Customizable Manufacturing of Polyamide Membranes with Programmable Layers and High Permselectivity by Electrospray...

Customizable printing of polyamide (PA) layer is intriguing due to achievement of controllable morphology and programmable crosslinking structure, producing high-quality PA membranes for wide use. However, the state-of-the-art electrospray facilitated interfacial polymerization only achieved control of layer thickness due to its indiscriminate monomer deposition. It lacked 3D design with slicing to specify layer geometry and is far away from customizable printing without achieving programmable features. Herein, a customizable manufacturing approach is established for printing the PA layer with an original programmable electrospray 3D printer, a coupled polymerization method and a numerical prediction model. In this approach, the PA layer is sliced into several ultrathin films. These films are printed individually by flexible use of interfacial, homogeneous, and surficial polymerization with the aid of the numerical model. The printed PA layer has programmable crosslinking degree varying layer by layer, ultrathin thickness of ≈14 nm, nanopores with narrow distribution of ≈0.32 nm, and intrinsic smoothness with ≈4 nm roughness. This structure enables the membranes to achieve water permeance and NaCl rejection of 3.1 L·m^{- 2}·h^-1·bar^-1 and 99.0%, respectively, approaching the limit of permeability-selectivity trade-off. This work offers a universal platform for on-demand fabrication of nanoscale membranes.