CHARACTERIZATION OF POLYMER SURFACES FOR POLYETHYLENE GLYCOL GRAFTING
Agyeman-Budu, David Nana
This research project describes the study of methods used to photochem- ically modify the surface of polystyrene (PS) and poly(methyl) methacrylate (PMMA) with the aim of improving their surface properties. The modified polymers and the corresponding characterization play a very important role in providing avenues for existing polymers to achieve novel functionality in microfluidic devices. PS and PMMA were modified by using two different techniques. These were UV treatment in the presence of oxygen (UV/O3 ) and surface oxidation with sodium hypochlorite. The UV/O3 method generates ozone which breaks the surface bonds of the polymers and oxidizes it. The amount of carboxyl groups generated were found to be as much as 24.3 nmol/cm2 which is almost as dou- ble as generated when using the UV/O3 method without sodium hypochlo- rite. Other methods investigated were the iodide and the photoinitiator (with benzophenone) methods. These processes utilize free radicals generated to ox- idize polymer surfaces, however, these methods in oxidizing the polymers, as found were significantly less than just UV/O3 . Finally, poly(ethylene) glycol was grafted onto the functionalized polymers. It was determined that PS had a grafting efficiency of 1.15% and PMMA, 0.16% and 0.23%.
Poly(ethylene) glycol, grafting, PEG, surface modification, free radicals
dissertation or thesis