Enhancing membrane surface antifouling by implanting amphiphilic polymer brushes using a swelling induced entrapment technique

Abstract

In this work, a swelling induced entrapment technique was developed to enhance the hydrophilicity and antifouling performances of polypropylene (PP) microfiltration membranes. By this method, three amphiphilic polymers with different chemical structures (i.e., a homopolymer (polypropylene glycol), a di-block copolymer (oligoethylene glycol monooctadecylether), and a tri-block copolymer of ethylene glycol (EO) and propylene glycol) were successfully implanted onto membrane surfaces to be polymer brushes with high density, without having a significant effect on the membrane pore structure. The polymer brushes significantly enhanced the hydrophilicity and protein fouling resistance of the membrane. In particular, when using the di-block copolymer with a short hydrophilic EO chain, the modified membrane showed a low water contact angle, down to 20°, and low adsorption of bovine serum albumin of 1.1 μg cm−2. Furthermore, the implanted polymer brushes exhibited excellent durability. The hydrophobic segments of amphiphilic polymers played a leading role in the implantation and stability of the brushes on the PP membrane surface. This work provides a feasible strategy to achieve surface hydrophilicity and antifouling performances in a hydrophobic membrane for use in high-efficiency water treatment.