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2005 Nuggets

Microdisplacement Printing
A. A. Dameron, J. R. Hampton, R. K. Smith, T. J. Mullen, S. D. Gillmor, and P. S. Weiss

We describe a new patterning technique that employs microcontact printing to replace preformed labile self-assembled monolayers (SAMs) selectively; we call this "microdisplacement printing". We demonstrate that this technique results in ordered molecular regions of both the patterning ("displacing") molecule as well as the remnant labile film, here 1-adamantanethiolate. The existence of the 1-adamantanethiolate SAM before patterning hinders lateral surface diffusion of the patterning molecules, and therefore permits the use of molecules that are otherwise too mobile to pattern by other methods.

 

Figure 1 Scanning tunneling microscopy image of a two-component, self-assembled monolayer of 1-adamantanethiolate and 1-decanethiolate, fabricated by microdisplacement printing. The ordered lattices of both components can be seen; the more protruding self-assembled monolayer domains with the smaller lattice spacing (arrow) are 1-decanethiolate. The area imaged is 175 × 175 Å2, recorded with a sample bias of 1 V and a tunneling current of 4.0 pA.
Figure 2 Matrix of scanning tunneling microscopy images of microdisplacement printing of a 1-adamantanethiolate self-assembled monolayer with an unpatterned poly(dimethylsiloxane) stamp inked with 1-decanethiol (imaged as protruding features). The concentrations of the 1-decanethiol solution used increase top to bottom, whereas the durations of the stamping process increase left to right. All imaged areas are 1000 × 1000 Å2, recorded with a sample bias of 1 V and tunneling currents between 1 and 2 pA.
Figure 3 Plots of the mean fractional coverage of 1-decanethiolate in scanning tunneling microscopy images of microdisplacement printed samples, (A) as a function of stamp time and (B) as a function of ink concentration. Each data point was averaged from a series of images that have areas of 1000 × 1000 Å2, were recorded with a sample bias of 1 V and tunneling currents between 1 and 2 pA.
Figure 4 (A) Schematic depicting microdisplacement printing on a 1-adamantanethiolate self-assembled monolayer with an 11-mercaptoundecanoic acid-inked stamp. A 1-adamantanethiolate self-assembled monolayer is first formed on gold by solution deposition for 24 h. Then, the molecularly inked stamp is contacted directly onto the 1-adamantanethiolate, resulting in patterned regions of both 1-adamantanethiolate and 11-mercaptoundecanoic acid that mirror the relief pattern on the stamp. Note that the schematic is not to scale. (B and C) Lateral force microscopy images of patterned Au{111} made by microdisplacement printing using a 1200 lines/mm poly(dimethylsiloxane) stamp inked with a 25 mM 11-mercaptoundecanoic acid solution (3 min stamp-substrate contact time). The high-friction (shown as light) stripes are the stamped 11-mercaptoundecanoic acid and the low-friction (shown as dark) stripes are the 1-adamantanethiolate self-assembled monolayer. (B) Lateral force micrograph of a 10 × 10 m2 area, recorded at a scan rate of 2 Hz with a force setpoint of 0.5 nN. (C) Lateral force micrograph of a 3 × 3 m2 area, recorded at a scan rate of 2 Hz with a force setpoint of 0.5 nN.
Figure 5 (A) Lateral force microscopy image of patterned Au{111} substrate made by microdisplacement printing using a poly(dimethylsiloxane) stamp with 5 m square wells at a 10 m pitch that was inked with a 100 mM 1-decanethiol solution for (3 min stamp-substrate contact time). The high-friction (shown as light) squares are the 1-adamantanethiolate self-assembled monolayer and the low-friction (shown as dark) background is the stamped 1-decanethiolate. The imaged area was 40 × 40 m2, recorded at a scan rate of 1 Hz at a force setpoint of 1.0 nN. (B) Lateral force microscopy image of a patterned Au{111} substrate made by microdisplacement printing using a poly(dimethylsiloxane) stamp with 10-m square posts at a 20-m pitch that was inked with a 25 mM 1-decanethiol solution for (5 min stamp-substrate contact time). The low-friction squares are stamped 1-decanethiolate, and the high-friction background is the 1-adamantanethiolate self-assembled monolayer. The imaged area was 40 × 40 m2, recorded at a scan rate of 2 Hz at a force setpoint of 2.0 nN.