PDMS Mixed Matrix Membranes With Molecular Interaction-Driven Tunable Free Volumes: Breaking the Trade-Off Between Permeability and Selectivity for Pervaporation

摘要

The development of membrane technologies based on molecular-scale separations such as pervaporation and gas separation continues to receive tremendous attention due to the inherent advantages of energy-saving and cost-effective. An ideal membrane demands for highly permeable and selective, but there is always a trade-off between permeability and selectivity exists for polymeric membranes, which are currently the dominant membranes for molecular separation because of their easy-processability and low-cost. In recent years, incorporating inorganic particles into polymers to fabricate mixed matrix membranes (MMMs) has been proven to be an efficient and cost-effective approach to improve the membrane permeability and selectivity. Although improved performance could be obtained by utilizing the high size or adsorption selectivity of the fillers, the inadequate particle dispersion and defective filler/polymer interface that lead to reduced membrane selectivity since the permeating species bypass the filler, are considered two of the major obstacles that impede the commercial implementation of this approach. Polydimethylsiloxane (PDMS), a benchmark membrane material for organophilic pervaporation (e.g., biofuels recovery from dilute aqueous solution and VOCs removal), has relative low separation performance that are still insufficient for practical applications. Previous work has developed a surface graft/coating approach to obtain a homogeneous dispersion of zeolite particles in polymer to prepare defect-free PDMS MMMs. Nevertheless, like most reported MMMs, the pervaporation performance of the zeolite/PDMS MMMs were yet trapped in permeability-selectivity trade-off.