Robert Macfarlane
California Institute of Technology

Materials by Design: Programmable Assembly at the Nanoscale

Location: EB1 Room 1011

Monday, December 15th 2014 - 1:15 pm

A key area of nanotechnology research deals with the assembly of nanoscale building blocks into complex three-dimensional structures. In many cases, these assemblies have been shown to exhibit novel and extremely useful emergent properties that are a direct result of the arrangement of the individual nanostructures within the assembly. As a result of these promising but nascent discoveries, there has been intense interest in devising strategies that can be used to organize nanomaterials of all types into well-defined hierarchical arrays, in which the spacings and symmetry are precisely controlled. In this talk, we will discuss the development of two unique systems that can be used to construct self-assembled materials with novel and useful physical properties, as well as provide means to programmably and predictably assemble nanomaterials by design. In the first, DNA is utilized as a molecular synthon to generate nanoparticle superlattices where lattice structure can be predicted a priori. The programmable nature of DNA allows for facile control over both nanoparticle bond length and strength, as well as nanoparticle bond selectivity. This talk will elucidate the design rules that have now been established to enable the synthesis of superlattices with independently controllable lattice parameters, nanoparticle sizes, and crystallographic symmetries. In the second, brush block copolymers are utilized to generate rapidly self-assembled 1-D photonic crystals that reflect light with band gaps tunable from 300-1400 nm. The photonic band gap can be controlled either by varying the molecular weight of the brush polymer or by adding in homopolymers to swell the lamellar arrays, providing a simple means of generating nanostructured materials with emergent photonic properties.

North Carolina State University