One-pot strategy for obtaining magnetic PMMA particles through ATRP using Fe(CO)5 as co-initiator

Abstract

The first aim of this study was to develop an ATRP process for methyl methacrylate (MMA) polymerization using Fe(CO)5 as co-initiator. The kinetics analysis of the reaction in solution confirmed the controlled characteristic of the polymerization process. The process displays a slow initiation step and presents bimolecular termination reactions at higher molecular weights, confirmed by NMR analysis. Also, these observations are sustained by GPC, FT-IR, and XPS analyses, explaining the rather unusual dispersity values (1.4) for an ATRP reaction. The use of formic acid, which shifts the equilibrium towards Fe2+ species affording a quasi-controlled controlled polymerization process, is a key element in achieving control over the reaction. The Fe2+/Fe3+ ratio at the end of the reaction, determined by XPS analysis, suggests the possibility to generate magnetic iron oxide particles. Therefore, the synthesis strategy was adapted for use in the suspension polymerization process of MMA which permitted the production of magnetic PMMA particles through a facile one-pot approach, using only an ammonia treatment stage. The obtained PMMA particles, characterized by SEM, XPS, TEM, TGA, and XRD analyses, have porous characteristics and magnetic properties which makes them good candidates as catalyst supports, separation processes, or biomedical applications.