Investigation of CO 2-induced plasticization in fluorinated polyimide membranes via molecular simulation

Sadiye Velioǧlu, M. Göktuǧ Ahunbay*, S. Birgül Tantekin-Ersolmaz

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

85 Citations (Scopus)


Molecular simulation techniques are used to estimate the correlations between the structural properties (d-spacing, glass transition temperature, fractional free volume, etc.) and plasticization of 6FDA-ODA, 6FDA-DPX and 6FDA-DAM polyimides (6FDA: 4,4-hexafluoroisopropylidene-diphthalic anhydride; DAM: 2,4,6-trimethyl-m-phenylene diamine; DPX: 2,5-dimethyl-p-phenylenediamine; ODA: 4,4-oxydianiline) induced by CO 2 sorption. Calculated structural properties were in good agreement with the experimental results available in the literature. The plasticization behavior was reproduced through sorption-relaxation cycles that yielded sorption coefficients estimated within the same order of magnitude as the experimental results. Sorption induced changes in the polymer matrices were investigated through radial distribution function and accessible free volume analyses. Results showed that plasticization resistance decreases with increasing accessibility of CO 2 molecules to the polyimide backbone. Furthermore, CO 2 sorption capacities of the three polyimides are proportional to the fractional free volume of the swollen polymer matrices, and the degree of plasticization can be predicted from the backbone flexibility of the polyimide chains.

Original languageEnglish
Pages (from-to)217-227
Number of pages11
JournalJournal of Membrane Science
Publication statusPublished - 1 Nov 2012


This work was supported in part by the Scientific and Technological Research Council of Turkey-TUBITAK (Grant# 106M339 ) and the National Center for High Performance Computing (Grant# 10932010 ). We thank Professor William J. Koros from Georgia Institute of Technology for valuable suggestions and comments on the manuscript.

FundersFunder number
National Center for High Performance Computing10932010
Scientific and Technological Research Council of Turkey-TUBITAK106M339


    • Membrane-based gas separation
    • Molecular simulation
    • Plasticization
    • Polyimide
    • Sorption


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