Development of high-performance polyelectrolyte-complex-nanoparticle-based pervaporation membranes via convenient tailoring of charged groups

Polymeric materials with charged groups present satisfactory performance in membrane separation due to their strong interaction with water molecules. However, the interactions between water and charged groups are complex, and it is still a big challenge to depict the role of charged groups on the pervaporation performance of polymeric membranes. Here, we constructed the polyelectrolyte complex nanoparticles (PECNPs) with four different charged groups and adopted them for preparation of pervaporation membranes. The PEC membranes were used for pervaporation tests. Low-field nuclear magnetic resonance (LF-NMR) was, for the first time, employed for identifying how the water survive in polymeric membranes with different charged groups. The result hints that the water state in the membrane varies quite different for the four kinds of PECNPs membranes (PECNPMs), which finally determines the performance of the prepared PECNPMs. The PEC-SO3− membrane, possessing both high freezable bound water and non-freezable bound water, showed the highest separation in dehydrating of 10 wt% water/ethanol mixtures at 70 °C, with a pervaporation separation index of 6.93 × 106, which outperforms other polymeric membranes reported. Thus, the performance of PEC membrane can be well-tailored by the conveniently tailoring charged groups, which paves a solid path for developing high-performance polymer membranes.