PDMS thin-film composite membrane fabricated by ultraviolet crosslinking acryloyloxy-terminated monomers

Polydimethylsiloxane (PDMS), as a representative membrane material with superior permeability, attracts great attention in gas separation, pervaporation and nanofiltration. However, the fabrication of defect-free ultrathin PDMS membrane remains great challenge mainly due to the difficulty in controlling the processability and substrate pore penetration of casting solution. In this work, for the first time, we employed PDMS monomer terminated with acryloyloxy groups (AC-PDMS) to implement fabrication of thin-film composite (TFC) membrane. The ultraviolet (UV) reactivity between acryloyloxy groups induced fast curing of AC-PDMS casting solution, thereby realizing formation of ultrathin selective layer (∼260 nm) and inhibition of substrate pore penetration. By optimizing the UV wavelength, irradiation time and polymer concentration, the resulting AC-PDMS TFC membrane achieved attractive CO₂ permeance of 9635 GPU, with CO₂/N₂ selectivity of 11.5. Furthermore, chain crosslinking and packing behavior, fabrication of TFC membrane and transport property of AC-PDMS were compared with conventional hydroxyl-terminated PDMS (OH-PDMS). Together with the potential in scalable fabrication, the strategy based on UV crosslinking acryloyloxy-terminated monomers provides a new avenue to produce ultrathin PDMS membranes toward practical application in molecular separation.