Symmetry breaking in particle-forming diblock polymer/homopolymer blends

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Abstract

Compositionally asymmetric diblock copolymers provide an attractive platform for understanding the emergence of tetragonally close-packed, Frank-Kasper phases in soft matter. Block-polymer phase behavior is governed by a straightforward competition between chain stretching and interfacial tension under the constraint of filling space at uniform density. Experiments have revealed that diblock copolymers with insufficient conformational asymmetry to form Frank-Kasper phases in the neat-melt state undergo an interconversion from body-centered cubic (bcc) close-packed micelles to a succession of Frank-Kasper phases (σ to C14 to C15) upon the addition of minority-block homopolymer in the dry-brush regime, accompanied by the expected transition from bcc to hexagonally packed cylinders in the wet-brush regime. Self-consistent field theory data presented here qualitatively reproduce the salient features of the experimental phase behavior. A particle-by-particle analysis of homopolymer partitioning furnishes a basis for understanding the symmetry breaking from the high-symmetry bcc phase to the lower-symmetry Frank-Kasper phases, wherein the reconfiguration of the system into polyhedra of increasing volume asymmetry delays the onset of macroscopic phase separation.

Original languageEnglish (US)
Pages (from-to)16764-16769
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume117
Issue number29
DOIs
StatePublished - Jul 21 2020

Bibliographical note

Funding Information:
We acknowledge discussions with Prof. Mahesh K. Mahanthappa, Aashish Jayaraman, and Andreas J. Mueller. This work was supported by the NSF Grant DMR-1719692. Computational resources were provided, in part, by the Minnesota Supercomputing Institute.

Funding Information:
ACKNOWLEDGMENTS. We acknowledge discussions with Prof. Mahesh K. Mahanthappa, Aashish Jayaraman, and Andreas J. Mueller. This work was supported by the NSF Grant DMR-1719692. Computational resources were provided, in part, by the Minnesota Supercomputing Institute.

Keywords

  • Block polymer
  • Frank-Kasper phases
  • Self-assembly
  • Self-consistent field theory

PubMed: MeSH publication types

  • Journal Article

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