| Abstract: | Polypropylene membranes were modified by the plasma etching of SO2, SO2? O2, or SO2? H2O, followed by the plasma polymerization coating of SO2/acetylene. The conditions for SO2 plasma etching were optimized by the measurement of the ion‐exchange capacity (IEC) as a function of the plasma‐etching power (10–30 W), gas pressure (40–60 mTorr), and treatment time (15–120 s). For the plasma etching of SO2? O2 and SO2? H2O, only the pressure ratio (SO2/O2 and SO2/H2O) was optimized under the optimized conditions determined from SO2 plasma etching. Plasma etching was then combined with the plasma polymerization coating of SO2/acetylene, for which the conditions were again optimized by the measurement of the IEC as a function of the plasma power (10–40 W), chamber pressure (50–200 mTorr), SO2/acetylene ratio (15/135–60/90), and treatment time (0–10 min). Next, the electrical resistance and water uptake were evaluated. The modified membranes were also analyzed with scanning electron microscopy, whereas plasma polymer coatings were characterized with Fourier transform infrared/attenuated total reflection. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 99: 3692–3699, 2006 |
