Self-assembly of nanometer-sized particles is an elegant and economical approach to achieve dense patterns over large areas beyond the resolution and throughput capabilities of electron-beam lithography. In this paper, we present results of self-assembly of oleylamine-capped gold nanoparticles with 8.0 ± 0.3 nm diameter into densely packed and well-ordered monolayers with center-to-center distance of ∼11 nm. Self-assembly was done in a Langmuir-Blodgett trough and picked up onto Si substrates. The nanoparticles undesirably assembled within micrometer-sized "droplets" that were organic in nature. However, within these droplets, we observed that the addition of the excess ligand, oleylamine, drastically enhanced the self-assembly of the nanoparticles into monolayers with near-perfect ordering. This approach has the potential use in templated self-assembly of nanoparticles for rearranging poorly ordered assembly into a commensurate prepatterned substrate.

Studies have shown that electrohydrodynamic patterning (EHD) can produce ordered pillar arrays in polymer films at the micrometer scale in fewer processing steps than other techniques. This paper reports the limitation encountered in reducing the feature size, generally characterized by the fastest growing wavelength (λmax), to submicrometer. An experiment designed to decrease λmax well below a micrometer produced poorly ordered pillars that were considerably coarser than expected. Further experiments demonstrated that dielectric breakdown of the polymer limits the extent of feature size.

The wide applications of two-dimensionally ordered nanoscale features have stimulated the development of cheap and fast fabrication techniques in recent years. We achieved large area of uniform film of nanoparticles between 49.8 6 8.7 and 117.6 6 6.7 nm via flow-coating. However, the single crystalline domains of a close-packed monolayer remained limited. That motivated deposition of initially ordered colloidal dispersions, attained through deionized solutions to extend electrostatic double layers for long-range repulsion. Although the deposition agreed reasonably well with our power-law model, the initial order was destroyed at high shear. While the particle order was partially preserved during deposition at low shear, the domain size was not particularly extensive due to the high compression of double layers during evaporation.