Angle resolved XPS characterization of cationic polyacrylamides

• Published in: Surface and interface analysis Vol. 41; no. 4; pp. 316 - 323
• Main Authors: Zekonyte, J., Williams, R. L., Beamson, G., Weightman, P.
• Format: Journal Article
• Language: English
• Published: Chichester, UK John Wiley & Sons, Ltd 01-04-2009; Wiley
• Subjects: angle resolved XPS; Applied sciences; cationic polyacrylamide; Composition; defects and impurities; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; copolymer block segregation; Electron and ion emission by liquids and solids; impact phenomena; Exact sciences and technology; Organic polymers; Photoemission and photoelectron spectra; Physicochemistry of polymers; Physics; Polymers; organic compounds; Properties and characterization; Solid surfaces and solid-solid interfaces; Surface properties; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Angular resolution; Surface contamination; Surface segregation; Glass; Polymer films; cationic polyacrylamide; Surface structure; angle resolved XPS; Thickness; copolymer block segregation; Acrylamide copolymer; Surface layers; X-ray photoelectron spectra
• ISSN: 0142-2421; 1096-9918
• DOI: 10.1002/sia.3025

In many applications surfaces are modified using polymer films and the polymers used are often complex copolymers. In biomedical applications it is critical to determine the surface properties of a substrate as it is these that mediate the cellular interactions. The surface structure of copolymer films can only rarely be established from their bulk composition alone. In this study angle resolved XPS was used to build a model of the structure of copolymer films produced on glass substrates from a family of poly(acrylamide) copolymers containing cationic blocks. The thickness of the copolymer films was demonstrated to be dependent on the concentration of the polymer solution and the ratio of non‐cationic to cationic blocks in the copolymer. The data demonstrated that the cationic blocks of the copolymer preferentially segregated to the glass surface and the non‐cationic poly(acrylamide) blocks preferentially segregated to the air–vacuum interface. A low concentration of the cationic functional groups was present throughout the poly(acrylamide) layer and it was suggested that this resulted from a small fraction of the cationic blocks being pulled into the poly(acrylamide) layer at points along the polymer chain where the two blocks are connected. Evidence of a thin surface hydrocarbon contamination layer was also observed. Copyright © 2009 John Wiley & Sons, Ltd.