New Methods for Anionic Polymerizations at Elevated Temperatures: ‘Retarded Anionic Polymerizations’

Abstract Summary: Living anionic polymerizations are one of the most important methods for the synthesis of well‐defined homo‐ and block copolymers, but these polymerizations are typically carried out at low temperatures, which limits their applications. Deffieux et al. recently reported new methods to lower, or retard, the rate of polymerization using different additives. He called this collection of different methods ‘retarded anionic polymerizations’. In addition to lowering the rate of propagation, these methods also stabilize the polymer chain end such that the rate of self‐termination is lowered. These polymerizations require elevated temperatures to reach reasonable rates of polymerization while still allowing the chain ends to remain active. This emergent area points at new directions to allow anionic polymerizations to be carried out under conditions that are more amenable to industrial synthesis and to synthesize new polymer architectures. A combination of NaH and i‐Bu3Al initiates and tempers the living/controlled anionic polymerization of styrene. The growing polystyrene chain ends can hypothetically be in different environments, but only the one with a square around it is active. magnified image A combination of NaH and i‐Bu3Al initiates and tempers the living/controlled anionic polymerization of styrene. The growing polystyrene chain ends can hypothetically be in different environments, but only the one with a square around it is active.