Chemically patterned flat stamps for microcontact printing.

Locally oxidized patterns on flat poly(dimethylsiloxane) stamps for microcontact printing were used as a platform for the transfer of a hydrophilic fluorescent ink to a glass substrate. The contrast was found to be limited. These locally oxidized patterns were conversely used as barriers for the transfer of hydrophobic n-octadecanethiol. In this case a good contrast was obtained, but the pattern was found to be susceptible to defects (cracks) in the barrier layer. Local stamp surface oxidation and subsequent modification with 1H,1H,2H,2H-perfluorodecyltrichlorosilane, for use as a barrier in the transfer of n-octadecanethiol, 16-mercaptohexadecanoic acid, and octanethiol, resulted in remarkably good contrast and stable patterns. The improved ink transfer control is ascribed to the reduction of undesired surface spreading and a superior mechanical stability of the stamp pattern. This new approach substantially expands the applicability of microcontact printing and provides a tool for the faithful reproduction of even extremely low filling ratio patterns.