Abstract: The control of locked and unlocked states in chain-growth polymerization has wonderful potential for the precisely synthetic polymers with specific structures or functions. Because a large number of living centers exist during chain propagation, if all or portion of them can be controllably switched between the locked and unlocked states, the chain propagation can either insert specific monomer units or block structures at specific sites. Ma's group at Dalian University of Technology reported an intriguing advance in living anionic polymerization (LAP) by a "locked-unlocked" mechanism in which the living anionic species can be quantitatively locked by end-capping with 1-(tri-isopropoxymethylsilylphenyl)-1-phenylethylene (DPE-Si(O-iPr)₃) and can be unlocked by adding the key, sodium 2, 3-dimethylpentan-3-olate (NaODP). This intriguing mechanistic finding of LAP reactions is expected to supplement the existing knowledge and facilitate the tailoring of specific structures for these polymerizations.