(767e) Spatial Control of Grafted Polymers on Ultrafiltration Membrane: A New Horizon of Aget-ATRP

Wickramasinghe, R., University of Arkansas
Sengupta, A., University of Arkansas
Qian, X., University of Arkansas
Controlled polymerization methods have been shown to be highly desirable when tailoring the three dimensional structure of membrane surfaces. However, selective modification either on the inside pore or outer membrane surface is much more complex. Activator generated electron transfer (AGET) radical polymerization has been demonstrated as a simple and well controlled method for Atom Transfer Radical Polymerization (ATRP) on regenerated cellulose (RC) membrane using 2-hydroxyethyl methacrylate (HEMA) as the monomer unit. The methodology was optimized with respect to initiator concentration, the time of AGET-ATRP and reductant concentration. AGET-ATRP was found to be less sensitive to the presence of air, water or traces of oxygen. The control of the polymer growth inside or outside the pores of RC membrane was investigated using different pore filling solvents having a wide range of viscosity and reactivity. Both of these factors were found to be responsible for surface selective modification of RC membranes. The polymer growth on the outer surface of the RC membranes was evident from FT-IR spectroscopy, while dextran and bovine serum albumin (BSA) rejection tests were used to probe changes in pore dimensions. Dextran rejection was determined by size exclusion chromatography and Total Organic Carbon (TOC) analysis while UV-vis spectroscopy was used for BSA analysis. Results that compare changes in flux and rejection for different pore filling solvents indicate the desirable properties for these solvents. Based on the fact that glycerol has a high viscosity and low miscibility with acetonitrile it was found to be the most promising pore filling solvent. The results obtained here demonstrate the possibility of selective surface modification inside the pores or on the external membrane surface.