In-situ crosslinking of Tröger's base polymer onto a 3D Tröger's base-bridged porous network as gas separation membranes

The typical procedure used to fabricate mixed matrix membranes (MMMs), where the pre-obtained filler and polymer are simply mixed together before casting, often suffers from limited polymer-filler adhesion. Herein, we prepare a series of novel MMMs with improved interfacial compatibility by preparing the matrix (Tröger’s base polymer, TB) and the filler (three-dimensional Tröger’s base-bridged porous network, 3D-TB) under the same reaction system, where in-situ crosslinking reaction between them happens simultaneously. Thanks to the excellent interfacial miscibility, the as-developed 10 wt%_3D-TB@TB membrane shows the tensile strength and elongation stain at break of 65.4 MPa and 10.12 %, respectively, which are higher than those of its counterpart synthesized by conventional procedure (55.82 MPa and 7.05 %, respectively). More importantly, both the gas permeability and selectivity of the in-situ crosslinked MMMs show an obvious improvement involving CO2/N2, CO2/CH4, and O2/N2 separation. Specifically, for O2/N2 binary gas separation, the 10 wt%_3D-TB@TB membrane displayed a O2 permeability of 53.2 Barrers and O2/N2 selectivity of 6.1, which are improved by 72 % and 45 % in comparison to the unfilled membrane, overcoming the 2008 Robson upper bound. Moreover, the physical aging of the in-situ crosslinked MMMs is also effectively controlled. These results demonstrate that the in-situ polymerization and crosslinking is an outstanding approach for the construction of defect-free MMMs with enhanced gas separation performances.