XPS characterization of poly(methylhydrosiloxane)-modified cellulose diacetate membranes

The surface composition of a series of poly(methylhydrosiloxane) (PMHS)-mod ified cellulose diacetate (CDA) membranes was examined by X-ray photoelectr on spectroscopy (XPS). The Si2p signal is a unique diagnostic feature for P MHS, thus allowing a straightforward determination of the relative proporti on of this modifier on the surface of CDA. The surface compositions of the membranes under test reach readily a steady composition as a result of various treatments (initial PMHS concentration, solvent volume and reaction time). This parallels the performance of the m embranes for reverse osmosis desalination. Chlorides were detected in the u ntreated CDA and the modified membrane for which salt rejection was poor. T he Si2p binding energy indicates possible covalent grafting of the PMHS to CDA via an Si-O-C linkage. (C)2000 Elsevier Science B.V. All rights reserve d.