A facile method for patterned assembly of nanoparticles using SAM-guided solvent dewetting

The directed assembly of functional nanoparticles (NPs) into desired geometries is crucial for various NP-based devices and applications. Over the past two decades, numerous bottom-up and top-down approaches have been reported for achieving this goal. In this study, we employed a bottom-up approach using a capillary-driven self-assembled monolayer (SAM)-defined template-assisted self-assembly of silver nanocubes (SNCs) and nanodiamonds (NDs). First, different SAM patterns were created on a gold-coated Si substrate using microcontact printing. Upon immersion of the SAM-patterned substrates in the NP solution, the SAM patterns guide the solvent to specific regions during drying. The directed solvent carries the NPs (SNCs and NDs) into these regions during drying owing to their lower energy state in the solvent compared with the SAM regions. Subsequently, the solvent deposits the NPs in these regions because of their interactions with the substrate. Micron-sized lines and rectangular patterns are explored to observe successful NP assembly. The density of the assembled SNCs depends on their concentration in the solvent, with higher concentrations resulting in densely packed assemblies. This effect is not observed for the NDs because of the differing regular and irregular shapes of the SNCs and NDs. This process can be extended to other NPs with suitable solvents and SAMs.