Sulfur‐Free Radical RAFT Polymerization of Methacrylates in Homogeneous Solution: Design of exo‐Olefin Chain‐Transfer Agents (R−CH(2)C(=CH(2))Z)

In this work, the development of exo‐olefin compounds (R−CH(2)C(=CH(2))Z) as chain‐transfer agents for the sulfur‐free reversible addition‐fragmentation chain transfer (RAFT) radical polymerization of methacrylates in homogeneous solution is described. A series of exo‐olefin compounds with a methyl methacrylate (MMA) dimer structure as the R group and a substituted α‐methylstyrene unit as the −CH(2)C(=CH(2))Z (Z: Ph−Y) group were synthesized and used for the radical polymerization of MMA in toluene and PhC(CF(3))(2)OH. These compounds underwent transfer of the CH(2)C(=CH(2))Z group via addition‐fragmentation of the propagating methacryloyl radical. More electron‐donating (Y) substituents, such as methoxy and dimethylamino groups, produced polymers with narrower molecular weight distributions. A continuous monomer addition method further improved molecular weight control and enabled the synthesis of colorless, sulfur‐free, multiblock copolymers of methacrylates in homogeneous solutions.