Anisotropy of building blocks and their assembly into complex structures
Original entry: Caspar Floryan, APPHY 225, Fall 2010
Glotzer SC and Solomon MJ "Anisotropy of building blocks and their assembly into complex structures" Nature Materials 6 (8): 557-562 AUG 2007
Recent times have seen a remarkable flowering in our ability to synthesize small particles with ever-more diverse shapes, compositions and functionalities. Anisotropic shape and chemical patchiness are two especially powerful tools for engineering new particle assemblies. Methods recently developed to produce the ever-widening array of particles include electrified jetting, microcontact printing, emulsion drying, selective deposition, surface templating, direct writing, and lithography. These have resulted in particle classes which include nanocolloidal cubes, icosahedra, triangles, tetrahedra prismes, Janus particles, half shells, striped particles, rods, arrows, tetrapods, tripods, stars, X shapes, and many more. These particles are moving towards attaining the structural complexity necessary for future applications.
Unfortunately there is not yet a nomenclature or systematic way of classifying these particles and their assemblies. This paper proposes one such classification scheme. There are several dimensions by which particles and their assemblies may be classified. Seen in figure 2, these include surface coverage, aspect ratio, faceting, pattern quantization, branching, chemical ordering, shape gradient, and roughness. One can also organize these dimensions on a multi-dimensional axis to effectively organize particles by these properties.