(690g) Self-Assembly Based Architecture of 2-D and 3-D Multi-Level Superstructure Nanoarrays

Micro-electro-mechanical systems (MEMS) devices coupled with nanophotonics and plasmonics extend a great deal of promise toward sensing chemical species, metabolites, volatile organic compounds, air pollutants, and noxious gases for application in medicinal equipments, pharmaceuticals and quality control. The plasmonic properties of nanomaterials on surfaces become crucial to sensing and consequently, meticulously-architectured designs are imperative to achieve high levels of sensitivity and selectivity. In an effort to mimic the macroscopic entities such as nature-crafted geometry and patterns on shells, peacock feathers, sun flowers and moth eyes at the nanoscale, we have investigated the design rules that are essential to produce desired architectures that led to the nanofabrication of flower-like patterns in the sub-100 nm regime over macroscopic areas.

We demonstrate here, an entirely self-assembly driven approach to fabricate two-dimensional and three dimensional arrays of binary or ternary flower-like superstructures of various material components. Macroscopic two-dimensional arrays of such superstructures presenting up to three levels of hierarchy are achieved using self-organization of reverse micelles of block copolymer up to the second level and directed electrostatic self-assembly of hard metal nanospheres at the third level. While three-dimensional arrays are fabricated with block copolymer micelles guiding the electrostatic self assembly at the first level of hierarchy which provides the platform for confinement-induced self assembly of block copolymers at the next level. In either case, the hierarchy at every level of the superstructure is meticulously engineered by introducing different material components at different hierarchical levels with ZnO, TiO₂, and Au nanoparticles being prototypes. Such entirely self assembly derived hybrid material architecture that mimic Nature offers rich flexibility in choice of material type, composition and stoichiometries, is unprecedented, and has extensive applications in sensing and plasmonics.