Deep eutectic solvents for green and efficient iron-mediated ligand-free atom transfer radical polymerization

A variety of deep eutectic solvents (DESs) were used as novel, green, and intriguing additives for atom transfer radical polymerization (ATRP) of methyl methacrylate with FeBr2 in the absence of any additional ligands. The polymerization processes had a well controlled capability for producing well-defined polymers with predictable molecular weights as well as narrow molecular weight distributions, and the living feature was further confirmed by chain extension experiments. Relative research on species, dosage, and hydrogen bonding interaction between the components of the DESs together with the solubility of the catalyst have been discussed in detail with the help of NMR spectra and cyclic voltammograms. This DESs-tuned ATRP provides us with the unique opportunity to utilize environmentally friendly media and drastically reduce the high costs of common ligands.