Unusual temperature dependence of the positron lifetime in a polymer of intrinsic microporosity

Rodrigo Lima de Miranda, Jan Kruse, Klaus Rätzke*, Franz Faupel, Detlev Fritsch, Volker Abetz, Peter M. Budd, James D. Selbie, Neil B. McKeown, Bader S. Ghanem

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

30 Scopus citations


The performance of polymeric membranes for gas separation is mainly determined by the free volume. Polymers of intrinsic microporosity are interesting due to the high abundance of accessible free volume. We performed measurements of the temperature dependence of the positron lifetime, generally accepted for investigation of free volume, in two polymers of intrinsic microporosity (PIM-1 and PIM-7) in the range from 143 to 523 K. The mean value of the free volume calculated from the ortho-positronium lifetime is in the range of typical values for high free volume polymers. However, the temperature dependence of the local free volume is non-monotonous in contrast to the macroscopic thermal expansion. The explanation is linked to the spirocenters in the polymer.

Original languageEnglish (US)
Pages (from-to)190-192
Number of pages3
JournalPhysica Status Solidi - Rapid Research Letters
Issue number5
StatePublished - Oct 2007
Externally publishedYes

ASJC Scopus subject areas

  • Condensed Matter Physics
  • General Materials Science


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