Entropy Favors Asymmetry in Colloidal Self-Assembly @ Harvard University

Author(s):

Guangnan Meng, Natalie Arkus, Michael P. Brenner, and Vinothan N. Manoharan

Two self-assembled colloidal clusters, as seen under the optical microscope. The cluster on the left, a tri-tetrahedron, and the cluster on the right, an octahedron, have the same energy. But in an experiment where both clusters are allowed to form randomly in solution, the less symmetric tri-tetrahedron occurs more than twenty times as often as the highly symmetric octahedron because of the many more ways to form the tri-tetrahedron. The findings reported recently in Science illustrate, in a tangible way, what entropy is and how it determines the structures of small self-assembled materials.

For more details, see press release here:

http://www.seas.harvard.edu/news-events/press-releases/using-magnetic-toys-as-inspiration-researchers-tease-out-structures-of-self-assembled-clusters

and article here:

http://physicsworld.com/cws/article/news/41645

Related publication(s):

1. Meng, G., Arkus, N., Brenner, M.P., and Manoharan, V.N. ,”The Free-Energy Landscape of Clusters of Attractive Hard Spheres,” Science 327 (5965), 560-563 (2010).      
2. Arkus, N., Manoharan ,V.N., and Brenner, M.P., “Minimal Energy Clusters of Hard Spheres with Short Range Attractions,” Phys. Rev. Lett. 103(11), 118303-4 (2009).