(625a) Membrane Modification and Synthesis for Fouling Control

Membrane processes are widely used in the biotechnology and pharmaceutical industries for sterile filtration of fermentation media, initial harvesting of therapeutic products, and purification of buffers and proteins.  Protein fouling is one of the critical factors governing the membrane performance in various filtration processes. In this study, we utilize the protein resistant property of polyethylene oxide (PEO) to modify the membranes to investigate the potential of utilizing PEO for fouling reduction.  Three surface modification techniques have been investigated: covalent, ionic, and self assembled monolayers. In the first system, polyethylene oxide (PEO) containing pluronic surfactant was UV grafted to 0.2 micron mixed cellulose esters membranes. Upon coating the membrane with a monolayer of allyldimethylchlorosilane (ADCS). The silanized membrane was covalently linked to Pluronic F127, a triblock copolymer of poly ethylene oxide and poly propylene oxide (PEO-PPO-PEO) by UV irradiation at wavelength above 215 nm. In the second system, polyelectrolytesterminated with polyethylene glycol, poly (oligoethylene glycol methacrylate co methacrylic acid), (OEGMA/MA), was applied to modify positively charged PVDF membranes.  In the third system, self-assembled monolayer with different terminal functional groups was formed on silver membranes.  Membranes modified covalent or ionic approach showed minimum effect on flux decline while membranes modified with alkanthiols with a terminal tri(ethylene glycol) functional groups showed significant reduction in flux decline during bovine serum albumin (BSA) filtration.  This shows that the density of the PEO group on the surface is critical in fouling control.  To increase the PEO density, we developed a new approach to fabricate membranes with PEO as the side chains in the polymer that forms the membrane using Glassy Self Assembly Templating.  This approach can lead to membranes with highly uniform and finely tunable nanometer-size pores whose dimensions dictated by the quasi-equilibrium thermodynamics of the glassy sugar/surfactant template.  In addition PEO can be incorporated throughout the membrane to reduce fouling potential.