Preparation of Polymeric Free-Radical Initiators by Anionic Synthesis: Polymeric Azo Derivatives

Abstract

The anionic polymerization is particularly suitable for the preparation of block copolymers (1, 2) This method, which leads to well defined copolymers of low polydispersity, is however restricted to monomers of low polarity like isoprene, butadiene or styrene. More polar monomers, as for instance vinyl chloride or maleic anhydride cannot be polymerized by this technique. Thus, in order to obtain block copolymers containing a sequence with such polar monomer units, it is necessary to use a free radical polymerization step. The initiation of this type of polymerization can be achieved with a polymeric initiator, e.g. a polymer containing peroxide or azo end groups. As the different types of synthesis which have been described for the preparation of such polymeric initiators, have generally the disadvantage to need several reaction steps (3-5), it seemed interesting to prepare these initiators in a one step reaction, by keeping the different advantages of the anionic