Conventional free radical polymerization processes are limited by thei
r inability to be used for the synthesis of resins of controlled molec
ular weights and complex architecture. New processes are being develop
ed in which the free radical propagating chain is reversibly terminate
d, allowing the free radical polymerization to behave in a living fash
ion. A review of these processes is presented, along with preliminary
results of chain extension studies of nitroxide-terminated polystyrene
as a model for block copolymer synthesis.