New copper(I) complex based initiating systems in redox polymerization and comparison with the amine/benzoyl peroxide reference

Abstract : Novel copper complex based initiating systems for redox free radical polymerization (FRP) of methacrylate resins under mild conditions are proposed. Remarkably, the FRP performance of the Cu(I)/ascorbic acid (Vitamin C - VitC)/benzoyl peroxide (BPO) redox system is noticeably more significant than that of the amine/BPO reference especially at the top surface where the oxygen inhibition is particularly deleterious. The Cu(I)/BPO interaction leads to a decomposition of the peroxide and generates a benzoyl radical and Cu(II) as a byproduct. The ascorbic acid acts as a reducing agent and allows the regeneration of Cu(I) from Cu(II). Hydroperoxides formed at the surface through the radical/O-2 interaction are also decomposed by the new proposed Cu complex leading to additional polymerization initiating species. The structure/ reactivity relationship of the new proposed Cu(I) complexes in the Cu(I)/VitC/BPO systems is studied. The use of Cu(I)/VitC/BPO/iodonium salt systems in redox photoactivated FRP is also explored.