Reevaluation of Poly(ethylene- alt-propylene)- block-Polydimethylsiloxane Phase Behavior Uncovers Topological Close-Packing and Epitaxial Quasicrystal Growth

Aaron P. Lindsay, Ashish Jayaraman, Austin J. Peterson, Andreas J Mueller, Steven Weigand, Kristoffer Almdal, Mahesh K. Mahanthappa, Timothy P. Lodge, Frank S. Bates

Research output: Contribution to journalArticlepeer-review

5 Scopus citations


Reanalysis of an asymmetric poly(ethylene-alt-propylene)-block-polydimethylsiloxane (PEP-PDMS) diblock copolymer first investigated in 1999 has revealed a rich phase behavior including a dodecagonal quasicrystal (DDQC), a Frank-Kasper σ phase, and a body-centered cubic (BCC) packing at high temperature adjacent to the disordered state. On subjecting the sample to large amplitude oscillatory shear well below the σ-BCC order-order transition temperature (TOOT), small-angle X-ray scattering evidenced the emergence of a twinned BCC phase that, on heating, underwent a phase transition to an unusually anisotropic DDQC state. Surprisingly, we observe no evidence of this apparent epitaxy on heating or cooling through the equilibrium σ-BCC transition. We rationalize these results in terms of a shear-induced order-order transition and an apparent BCC-DDQC epitaxy favored by micelle translation-mediated ordering dynamics far below TOOT.

Original languageEnglish (US)
Pages (from-to)9453-9468
Number of pages16
JournalACS nano
Issue number6
StatePublished - Jun 22 2021

Bibliographical note

Funding Information:
We would like to express our thanks to all the staff at Sector 5 who provided invaluable help in conducting these experiments, keeping science moving forward in spite of the ongoing pandemic. SAXS experiments were performed at the DuPont-Northwestern-Dow Collaborative Access Team (DND-CAT) located at Sector 5 of the Advanced Photon Source (APS). DND-CAT is supported by Northwestern University, The Dow Chemical Company, and DuPont de Nemours, Inc. This research used resources of the Advanced Photon Source, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357. Data were collected using an instrument funded by the National Science Foundation under award number 0960140.

Funding Information:
This work was supported by the National Science Foundation under grants no. DMR-1801993 (A.P.L., A.J.M., and F.S.B.) and CHE-1807330 (A.J. and M.K.M.) as well as a National Science Foundation Graduate Research Fellowship under grant no. 00039202 (A.P.L.).

Publisher Copyright:


  • block copolymer
  • epitaxy
  • quasicrystal
  • self-assembly
  • shear orientation
  • topological close-packing

PubMed: MeSH publication types

  • Journal Article


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