Assembly and alignment of metallic nanorods on surfaces with patterned wettability

A method for the self-assembly and alignment of metallic nanorods dispersed in water on substrates with patterned wettability was investigated. Nanorod suspensions were first casted on substrates with patterned wettability. Nanorods were allowed to settle in the water suspension, which resulted in a higher concentration of nanorods close to the substrate surface. A pipette was used to remove the excess suspension from the substrate, leaving behind discrete, small droplets of the nanorod suspension covering the hydrophilic regions. It was observed that most of the nanorods were confined within designed hydrophilic regions with random orientation. It was possible to demonstrate the assembly of nanorods onto organic flexible substrates, by patterning a plastic substrate into regions with an appropriate water-contact angle.