively charge the membrane. The pure water flux and protein solution permeation through the prepared membranes were increased with the increase of the degree of sulfonation. The cycle ultrafiltration experiments for protein solution revealed that nonspecific protein adsorption, especially irreversible protein adsorption, for the SPPSU membranes was significantly reduced, suggesting superior antifouling performance.