Tuning conformational asymmetry in particle-forming diblock copolymer alloys

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Abstract

Self-consistent field theory is employed to compute the phase behavior of binary blends of conformationally asymmetric, micelle-forming diblock copolymers with miscible corona blocks and immiscible core blocks (a diblock copolymer “alloy”). The calculations focus on establishing conditions that promote the formation of Laves phases by tuning the relative softness of the cores of the two different Laves phase particles via independent control of their conformational asymmetries. Increasing the conformational asymmetry of the more spherical particles of the Laves structure has a stabilizing effect, consistent with the expectations of increased imprinting of the Wigner-Seitz cells on the core/corona interface as conformational asymmetry increases. The resulting phase diagram in the temperature-blend composition space features a more stable Laves phase field than that predicted for conformationally symmetric systems. The phase field closes at low temperatures in favor of macrophase separation between a hexagonally-packed cylinder (hex) phase and a body-centered cubic phase. Companion calculations, using an alloy whose components do not produce a hex phase in the neat melt state, suggest that the Laves phase field in such a blend will persist at strong segregation.

Original languageEnglish (US)
Pages (from-to)90-97
Number of pages8
JournalSoft Matter
Volume19
Issue number1
DOIs
StatePublished - Nov 28 2022

Bibliographical note

Funding Information:
The authors thank Benjamin R. Magruder for helpful discussions and So Jung Park for valuable guidance regarding grand canonical ensemble methodologies. This work was supported by the National Science Foundation through DMR-1725272. Computational resources were provided in part by the Minnesota Supercomputing Institute.

Publisher Copyright:
© 2023 The Royal Society of Chemistry.

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