Role of intrachain rigidity in the plasticization of intrinsically microporous triptycene-based polyimide membranes in mixed-Gas CO2/CH4 separations

Raja Swaidan, Bader Ghanem, Majed Al-Saeedi, Eric Litwiller, Ingo Pinnau

Research output: Contribution to journalArticlepeer-review

68 Scopus citations

Abstract

Based on high-pressure pure- and mixed-gas (50:50) CO2/CH4 separation properties of two intrinsically microporous triptycene-based polyimides (TPDA-TMPD and TPDA-6FpDA), the intrachain rigidity central to "conventional PIM" design principles is not a singular solution to intrinsic plasticization resistance. Despite the significant intrachain rigidity in TPDA-TMPD, a 300% increase in PMIX(CH4), 50% decrease in α(CO2/CH4) from 24 to 12, and continuous increase in PMIX(CO2) occurred from 4 to 30 bar. On the other hand, the more flexible and densely packed TPDA-6FpDA exhibited a slight upturn in PMIX(CO2) at 20 bar similar to a dense cellulose acetate (CA) film, also reported here, despite a 4-fold higher CO2 sorption capacity. Microstructural investigations suggest that the interconnected O2- and H2-sieving ultramicroporosity of TPDA-TMPD is more sensitive to slight CO2-induced dilations and is the physical basis for a more extensive and accelerated plasticization. Interchain rigidity, potentially by interchain interactions, is emphasized and may be facilitated by intrachain mobility.
Original languageEnglish (US)
Pages (from-to)7453-7462
Number of pages10
JournalMacromolecules
Volume47
Issue number21
DOIs
StatePublished - Oct 22 2014

ASJC Scopus subject areas

  • Materials Chemistry
  • Organic Chemistry
  • Polymers and Plastics
  • Inorganic Chemistry

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