Sonochemistry-assisted photocontrolled atom transfer radical polymerization enabled by manganese carbonyl

Abstract

Light offers intriguing possibilities to control polymerization, but it suffers from the concentration gradient induced by its weak penetration ability. In this study, sonochemistry-assisted photocontrolled atom transfer radical polymerization (SAP-ATRP) is developed to circumvent the problem caused by the low penetration depth of light. Mn₂(CO)₁₀ is demonstrated to be a dual-responsive (light or ultrasound) compound that decomposes into reductive metalloradicals for the generation of activators to induce atom transfer radical polymerization. Compared with polymerization with a single stimulus, the synergistic utilization of ultrasound and light contributes to the dramatically elevated polymerization kinetics, giving an increment of over 100% in the apparent rate constant of propagation (k_p,app). This procedure is compatible with a broad scope of monomers including acrylates, methacrylates, and acrylonitrile under low-intensity ultrasonication and hood light with ppm-level Cu catalysts. Excellent control over polymerization by the stimuli gives rise to well-defined polymers with a predetermined molecular weight, low dispersity, and high chain-end fidelity.