# Halogen Effect in Dual-Catalysis PhotoATRP

## TL;DR

This paper studies how different halogens affect the efficiency of a light-driven polymerization process called photoATRP.

## Contribution

It reveals that bromine-based systems outperform chlorine-based ones in terms of speed and efficiency in dual-catalyzed photoATRP.

## Key findings

- Br-based systems enable faster polymerization and require lower catalyst loadings than Cl-based systems.
- MA polymerizes faster than MMA despite MMA's higher ATRP equilibrium constants.
- Ligand choice significantly affects polymerization control and dispersity.

## Abstract

The effect of halogen type in dual-catalyzed photoinduced
atom
transfer radical polymerization (photoATRP) of methyl acrylate (MA)
and methyl methacrylate (MMA) was systematically investigated under
green LED irradiation (λ ∼ 527 nm) using rhodamine 6G
(RD-6G) as a photocatalyst. Poly­(methyl acrylate) and poly­(methyl
methacrylate) with ω-bromo and ω-chloro chain ends were
synthesized via CuX2/ligand (X = Br, Cl) complexes with
excess ligand as an electron donor. Kinetic analyses revealed that
Br-based systems exhibited significantly faster activation and allowed
controlled polymerizations at markedly lower copper and photocatalyst
loadings than their Cl-based counterparts. MA polymerizations were
faster than MMA despite the latter’s larger ATRP equilibrium
constants, attributed to the higher propagation rate constant of acrylates
and similar rates of reduction of CuX2/ligand deactivators.
Optimal ligand selection (Me6TREN for MA, TPMA for MMA)
was important for control of the polymerization rate and low dispersity.
Chain-extension experiments confirmed high chain-end fidelity, and
temporal control studies demonstrated efficient light-mediated regulation.
These findings provide detailed design guidelines for halogen- and
monomer-dependent optimization in dual-catalyzed photoATRP.