![]() In a typical iron-mediated ATRP catalytic system, ligands should be added to complex with iron halide to form iron-based catalysts and to modulate the redox potential of metal centers to maintain proper reactivity and kinetics of atom transfer during ATRP. However, the development of iron-based catalysts remains of great attention due to its unique advantages of low toxicity, abundance, low cost, biocompatibility and environmental friendliness ( 6). Among these metals, copper-based ATRP catalysts are the most deeply investigated metal for the synthesis of well controlled polymers ( 5). Various metal catalysis such as copper, ruthenium, iron, other transition metals have been investigated ( 4). Metal complexes play an important role on this equilibrium in regulating the catalytic cycle associated with the efficiency of the catalytic system. For achieving a controlled/living polymerization process, it should maintain low numbers of growth free radicals and large excess of dormant centers in the ATRP reaction medium to suppress chain termination reactions, and should quickly establish a balance between the transition metal complexes in the low oxidation state and the higher oxidation state complexes which acts as the deactivator. Transition metal complex catalyzed ATRP (Atom Transfer Radical Polymerization) for the synthesis of well-defined polymers was reported over 20 years ago ( 1, 2, 3). ![]()
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