Toward Electrochemically Mediated Reversible Addition-Fragmentation Chain-Transfer (eRAFT) Polymerization: Can Propagating Radicals Be Efficiently Electrogenerated from RAFT Agents?

Electrochemistry provides easily tunable parameters for the preparation of well-defined polymers in a spatiotemporal controlled manner under mild conditions. This work discusses the requisites for an electrochemically mediated reversible addition-fragmentation chain-transfer (eRAFT) polymerization, in which electrochemical stimuli are used to reduce the RAFT agent, either directly or in the presence of a mediator. The redox properties of several RAFT agents were investigated by cyclic voltammetry and correlated to their structures. The direct electrolysis of RAFT agents in the presence of a monomer caused the loss of RAFT agents, thus leading to uncontrolled polymerizations. These issues could partially be overcome by using a mediator that shuttles the electrons from the electrode to the RAFT agent in solution. Several compounds were tested to define the characteristics of suitable mediators.