Near‐Infrared Light‐Induced Reversible Deactivation Radical Polymerization: Expanding Frontiers in Photopolymerization

Abstract

Abstract Photoinduced reversible deactivation radical polymerization (photo‐RDRP) or photoinduced controlled/living radical polymerization has emerged as a versatile and powerful technique for preparing functional and advanced polymer materials under mild conditions by harnessing light energy. While UV and visible light (λ = 400–700 nm) are extensively employed in photo‐RDRP, the utilization of near‐infrared (NIR) wavelengths (λ = 700–2500 nm) beyond the visible region remains relatively unexplored. NIR light possesses unique properties, including enhanced light penetration, reduced light scattering, and low biomolecule absorption, thereby providing opportunities for applying photo‐RDRP in the fields of manufacturing and medicine. This comprehensive review categorizes all known NIR light‐induced RDRP (NIR‐RDRP) systems into four mechanism‐based types: mediation by upconversion nanoparticles, mediation by photocatalysts, photothermal conversion, and two‐photon absorption. The distinct photoinitiation pathways associated with each mechanism are discussed. Furthermore, this review highlights the diverse applications of NIR‐RDRP reported to date, including 3D printing, polymer brush fabrication, drug delivery, nanoparticle synthesis, and hydrogel formation. By presenting these applications, the review underscores the exceptional capabilities of NIR‐RDRP and offers guidance for developing high‐performance and versatile photopolymerization systems. Exploiting the unique properties of NIR light unlocks new opportunities for synthesizing functional and advanced polymer materials.

Keywords

• controlled/living radical polymerization
• near‐infrared light
• photochemistry
• photopolymerization
• reversible deactivation radical polymerization
• upconversion nanoparticles