Fluorinated amphiphilic block copolymers: Combining anionic polymerization and selective polymer modification

We report the preparation of novel fluorinated block copolymers using a two-step modification sequence. We first prepared model polyisoprene-poly-tert- butylmethacrylate block copolymers by anionic polymerization. Exposing these materials to difluorocarbene (generated by the thermolysis of hexafluoropropylene oxide) resulted in modification of the polyisoprene block to the corresponding difluorocyclopropane repeating unit without compromising the integrity of the poly-tert-butylmethacrylate block. Hydrolysis of the difluorocarbene-modified materials gave the corresponding difluorocarbene- modified polyisoprene-polymethacrylic acid diblock copolymers. These amphiphilic materials are expected to exhibit interesting self-assembly behavior in aqueous solution.