Thermal and hydrolytic stability of sulfonated polyimide membranes with varying chemical structure

Wonbong Jang, Choonkeun Lee, Saimani Sundar, Yong Gun Shul, Haksoo Han

Research output: Contribution to journalArticle

36 Citations (Scopus)

Abstract

Many important properties required for fuel cell applications including hydrolytic stability, depend on various factors like flexibility of the polymer backbone, ring structure and phase separation. This paper is primarily focused on studying the effect of the chemical backbone structure on the hydrolytic stability and other properties. To study the difference in the hydrolytic stability with change in the chemical backbone structure of sulfonated polyimides we synthesized phthalic sulfonated polyimides and naphthalenic sulfonated polyimides. Two series of phthalic sulfonated polyimides were prepared using 4,4′-oxydiphthalic anhydride (ODPA) and 4,4′-methylene dianiline (MDA), and 4,4′-(hexafluoroisopropylidine) diphthalic anhydride (6FDA) and oxydianiline (ODA). 4,4′-Diaminobiphenyl- 2,2′-disulfonic acid (BDSA) was used to introduce sulfonic acid group into both series. Naphthalenic polyimides were synthesized from 1,4,5,8- naphthalenetetra-carboxylic dianhydride, BDSA, MDA and ODA. Also to observe other properties according to variation of sulfonic acid content, the degree of functionalisation was effectively controlled by altering the mole ratio between the sulfonated and non-sulfonated diamine monomers in phthalic sulfonated polyimides. The hydrolytic stability of the polyimides was followed by FT-IR spectroscopy at regular intervals. Polyimides prepared using naphthalenic dianhydride, NTDA, exhibited higher hydrolytic stability than the phthalic dianhydrides. The proton conductivity, ion exchange capacity (IEC) and water uptake measurements revealed the dependence on the molecular weight of the repeating unit. The proton conductivity of the sulfonated polyimides was found to vary with chemical backbone structure.

Original languageEnglish
Pages (from-to)431-440
Number of pages10
JournalPolymer Degradation and Stability
Volume90
Issue number3
DOIs
Publication statusPublished - 2005 Dec 1

All Science Journal Classification (ASJC) codes

  • Condensed Matter Physics
  • Mechanics of Materials
  • Polymers and Plastics
  • Materials Chemistry

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