A rational approach to activated polyacrylates and polymethacrylates by using a combination of model reactions and SET-LRP of hexafluoroisopropyl acrylate and methacrylate

The transesterification of hexafluoroisopropyl esters mediated by two mild bases, 1,8-diazabicycloundec-7-ene (DBU) and 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) was investigated as model reaction for the transesterification of poly(1,1,1,3,3,3-hexafluoroisopropyl acrylate) [poly(HFIPA)] and poly(1,1,1,3,3,3-hexafluoropropyl methacrylate) [poly(HFIPM)]. Unexpectedly, the rate of transesterification of the hexafluoroisopropyl esters was higher than that of the more reactive pentafluorophenyl esters although the rate of uncatalyzed aminolysis followed the reverse trend. Subsequently SET-LRP of HFIPA up to [M]₀/[I]₀ = 92 at 25 °C and of HFIPM up to [M]₀/[I]₀ = 86 at 50 °C with activated Cu(0) wire as catalyst, Me₆-TREN as ligand, and trifluoroethanol as solvent in the presence of acetic acid to generate the corresponding polymers with well-defined molecular weight, narrow molecular weight distribution and near-quantitative chain-end functionality was elaborated. Using reaction conditions established with model compounds a highly efficient transesterification of poly(HFIPA) and of poly(HFIPM) using DBU as catalyst at 25 °C has been developed. Therefore, this combination of experiments demonstrated that hexafluoroisopropyl esters provide a new class of activated carboxylic acids with applications in functional group transformation of interest both to organic and macromolecular synthesis.