Electrospray interface-less polymerization to fabricate high-performance thin film composite polyamide membranes with controllable skin layer growth

High-performance thin film composite polyamide (TFC-PA) membranes with controllable structure and transport properties are of great significance. However, TFC-PA membranes prepared by interfacial polymerization are far from ideal due to their quick and uncontrollable reaction process. In this study, we reported a novel strategy to fabricate TFC-PA membranes via an electrospray interface-less polymerization (EILP) technique with a miscible solvent system. The miscible solvent system facilitated both the stable and fine spraying of monomer solutions and the efficient polymerization of monomers, and thus resulting in the formation of a smooth and defect-free PA skin layer. Moreover, the crosslinking degree and thickness of the EILP membrane skin layer could be controlled easily by regulating the concentration and dose of sprayed monomers. Attenuated total reflectance-Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, zeta potential and mean effective pore size were employed to characterize the EILP membrane and clarify the separation mechanism. The optimum EILP membrane showed excellent filtration performance with a high water flux of up to 17.7 L m−2 h−1 bar−1, high salt rejection (98.2% of Na2SO4) and complete dye rejection for Congo red. This study provides new insights into the understanding of electrospray procedures and enlightens the design and manufacture of advanced membrane materials through electrospray. [Display omitted] •TFC-PA membranes were firstly prepared by electrospray interface-less polymerization.•Electrospray process parameters were systematically investigated for optimization.•Controllable growth of PA skin layer with nanometer-level precision was achieved.•The optimal membrane exhibited high removal rates of dye/salt.