SET-LRP of methacrylates in fluorinated alcohols

Abstract

Activated Cu(0) wire-mediated single-electron transfer living radical polymerization (SET-LRP) of methyl methacrylate (MMA), ethyl methacrylate (EMA) and n-butyl methacrylate (BMA) was performed in two fluorinated alcohols, 2,2,2-trifluoroethanol (TFE) and 2,2,3,3-tetrafluoropropanol (TFP) using tosyl chloride (TsCl) as initiator, hydrazine-activated Cu(0) wire as catalyst, and Me₆-TREN as ligand at 50 °C. The ability of these two solvents to solubilize these monomers, the resulting polymers, and mediate an efficient disproportionation of Cu(I)Br in the presence of Me₆-TREN ligand to produce the “nascent” Cu(0) activator, Cu(II)Br₂ deactivator and to stabilize Cu(II)Br₂/Me₆-TREN complex make them excellent solvents for SET-LRP of methacrylates. To the best of our knowledge, this is the first report of SET-LRP of methacrylates in fluorinated alcohols and also the first efficient SET-LRP of EMA and BMA in any solvent. The kinetic experiments and molecular weight analyses demonstrate that in all experiments a living polymerization takes place with excellent evolution of molecular weight and with narrow molecular weight distribution until almost complete monomer conversion. It was also demonstrated that the rate of polymerization conducted in TFE and TFP could be significantly enhanced by a synergistic solvent effect upon addition of a small amount of water, which mediates an even faster disproportionation of Cu(I)Br into Cu(0) activator and Cu(II)Br₂ deactivator.