Correlating backbone-to-backbone distance to ionic conductivity in amorphous polymerized ionic liquids

David Salas-De La Cruz, Matthew D. Green, Yuesheng Ye, Yossef A. Elabd, Timothy E. Long, Karen I. Winey

Research output: Contribution to journalArticlepeer-review

129 Scopus citations

Abstract

The morphology and ionic conductivity of poly(1- n-alkyl-3- vinylimidazolium)-based homopolymers polymerized from ionic liquids were investigated as a function of the alkyl chain length and counterion type. In general, X-ray scattering showed three features: (i) backbone-to-backbone, (ii) anion-to-anion, and (iii) pendant-to-pendant characteristic distances. As the alkyl chain length increases, the backbone-tobackbone separation increases. As the size of counterion increases, the anion-to-anion scattering peak becomes apparent and its correlation length increases. The X-ray scattering features shift to lower angles as the temperature increases due to thermal expansion. The ionic conductivity results show that the glass transition temperature (T g) is a dominant, but not exclusive, parameter in determining ion transport. The Tg-independent ionic conductivity decreases as the backbone- to-backbone spacing increases. Further interpretation of the ionic conductivity using the Vogel-Fulcher-Tammann equation enabled the correlation between polymer morphology and ionic conductivity, which highlights the importance of anion hoping between adjacent polymer backbones.

Original languageEnglish (US)
Pages (from-to)338-346
Number of pages9
JournalJournal of Polymer Science, Part B: Polymer Physics
Volume50
Issue number5
DOIs
StatePublished - Mar 1 2012
Externally publishedYes

Keywords

  • Ionic conductivity
  • Ionic liquids
  • Morphology
  • Polymerized ionic liquids
  • SAXS
  • Structure
  • Structure- property relations
  • X-ray scattering

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Physical and Theoretical Chemistry
  • Polymers and Plastics
  • Materials Chemistry

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