Mechanochemical atom transfer radical polymerization unlocks functional methacrylate lifecycles of controlled...

Mechanochemical polymerization offers a solvent-free alternative to conventional solution-based methods. However, achieving controlled radical polymerization poses challenges due to the competing interplay between chain propagation and polymer degradation. Herein, we explore atom transfer radical polymerization (ATRP) under optimized mechanochemical conditions to enhance controlled polymerization and systematically analyze the overall reaction process, encompassing polymer synthesis, degradation, and depolymerization. By expanding the range of aromatic methacrylate monomers, we demonstrate that the size of pendant groups significantly impacts the kinetics of mechanochemical ATRP. Notably, the propagation rate constant in this process surpasses that of conventional ATRP, indicating significantly faster kinetics in solid-state reactions. Semi-quantitative MALDI-ToF analysis and computational simulations elucidated the contributions of main-chain, pendant-group, and end-group scissions with respect to the pendant group size, affirming the influence of steric effects on degradation pathways. Additionally, we observe the depolymerization process concurrent with polymer degradation, offering further insights into mechanochemical ATRP. This study provides valuable insights on efficient design and the mechanistic understanding of mechanochemical polymerization.