High Flux Thermally Rearranged Polymer Membranes With Tuned Microcavities for Gas Separation

Microporous materials have been of great interest for various applications such as gas separation, gas storage, energy storage, and energy conversion, due to their beneficial properties from high surface area and high pore volume. As gas separation membrane materials, microporous materials exhibit high flux based on the fast gas transport through membrane matrix. Compared to the inorganic materials, such as zeolite, silica, and metal organic frameworks (MOFs), organic microporous materials have advantages in their mass production and processability for various applications. Poly(1-(trimethylsilyl)- 1-propyne) (PTMSP), amorphous fluoropolymers, polymers with intrinsic microporosity (PIMs) and thermally rearranged (TR) polymers have been reported with their extraordinary permeability from high free volume elements [1].

Recently reported rigid polymer membranes, so-called thermally rearranged (TR) polymer membranes have been developed from ortho-functionalized polyimides by a post thermal conversion process. They demonstrate bimodal cavity sizes of 0.3-0.4 nm and 0.7-0.9 nm, and narrow cavity size distributions characterized by PALS measurement as a shape reminiscent of aquaporin which is an efficient transport path for small gas penetrants. Therefore, TR polymer membranes exhibit both high permeability and high selectivity based on high diffusivity of small gas molecules [2,3]. One of great benefits of TR polymers is the ability to tune the cavity sizes by designing polymer structures and thermal conversion routes for specific gas separation applications including CO₂ capture from flue gas [4]. Copolymerization as well as the control of thermal conversion ratio also provides the variety of gas separation performance of TR polymer membranes [5]. In this presentation, various high flux TR polymer membranes for targeted applications will be summarized.

References

[1] S.H. Han, Y.M. Lee, Recent high performance polymer membranes for CO₂ separation, Membrane Engineering for the Treatment of Gases: Gas-separation Problems with Membranes, RSC Publishing (2010)

[2] H.B. Park, C.H. Jung, Y.M. Lee, A.J. Hill, S.J. Pas, S.T. Mudie, E. Van Wagner, B.D. Freeman, D.J. Cookson, Polymers with cavities tuned for fast selective transport of small molecules and ions, Science 318, 254–258 (2007)

[3] S.H. Han, N. Misdan, S. Kim, C.M. Doherty, A.J. Hill, Y.M. Lee, Thermally rearranged (TR) polybenzoxazole: effects of diverse imidization routes on physical properties and gas transport behaviors, Macromolecules 43, 7657-7667 (2010)

[4] S.H. Han, H.J. Kwon, K.Y. Kim, J.G. Seong, C.H. Park, S. Kim, C.M. Doherty, A.W. Thornton, A.J. Hill, A.E. Lozano, K.A. Berchtold, Y.M. Lee, Tuning microcavities in thermally rearranged polymer membranes for CO₂ capture, Physical Chemistry Chemical Physics 14, 4365-4373 (2012)

[5] J.I. Choi, C.H. Jung, S.H. Han, H.B. Park, Y.M. Lee, Thermally rearranged (TR) poly(benzoxazole-co-pyrrolone) membranes tuned for high gas permeability and selectivity, Journal of Membrane Science 349, 358-368 (2010)