Instant living cationic polymerization using SnCl4/EtAlCl2 with a weak Lewis base: Ultrafast polymerization in seconds

Abstract

The living cationic polymerization of isobutyl vinyl ether in 1–2 s is demonstrated with SnCl4 and EtAlCl2 in the presence of a weak base, ethyl chloroacetate, at subzero temperatures. The reaction proceeds 105 times faster than the reaction with conventional EtAlCl2 systems in the presence of a stronger base such as ethyl acetate at 0 °C yet remains highly controlled, yielding polymers with the near theoretical number-average molecular weight and with narrow molecular weight distributions (weight-average molecular weight/number-average molecular weight = 1.03). Two Lewis acids play different important roles in this system: EtAlCl2 generates initiating species quantitatively from an adduct of isobutyl vinyl ether and acetic acid, whereas SnCl4 promotes rapid polymerization.