Scalable Layer‐by‐Layer Electrospray‐Assisted Interfacial Polymerization: Enabling Large‐Area Polyamide Membrane Fabrication

ABSTRACT Layer‐by‐layer electrospray‐assisted interfacial polymerization (LBL‐EAIP) has recently been proposed as an alternative approach for fabricating polyamide membranes with precisely controlled thickness and polymerization degree, showing great potential for reverse osmosis (RO) membrane synthesis. In this article, we report a scale‐up strategy for LBL‐EAIP to enable its practical application in RO membrane manufacturing. A multi‐jet electrospray apparatus was developed, and the device configuration and process parameters were carefully adjusted to produce polyamide‐on‐polyethersulfone thin film composite (TFC) membranes with consistently high salt rejection and water permeance across the membrane area. Specifically, an average 97.1% NaCl rejection from a 2000 ppm NaCl feed was achieved with an area‐to‐area deviation of 1%, along with a deionized water permeance of 0.90 ± 0.11 LMH/bar at 15 bar feed pressure. In addition, a Fourier‐transform infrared spectroscopy (FTIR)‐based analytical method was developed for semi‐quantitative assessment of membrane thickness and compositional uniformity, enabling rapid mapping of film microstructure and chemical variations. This work provides a pathway to scale up LBL‐EAIP technology, bridging the gap between laboratory‐scale innovation and industrial‐scale manufacturing.