Chemical cross-linking modification of polyimide membranes for gas separation

Ye Liu, Rong Wang, Tai Shung Chung*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

283 Scopus citations


We have developed an extremely simple room temperature chemical cross-linking technology for the modification of polyimide films for gas separations of He/N2 and O2/N2. Using 6FDA-durene as an example, chemical modification is performed by immersing the dense 6FDA-durene films in a p-xylenediamine methanol solution for a certain period of time followed by washing with fresh methanol and drying at ambient temperature. The chemical structure changes during the cross-linking process were monitored by FTIR, which indicated that imide groups were turned to amide groups during the modification process. TGA analyses showed cross-linked polyimides were thermally stable for gas separation applications. Gas permeation properties of modified polyimides to He, O2, N2 and CO2 were measured at 35°C and 10atm. It is found that the gas permeability decreased significantly in the order of CO2 > N2 > O2 > He with an increase in the degree of cross-linking, which were mainly attributed to the significant decreases in diffusion coefficients. The permselectivities of He/N2 and O2/N2 increased from 10 to 86 and from 4.1 to 5.9, respectively, but CO2/N2 decreased from 12 to 5.4, which suggest this cross-linking approach is most useful for the application of He/N2 and O2/N2 separations.

Original languageEnglish (US)
Pages (from-to)231-239
Number of pages9
JournalJournal of Membrane Science
Issue number2
StatePublished - Aug 15 2001
Externally publishedYes


  • 6FDA-durene polyimide
  • Chemical modification
  • Cross-linking
  • Fluoropolyimide
  • Gas-separation membranes

ASJC Scopus subject areas

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


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