Two-Dimensional Directed Assembly of Dicolloids.

The assembly of ordered dicolloid monolayers is directedby anelectric field. The dicolloid particles are polystyrene latex witha maximum equatorial diameter 3.45 μm and length 4.63 μm.The monolayer structure is characterized using small-angle light scatteringand bright-field microscopy. With increasing field strength from 26.7to 200 VRMS/cm, a transition from a disordered monolayer,to first orientationally ordered, and then translationally orderedtwo-dimensional (2D) arrays occurs. A c2mmplane group symmetry dominates the ordered structure but is presentalongside structures with p2 symmetry, leading toa spread in the angular distribution of the light scattering peaks.The order–disorder transition dependence on field strengthand frequency is similar to that observed for colloidal spheres; athigher frequencies, stronger fields are required to assemble particles.Optimal ordered structures reflect a balance between inducing sufficientlystrong interparticle interactions while limiting the rate of formationto ensure the growth of large crystalline domains. [ABSTRACT FROM AUTHOR]