The preparation and characterization of novel charged polyacrylonitrile/PES-C blend membranes used for ultrafiltration

2-Acrylamido-2-methylpropane-sulfonic acid (AMPS) was incorporated into polyacrylonitrile by water-phase precipitation copolymerization successfully. The chemical structure, molecular weight and chemical composition of the synthesized copolymer were characterized by IR, viscosity measurement and elemental analysis, respectively. Furthermore, blends of phenolphthalein poly(ether sulfone) (PES-C) and the synthesized copolymer with different composition dissolved in dimethylformamide (DMF) were used to prepared the ultrafiltration membranes by means of classical phase inversion process. And then, the effect of the blend composition on the hydrophilicity, electrical properties, morphologies and permeation properties of the blend membranes was investigated elaborately. The static water contact angle of the blend membrane surface decreased from 78.7 ± 0.9° to 42.6 ± 3.5° with the increase of PAN-co-AMPS from 0 to 20%. It was found that salt retention properties of the blend membranes were influenced intensely by both the content of the charged copolymer and the pH of feed solution. In addition, FESEM images of membrane surface and cross-section displayed that pore size decreases, the top layer became thicker and the finger-like macrovoids disappeared gradually as the PAN-co-AMPS was added. As a result, the water flux is decreased from 230 to 40 L/m2 h and rejection of PEG20000 and PEG35000 was increased from 0.129 to 0.7389, and 0.5528 to 0.91, respectively (as measured at 100 kPa).