Ultrafiltration Membranes Produced from Polymerization of Water/Oil/Block Copolymer Self-Assembly

As human population continues to grow, demands for clean water will increase, necessitating further development of water purification technologies. Ultrafiltration is a necessary step in the treatment of both drinking water and wastewater in which suspending particles, viruses, and bacteria are removed. Conventional ultrafiltration (UF) membranes are produced through non-solvent induced phase separation (NIPS). However, the NIPS technique is not ecofriendly and resultant membranes are anisotropic with low surface area and porosity. The self-assembly of block copolymers at an oil/water interface has been widely studied for applications ranging from drug delivery to energy storage. The purpose of this research is to utilize self-assembly as a template for producing mesoporous polymeric materials to be used as UF membranes. A tri-block copolymer of poly(ethylene oxide), PEO, and poly(propylene oxide), PPO, with (PEO)₁₃-(PPO)₃₀-(PEO)₁₃ composition is used, and different water/oil/block copolymer concentrations and compositions are studied. The oil phase consists of butyl acrylate as well as ethylene glycol dimethacrylate, a cross-linker, and can be polymerized via photo- and thermal initiators. Upon self-assembly of the water/oil/block copolymer mixture into a desired mesostructure, the oil phase is polymerized and a mesoporous polymer is obtained. Resultant materials are characterized through polarized light microscopy (PLM), rheology, BET, and small angle X-ray scattering (SAXS). The produced membranes are found to have mesopores in the range of 70 nm with improved permeability over conventional UF membranes, as measured in a dead-end flow using an oil-in-water emulsion as feed stream.