UV photo-grafting of hydrophilic monomers onto the surface of nano-porous PES membranes for improving surface properties

Polyethersulfone (PES) membrane was prepared via immersion precipitation technique and modified by UV photo-grafting of hydrophilic monomers on the top surface of the membrane. Acrylic acid (AA) and 2-hydroxyethylmethacrylate (HEMA) as acrylic monomers and 1,3-phenylenediamine (mPDA) and ethylene diamine (EDA) as amino monomers were used at different concentrations to improve the surface properties of the membrane. The unmodified and modified PES membranes were characterized by contact angle, ATR-FTIR, scanning electron microscopy (SEM), atomic force microscopy (AFM), cross flow filtration and fouling analysis. The contact angle measurements indicated that the hydrophilicities of the membranes were significantly increased by UV photo-grafting of hydrophilic monomers onto the membrane surface. The ATR-FTIR spectra, SEM and AFM images confirmed that the modification on the PES membrane surface was carried out by UV photo-grafting of hydrophilic monomers. The solute transport data showed that the surface mean pore size of the unmodified membrane declined from 15.8 nm to 6.1, 3.9, 5.5 and 5.7 nm for 6 wt.% of AA, HEMA, mPDA and 5 wt.% of the EDA modified membranes, respectively. The pure water flux and milk water permeation of the membranes were declined by UV photo-grafting but the protein rejection was improved. Moreover, the antifouling properties and flux recovery of the PES membrane were modified by UV photo-grafting of hydrophilic monomers.