Structure and packing of colloidal particles - Can we go beyond FCC?
Ning Wu
Department of Chemical & Biological Engineering, Colorado School of Mines
The assembly or organization of atoms and molecules into well-defined structures
is a fundamental principle by which materials form. Spherical particles of 1-1000 nm in
diameter with isotropic interactions have been extensively modeled as artificial atoms
and efficient building blocks in materials science and soft condensed-matter physics
during the past century. Under most circumstances, face center cubic (or hexagonal closepacked) structure are found for spherical particles. However, new building blocks of
"anisotropic particles" are better mimics of "atoms" and "molecules" due to the presence
of anisotropy in the physical properties, chemical compositions, surface functionalities,
geometric sizes, or shapes. Just like real atoms and molecules with valency, anisotropic
particles can recognize each other and assemble themselves via directional and specific
interactions, forming potentially large numbers of close-packed and non-close-packed
crystalline structures that the isotropic spheres cannot form. My talk will discuss some
discoveries that we have made in the past year. I will also demonstrate that our
understanding on the physical mechanisms of assembly can be advanced by studying
model systems of "anisotropic particles". Finally, I will discuss some potential
applications of those superstructures formed by anisotropic particles, which could possess
novel collective properties that are not manifested in single particle or in bulk material.