Kinetic Insights into the Iron-Based Electrochemically Mediated Atom Transfer Radical Polymerization of Methyl Methacrylate

An ironand methyl methacrylate (MMA)-based electrochemically mediated atom transfer radical polymerization (eATRP) system was developed for the first time. Kinetic behaviors, including the effect of applied potential and catalyst loading, were systematically investigated. Results indicated that with more negative electrode potential, the polymerization rate increased until the mass transport limitation was reached. However, reduction of the catalyst loading had adverse effects on polymerization behaviors, such as decreased polymerization rate and increased molecular weight distributions (Mw/Mn). In addition, a kinetic model based on the method of moments was also constructed to explain the mismatch in Mn and Mn,theo. Simulation results showed that slow initiation significantly influenced on the kinetic behaviors in this system. Iron(II) bromide-catalyzed normal ATRP, iron(III) bromidecatalyzed eATRP, and copper(II) bromide-catalyzed eATRP were conducted to compare and elucidate their respective polymerization reaction kinetic characteristics qualitatively. This work expanded the scope of eATRP from a copper-based system to an iron-based system in terms of polymerization kinetics, with the hope of promoting the widespread application of this method.