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Halogen Effect in Dual-Catalysis PhotoATRP
Halil Ibrahim Coskun1, Rushik Radadiya1, Gorkem Yilmaz1
1Chemistry Department, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States.
Macromolecules
|March 2, 2026
Summary
Bromine-based dual-catalyzed photoATRP offers faster polymerization and lower catalyst requirements than chlorine-based systems for methyl acrylate and methyl methacrylate. This study provides key insights for optimizing halogen and monomer choices in controlled radical polymerization.
Area of Science:
- Polymer Chemistry
- Photocatalysis
- Organic Synthesis
Background:
- Atom Transfer Radical Polymerization (ATRP) is a powerful controlled radical polymerization technique.
- Photoinduced ATRP (photoATRP) utilizes light to initiate and control polymerization, offering spatiotemporal control.
- Dual-catalyzed photoATRP combines photocatalysis with a metal catalyst for enhanced control and efficiency.
Purpose of the Study:
- To investigate the influence of halogen type (bromine vs. chlorine) on dual-catalyzed photoATRP of methyl acrylate (MA) and methyl methacrylate (MMA).
- To compare the efficiency, kinetics, and control of Br-based versus Cl-based systems under green LED irradiation.
- To establish design guidelines for optimizing halogen and monomer selection in photoATRP.
Main Methods:
- Systematic investigation of photoATRP using rhodamine 6G (RD-6G) as a photocatalyst and CuX2/ligand complexes (X = Br, Cl) under green LED light.
- Kinetic analysis of polymerization rates, activation, and deactivation processes.
- Synthesis of polymers with defined chain ends (ω-bromo and ω-chloro) and characterization of dispersity.
- Chain-extension experiments and temporal control studies to assess chain-end fidelity and light-mediated regulation.
Main Results:
- Bromine-based systems demonstrated significantly faster activation and controlled polymerization compared to chlorine-based systems.
- Lower catalyst and photocatalyst loadings were required for Br-based systems.
- Polymerization of MA was faster than MMA, attributed to propagation rate constants and deactivator reduction rates.
- Optimal ligand selection (Me6TREN for MA, TPMA for MMA) was crucial for controlling polymerization rate and achieving low dispersity.
- High chain-end fidelity and efficient temporal control were confirmed.
Conclusions:
- Halogen type plays a critical role in the performance of dual-catalyzed photoATRP.
- Bromine-based systems offer superior performance in terms of speed and catalyst efficiency for MA and MMA polymerization.
- The findings provide valuable design principles for tailoring photoATRP processes based on specific monomers and desired outcomes.
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