Introducing amphipathic copolymer into intermediate layer to fabricate ultra-thin Pebax composite membrane for efficient CO2 capture

Pebax-based membranes have attracted intensive interest for high separation efficacy of carbon dioxide. For achieving excellent gas permeance, ultrathin membrane thickness is always the pursuit of composite membrane technology, in which controlling the interfacial property of the multi-layer remain a great challenge. Herein, we introduced an amphipathic copolymer polydimethylsiloxane (PDMS)-block-polyethylene oxide (PEO) (PDMS-b-PEO) into the intermediate layer to tune the interfacial adhesion, enabling fabrication of ultra-thin Pebax composite membrane. It was demonstrated that surface segregation of PEO segments not only suppressed formation of dense SiOx layer due to the plasma treatment on PDMS intermediate layer, but also provided extra hydrophilic sites and interfacial compatibility for subsequent Pebax selective layer coating. With the present of PDMS-b-PEO in the intermediate layer, an integrated Pebax selective layer with thickness of ∼50 nm was successfully fabricated. The resulting ultra-thin Pebax composite membrane exhibited outstanding performance with CO2 permeance of 2142 GPU and CO2/N2 selectivity of 36. The strategy of using amphipathic copolymer as intermediate layer enhanced the composite membrane integrity and simplified the plasma pre-treatment, showing great potential in developing highly permeable membrane for efficient CO2 capture.