title: Tailoring the properties of asymmetric cellulose acetate membranes by gas plasma etching.
abstract: Cellulose triacetate (CTA) ultrafilters and cellulose acetate blend (CAB) desalination membranes were treated with a radiofrequency gas plasma (tetrafluoromethane (CF(4)) or carbon dioxide (CO(2)), 47-49 W, 0.04-0.08 mbar). Treatment times were varied between 15 s and 120 min. The plasma-treated top layer of the membranes was characterized by scanning electron microscopy, X-ray photoelectron spectroscopy, and contact angle measurements to obtain information about surface structure, chemistry, and wettability, respectively. The membrane properties (e.g., permeability, selectivity, fouling) were studied by waterflux measurements, molecular weight cutoff measurements, and fouling experiments with bovine serum albumin. CO(2) plasma treatment resulted in gradual etching of the membrane's dense top layer. Permeation and selectivity changed significantly for treatment times of 0-15 min for CTA and 5-60 min for CAB membranes. Moreover, CTA membranes were hydrophilized during CO(2) plasma treatment whereas CF(4) plasma treatment led to hydrophobic surfaces due to strong fluorination of the top layer. This study shows that gas plasma etching can tailor the properties of asymmetric cellulose acetate membranes by simultaneously modifying the chemistry and structure of the top layer. The low fouling properties of CTA membranes were thereby largely maintained.
authors.affiliation: Department of Chemical Technology, Section of Polymer Chemistry and Biomaterials and Institute for Biomedical Technology, University of Twente, P.O. Box 217, AE Enschede, 7500, The Netherlands.
authors.forename: M B
authors.initials: MB
authors.lastname: Olde Riekerink
authors.forename: G H M
authors.initials: GH
authors.lastname: Engbers
authors.forename: M
authors.initials: M
authors.lastname: Wessling
authors.forename: J
authors.initials: J
authors.lastname: Feijen
mesh_terms: D000818:Animals; D001672:Biocompatible Materials / Q000737:chemistry*; D002417:Cattle; D002463:Cell Membrane Permeability; D002482:Cellulose / Q000031:analogs & derivatives* / Q000737:chemistry; D005740:Gases; D008567:Membranes, Artificial; D008970:Molecular Weight; D012710:Serum Albumin, Bovine; D013499:Surface Properties
chemical_list: D001672:Biocompatible Materials; D005740:Gases; D008567:Membranes, Artificial; D012710:Serum Albumin, Bovine; C005062:acetylcellulose; D002482:Cellulose