Time-Resolved Electrochemical Monitoring of Metal-Catalyzed Radical Polymerization Using a Carbon Ultramicroelectrode

Abstract

An electrochemical method was optimized in this study to monitor the polymerization of polystyrene and poly(methyl methacrylate) via atom transfer radical polymerization (ATRP). The presence of a metal catalyst adsorbed on the ultramicroelectrode (UME) surface, arising from the use of a transition metal catalyst such as copper(I) bromide in ATRP, negatively affects the current value. To overcome this limitation, selecting an electrode material that mitigates the adsorption associated with the metal catalyst redox processes is critical. Therefore, a carbon UME was employed, owing to its resistance to copper adsorption, ensuring more stable and reproducible signals. These results indicate that the decrease in current during polymerization is mainly associated with viscosity-dependent mass transport caused by increases in polymer molecular weight and concentration rather than changes in solvent volume. This study demonstrates the applicability of the electrochemical method for the time-resolved monitoring of polymer molecular weight during ATRP, providing a rapid complementary tool for assessing the polymerization progress at specific time points.