Winning Strategy for Iron-Based ATRP Using In Situ Generated Iodine as a Regulator

Iron-based catalysts for atom-transfer radical polymerization (ATRP) are attractive in the sustainability aspects of green polymer chemistry but usually exhibit lower efficiency and controllability over the polymerization, as well as poorer tolerance to polar groups, compared to copper catalysts. Herein, beta-ketamine/iron complexes, combining a strategy employing in situ generated iodine as a regulator, have been developed for improving the efficiency and robustness of iron-catalyzed ATRP. The catalyst system realizes low catalyst loading, ultrahigh molecular weight, robustness over polar groups, efficient polymerization of acrylate, and forthrightly synthesizing block copolymers, which are challengeable for common iron catalysts. A mechanism was proposed based on experimental results, which mainly involves the ATRP activation process by Fe(II) and the I-2-mediated deactivation process.