title: Shape-sensitive crystallization in colloidal superball fluids.
abstract: Guiding the self-assembly of materials by controlling the shape of the individual particle constituents is a powerful approach to material design. We show that colloidal silica superballs crystallize into canted phases in the presence of depletants. Some of these phases are consistent with the so-called "Λ1" lattice that was recently predicted as the densest packing of superdisks. As the size of the depletant is reduced, however, we observe a transition to a square phase. The differences in these entropically stabilized phases result from an interplay between the size of the depletants and the fine structure of the superball shape. We find qualitative agreement of our experimental results both with a phase diagram computed on the basis of the volume accessible to the depletants and with simulations. By using a mixture of depletants, one of which is thermosensitive, we induce solid-to-solid phase transitions between square and canted structures. The use of depletant size to leverage fine features of the shape of particles in driving their self-assembly demonstrates a general and powerful mechanism for engineering novel materials.
authors: James Franck institute, Department of Physics, University of Chicago, Chicago, IL 60637; Van't Hoff Laboratory for Physical and Colloid Chemistry, Debye Institute for Nano-materials Science, Utrecht University, 3584 CH Utrecht, The Netherlands; L.Rossi@uva.nl soni@uchicago.edu wtmirvine@uchicago.edu.
authors: Laura
authors: L
authors: Rossi
authors: James Franck institute, Department of Physics, University of Chicago, Chicago, IL 60637; L.Rossi@uva.nl soni@uchicago.edu wtmirvine@uchicago.edu.
authors: Vishal
authors: V
authors: Soni
authors: Soft Condensed Matter, Debye Institute for Nano-materials Science, Utrecht University, 3584 CC Utrecht, The Netherlands; and.
authors: Douglas J
authors: DJ
authors: Ashton
authors: Center for Soft Matter Research, Department of Physics, and.
authors: David J
authors: DJ
authors: Pine
authors: Van't Hoff Laboratory for Physical and Colloid Chemistry, Debye Institute for Nano-materials Science, Utrecht University, 3584 CH Utrecht, The Netherlands;
authors: Albert P
authors: AP
authors: Philipse
authors: Center for Soft Matter Research, Department of Physics, and.
authors: Paul M
authors: PM
authors: Chaikin
authors: Soft Condensed Matter, Debye Institute for Nano-materials Science, Utrecht University, 3584 CC Utrecht, The Netherlands; and.
authors: Marjolein
authors: M
authors: Dijkstra
authors: Molecular Design Institute, Department of Chemistry, New York University, New York, NY 10003.
authors: Stefano
authors: S
authors: Sacanna
authors: James Franck institute, Department of Physics, University of Chicago, Chicago, IL 60637; L.Rossi@uva.nl soni@uchicago.edu wtmirvine@uchicago.edu.
authors: William T M
authors: WT
authors: Irvine
keywords: Monte Carlo simulations; dense packings; depletion interactions; phase behavior; superballs