title: Tailoring SU-8 surfaces: covalent attachment of polymers by means of nitrene insertion.
abstract: The photoresist material SU-8 has found a variety of applications in microfabricated systems, such as microelectromechanical (MEMS) and lab-on-a-chip devices. Although the bulk properties of SU-8 are appropriate for many such applications, tailoring its surface-chemical properties has, until now, proven to be challenging but is essential in order to carry out any subsequent self-assembly steps. We have demonstrated that the SU-8 surface can be functionalized by the covalent grafting of a wide variety of polymers by means of nitrene insertion. This is readily achieved with poly(allylamine)-graft-perfluorophenyl azide (PAAm-g-PFPA) or poly(ethyleneimine)-graft-PFPA (PEI-g-PFPA), which can form covalent bonds to both the SU-8 surface and a functionalizing polymer. As examples, poly(diallyl-dimethylammonium chloride) (PDDA) and poly(styrenesulfonate) (PSS) have been covalently linked to a SU-8 substrate, yielding positively and negatively charged surfaces, respectively. The grafted polymers were characterized by means of X-ray photoelectron spectroscopy, and their charge characteristics were confirmed via charged-particle adsorption.
authors.affiliation: Laboratory for Surface Science and Technology, Department of Materials, ETH Zurich , Wolfgang-Pauli-Strasse 10, CH-8093 Zurich, Switzerland.
authors.forename: Venkataraman V
authors.initials: VV
authors.lastname: Nagaiyanallur
authors.forename: Deepak
authors.initials: D
authors.lastname: Kumar
authors.forename: Antonella
authors.initials: A
authors.lastname: Rossi
authors.forename: Stefan
authors.initials: S
authors.lastname: Zürcher
authors.forename: Nicholas D
authors.initials: ND
authors.lastname: Spencer