The crucial role of the diffusion layer in externally controlled heterogeneous <scp>reversible deactivation radical polymerization</scp> systems: A case study of <scp>eATRP</scp>

Abstract In this work, taking electrochemically mediated atom transfer radical polymerization (eATRP) as an example, the importance of diffusion layer thickness in externally controlled heterogeneous reversible deactivation radical polymerization (RDRP) systems was studied. The diffusion layer thickness was regulated by varying stirring rate and introducing ultrasound, and the diffusion layer thickness under different conditions was determined using linear sweep voltammetry (LSV). The impact of diffusion layer thickness and monomer‐solvent ratio on the kinetics of the polymerization reaction was examined through a combination of theoretical simulations and experimental methods. The results show that employing external mass transfer enhancement techniques, such as ultrasound, can substantially accelerate polymerization in systems with initially thick diffusion layers without adversely affecting the controllability or the quality of the polymer products. This work offers valuable insights into the process intensification of externally controlled heterogeneous RDRP.