Which polymerization mechanism would you expect to produce the most uniform polymer chain lengths?

Living polymerization gives the most uniform chain lengths because it eliminates chain‑termination events and keeps every growing chain active until the monomer is exhausted. In this mechanism, initiators generate radicals that are stabilized by a catalyst or a reversible chain‑transfer agent, so each chain grows at the same rate. As a result, all chains reach the same length when the monomer is consumed, producing a very narrow dispersity. For example, in atom‑transfer radical polymerization (ATRP) the metal catalyst controls the radical concentration, ensuring that every chain grows to the same length before the reaction stops. Thus, living polymerization is the mechanism that yields the most uniform polymer chain lengths.