Polymer Microbead-Templated Nanostructures

In this chapter, nanostructures templated by polymer microbead, which is usually made of polystyrene with a diameter range of 300 nm–1 µm, are reviewed. We first focus on formation of the microbead monolayer in terms of the driving force for self-assembly, the junction among the neighbouring microbeads and the uniformity of microbead monolayer. Then, we discuss applications of microbead monolayer as a template for nanostructure fabrication. Because the assembled monolayer features an ordered structure scaling up to centimetre (cm) size, microbead-templated nanostructures also show an ordered arrangement in cm size, which is attractively simple and can be achieved in common laboratories. From the microbead monolayer template, the subsequent fabrication approaches include electrochemical deposition, sputter coating deposition, plasma etching, annealing, wet etching and dry etching as well. The templating targets include metals, semiconductors, polymers, and nano-moieties such as nanobeads and nanocubes. Various types of nanostructure have been fabricated using these approaches individually or by combining them to increase the flexibility of fabrication. Controllable and ordered nanostructures have been achieved by adjusting the fabrication parameters. Finally, we review the application of nanostructures templated by the polymer microbeads, particularly as surface-enhanced Raman scattering (SERS) substrates. We demonstrate approaches for identifying the position of the hot spot and how to achieve single-molecule detection.