Modification of thin film composite polyamide membranes with 3D hyperbranched polyglycerol for simultaneous improvement in their filtration performance and antifouling properties

This study investigated a novel surface modification strategy for thin film composite (TFC) polyamide membranes using hyperbranched polyglycerol (hPG), which is not only super-hydrophilic to mitigate fouling, but also has a unique three-dimensional globular architecture to enhance water transport. Membrane surface modification with hydrophilic polymers has been shown to improve the membrane fouling resistance, but often at the expense of decreased water flux. To solve this dilemma, a highly permeable antifouling layer was created by grafting hPG onto the polyamide surface of a TFC membrane via a layer-by-layer interfacial polymerization method. The grafted hPG remarkably enhanced the hydrophilicity of the TFC polyamide surfaces, resulting in an extremely low water contact angle (16.4 degrees), and significantly increased the water permeability by 41.5% compared to pristine TFC membranes. Furthermore, the hPG-grafted TFC polyamide membrane exhibited an improved antifouling performance with both reduced BSA protein adsorption in static fouling experiments and lower water flux decline in dynamic fouling tests. Therefore, our work sheds light on using novel 3D hyperbranched polymers for effectively and efficiently engineering membrane surfaces to simultaneously improve their antifouling properties and filtration performances in forward osmosis membrane processes.