Abstract
High-performance membranes exceeding the conventional permeability-selectivity upper bound are attractive for advanced gas separations. In the context microporous polymers have gained increasing attention owing to their exceptional permeability, which, however, demonstrate a moderate selectivity unfavorable for separating similarly sized gas mixtures. Here we report an approach to designing polymeric molecular sieve membranes via multi-covalent-crosslinking of blended bromomethyl polymer of intrinsic microporosity and Tröger’s base, enabling simultaneously high permeability and selectivity. Ultra-selective gas separation is achieved via adjusting reaction temperature, reaction time and the oxygen concentration with occurrences of polymer chain scission, rearrangement and thermal oxidative crosslinking reaction. Upon a thermal treatment at 300 °C for 5 h, membranes exhibit an O2/N2, CO2/CH4 and H2/CH4 selectivity as high as 11.1, 154.5 and 813.6, respectively, transcending the state-of-art upper bounds. The design strategy represents a generalizable approach to creating molecular-sieving polymer membranes with enormous potentials for high-performance separation processes.
Highlights
High-performance membranes exceeding the conventional permeability-selectivity upper bound are attractive for advanced gas separations
In this work, the bromomethylated polymers of intrinsic microporosity (PIMs) were prepared through converting methylated PIM-1 to PIMs with bromomethyl groups by using N-bromosuccinimideas bromomethylating agent[25]
In this work, we describe a method of designing microporous polymer blend membranes through multi-covalent-crosslinking of PIM-BM/Tröger’s base polymers (TB)
Summary
High-performance membranes exceeding the conventional permeability-selectivity upper bound are attractive for advanced gas separations. Crosslinking or rearrangement of aforementioned polymer systems induced by chemical, light, or heat treatment offer further approaches to tailor microscopic structures of polymers[17,18,19] All of these approaches demonstrate potentials to prepare membranes with promising gas separation properties, microstructural engineering of polymers to narrow the pore size distribution and enhance molecular sieving properties has remained a crucial challenge for high-performance gas separation membranes. In comparison with intra-molecularly crosslinked PIMBM, XPIM-BM/TB membranes perform far beyond the current permeability-selectivity upper bounds for multiple gas pairs (e.g., CO2/CH4, H2/CH4, H2/N2, O2/N2) We attribute such high separation performance to finely tuned pore size distribution in crosslinked membranes through integrated multi-covalent crosslinking reactions including self-crosslinking within PIMBM and inter/intra-molecular crosslinking of polymer blends (PIM-BM and TB). The membranes demonstrate appealing gas separation performance enabling ultra-selective separation of industrially relevant gas pairs as discussed in this work
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
