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Title: Low-symmetry sphere packings of simple surfactant micelles induced by ionic sphericity

We report the discovery of an ionic small molecule surfactant that undergoes water-drive self- assembly into quasispherical micelles, which pack into the first lyotropic liquid crystalline Frank–Kasper σ phase. Small-angle X-ray scattering studies indicate that this unexpected, low-symmetry phase is characterized by a tetragonal unit cell, in which 30 sub-2 nm micelles of five discrete types are arranged into a tetrahedral close packing with exceptional translational order. Varying the relative amounts of surfactant and water in these lyotropic phases enables formation of a Frank–Kasper A15 sphere packing and a more common body-centered cubic structure. MD simulations reveal that the symmetry breaking that drives the selection of the σ and A15 phases arises from a delicate interplay between the drive to maintain local spherical particle symmetry and the maximization of electrostatic cohesion between the soft micellar particles.
 [1] ;  [2] ; ORCiD logo [2] ; ORCiD logo [1]
  1. Univ. of Minnesota, Minneapolis, MN (United States). Dept. of Chemical Engineering & Materials Science
  2. Univ. of Wisconsin, Madison, WI (United States). Theoretical Chemistry Inst., Dept. of Chemistry
Publication Date:
Grant/Contract Number:
SC0010328; AC02-06CH11357
Published Article
Journal Name:
Proceedings of the National Academy of Sciences of the United States of America
Additional Journal Information:
Journal Volume: 114; Journal Issue: 16; Journal ID: ISSN 0027-8424
National Academy of Sciences, Washington, DC (United States)
Research Org:
Univ. of Wisconsin, Madison, WI (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Contributing Orgs:
Argonne National Laboratory (ANL), Argonne, IL (United States). Advanced Photon Source
Country of Publication:
United States
36 MATERIALS SCIENCE; self-assembly; liquid crystals; surfactants; Frank-Kasper phases; lyotropic phases
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1362093