Editorial Article

Polymers of Intrinsic Microporosity for Gas Separations

Dr. Li Pei,
Zhikang Tian, Bing Cao, Pei Li*
College of Materials Science and Engineering, Beijing University of Chemical Technology, Beijing 100029, China
*Corresponding author:

Pei Li, College of Materials Science and Engineering, Beijing University of Chemical Technology, Beijing 100029, China, Email: lipei@mail.buct.edu.cn

Today,membrane separation as a green technology is receiving increasing attention because of its intrinsic advantages such as energy saving, easy operation, small scale, high efficiency, etc.Membrane gas separation has been widely applied in different processes, such as O2/N2 separation, NH3/H2 separation, flue gas separation, natural gas sweetening, and Olefin/paraffin separation.Up to now, commercial membranes for gas separation are mainly made from polymers including Polyimide, cellulose acetate, polydimethylsiloxane, Polysulfone,and polycarbonate because of the low manufacturing cost and better membrane forming properties [1]. However, traditional polymeric membranes usually suffer from a“trade-off”relation between permeability and selectivity, that is, higher permeability typically with low selectivity and vice versa.This limits the commercializationof polymeric membranes, but attracts great attention from both industry and academia to develop novel polymeric membranes being able to break the “trade-off” restriction.

In the last 20 years, literature results suggest that increasing polymer backbone stiffness can improve both permeability and selectivity of polymer membrane. For instance, polymers of intrinsic microporosity(PIMs)have a highly rigid ladder-like backbone and contorted macromolecular structure that hinder the rotation of polymer backbone and increase polymer free volume. In addition, the stiff chain structure behaves like molecular sieve that increases the diffusivity selectivity of the relatively small gas molecules like CO2 and H2 to large molecules like CH4 and N2. Furthermore, the solubility selectivity of PIMs to CO2 can be tuned by introducing specific functional groups such amine or carboxylate groups. Therefore, separation performances of PIMs of CO2/N2 and O2/N2 have surpassed the “2008 Robeson Upper Limit”. However, there are still two challenges at least for PIMs, which are severe physical ageing and plasticization, respectively. Our group and others have done a lot of research works to address these two problems and some good results have been obtained, such as cross-link or blend modification that showed significant improvement of inhibiting physical ageing and plasticization [2].
Recently, PIMs also showed great prospect for oil/water separation[3,4], dye absorption[5],homogeneous catalysis etc by taking the advantage of their high surface area and specific physiochemical interactions.Therefore, combining the unique physical property (microporosity) with the tunable chemical property, PIMs can find more applications.

[1] Zhang, C., Cao, B., Coleman, M. R., & Li, P. (2016). Gas transport properties in (6FDA-RTIL)-(6FDA-MDA) block copolyimides. Journal of Applied Polymer Science, 133(9).
[2] Zhang, C., Li, P., & Cao, B. (2017). Decarboxylation crosslinking of polyimides based on olecularly designed carboxylic acid contaimzning diamines with high CO2/CH4, separation performance and plasticization resistance. Journal of Membrane Science, 528(-), 206-216.
[3] Zhang, C., Li, P., & Cao, B. (2016). Electrospun polymer of intrinsic microporosity fibers and their use in the adsorption of contaminants from a nonaqueous system. Journal of Applied Polymer Science, 133(22).
[4] Zhang, C., Li, P., & Cao, B. (2016). Fabrication of Superhydrophobic–Superoleophilic Fabrics by an Etching and Dip-Coating Two-Step Method for Oil–Water Separation. Industrial & Engineering Chemistry Research, 55(17), 5030-5035.
[5] Zhang, C., Li, P., Huang, W., & Cao, B. (2016). Selective adsorption and separation of organic dyes in aqueous solutions by hydrolyzed PIM-1 microfibers. Chemical Engineering Research and Design, 109, 76-85.

Published: 05 April 2017


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