Nanoscale Chemical Patterns Fabricated by Using Colloidal Lithography and Self-Assembled Monolayers

A method for preparing surfaces with well-defined nanoscale chemical patterns is described. The fabrication strategy involves creating nanoscale Au pits surrounded by a TiO2 matrix, or vice versa, using colloidal lithography, followed by selective functionalization of the Au areas by CH3-terminated alkanethiols. Using AFM force spectroscopy with chemically modified tips (OH, CH3), we show that the nanopatterned surfaces display strong chemical contrast, in the form of hydrophobic CH3 nanopatches surrounded by a hydrophilic TiO2 surface, or vice versa. The nanofabrication approach presented here offers several advantages over existing patterning technologies, among which are easiness (no sophisticated instrumentation is required), versatility (patterns with a range of surface functionalities can be prepared), and the possibility to produce patterns over large areas at low cost.