Unimolecular and bimolecular exchange reactions in controlled radical polymerization

: Well defined polymers can be produced by radical polymerization using three different approaches: degenerative, transfer, reversible homolytic cleavage of covalent species, and reversible homolytic cleavage of persistent radicals. The first method requires high degenerative transfer coefficients but allows for slow initiation; the other two methods require that the equilibrium be strongly shifted towards dormant species, and that initiation is fast. All three approaches may provide controlled polymerizations, but not living polymerizations, because chain breaking reactions can not be eliminated although their contribution can be strongly reduced.