)- alk yl ▁species , ▁which ▁re - init i ates ▁a ▁new ▁growing ▁polym er ic ▁radical ▁( re vers ible ▁term ination , ▁equilibrium ▁ 1 ). ▁The ▁main ▁products ▁of ▁catal yt ic ▁chain ▁transfer ▁polym er ization ▁are ▁therefore ▁vin yl ▁terminated ▁polym er ▁ch ains ▁which ▁are ▁shorter ▁than ▁in ▁conventional ▁( free ) ▁radical ▁polym er ization . ▁ ▁Control ▁via ▁deg ener ative ▁transfer ▁One ▁of ▁the ▁dis adv antages ▁of ▁controlled ▁radical ▁polym er ization ▁re actions ▁is ▁that ▁they ▁tend ▁to ▁become ▁rather ▁slow . ▁Control led ▁polym er ization ▁conditions ▁are ▁usually ▁achieved ▁by ▁extending ▁the ▁life - time ▁of ▁the ▁growing ▁polym er ▁chain ▁radical , ▁by ▁keeping ▁it ▁in ▁a ▁d orm ant ▁state ▁for ▁most ▁of ▁the ▁time ▁( known ▁as ▁the ▁Pers istent ▁Rad ical ▁Effect ). ▁There by ▁the ▁control ▁agent ▁substantial ly ▁slow s - down ▁the ▁over - all ▁radical ▁polym er isation ▁reaction . ▁However , ▁some ▁C MR P ▁re actions ▁proceed ▁via ▁a ▁different ▁mechanism , ▁called ▁deg ener ative ▁transfer ▁( DT ), ▁which ▁allows ▁controlled ▁radical ▁polym er ization ▁re actions ▁to ▁proceed ▁at ▁roughly ▁the ▁same ▁rate ▁as ▁any ▁un control led ▁free ▁radical ▁polym er isation . ▁ ▁The ▁deg ener ative ▁transfer ▁mechanism ▁is ▁based ▁on ▁very ▁fast ▁exchange ▁equilib ria ▁between ▁small ▁free ▁radical s ▁( be ing ▁continu ously ▁inject ed ▁into ▁the ▁solution ) ▁and ▁d orm ant ▁polym ery l ▁radical s ▁( protected