Doctor-blading-assisted interfacial polymerization for green and scalable polyamide membrane fabrication

Industry-leading polyamide membranes are thin-film composites produced via interfacial polymerization (IP) at an alkane-water interface. However, the current fabrication method results in suboptimal membrane microstructure and compromised performance due to insufficient control of mass and heat transfer within the interfacial reaction zone. Furthermore, the fabrication process utilizes volatile alkane solvents, contributing to a significant environmental burden. Here, we report an IP strategy at an ionic liquid/water interface to synchronously achieve kinetic and thermodynamic control of the interfacial reaction, thereby optimizing the microstructure of polyamide membranes. The high viscosity and low volatility of the ionic liquid facilitate the integration of the industrial doctor blading technique into the IP process, enabling rapid, eco-friendly, and scalable polyamide membrane production. The resulting membrane exhibits an unprecedented combination of high pure water permeance (25.8 LMH/bar) and excellent salt (sodium sulfate) rejection (96.54%), surpassing the performance of commercial benchmark polyamide membranes. This facile fabrication strategy paves the way for the design and production of next-generation, high-performance thin-film composite membranes. Polyamide membranes are often fabricated using interfacial polymerization methods, though these methods can compromise membrane structure and performance. Here the authors design a polymerization method using ionic liquid and a doctor blading method to optimize membrane fabrication.