Tailoring the polyester/polyamide backbone stiffness for the fabrication of high performance nanofiltration membrane

According to the Freeman theory, increasing the backbone stiffness to some extent is an effective way to obtain the remarkable membrane with both high permeability and selectivity. In this work, a high performance nanofiltration (NF) membrane was prepared via tailoring the polyester/polyamide backbone stiffness. The flexible monomer-piperazine (PIP) and the rigid monomer-bisphenol F (BPF) were selected as the aqueous phase monomers, and they were interfacial reacted with trimesoyl chloride (TMC) on the polyethersulfone (PES) UF membrane to generate the polyester/polyamide layer. By mixing PIP with BPF, both of the polyester/polyamide backbone stiffness and microporosity degree enhanced. As a result, the PIP/BPF NF membrane possessed a 2.6-fold pure water flux (PWF) of the PIP NF membrane (the salt rejection remained at the same level), and 4.8-fold PWF of the BPF NF membrane. Our results revealed a novel and facile way to improve the NF membrane performance.