In Situ Direct Mechanistic Transformation from FeCl3‐Catalyzed Living Cationic to Radical Polymerizations

A trivalent iron chloride (FeCl3) catalyst induced both living cationic and radical polymerizations of various monomers in the presence of an appropriate additive or ligand to yield polymers with controlled molecular weights and narrow molecular‐weight distributions. The in‐situ mechanistic transformation from a living cationic to a radical growing species during the styrene polymerization was achieved in a FeCl3‐based system with the simple addition of phosphine followed by an elevation of the reaction temperature. The growing cationic species was effectively converted into the radical species to produce a series of block copolymers that consist of styrene and various acrylic monomers.