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 language||English (US)|
|Number of pages||6|
|Journal||Proceedings of the National Academy of Sciences of the United States of America|
|State||Published - Jul 21 2020|
Bibliographical noteFunding 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.
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.
- Block polymer
- Frank-Kasper phases
- Self-consistent field theory