Photonic Microcapsules Containing Single-Crystal Colloidal Arrays with Optical Anisotropy

Tae Min Choi, Gun Ho Lee, Young Seok Kim, Jin Gyu Park, Hyerim Hwang, Shin Hyun Kim

Research output: Contribution to journalArticlepeer-review

41 Scopus citations

Abstract

Colloidal particles with a repulsive interparticle potential spontaneously form crystalline lattices, which are used as a motif for photonic materials. It is difficult to predict the crystal arrangement in spherical volume as lattices are incompatible with a spherical surface. Here, the optimum arrangement of charged colloids is experimentally investigated by encapsulating them in double-emulsion drops. Under conditions of strong interparticle repulsion, the colloidal crystal rapidly grows from the surface toward the center of the microcapsule, forming an onion-like arrangement. By contrast, for weak repulsion, crystallites slowly grow and fuse through rearrangement to form a single-crystal phase. Single-crystal structure is energetically favorable even for strong repulsion. Nevertheless, a high energy barrier to colloidal rearrangement kinetically arrests the onion-like structure formed by heterogeneous nucleation. Unlike the isotropic onion-shaped product, the anisotropic single-crystal-containing microcapsules selectively display—at certain orientations but not others—one of the distinct colors from the various crystal planes.

Original languageEnglish
Article number1900693
JournalAdvanced Materials
Volume31
Issue number18
DOIs
StatePublished - 3 May 2019

Keywords

  • colloidal crystals
  • microcapsules
  • microfluidics
  • photonic crystals
  • single crystals

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