Atom Transfer Radical Polymerization with Different Halides (F, Cl, Br, and I): Is the Process "Living" in the Presence of Fluorinated Initiators?

Atom transfer radical polymerization (ATRP) is often used for grafting from fluorinated polymers. Nevertheless, the possibility to initiate an ATRP from a C-F functionality and the activity of the catalysts in the presence of fluoride anions are essentially unexplored. Therefore, we investigated the thermodynamics and kinetics of C-F bond activation by ATRP catalysts and compared it with other halide systems. The ATRP equilibrium constant was estimated to be small for the reaction between [Cu(I)TPMA](+) and benzyl fluoride (TPMA = tris(2-pyridylmethyl)-amine). However, [Cu(I)TPMA](+) could react with the more active initiator diethyl fluoromalonate (DEFM). With DEFM as initiator and (CuBr)-Br-I/TPMA as catalyst, ATRP of methyl acrylate and styrene displayed initiation efficiencies of 73% and 95%, respectively. ATRP deactivation by [F-Cu(II)TPMA](+) was slow and followed by even slower activation of newly formed C-F bonds, leading to limited conversion. Comparison with other halides indicates that Br- and Cl-based ATRP systems are more efficient that I- and F-based systems.