Photoinduced Grafting of Filtration Membranes: Principles and Applications

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CTS-0094765Georges BelfortRensselaer Polytechnic InstitutePhoto-induced Grafting of Filtration Membranes: Principles and Applications ABSTRACT The goals of this work are to determine the underlying principles of photo-induced graft modification of poly(ether sulfone) (PES) membranes and to use this understanding to modify the surface of commercially available PES membranes so that they exhibit less fouling during ultrafiltration of protein solutions. Ultraviolet (UV)-assisted graft polymerization of hydrophilic monomers is the modification technique chosen for this study because it is simple and easy to scale industrially. PES ultrafiltration membranes are selected because they are widely used in the biotechnology industry, but they are relatively hydrophobic, exhibit severe protein fouling, and are intrinsically photoactive. The specific aims are: 1. To investigate the mechanism of the photo-induced grafting of PES with a view towards elucidating the identity of the photoactive chromophore(s) and to identify the optimal irradiation conditions. 2. To evaluate a series of hydrophilic vinyl monomers in lieu of N-vinyl-2-pyrrolidinone (NVP), the most well-studied monomer to date. We postulate that other commercially available hydrophilic monomers could offer advantages over NVP. 3. To demonstrate the efficacy of using our new surface-modification technology by developing an affinity membrane with low protein adsorption and high cation-exchange capacity. 4. To evaluate the chemical and physical stability and lifetime of the most promising modified PES membranes. There is an urgent need in the biotechnology, food and beverage, and wastewater- treatment industries for better, low-biofouling synthetic membranes. The current most widely used membrane, poly(ether sulfone), exhibits high non-specific protein fouling and needs to be replaced. However, developing new polymeric materials with appropriate surface or functional characteristics as well as mechanical properties for diverse membrane-filtration applications involves great effort and expense. As a result, over the past 30 years, few polymers have been used for membrane production. In this comprehensive three-year research program, an alternate route, i.e. the facile modification of commercial PES membranes, is offered. The new method proffers a relatively inexpensive, simple, scalable, and well-tested modification procedure for producing poly(aryl sulfone) membranes with improved properties.