Studies on Surface Properties of Polyethersulfone Membrane by Remote Argon Plasma

Using double suspension probe and electron spin resonance method, we studied the concentration distribution of electrons, ions and free radicals in remote argon plasma and the optimal surface modification region was to be predicted. To be specific, PES membranes were placed in this region and modified by remote argon plasma. In addition, water contact angle measurement, bovine serum albumin separation experiment, X-ray photoelectron spectroscopy and scanning electron microscope were used to characterize the surface structure and properties of PES membranes. It is found that the relative concentration of electrons and ions in remote region were gradually decreased along the axial. But free radicals still maintain above 90% at the position of 40 cm, which was the best possible surface modification region. The modified PES membranes by remote plasma obtained a higher hydrophilicity and did not showed significant etch on PES membranes surface. And the remote argon plasma contributed more effectively to the oxygen-containing groups (O/C = 0.43) from PES membranes than untreated PES membranes (O/C = 0.18). Moreover, the membrane fouling rate after modification reduced from 70.3% to 64.7% and contact angle decreased from 67° to 18°. The above results indicated that the possibility of free radicals reaction can be enhanced by remote argon plasma.