Pebax–polydopamine microsphere mixed‐matrix membranes for efficient CO₂ separation

Abstract

ABSTRACT Novel facilitated‐transport mixed‐matrix membrane (MMM) were prepared through the incorporation of polydopamine (PDA) microspheres into a poly(amide‐ b ‐ethylene oxide) (Pebax MH 1657) matrix to separate CO 2 –CH 4 gas mixtures. The Pebax–PDA microsphere MMMs were characterized by Fourier transform infrared spectroscopy, scanning electron microcopy, X‐ray diffraction, differential scanning calorimetry, and thermogravimetric analysis. The PDA microspheres acted as an adhesive filler and generated strong interfacial interactions with the polymer matrix; this generated a polymer chain rigidification region near the polymer–filler interface. Polymer chain rigidification usually results in a larger resistance to the transport of gas with a larger molecular diameter and a higher CO 2 –CH 4 selectivity. In addition, the surface of PDA microspheres contained larger numbers of amine, imine, and catechol groups; these were beneficial to the improvement of the CO 2 separation performance. Compared with the pristine Pebax membrane, the MMM with a 5 wt % PDA microsphere loading displayed a higher gas permeability and selectivity; their CO 2 permeability and CO 2 –CH 4 selectivity were increased by 61 and 60%, respectively, and surpassed the 2008 Robeson upper bound line. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 44564.