Convectively assembled nonspherical mushroom cap-based colloidal crystals.

Monolayers from mushroom cap-shaped polymer colloids were fabricated by a vertical substrate deposition technique. As confirmed by SEM and autocorrelation analysis, the monolayers show long-range hexagonal packing with particle orientational freedom restricted to either "heads up" or "heads down" alignment with respect to the substrate. The monolayers are modeled as a 2D diffraction grating and were studied with selected area laser diffraction. The stacking of ordered monolayers into the third dimension was achieved via layer-by-layer deposition. Convective assembly is shown as a viable approach to the large-scale crystallization of monodisperse nonspherical colloids.