Controlled copolymerization of n-butyl acrylate with semifluorinated acrylates by RAFT polymerization

Abstract

By reversible addition fragmentation chain transfer (RAFT) copolymerization of n-butyl acrylate (nBuA) with semifluorinated acrylates, such as 2,2,2-trifluoroethyl acrylate (TFEA), 2,2,3,3,3-pentafluoropropyl acrylate (PFPA) and 2,2,3,3,4,4,4-heptafluorobutyl acrylate (HFBA), up to 90.2% co-monomer conversion was accomplished. When using dibenzyl trithiocarbonate (DBTTC) as a chain transfer agent (CTA) in DMF at 65 °C, excellent control of molecular weight (M_n) together with a low molecular weight distribution (PDI) was achieved. The successful synthesis of well-controlled semifluorinated copolymers was checked by a combination of ¹H NMR, ¹⁹F NMR, SEC and ESI-TOF mass spectrometry, proving their composition via¹H NMR and ESI-TOF mass spectrometry. The reactivity ratios (r) of each pair of co-monomers were assessed using Fineman–Ross (FR) and Kelen–Tüdos (KT) laws: in all cases, the product (r_M1 × r_M2) was close to unity, indicating a random distribution of each pair of co-monomers along the semifluorinated copolymer backbone. Results were further confirmed by applying the Q–e scheme.