Effect of molecular weight on the mechanical and electrical properties of block copolymer electrolytes

Mohit Singh, Omolola Odusanya, Gregg M. Wilmes, Hany B. Eitouni, Enrique D. Gomez, Amish J. Patel, Vincent L. Chen, Moon Jeong Park, Panagiota Fragouli, Hermis Iatrou, Nikolaos Hadjichristidis, David Cookson, Nitash P. Balsara*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

384 Scopus citations

Abstract

The relationship between ionic conductivity, morphology, and Rheological properties of polystyrene-Wocfc-poly(ethylene oxide) copolymers (SEO) doped with a lithium salt, Li[N(SO2CF3)2], is elucidated. We focus on lamellar samples with poly(ethylene oxide) (PEO) volume fractions, φ, ranging from 0.38 to 0.55, and PEO block molecular weights, M PEO, ranging from 16 to 98 kg/mol. The low-frequency storage modulus (G′) at 90 °C increases with increasing MPEO from about 4 × 105 to 5 × 107 Pa. Surprisingly, the conductivity of the SEO/salt mixtures with the molar ratio of Li to ethylene oxide moieties of 0.02 σ, also increases with increasing MPEO, from 6.2 × 10-5 to 3.6 × 10-4 S/cm at 90 °C. We compare σ with the conductivity of pure PEO/salt mixtures, σPEO. and find that σ/[(φσPEO] of our highest molecular weight sample is close to 0.67, the theoretical upper limit for transport through randomly oriented lamellar grains.

Original languageEnglish (US)
Pages (from-to)4578-4585
Number of pages8
JournalMacromolecules
Volume40
Issue number13
DOIs
StatePublished - Jun 26 2007

ASJC Scopus subject areas

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

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