Quasiliving atom transfer radical polymerization of styrene and n-butyl acrylate as non-fluorous monomers in a fluorinated solvent, benzotrifluoride

Quasiliving atom transfer radical polymerization (ATRP) of non-fluorous monomers, styrene and n-butyl acrylate, was attempted in benzotrifluoride (BTF; α,α,α-trifluorotoluene, TFT), the simplest trifluoromethylated aromatic compound, as an alternative solvent to widely used polymerization media in ATRP and other radical polymerizations, such as benzene, toluene, xylene, diphenylether etc., with toxic, carcinogenic or corrosive labels. In the absence of any other fluorinated additive, BTF was found to be a suitable reaction medium for ATRP of these monomers with the CuBr/N,N,N′,N″,N″-penta-methyldiethylenetetramine (PMDETA) non-fluorous catalyst system at 90 °C. The higher number average molecular weights than that of the theoretical ones at relatively low conversions in styrene polymerization with the 1-phenylethyl bromide (PhEtBr) initiator indicates quasiliving polymerization of styrene in BTF with slow initiation. This is confirmed by the linear correlation of the obtained data in the slow initiation plot, i.e. ln(1−f) + f versus ln(1−C), where f and C stand for the initiating efficiency and conversion, respectively. Quasiliving ATRP of n-butyl acrylate with rapid quantitative initiation was found by the ethyl-2-bromoisobutyrate (Et-2BriBu)/CuBr/PMDETA initiating system in BTF. In both cases, the absence of any kind of significant side reactions, i.e. chain transfer to solvent or irreversible termination, was observed. Thus, in contrast to the general perception of the immiscibility between fluorous and non-fluorous solvent/polymer systems, our findings indicate that BTF, as a fluorinated solvent, due to its unique properties, including its moderately high polarity, low vapor pressure and low toxicity etc., can be considered as an outstanding solvent with broad application possibilities for a large array of polymerization reactions and other chemical processes of non-fluorous monomers, polymers and many other compounds as well.