Synergistic in situ growth and interfacial modification of ZIF-8@PDMS membranes for efficient DMC/methanol separation

Polydimethylsiloxane (PDMS) membranes have shown potential for organic-organic pervaporation separations. However, their practical application is often limited by excessive swelling and insufficient selectivity, particularly in polar azeotropic systems. To address these challenges, a synergistic strategy integrating in situ growth of ZIF-8 nanoparticles with OTES-mediated interfacial alkylation was developed to fabricate a ZIF-8@PDMS mixed-matrix membrane for the separation of dimethyl carbonate (DMC)/methanol (MeOH) azeotropic mixtures. ZIF-8 nanoparticles were grown in situ within the PDMS matrix to establish selective transport pathways. Meanwhile, n -octyltriethoxysilane (OTES) was introduced to functionalize the membrane surface via alkylation, thereby modulating interfacial solvent affinity and mitigating membrane swelling. Under the optimized fabrication conditions (OTES content of 5 wt%, reaction temperature of 100 °C, and reaction time of 4 h), the resulting OTES-ZIF-8@PDMS membrane exhibited a high permeation flux of 9544.20 g·m −2 ·h −1 and a separation factor of 4.63 at 40 °C with a feed composition containing 30 wt% DMC. The membrane maintained stable separation performance over 20 days of continuous operation, demonstrating good operational durability. This study provides a rational membrane design strategy for the efficient pervaporation separation of organic-organic azeotropic systems.