Control of Surface Properties Using Fluorinated Polymer Brushes Produced by Surface-Initiated Controlled Radical Polymerization

Published

November 1, 2004

Author(s)

L Andruzzi, A Hexemer, X Li, Christopher K. Ober, E K. Kramer, Giancarlo Galli, E Chiellini, Daniel A. Fischer

Abstract

Surface-grafted styrene-based homopolymer and diblock copolymer brushes bearing semifluorinated alkyl groups were synthesized by nitroxide-mediated controlled radical polymerization on planar silicon oxide surfaces. The polymer brushes were characterized by X-ray photoelecton spectroscopy (XPS), near-edge X-ray absorption fine structure (NEXAFS) and time-dependent water contact angle measurements. Angle resolved XPS studies and water contact angle measurements showed that in the case of the diblock copolymer brushes, the second block to be added was always exposed at the polymer-air interface regardless of its surface energy. Values of z*/Rg were estimated based on the radius of gyration, Rg, of the grafted homopolymer or block copolymer chains for the grafted brushes and thickness of the brush, z*. The fact that z*/Rg>1, suggests that all these brushes are stretched. These results support the idea that after grafting the first block onto the surface the nitroxide-end capped polymer chains were able to polymerize the second block in a living fashion and the stretched brush so formed was dense enough that the outermost block in all cases completely covers the surface. NEXAFS analysis showed a relationship between the surface orientation of the fluorinated side chains and brush thickness with thicker brushes having more oriented side chains. Time-dependent water contact angle measurements revealed that the orientation of the side chains of the brush improved the surface stability towards recontruction upon prolonged exposure to water.

Citation

Langmuir

Volume

20

Issue

No. 24

Pub Type

Journals

Keywords

NEXAFS, orientation, polymers, soft x-ray

Citation

Andruzzi, L. , Hexemer, A. , Li, X. , Ober, C. , Kramer, E. , Galli, G. , Chiellini, E. and Fischer, D. (2004), Control of Surface Properties Using Fluorinated Polymer Brushes Produced by Surface-Initiated Controlled Radical Polymerization, Langmuir (Accessed July 21, 2024)