Fabrication of antifouling polypropylene hollow fiber membrane breaking through the selectivity-permeability trade-off

Abstract To overcome the permeability-selectivity trade-off in the polymer-based membranes, our key strategy is to construct the microstructures of polypropylene hollow fiber membranes by in situ ultrasonic wave-assisted graft polymerization, and incorporate hydrophilic groups into the inner of membranes. The main objective is to eliminate the drawback resulted from pore sizes decreased in the surface modification through increasing the hydrophilicity of the membrane inner. Functional groups were incorporated on the surface and inner of membranes through altering grafted monomers and the amino acids induced epoxy ring opening reaction. The hydrophilicity of the membrane inner was largely enhanced due to the introduction of zwitterionic copolymers. The as-prepared membrane PPM3 had excellent pure water flux (264 L/m2 h) and rejections of BSA (99.9%), Cong red (99.9%) as well as methylthionine chloride (99.2%) at the transmembrane pressure of 0.2 MPa. This study can provide new insights into breaking through the permeability-selectivity trade-off.