Characterization of surface-charge-mosaic-modified ultrafiltration membranes prepared by laser-induced surface graft polymerization

✍ Scribed by Noboru Saito; Shuzo Yamashita

• Publisher: John Wiley and Sons
• Year: 1998
• Tongue: English
• Weight: 334 KB
• Volume: 67
• Category: Article
• ISSN: 0021-8995
• DOI: 10.1002/(sici)1097-4628(19980207)67:6<1141::aid-app22>3.0.co;2-1

✦ Synopsis

Surface-charge-mosaic-modified ultrafiltration membranes with charged domains of various sizes (500, 100, or 50 mm) were prepared by two-step laser-induced surface graft polymerization using a striped photomask. First, the surface of an ultrafiltration membrane was treated with 4-vinylpyridine after laser irradiation using a striped photomask. Subsequently, the striped photomask was shifted and the surface that was initially shaded from the laser beam by the photomask was exposed to laser irradiation and treated with acrylic acid. The surface element distribution, surface chemical structure, and ion-exchange capacities of the treated membrane were determined by scanning X-ray photoelectron spectroscopy (XPS) analysis, time-of-flight secondary ion mass spectrometry (TOF-SIMS) with imaging capacities, and acid-base titration, respectively. Oxygen and carbon distribution maps determined by the scanning XPS analysis and the TOF-SIMS maps for 16 O 0 and 26 CN 0 ions show that the surface of the treated membrane had striped domains composed of poly(4-vinylpyridine) and poly(acrylic acid). The anion-and cation-exchange capacities of the treated membranes were approximately 2.0 mEq/m 2 . The ultrafiltration rate of these membranes was markedly lower than that of a nontreated ultrafiltration membrane, but increased as the charge domain size decreased. The membrane flux of sodium ions also increased with decreasing charge domain size. This tendency was much stronger for sodium ions than for glucose.