AVS 46th International Symposium
    Applied Surface Science Division Tuesday Sessions
       Session AS-TuP

Paper AS-TuP7
Surface-attached Polymer Brushes via Physisorbed Monolayers of Macroinitiators

Tuesday, October 26, 1999, 5:30 pm, Room 4C

Session: Poster Session
Presenter: T. Stöhr, Max-Planck-Institute for Polymer Research, Germany
Authors: T. Stöhr, Max-Planck-Institute for Polymer Research, Germany
J. Rühe, Max-Planck-Institute for Polymer Research, Germany
Correspondent: Click to Email
Block copolymer adsorption is a frequently used procedure to modify the surface of solid substrates.@footnote 1@ Such systems, usually A-B block copolymers, consist of an anchor block which allows attachment to the substrate surface and a buoy block which carries the desired surface properties. Since one part of the molecule has to have only a weak interaction with the surface and the other a strong one, the two blocks should be rather different from a chemical point of view. This renders the task of finding a suitable solvent process non-trivial. Monolayers prepared by this technique are inherently very thin with thicknesses typically between 3 and 5 nm. The reason for this is a kinetic hindrance for the attachment of polymer chains due to a diffusion barrier created by the already attached molecules. Recently radical polymerization using chemisorbed azo-type initiators has been established.@footnote 2@ In this case the polymer is grown directly at the surface of the substrate. We present a macroinitiator system that allows to create hydrophobic layers on hydrophilic substrate surfaces. Here a hydrophilic anchor block bearing initiator groups is physisorbed to a hydrophilic surface. The hydrophobic buoy block is polymerized in situ resulting in a block copolymer monolayer. A poly(epsilon-caprolactone) macroinitiator containing azo moieties was synthesized and adsorbed to silicon oxide surfaces. The surface-attached monolayer was subsequently used for the polymerization of n-alkyl methacrylates resulting in thicknesses up to 100 nm. By this route the limitations of the block copolymer physisorption process, such as solubility problems of the block copolymer and intrinsic limitations of the layer thickness, can be overcome. @FootnoteText@ @footnote 1@ Fleer, G. J.; Cohen Stuart, M. A.; Scheutjens, J. M. H. M.; Cosgrove, T.; Vincent, B. Polymers at Interfaces; Chapman & Hall: London, 1993; Chapter 6. @footnote 2@ Prucker, O.; Rühe, J. Macromolecules 1998, 31, 592.