Chimney-Shaped Phase Diagram in a Polymer Blend Electrolyte

Neel J. Shah, Marwan Shalaby, Lilin He, Xin Wang, David Deslandes, Bruce A. Garetz, Nitash P. Balsara

Research output: Contribution to journalArticlepeer-review


The phase behavior of polymer blend electrolytes comprising poly(ethylene oxide) (PEO)/poly(methyl methacrylate) (PMMA)/lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) was determined using a combination of light and small angle neutron scattering (SANS) experiments. The results at a fixed temperature (110 °C) are presented on a PEO concentration versus salt (LiTFSI) concentration plot. The blends are miscible at all PEO concentrations in the absence of salt. With added salt, a region of immiscibility is obtained in PEO-lean polymer blend electrolytes; blends rich in PEO remain miscible at most salt concentrations. A narrow region of immiscibility juts into the miscible region, giving the phase diagram a chimney-like appearance. The data are qualitatively consistent with a simple extension of Flory-Huggins theory with a composition-dependent Flory-Huggins interaction parameter, χ, that was determined independently from SANS data from homogeneous blend electrolytes. Phase diagrams like the one we obtained were anticipated by self-consistent field theory calculations that account for correlations between ions. The relationship between these theories and measured χ remains to be established.

Original languageEnglish (US)
Pages (from-to)874-879
Number of pages6
JournalACS Macro Letters
Issue number7
StatePublished - Jul 18 2023

ASJC Scopus subject areas

  • Organic Chemistry
  • Polymers and Plastics
  • Inorganic Chemistry
  • Materials Chemistry


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