AbstractMacromonomers were obtained by cationic polymerization of propylene oxide and epichlorohydrin proceeding by the activated monomer mechanism with hydroxyethyl acrylate as initiator. Up toDPn∼ 15 for propylene oxide andDPn∼ 20 for epichlorohydrin, polymerization proceeds as a living process, giving with quantitative yields macromonomers with functionality equal to one, controlled molecular weight and narrow molecular weight distribution (MwMn<1.2) free of side products. In the higer molecular weight region, side reactions become increasingly noticeable. Propylene oxide macromonomers undergo radical homopolymerization. Homopolymerization of macromonomer withMn= 8×102gives graft copolymers withMnup to 7.2×103in copolymerization with styrene, completely soluble graft copolymers withMn∼ 2×104were obtained. Radical copolymerization of epichlorohydrin macromonomers with styrene gives initially soluble products withMn∼ 6×104were obtained. Radical copolymerization of epichlorohydrin macromonomers with styrene gives initially soluble products withMn∼ 6×104, which are converted in the later stages into insoluble gels, apparently due to the chain transfer to chloromethly groups of the polyepichlor