Kinetic insight into electrochemically mediated ATRP gained through modeling

Abstract

A detailed kinetic model was constructed using the method of moments to elucidate the electrochemically mediated atom transfer radical polymerization (eATRP). Combined with electrochemical theory, the reducing rate coefficient relevant to the overpotential in eATRP was coupled into the kinetic model. The rate coefficients for eATRP equilibrium and the reducing rate coefficient were fitted to match the experimental data. The effects of catalyst loading, overpotential, and application of programmable electrolysis on the eATRP behavior were investigated based on the tested kinetic model. Results showed that the apparent polymerization rate exhibited a square root dependence on catalyst loading. In addition, a more negative potential accelerated the polymerization rate before the mass transport limitation was reached. This phenomenon indicated that the polymerization rate could be artificially controlled by the designed program (i.e., stepwise and intermittent electrolysis programs). What is more, the normal ATRP, photo‐ATRP, and eATRP were compared to obtain a deeper understanding of these ATRP systems. © 2015 American Institute of Chemical Engineers AIChE J, 61: 4347–4357, 2015

How the catalyst circulates and works in organocatalyzed atom transfer radical polymerization

“…For example, the extremely active photoexcited catalyst (Cat à ) can either reduce the alkyl halogen or decay to the ground state catalyst (Cat). 19,20,31,33,[48][49][50][51] As in those metal-catalyzed ATRP systems, the catalyst is in high-oxidation-state at the beginning of the reaction, and the deactivation effect is strong during the entire polymerization. As a result, the concentration of deactivator is low at the early stage of polymerization, as shown in Figure 2A.…”

“…This explanation can be validated by the extremely high molecular weight and dispersity when 200 ppm of catalyst is used (Figures 6B, C). 19,51 A higher radical species concentration leads to a higher probability of termination reactions and consequently to a lower degree of livingness. When the catalyst loading exceeds the threshold value, a significant positive correlation between the polymerization rate and catalyst loading occurs ( Figure 6A).…”

Electrochemically Mediated Reversible Addition–Fragmentation Chain-Transfer Polymerization

“…20,21 Computational simulations were also conducted for e ATRP, elucidating the key parameters. 22 The application of Fe-based catalyst broadened the application of e ATRP. 23 …”

Electrochemical Atom Transfer Radical Polymerization in Miniemulsion with a Dual Catalytic System

“…88 “On–off” polymerization can be obtained by simply stepping E app between negative and positive values (i.e., by reduction and reoxidation of the catalyst), 41 whereas the rate of polymerization ( R p , eq 1) 30 can be enhanced until mass-transfer limit by quantitatively reducing the catalyst to Cu I /L. 100 …”