Structure-property correlations of sulfonated polyimides. I. Effect of bridging groups on membrane properties

Choonkeun Lee, Saimani Sundar, Jinuk Kwon, Haksoo Han

Research output: Contribution to journalArticlepeer-review

67 Citations (Scopus)

Abstract

A series of six-membered sulfonated polyimides were synthesized using 1,4,5,8-naphthalenetetracarboxylic dianhydride, 4,4′-diaminobiphenyl 2,2′-disulfonic acid as the sulfonated diamine, and various nonsulfonated diamine monomers having different bridging groups. These bulky bridging groups have the capacity to increase hydrolytic stability and proton conductivity. Polyimides with bulky bridging groups showed increased solubility but exhibited lower thermal stability. The ion exchange capacity and water uptake reduced with increase in the bulkiness of the bridging group. This was attributed to the increase in the molecular weight of the repeating unit and hence effectively reduced the sulfonic acid content. In low temperatures, the conductivity was lower than Nafion®115 and, with increase in temperature, the conductivity rapidly increased and exhibited better conductivity than Nafion®115. Polyimides with bulky bridging groups 4-amino phenyl sulfone, and 2-bis[4-(4-aminophenoxy)phenyl]-hexafluoropropane showed higher conductivity than other polyimides and Nafion®115 despite low ion exchange capacity. The hydrolytic stability of the polyimides with bulky bridging groups was higher than the polyimides with less bulky atoms because of the imparted flexibility.

Original languageEnglish
Pages (from-to)3612-3620
Number of pages9
JournalJournal of Polymer Science, Part A: Polymer Chemistry
Volume42
Issue number14
DOIs
Publication statusPublished - 2004 Jul 15

All Science Journal Classification (ASJC) codes

  • Polymers and Plastics
  • Organic Chemistry
  • Materials Chemistry

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