Influence of support layer pore size on interfacial polymerization and polyamide selective layer characterization

Thin film composite (TFC) technology has been widely used to prepare reverse osmosis (RO) membrane, in which the relationship between support layer and selective layer plays a significant role. To thoroughly clarify the influence of support layer pore size on the properties of selective layer, herein, we prepared a series of polysulfone (PSf) support layers with different surface pore sizes by adjusting casting solution concentrations. Afterward, polyamide (PA) selective layers were prepared on top of PSf support layers via interfacial polymerization method. Detailed studies were performed to illustrate membrane-forming dynamics, TFC morphologies and membrane performances. The pore size of support layer has a substantial effect on the aqueous monomer diffusion behavior as well as selective layer morphologies and overall performances; specifically, resulting in differences in both thickness and roughness of PA layer and also inducing different membrane performances. Combined with anti-backflush experiments, we also provide an insight view into the interfacial adhesion between support layer and selective layer.