Reverse iodine transfer polymerization (RITP) of chloroprene

Abstract

Reversible-deactivation radical polymerization (RDRP) of chloroprene (2-chloro-1,3-butadiene, CP) using reverse iodine transfer polymerization (RITP) has been demonstrated for the first time. Reverse iodine transfer polymerizations of CP were studied in benzene at 50 °C using 2,2′-azobis(isoheptonitrile) (ABVN) as a radical initiator, where a molar ratio ABVN/I₂ = 1.7 was used. The process efficiently controls the molar mass (characterized by size exclusion chromatography, SEC) and the structure of the polymer (confirmed by ¹H NMR spectra). For example, polychloroprene (PCP) samples of M_n,SEC = 4900 g mol⁻¹ and M_w/M_n = 1.73 (M_n,th = 4800 g mol⁻¹), M_n,SEC = 7300 g mol⁻¹ and M_w/M_n = 1.89 (M_n,th = 7300 g mol⁻¹), and M_n,SEC = 9000 g mol⁻¹ and M_w/M_n = 1.86 (M_n,th = 9300 g mol⁻¹) were successfully obtained. Furthermore, the influence of solvent, initiator and temperature were studied. Last, the controlled nature of the polymer was confirmed by the preparation of polychloroprene-b-polystyrene (PCP-b-PSt) and polychloroprene-b-poly(methyl methacrylate) (PCP-b-PMMA) diblock copolymers.