Mechanistic aspects of ‘ligated’ anionic living polymerization (LAP): The case of (meth)acrylic ester monomers

The recently developed ‘ligated’ technique has proved to be very successful in promoting living anionic polymerization of (meth) acrylic ester monomers. The efficient ligands discovered to date include μ, σ and μ–σ dual types. The roles of these ligands in the control of livingness and stereoregularity of anionic polymerization of (meth) acrylates are discussed in detail. There is convincing evidences that both ligation thermodynamics (electron density redistribution and steric hindrance in the formed active complex) and kinetics (how fast and in which way ligation occurs) are very critical in promoting the livingness. Moreover, steric hindrance appears to be a determining factor maintaining the process ‘living’ under more demanding conditions.