(463d) Fundamental Water and Salt Transport Properties in Zwitterionic Polymers and Their Use for Membrane Surface Modification to Enhance Antifouling Properties
Fouling by suspended solids and dissolved organic matters presents a great challenge for polymeric membranes for desalination and wastewater treatment. With superior hydrophilicity, zwitterionic polymers have been explored for membrane surface modification to enhance antifouling properties. However, there is a lack of understanding of relationship between polymer structure and water and salt transport properties. In this study, two series of zwitterionic polymers were prepared from sulfobetaine methacrylate (SBMA) and 2â??methacryloyloxyethyl phosphorylcholine (MPC). These polymers were thoroughly characterized in terms of sol-gel fraction, density, glass transition temperature, contact angle, and water and salt transport properties.Â Interestingly, the zwitterionic polymers exhibit water sorption and permeability similar to nonâ??charged poly(ethylene glycol) (PEG)â??based materials. These zwitterionic polymers exhibit lower NaCl diffusivity and permeability and thus higher water/NaCl selectivity than the nonâ??charged PEGâ??based materials. Moreover, we have modified ultrafiltration (UF) membranes using a solution containing dopamine and sulfobetaine methacrylate (SBMA).Â The dopamine and SBMA react and form a thin film on the surface, while dopamine provides adhesion to the membrane surface and SBMA provides superhydrophilic properties.Â The coating enhances the surface hydrophilicity, which is confirmed by contact angle measurement.Â The coated membranes demonstrate better stability and higher water flux than those of dopamine-coated and uncoated ones, when tested with water containing bovine serum albumin (BSA). For instance, the membrane coated with dopamine and SBMA exhibits water permeance 80% higher than the uncoated one, after 3 hour filtration using a 3g/L BSA solution in a crossflow system.