ol ym ers . ▁This ▁is ▁where ▁controlled ▁( or ▁living ) ▁radical ▁polym er ization ▁comes ▁into ▁play . ▁Several ▁CR P ▁re actions ▁have ▁been ▁developed ▁over ▁the ▁past ▁years , ▁some ▁of ▁which ▁capable ▁of ▁producing ▁well - defined ▁polym ers ▁with ▁narrow ▁mole cular ▁weight ▁distributions . ▁ ▁Cob alt ▁medi ated ▁radical ▁polym er isation ▁( C MR P ) ▁is ▁one ▁of ▁these ▁methods , ▁which ▁offers ▁some ▁specific ▁advantages . ▁Most ▁not ably , ▁C MR P ▁allows ▁R P ▁of ▁a ▁broad ▁substr ate ▁scope ▁( am ong ▁others ▁ac ry l ates , ▁ac ry lic ▁acid , ▁vin yl ▁est ers , ▁vin yl ▁ac et ate , ▁ac ry lon it rile , ▁vin yl py r rol id one ) ▁under ▁various ▁reaction ▁conditions , ▁and ▁( for ▁some ▁catal yst s ) ▁gives ▁access ▁to ▁very ▁fast ▁CR P ▁re actions ▁with ▁rates ▁approaching ▁those ▁of ▁conventional ▁un control led ▁free ▁radical ▁polym er ization ▁re actions . ▁ ▁Most ▁commonly ▁applied ▁c ob alt ▁comp ounds ▁are ▁c ob al ox imes , ▁c ob alt ▁por ph yr ins ▁and ▁Co ( ac ac ) 2 ▁derivatives , ▁used ▁in ▁combination ▁with ▁various ▁radical ▁initi ators ▁( such ▁as ▁A IB N ▁or ▁V 7 0 ). ▁ ▁Cob alt ▁can ▁control ▁radical ▁polym er ization ▁( R P ) ▁re actions ▁by ▁essentially ▁three ▁mechan isms : ▁ ▁Catal yt ic ▁chain ▁transfer ▁( C CT )