Control of Physical Aging in Super Glassy Polymer
Membranes Without Permeability Loss.
Authors: Matthew R. Hill,2Phuc Tien Nguyen,1 * Kristina Konstas,2 Cara M. Doherty,2 Cher
Hon Lau,2 Laure Bourgeois,3 Timothy J. Bastow,2 Anita J. Hill, 2 Douglas L. Gin,1 and Richard D.
Noble1
1
Department of Chemical and Biological Engineering, University of Colorado, Boulder, CO 80309 USA.
2
CSIRO Materials Science and Engineering and Process Science and Engineering, Private Bag 33, Clayton South
MDC, Victoria 3169 Australia.
3
Centre for Electron Microscopy, Department of Materials Engineering, Monash University, Clayton Victoria 3800
Australia
* matthew.hill@csiro.au
Abstract: Aging in super-glassy polymers such as poly(trimethylsilylpropyne) (PTMSP)
prohibits it from being used in polymer membranes for separating gas mixtures. While these
polymers are initially very porous and large amounts of gas can selectively pass through them,
they quickly pack into a denser phase becoming much less porous and permeable. This
age-old problem has been solved by the use of an ultraporous additive that allows PTMSP to
maintain its low-density, porous initial state by absorbing a portion of the polymer chains within
its pores, and holding them in position. This is the first time that this aging process has been
stopped in PTMSP without diminishing its properties when prepared as a gas separation
membrane.1,2 In fact, the membrane properties are enhanced with an additive,3 and over
approximately one year of long-term measurements show that the performance is maintained.
The addition of a very specific porous microparticle forms an interwoven nanocomposite with
PTMSP, freezing the structure and hence stopping the aging process, but doing so whilst
increasing the permeability and maintaining the selectivity. Porous Aromatic Frameworks
(PAFs) are carbon-based structures formed by the self-condensation of tetrahedral monomer
nodes to establish an ultraporous array.4 The regular nanopores of around 1.2 nm diameter
are attractive for the intercalation of polymer side-chain components when incorporated within
the PTMSP matrix, thereby freezing the as-cast lower-density polymer structure in place and
stopping the aging process. This mechanism is distinct from the enhanced permeability effect
of non-porous nanoparticle and porous nanoparticle additions to PTMSP that prop open the
polymer chains at the nanoparticle/polymer boundary but do not prevent aging.
References
1.
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Lyndon, R.; Konstas, K.; Ladewig, B. P.; Hill, M. R. GAS SEPARATION PROCESSES TW8699/AU/PROV,
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