Abstract
Conductive molecular wires of controlled size and length are important components in the emerging field of molecular electronics. In this work we report the preparation of nanometer size polyaniline wires on a silicon wafer surface. Through a surface-initiated polymerization from a mixed self-assembled monolayer in which initiators (tetraanilines) are randomly and sparsely tethered, polyaniline chains well separated from each other were generated. A self-assembled mixed monolayer of n-nonylsilane and 10-undecylenylsilane was first generated by treating a hydroxylated silicon surface with a mixture of n-nonyltrichlorosilane and 10-undecylenyltrichlorosilane in various molar ratio. The terminal vinyl group was oxidized with KMnO4 to carboxyl group, which was activated with carbonyldimidazole. Aniline oligomer (p-tetraaniline) was tethered to the surface through the amidation reaction. Graft polymerization of aniline from the tetraaniline moiety was carried out to give conductive polyaniline (PANI) in nanometer lengths[1] The surface composition, distribution, and morphology of the mixed monolayer, as well as the grafted PANI, were characterized by attenuated total reflectance Fourier transform infrared (ATR/FT-IR) spectroscopy, atomic force microscopy (AFM), contact angle measurement, and fluorescent dansyl probe. The method provides a functional surface with well-dispersed active sites as a reaction template for further derivatization/polymerization. In our case, it provides a new strategy for the generation of isolated conductive polymer wires via graft polymerization.