Pure- and mixed-gas permeation properties of a microporous spirobisindane-based ladder polymer (PIM-1)

Sylvie Thomas, Ingo Pinnau*, Naiying Du, Michael D. Guiver

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

231 Scopus citations


PIM-1, a glassy, spirobisindane-based ladder polymer is a novel intrinsically microporous membrane material. The pure- and mixed-gas permeation properties of PIM-1 are compared to those of highly permeable, microporous, linear chain, acetylene-based polymers, such as poly(1-trimethylsilyl-1-propyne) (PTMSP). PIM-1 exhibits very high permanent gas permeabilities coupled with moderate selectivities. For example, the oxygen permeability of PIM-1 at 25 °C is 1300 × 10-10 cm3 (STP) cm/cm2 s cmHg combined with an oxygen/nitrogen selectivity of 3.8. Those values place PIM-1 above the Robeson trade-off curve for oxygen/nitrogen separation. Like microporous linear chain PTMSP, ladder-type PIM-1 is more permeable to large, condensable organic vapors, such as n-butane, than to small, permanent gases, such as methane. PIM-1 exhibits a mixed-gas n-butane/methane selectivity of up to 25, which is similar to that of PTMSP, the most permeable and selective polymer known for this separation. Because PIM-1 has significantly better solvent resistance than PTMSP, it could find applications as an advanced membrane material for the separation of organic vapor/permanent gas mixtures.

Original languageEnglish (US)
Pages (from-to)125-131
Number of pages7
JournalJournal of Membrane Science
Issue number1-2
StatePublished - May 1 2009


  • Gas permeation
  • Ladder polymers
  • Microporosity
  • Mixtures
  • PIM
  • Temperature

ASJC Scopus subject areas

  • Biochemistry
  • General Materials Science
  • Physical and Theoretical Chemistry
  • Filtration and Separation


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