Copper‐Mediated Controlled/“Living” Radical Polymerization in Polar Solvents: Insights into Some Relevant Mechanistic Aspects

Abstract

The field of transition-metal-mediated controlled/"living" radical polymerization (CLRP) has become the subject of intense discussion regarding the mechanism of this widely-used and versatile process. Most mechanistic analyses (atom transfer radical polymerization (ATRP) vs. single-electron transfer living radical polymerization (SET-LRP)) have been based on model experiments, which cannot correctly mimic the true reaction conditions. We present, for the first time, a determination of the [Cu(I)Br]/[L] (L=nitrogen-based chelating ligand) ratio and the extent of Cu(I)Br/L disproportionation during CLRP of methyl acrylate (MA) in dimethylsulfoxide (DMSO) with Cu(0) wire as a transition-metal catalyst source. The results suggest that Cu(0) acts as a supplemental activator and reducing agent of Cu(II)Br(2)/L to Cu(I)Br/L. More importantly, the Cu(I)Br/L species seem to be responsible for the activation of SET-LRP.

Mechanism of supplemental activator and reducing agent atom transfer radical polymerization mediated by inorganic sulfites: experimental measurements and kinetic simulations

“…21,22,24 In SARA ATRP, however, they can also be activated by the SARA agent. This supplemental activation was confirmed using a model system, in the absence of Cu species, for the polymerization of MA in the presence of the initiator (EBiB) and Na 2 S 2 O 4 in MA/EtOH/H 2 O = 2/0.9/0.1 (v/v/v) at 30 °C (Fig.…”

Effect of cholesterol-poly(N,N-dimethylaminoethyl methacrylate) on the properties of stimuli-responsive polymer liposome complexes

“…In this regard, the tailored synthesis of macromolecules based on control/living radical polymerization (LRP) method is a suitable approach [12]. In particular, ATRP is very well established for different families of monomers [13], and has several advantages over other methods, such as, mild work conditions, fast kinetics, and very high tolerance to different functionalities [13]. In addition, the polymers can have different architectures, topologies and compositions, providing a high degree of control over polymer microstructure [14].…”

Synergistic Effect of 1-Butyl-3-methylimidazolium Hexafluorophosphate and DMSO in the SARA ATRP at Room Temperature Affording Very Fast Reactions and Polymers with Very Low Dispersity

“…4 Aiming to reduce the amount of metal complexes required to control the polymerizations, new ATRP variations were proposed, such as activators regenerated by electron transfer (ARGET) ATRP using inorganic or organic reducing agents; 5,6 supplemental activator and reducing agent (SARA) ATRP involving the use of zerovalent transition metals 3,5,7−9 or inorganic sulfites; 10−12 initiators for continuous activator regeneration (ICAR) ATRP employing conventional thermal radical initiators; and electrochemically mediated ATRP ( e -ATRP) that uses electrical current for the reduction process. 13 The use of reducing agents allows the continuous regeneration of Cu(I) species during the polymerization, lowering the amount of catalyst to ppm levels.…”