Granick Research Group
University of Illinois at Urbana-Champaign
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We study the assembly of spherical particles with opposite electric charge on both hemispheres, in the case that the particle diameter exceeds the electrostatic screening length. Clusters result, not strings. The cluster shapes are analyzed by combined epifluorescence microscopy and Monte Carlo computer simulations with excellent agreement, indicating that the particles assemble in aqueous suspension to form equilibrated aggregates. The simulations show that charge asymmetry of individual Janus particles is preserved in the clusters.


  1. Qian Chen, Sung Chul Bae, and Steve Granick,"Directed self-assembly of a colloidal kagome lattice," Nature 469, 381 (2011). [PDF; supporting information; movie 1; movie 2; movie 3].
  2. Qian Chen, Jonathan Whitmer, Shan Jiang, Sung Chul Bae, Erik Luijten, and Steve Granick, "Supracolloidal Reaction Kinetics of Janus Spheres," Science 331, 199 (2011) [PDF; supporting information; movie 1; movie 2; movie 3; movie 4; movie 5; movie 6].
  3. Steve Granick, Shan Jiang, Qian Chen, "Janus Particles," Physics Today 62, 68 (2009). [PDF]
  4. Shan Jiang and Steve Granick, "Controlling the Geometry (Janus Balance) of Amphiphilic Colloidal Particles," Langmuir, , 24, 2438 (2008) [PDF].
  5. Liang Hong, Angelo Cacciuto, Erik, Luijten, and Steve Granick, "Clusters of Amphiphilic Colloid Spheres," Langmuir, 24, 621 (2008) [PDF].

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The Granick research group is an affiliated member of the Materials Research Laboratory,
the Beckman Institute, the Center for Nanoscale Science and Technology.