Fluorinated Metal-Organic Framework-Polymer Mixed Matrix Membrane with Tunable Hydrophobic Channel for Efficient Pervaporation of Butanol/Water

The permeability-selectivity trade-off of membrane is a major challenge limiting the development of pervaporation (PV) technology. Rational design of high-performance mixed matrix membranes (MMMs) has the potential to break off the trade-off. Herein, a solvent-assisted linker exchange-based strategy is reported to introduce fluoroalkyl into metal-organic framework-808 (MOF-808). The pore size of fluorinated MOF-808 can be adjusted with fluoroalkyl of different chain length (like trifluoromethyl and pentafluoropropyl). Then, the fluorinated MOF-808/polyether block amide (PEBA) MMMs are prepared for the PV of n-butanol/water. Compared with pristine PEBA membrane, 20 wt% 3F-MOF-808(P)/PEBA MMMs (3F = -CF3 group; P = postmodification method) exhibit 69% increase in permeation flux and 33% increase in separation factor in the PV of 2.5 wt% n-butanol aqueous solutions at 70 degrees C. Based on Grand Canonical Monte Carlo and molecular dynamics simulations, fluorinated MOF-808 shows better butanol affinity (pull effect) and stronger water repulsion ability (push effect). And the "push-pull effect" between fluorinated MOF-808 with butanol/water is helpful to enhance the PV performance of MMMs. The application of "push-pull effect" provides a new strategy for the rational design of high-performance MMMs, which is of great significance for the in-depth research and application of PV technology.