In-depth mechanistic and kinetic investigation of sonochemically mediated atom transfer radical polymerization using modeling approach

Abstract

Mechano/sonochemically mediated reversible deactivation radical polymerization has attracted great attention because of the novel electron transfer regulation process and high-efficient process intensification on mass transfer. Herein, a multi-scale modeling strategy combining quantum chemical calculation and kinetic modeling was developed for sonochemically induced electron transfer controlled atom transfer radical polymerization (SET-ATRP) to study the complicated SET process and its effects on polymerization. At the molecular scale, density functional theory (DFT) calculations were used to acquire the electron characteristic and structure–reactivity of the reactants, intermediates and products during SET process, which provides guideline to figure out the underlying mechanism. Results showed that DMSO•• generated under ultrasonication could react with free Me6TREN to induce electron transfer for the reduction of CuIIBr/L+ to produce CuI/L+, which is the key step for a successful polymerization. The corresponding elementary reaction rate coefficients were calculated by thermodynamic formulae combining transition state theory and Marcus theory. At the micro-scale, kinetic modeling based on method of moment was established to account for the role of SET process in regulating polymerization. Good agreements between the simulation results and experimental data confirmed the reliability of the as-developed multi-scale modeling strategy. More Me6TREN and CuIIBr/L+ resulted in more electron transfer and faster polymerization rate. This work provides an in-depth mechanism insights and kinetic understanding for SET-ATRP, which has a promising potential to promote its progress of application.