PDMS Mixed Matrix Membrane with Confined Mass Transfer Structure: The Effect of COFs with Different Porous Structures and Chemical Properties in the Pervaperation Process

In this study, hydrophilic covalent organic framework (COF) nanosheets with triazine structures and hydrophobic COF nanosheets with fluorinated imine skeletons were designed to enhance the membrane separation process for ethanol pervaporation. The mass transfer of ethanol-water mixtures within the confined structures of COF nanosheets was investigated through experimental characterization and computational simulations, establishing a quantitative relationship between mass transfer performance and the pore size/chemical properties of COF nanosheets. These COF nanosheets were employed to optimize the confined architecture of mixed matrix membranes (MMMs), effectively regulating the critical parameters of MMMs and improving their separation performance. Through systematic investigation of formation mechanisms and modulation principles, we revealed the correlation between confined structural parameters and membrane separation efficiency. This work develops methodologies and foundational theories to overcome the permeability-selectivity trade-off effect, providing theoretical guidance for designing novel membrane materials with ethanol-permelective COF-based MMMs.