Engineering the Spatial Selectivity of Surfaces at the Nanoscale Using Particle Lithography Combined with Vapor Deposition of Organosilanes

Particle lithography is a practical approach to generate millions of organosilane nanostructures on various surfaces, without the need for vacuum environments or expensive instrumentation. This report describes a stepwise chemistry route to prepare organosilane nanostructures and then apply the patterns as a spatially selective foundation to attach gold nanoparticles. Sites with thiol terminal groups were sufficiently small to localize the attachment of clusters of 2-5 nanoparticles. Basic steps such as centrifuging, drying, heating, and rinsing were used to generate arrays of regular nanopatterns. Close-packed films of monodisperse latex spheres can be used as an evaporative mask to spatially direct the placement of nanoscopic amounts of water on surfaces. Vapor phase organosilanes deposit selectively at areas of the surface containing water residues to generate nanostructures with regular thickness, geometry, and periodicity as revealed in atomic force microscopy images. The area of contact underneath the mesospheres is effectively masked for later synthetic steps, providing exquisite control of surface coverage and local chemistry. By judicious selection in designing the terminal groups of organosilanes, surface sites can be engineered at the nanoscale for building more complex structures. The density of the nanopatterns and surface coverage scale predictably with the diameter of the mesoparticle masks. The examples presented definitively illustrate the capabilities of using the chemistry of molecularly thin films of organosilanes to spatially define the selectivity of surfaces at very small size scales.