Open-Air Growth of Polymer Brushes by Surface-Initiated PhotoATRP under Red-Light Irradiation

High Resolution Image Download MS PowerPoint Slide The translation of polymer brushes into technologically relevant coatings hinges on the development of scalable and robust fabrication strategies that are tolerant of environmental conditions. Surface-initiated photoinduced atom transfer radical polymerization (SI-photoATRP) has emerged as a powerful tool for synthesizing functional brushes with precise control over their architectural parameters. However, traditional SI-photoATRP requires high-energy light and confined setups to mitigate oxygen inhibition within nondeoxygenated mixtures, limiting substrate versatility and process scalability. Herein, we report a red-light-driven SI-photoATRP process enabled by a catalytic system composed of methylene blue (MB + ) and a Cu-based ATRP catalyst, which achieves efficient polymer brush growth under fully open-air conditions. Systematic variation of reaction parameters─including light intensity, composition of the catalytic system, and solvent─enabled rapid growth of compositionally different brushes with high and tunable thickness. The deep penetration capability of red light was exploited to decorate microporous three-dimensional materials with polymer brushes. Spatially defined brush growth was demonstrated by shifting the wavelength of light irradiation, alternatively stimulating surface-initiated polymerization in the outer volumes of the support or uniformly across the entire microporous material.