Fabrication of high-performance mixed-matrix membranes via constructing an in-situ crosslinked polymer matrix for gas separations

In this work, a binaphthyl-ether tetramine (BNTA) monomer was designed, synthesized, and reacted with 6FDA to form an in-situ crosslinked polyimide (6FDA-BNTA). Then, novel mixed-matrix membranes (MMMs) were prepared by incorporating the titanium dioxide (TiO2) nanoparticles into the 6FDA-BNTA polymer matrix to fabricate TiO2/6FDA-BNTA MMMs for gas separations. The desirable interfacial morphology and uniform dispersion of TiO2 were obtained due to the nano-confinement effect and stronger hydrogen bond interactions between TiO2 and 6FDA-BNTA when compared with these of their linear analogues as polymer matrixes. The pristine 6FDA-BNTA membrane and MMMs containing 5-23 wt% of TiO2 had good mechanical properties, which possessed tensile strengths in the range of 65.2-116.6 MPa and elongation at break of 4.8-7.8%. Gas transport results further revealed that the overall performances of TiO2/6FDA-BNTA MMMs were maintained with the increasing of the TiO2 loading content. Specifically, 6FDA-BNTA MMMs with TiO2 loading of 23 wt% exhibited the highest gas permeability (e.g. PCO2 = 376.2 Barrer, PO2 = 76.3 Barrer) and moderate selectivity (e.g. alpha CO2/ N2 = 24.3, alpha O2/N2 = 4.9), locating near the Robeson 2008 upper bounds very closely for O2/N2, H2/N2, and CO2/CH4 gas pairs. This facile approach, aiming at improving the incompatibility between two phases via constructing an in-situ crosslinked polymer matrix, provides a new insight for rational design of highperformance MMMs.

Automated summary

In this study, a novel mixed-matrix membrane (MMMs) of TiO2/6FDA-BNTA was successfully prepared for gas separations by incorporating titanium dioxide nanoparticles into a crosslinked polymer matrix. The MMMs exhibited good mechanical properties and gas separation performances, showing potential for high-performance gas separation membranes.