Interfacial polymerization of thin film selective membrane layers: Effect of polyketone substrates

Nanofiltration Membrane with Enhanced Ion Selectivity Based on a Precision-Engineered Ultrathin Polyethylene Supporting Layer

Nanofiltration (NF) technology is increasingly used in the water treatment and separation fields. However, most research has focused on refining the selective layer while overlooking the potential role of the supporting layer. With expertise in ultrathin polymer films, particularly in the production of polyethylene (PE) membranes, we explore the possibility of improving NF membrane performance by precisely controlling the structure and surface properties of the ultrathin supporting layer in this work. Here, we introduced an innovative NF membrane that used a submicrometer ultrathin PE membrane produced through a biaxial stretching process, which is significantly thinner than commercial PE membranes available on the market. The core innovations are as follows: first, we focused on precise control of the supporting layer rather than just the selective layer, achieving significant enhancements in overall NF membrane performance; second, the ultrathin PE supporting layer served as a tunable interface for interfacial polymerization, offering possibilities for structural control of the selective layer and advancing membrane performance innovations. The resulting NF membrane boasts an overall thickness of ∼630 nm, which represents the thinnest NF membrane documented to date. This ultrathin NF membrane showed an ultrahigh Cl-/SO42- selectivity of 338.03, placing it at the forefront of existing literature. This study sheds light on the important role of the supporting layer in the preparation of selective layers. We believe that this approach has the potential to contribute to the development of ultrathin, high-performance NF membranes.

Development of Support Layers and Their Impact on the Performance of Thin Film Composite Membranes (TFC) for Water Treatment

Thin-film composite (TFC) membranes have gained significant attention as an appealing membrane technology due to their reversible fouling and potential cost-effectiveness. Previous studies have predominantly focused on improving the selective layers to enhance membrane performance. However, the importance of improving the support layers has been increasingly recognized. Therefore, in this review, preparation methods for the support layer, including the traditional phase inversion method and the electrospinning (ES) method, as well as the construction methods for the support layer with a polyamide (PA) layer, are analyzed. Furthermore, the effect of the support layers on the performance of the TFC membrane is presented. This review aims to encourage the exploration of suitable support membranes to enhance the performance of TFC membranes and extend their future applications.

When self-assembly meets interfacial polymerization

Interfacial polymerization (IP) and self-assembly are two thermodynamically different processes involving an interface in their systems. When the two systems are incorporated, the interface will exhibit extraordinary characteristics and generate structural and morphological transformation. In this work, an ultrapermeable polyamide (PA) reverse osmosis (RO) membrane with crumpled surface morphology and enlarged free volume was fabricated via IP reaction with the introduction of self-assembled surfactant micellar system. The mechanisms of the formation of crumpled nanostructures were elucidated via multiscale simulations. The electrostatic interactions among m-phenylenediamine (MPD) molecules, surfactant monolayer and micelles, lead to disruption of the monolayer at the interface, which in turn shapes the initial pattern formation of the PA layer. The interfacial instability brought about by these molecular interactions promotes the formation of crumpled PA layer with larger effective surface area, facilitating the enhanced water transport. This work provides valuable insights into the mechanisms of the IP process and is fundamental for exploring high-performance desalination membranes.