In a controlled polymerization process, how would the mechanism of living polymerization affect the molecular weight distribution when utilizing a chain growth polymerization method?

Living polymerization keeps every growing chain active and prevents termination or chain transfer, so all chains start and grow together. Because no chains stop or change length, each chain adds monomer at the same rate. This uniform growth gives a very narrow molecular weight distribution, often measured by a low polydispersity index. The width of the distribution is mainly set by the ratio of active to dormant chains during the process. For example, ATRP of methyl methacrylate routinely produces a polydispersity index of about 1.