(557c) Visualization of Electrospray Technique for Membrane Manufacturing

The membrane research community has explored materials with exceptional properties for use as selective layers in membranes. However, they face challenges in transitioning these findings to commercial applications due to a dependence on traditional manufacturing technologies, particularly when ultra-thin films are needed. Traditional approaches for making ultra-thin films such as spin coating or atomic layer deposition are effective for lab scale, but they are unsuitable for industrial-scale manufacturing. Identifying new approaches for making ultra-thin films that are defect free yet scalable continues to be a challenge.

Electrospray layer-by-layer deposition has the potential to overcome these challenges by processing novel material with exceptional separation property into ultra-thin homogenous selective layer and multi-jet system for continuous fabrication. Electrospray deposition utilizes an electric field established between the spray tip and the deposition surface. Charged spray droplets undergo coulombic fission during their trajectory, resulting in a finely dispersed spray mist capable of forming membranes with thicknesses on the order of nanometers.

In the controlled layer-by-layer coating process using electrospray, specific parameters play pivotal roles in ensuring quality control and achieving precise membrane thickness. Factors like spray area, shape, droplet size, and solvent evaporation are essential to single needle whereas overlapping spray area, needle spacing, needle alignment, etc. is crucial for multi-nozzles electrospray deposition. Achieving uniformity, stability and/or precision in spray area for scale-up process holds the potential to optimize membrane performance, particularly in terms of enhancing both selectivity and permeance. This research focuses on elucidating the significance of spray area & shape, single and/or multi-jet trajectory in single needle configuration, providing insights into the multi-nozzle organization for continuous electrospray fabrication for uniform film formation.