title: Metastable orientational order of colloidal discoids.
abstract: The interplay between phase separation and kinetic arrest is important in supramolecular self-assembly, but their effects on emergent orientational order are not well understood when anisotropic building blocks are used. Contrary to the typical progression from disorder to order in isotropic systems, here we report that colloidal oblate discoids initially self-assemble into short, metastable strands with orientational order—regardless of the final structure. The model discoids are suspended in a refractive index and density-matched solvent. Then, we use confocal microscopy experiments and Monte Carlo simulations spanning a broad range of volume fractions and attraction strengths to show that disordered clusters form near coexistence boundaries, whereas oriented strands persist with strong attractions. We rationalize this unusual observation in light of the interaction anisotropy imparted by the discoids. These findings may guide self-assembly for anisotropic systems in which orientational order is desired, such as when tailored mechanical properties are sought.
authors.affiliation: Department of Chemical Engineering, University of Michigan, Ann Arbor, Michigan 48109, USA.
authors.forename: Lilian C
authors.initials: LC
authors.lastname: Hsiao
authors.affiliation: Department of Physics, University of Michigan, Ann Arbor, Michigan 48109, USA.
authors.forename: Benjamin A
authors.initials: BA
authors.lastname: Schultz
authors.affiliation: Department of Chemical Engineering, University of Michigan, Ann Arbor, Michigan 48109, USA.
authors.forename: Jens
authors.identifier: http://orcid.org/0000-0003-1852-3849
authors.initials: J
authors.lastname: Glaser
authors.affiliation: Department of Chemical Engineering, University of Michigan, Ann Arbor, Michigan 48109, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Engel
authors.affiliation: Department of Chemical Engineering, University of Michigan, Ann Arbor, Michigan 48109, USA.
authors.forename: Megan E
authors.initials: ME
authors.lastname: Szakasits
authors.affiliation: Department of Chemical Engineering, University of Michigan, Ann Arbor, Michigan 48109, USA.|Department of Physics, University of Michigan, Ann Arbor, Michigan 48109, USA.|Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109, USA.
authors.forename: Sharon C
authors.initials: SC
authors.lastname: Glotzer
authors.affiliation: Department of Chemical Engineering, University of Michigan, Ann Arbor, Michigan 48109, USA.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Solomon