Copolymerization of 2,3,4,5,6-Pentafluorostyrene and Methacrylic Acid by Nitroxide-Mediated Polymerization: The Importance of Reactivity Ratios

Amphiphilic block copolymers of 2,3,4,5,6-pentafluorostyrene (PFS) and methacrylic acid (MAA) are synthesized via nitroxide-mediated polymerization (NMP). It is established that to obtain a controlled copolymerization a minimum of 40 mol% of PFS is required, which is significantly greater than other copolymerization systems such as using 4.5-8 mol% styrene or 1 mol% of 9-(4-vinylbenzyl)-9H-carbazole to control the copolymerization of methacrylates. It is surmised that this lack of control is due to the reactivity ratios that favor the addition of MAA rather than PFS (r(PFS) = 0.14, r(MAA) = 6.97). However this reactivity ratio pair suggests that a one-shot delayed injection approach can be utilized to synthesize almost pure block copolymers in one pot. Therefore, poly(PFS)-b-(PFS-ran-MAA) block copolymers are synthesized by a one-shot delayed addition of MAA. While the concentration of irreversibly terminated chains is evident these results suggest a promising route to the synthesis of fluorinated amphiphilic block copolymers by NMP.