Aging and free volume in a polymer of intrinsic microporosity (PIM-1)

S. Harms, K. Rätzke, F. Faupel, N. Chaukura, P. M. Budd, W. Egger, L. Ravelli

    Research output: Contribution to journalArticlepeer-review


    There is a growing market for polymeric gas separation membranes for applications such as air separation and carbon dioxide capture. One of the key properties dominating transport is the free volume between atoms, allowing gas diffusion. However, thin films, in particular, undergo aging, decreasing free volume, and, hence, performance with time. We have measured the change in free volume during aging of thin films of a polymer of intrinsic microporosity (PIM-1) by depth-resolved positron annihilation lifetime spectroscopy. For films with thickness, d, smaller than 1m, aging is nearly complete after 3 months, whereas for films with d>1 μm aging continues even after several months. Aging is thickness-and time-dependent and the free volume diffuses through the film to the free surface. © 2012 Copyright Taylor and Francis Group, LLC.
    Original languageEnglish
    Pages (from-to)608-619
    Number of pages11
    JournalJournal of Adhesion
    Issue number7
    Publication statusPublished - 1 Jul 2012


    • Aging
    • Free volume
    • Polymeric membranes
    • Polymers of intrinsic microporosity
    • Positron annihilation lifetime spectroscopy
    • Thin films


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