Copper radical reactivity: pushing the frontiers of atom transfer radical polymerization – CuRad

Since its discovery in 1995, atom transfer radical polymerization (ATRP) has drawn the keen attention of both academic and industrial researchers because of its revolutionary perspectives in terms of new advanced materials synthesis. This is a metal-catalyzed process, the most efficient catalysts being based on copper. However, the same copper complexes needed to control the polymerization also catalyze an unwanted side reaction, catalyzed radical termination (CRT), which lowers the chain-end fidelity and limits high-tech applications. This phenomenon occurs by radical trapping to an organocopper(II) dormant species followed by reaction with a second radical. A second problem in ATRP is the failed extension to the polymerization of less-activated monomers (LAMs), caused by the difficult reactivation of the stronger Cu(II)-C bond in the organocopper(II) dormant species. In order to remove these two bottlenecks, the main objectives of this project are: Task 1) to fully elucidate the CRT mechanism; Task 2) to limit or fully suppress CRT by ligand engineering and reaction condition optimization; Task 3) to extend ATRP to LAMs. Task 1 will involve termination studies of model radicals generated in the absence and presence of Cu termination catalysts and the investigation of the reactivity of isolated alkylcopper(II) complexes with model radicals, accompanied by DFT calculations. Task 2 will comprise the development of new ligands based on the mechanistic information learned from Task 1 and the application of new activation strategies (photo- and sonochemistry). Task 3 will deal with the application of the new ATRP catalysts and conditions developed in Task 2 to the polymerization of LAMs. The combination of the expertise of the two participating teams in Cu-ATRP and in radical coordination chemistry/organometallic mechanisms, respectively, is unique in the World.