Structure formation nonspherical particles

Even if the peculiarities of net-formation of nonspherical particles are not taken into account, at least two fundamentally new effects arise during the flow of dispersion. First, this is the possibility to be oriented in the flow, as a consequence of which the medium becomes anisotropic. And second, this is the possibility to rotate the spherical particles in the flow (spherical particles can, of course, rotato too, but their rotation does not affect the structure of the system as a whole). 

Any study of colloidal crystals requires the preparation of monodisperse colloidal particles that are uniform in size, shape, composition, and surface properties. Monodisperse spherical colloids of various sizes, composition, and surface properties have been prepared via numerous synthetic strategies [67]. However, the direct preparation of crystal phases from spherical particles usually leads to a rather limited set of close-packed structures (hexagonal close packed, face-centered cubic, or body-centered cubic structures). Relatively few studies exist on the preparation of monodisperse nonspherical colloids. In general, direct synthetic methods are restricted to particles with simple shapes such as rods, spheroids, or plates [68]. An alternative route for the preparation of uniform particles with a more complex structure might consist of the formation of discrete uniform aggregates of self-organized spherical particles. The use of colloidal clusters with a given number of particles, with controlled shape and dimension, could lead to colloidal crystals with unusual symmetries [69]. 

Alternatively, nonspherical potentials have also been used, where active spots are located on the particle surface [27], or many body interactions, such as a maximum number of neighbors attracted [28], or combination of both [29], Using these structural or energetic constraints, the formation of a dense phase is hindered, thus impeding crystallization and liquid-liquid crystallization. 

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