Mechanistic and Physicochemical Insights into the Photoactivation Pathways of a Charge Transfer ATRP Photoinitiator

A comprehensive elucidation of the photopolymerization mechanism of a novel “V-shaped” photosensitizer, engineered for strong visible-light absorption and a highly reactive triplet excited state lays the groundwork for future advancements in both one- and two-photon-mediated ATRP.

Photochemistry has revolutionized the chemical industry by introducing sustainable and energy-efficient processes that are vital for the manufacture of advanced materials which align with Industry 4.0 standards. Among photochemical techniques, photopolymerization stands out as a rapid, controlled, and eco-friendly approach, making it particularly suitable for applications like 3D printing. This research in two-photon-induced photopolymerization for 3D microfabrication led to groundbreaking performance, thanks to the use of custom π-extended molecular architectures as photoinitiators. Building on these results, a photoactivable initiation system for photoinduced-atom transfer radical polymerization (photoATRP) is now reported using a similar π-extended photoinitiator. Through comprehensive optimization, we successfully created a functional multicomponent photoinitiating system, with its detailed mechanism thoroughly established in solution. By covalently attaching alkyl halides to glass surfaces, we were able to implement the surface-induced photo-ATRP technique to create customized brush polymer architectures. This work not only advances the understanding of photoATRP mechanisms but also introduces new strategies for functional surface engineering, with potential applications in two-photon-induced surface modification of 3D/4D structures via photoATRP.

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