π-Conjugated Macromolecular Wiring between Gold Nanorods via Surface-Initiated and Surface-Terminated Polymerization for Molecular Electronics and Nanoscale Interconnects

We report a methodology using surface-initiated and surface-terminated polymerization to construct high-density π-conjugated polymer brushes on gold (Au) substrates and enable molecular wiring between Au nanorods for applications in molecular electronics and nanoscale interconnects. Polyfluorene (PFO) brushes were fabricated via chain-growth condensation polymerization of AB-type fluorene monomers, initiated by a self-assembled monolayer (SAM) of initiator formed on either a flat Au substrate or a Au nanorod array substrate (12 nm diameter, 120 nm height, 17 nm spacing, hexagonal lattice). PFO brush substrates were also fabricated via surface termination of living PFO chains with a terminator SAM formed on the Au surfaces. Surface-initiated and surface-terminated polymerizations were combined by using a mixed SAM of initiator and terminator to wire PFO between adjacent Au nanorods. The Au nanorod array substrates served as surface-enhanced Raman scattering platforms, enabling the chemical analysis of surface reactions via Raman spectroscopy and quantitative evaluation of initiation, termination, and wiring efficiency.