Surface Modification of Polyvinylidene Fluoride Membrane by Remote Argon Plasma

The concentration distributions of ions and active particles in remote argon plasma were studied by Langmuir probe and emission spectroscopy method to predict the optimal surface modification region. Then, PVDF membranes were modified by remote argon plasma and the optimal combination of factors was explored by designing orthogonal experiments for the remote argon plasma membrane modification. The water contact angle was used to characterize the hydrophilic properties of the membrane surface pro and post modification. Meanwhile, SEM and XPS were used to characterize the surface morphologies and chemical compositions of the PVDF membranes. Finally, the strength of the modified PVDF ultrafiltration membranes was characterized by mechanical-tensile performance test, and the filtration and anti-fouling performance of membranes before and after modification were evaluated by sodium alginate filtration experiment. The experimental results show that the optimum conditions for the remote argon plasma modification are the RF power of 90 W, treatment time of 90 s, pressure of 20 Pa, and 40 cm away from the discharge center. The remote argon plasma improves its surface hydrophilicity by introducing oxygen-containing and nitrogen-containing functional groups into the surface of the PVDF membranes, and the water contact angle is reduced from 95.63° to 62.19°. The maximum tensile strength of the modified membrane is increased from 403.11 gf/cm2 to 439.37 gf/cm2. Through the SA filtration experiment, the modified PVDF membrane has a good filtration and anti-fouling performance, and its water flux and sodium alginate (SA) flux are respectively from 123.36 L/(m2•h), 49.08 L/(m2•h) increased to 151.98 L/(m2•h), 68.10 L/(m2•h), the rejection rate is increased from 77.35% to 87.25%, and the fouling rate is decreased from 72.50% to 60.20%. © 2021, Editorial Board of Polymer Materials Science & Engineering. All right reserved.