Copper-catalyzed ARGET ATRP of styrene from ethyl α-haloisobutyrate in EtOAc/EtOH, using ascorbic acid/Na2CO3 as reducing system

Atom transfer radical polymerization (ATRP) is one of the most powerful techniques to synthesize precisely tailored polymers and macrostructures. Activators regenerated by electron transfer (ARGET) ATRP was developed as a green strategy to decrease the load of the metal catalyst. However, ARGET ATRP usually uses not-sogreen reducing agents (e.g. Sn2+) or expensive and industrially impractical procedures. For these reasons, we report an ARGET ATRP of styrene with various carbonates as reducing agents, both alone and paired with ascorbic acid (AA), using monofunctional initiators and Cl or Br as exchanging atoms. The solvent mixture is composed of the green combination of EtOAc and EtOH, even in the presence of modest amounts of H2O. Cyclic voltammetry was used to evaluate the effect of H2O on the catalyst, as well as the absence of AA. The system returned high yields and low dispersities with low amounts of catalyst (similar to 60 ppm) and moderate reaction times. Excellent results were obtained only with the Cl-ATRP system. NMR spectroscopy and kinetic analyses proved the livingness of the final polymer chains.

Automated summary

ARGET ATRP of styrene was conducted using various carbonates as reducing agents, with or without ascorbic acid (AA), in a solvent mixture of EtOAc and EtOH. The system showed high yields and low dispersities with low amounts of catalyst and moderate reaction times, with the Cl-ATRP system providing excellent results. NMR spectroscopy and kinetic analyses confirmed the livingness of the final polymer chains.