Paper SS2-ThM5
Fabrication of a Full-Coverage Polymer Nanobrush on Electron-Beam-Activated Monomolecular Template

Thursday, November 12, 2009, 9:20 am, Room N

Along with chemistry, morphology is an important tool to adjust properties of surfaces and interfaces. One of the most promising approaches to control over surface morphology down to the nanometer scale is the fabrication of 3D polymer brush patterns by surface-initiated polymerization (SIP) combined with electron beam lithography (EBL). However, polymer brush patterns made by EBL-SIP are chemically inhomogeneous. Whereas the polymer brush itself is comprised of a polymer, the areas between the 3D features have a different chemical identity determined by the original template. As a result, the effects of morphology on one side and chemistry and surface energy on the other side can be entangled when using such patterns as model surfaces for, e.g., biology-inspired research. Here, we show that this drawback can be overcome by using a sophisticated primary template comprised of monomolecular film with mostly deactivated amino tail groups suitable for SIP. Whereas SIP on such a template gives a thin, homogeneous “background” brush, the regeneration of these groups by electron beam activation lithography promotes the controlled growth of 3D polymer features on this background, resulting in the formation of chemically homogeneous morphology pattern exclusively comprised of the polymer material. The technique relies upon commercially available compounds and requires a comparably low patterning dose. Using a biologically relevant polymer, poly-N-isopropylacrylamide, as a test system, we demonstrated the fabrication of both complex gradient-like brushes and marine-mammals-skin-inspired surfaces on the electron-beam-engineered monomolecular templates.