Ultrathin and high-performance covalent organic frameworks composite membranes generated by oligomer triggered interfacial polymerization

The practical application of covalent organic frameworks (COFs) membrane still faces major challenges emanated from harsh fabrication condition, non-uniform performance and high production cost. To address these issues, oligomer triggered interfacial polymerization (OT-IP) was proposed to fabricate COFs/PSf composite membranes, in which two reactive monomers having extremely low concentration (0.6 mM) were in advance pre-mixed in n-hexane to generate oligomers with planar structure, which was then subsequently grew under the catalysis of acetic acid to form an ultrathin and continuous COFs layer. The as-prepared TpPa/PSf (OT-IP), TpBd/PSf (OT-IP) and TpDp/PSf (OT-IP) composite membranes exhibited superior permeability of 52–85 L·m−2·h−1·bar−1 and congo red rejection of 93–99%, precisely in consistent with the pore sizes of COFs. The OT-IP technique would not only inspire the fabrication of COFs/PSf composite membranes with a greater variety but also make their scale-up and application feasible and economical.