PDMS Regulated Growth of Cyclodextrin Polyester Membranes for Natural Gas Dehydration

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Membrane separation is an energy-efficient route for natural gas dehydration, but achieving high water permeance, H2O/CH4 selectivity, and humid-state stability remains challenging. Here, a PDMS-mediated interfacial polymerization strategy was developed to construct ultrathin cyclodextrin-derived polyester selective layers on PES supports. The PDMS interlayer sealed surface pores, regulated monomer diffusion, and enabled the formation of a continuous selective layer of approximately 70 nm. Among α-, β-, and γ-cyclodextrin membranes, the β-CD/TMC membrane showed the best performance, reaching an H2O permeance of 76,423 GPU and an H2O/CH4 selectivity of 78,602. Its superior performance results from the balanced cavity size, hydrophilic oxygen-containing groups, and low transport resistance of the cross-linked polyester layer. The membrane also maintained stable separation under highly humid conditions for 7 days, demonstrating the effectiveness of PDMS-regulated cyclodextrin polyester membranes for natural gas dehydration.