DUAL LIVING FREE-RADICAL AND RING-OPENING POLYMERIZATIONS FROM A DOUBLE-HEADED INITIATOR

The concept of performing dual living polymerizations from a single in itiating molecule with no intermediate activation, or transformation, steps is presented. The compatibility of ''living'', or controlled fre e radical procedures, either nitroxide mediated or atom transfer radic al polymerization (ATRP), with the living ring opening polymerization of epsilon-caprolactone, and vice versa, is demonstrated by the synthe sis of a variety of well-defined block copolymers. For example, from a hydroxy-functionalized alkoxyamine, either the living ring opening po lymerization of epsilon-caprolactone, or the ''living'' free radical p olymerization of styrene can be performed leading to narrow polydisper sity polymeric initiators. These polymeric initiators can then be used to initiate the living polymerization of the other monomer system wit hout the need for intermediate steps. In a similar way, hydroxy-functi onalized ATRP initiators can be used as bifunctional initiators for th e polymerization of both epsilon-caprolactone and a variety of other v inyl monomers. The novel block copolymers that are obtained were shown to have low polydispersities and controllable molecular weights for b oth of the blocks.