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

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.

Red-Light-Driven Atom Transfer Radical Polymerization for High-Throughput Polymer Synthesis in Open Air

“…The use of low-energy red/near-infrared (NIR) light has become increasingly popular in polymer chemistry due to its high biocompatibility, penetrability, reduced scattering, and minimal side reactions. , Its potential applications include 3D printing, polymerization-induced self-assembly (PISA), and polymerization in vivo and through barriers. − Therefore, the development of photo-RDRP systems with suitable photoredox catalysts (PCs) that can trigger RDRP under long-wavelength light is desirable. There are several examples of red/NIR-light-mediated RDRP using PCs, such as bacteriochlorophyll, porphyrines, phthalocyanines, ,− conjugated porphyrin for RAFT polymerization and Zn porphyrin, conjugated phenothiazines or phosphine, , cyanines, , or upconverting nanoparticles for ATRP. , However, most of these photocatalysts are not commercially available, require multistep synthesis, or are only soluble in organic solvents.…”

Design and Synthesis of a New Indazole-Decorated RAFT Agent for Highly Efficient PET-RAFT Polymerization

“…Photocontrolled reversible deactivation radical polymerization (photo-RDRP) makes use of light energy to control production of polymers with precise molecular weight, composition, and architecture under ambient conditions. − Unlike cationic and anionic polymerization, − photo-RDRP is compatible with diverse solvents, including aqueous solutions. − A good example of such systems is photoinduced electron/energy transfer reversible addition–fragmentation chain transfer (PET-RAFT) polymerization catalyzed by zinc tetraphenyl porphyrin (ZnTPP), a sustainable and biocompatible photocatalyst (PC). − Notably, ZnTPP-catalyzed PET-RAFT systems are capable of controlling oxygen-present radical polymerization, because its populated triplet excited states ( 3 PC*) can transform ground-state oxygen (O 2 ) into singlet oxygen ( 1 O 2 ), allowing for subsequent elimination by vinyl monomers or the solvent . They are even compatible to open-air conditions, potentially suitable for a broad spectrum of aerobically biological and photocuring applications. − …”

Integrating Hybrid Perovskite Nanocrystals into Metal–Organic Framework as Efficient S-Scheme Heterojunction Photocatalyst for Synergistically Boosting Controlled Radical Photopolymerization under 980 nm NIR Light

“…6 Some photocatalysts such as lanthanide-doped upconversion nanoparticles, self-assembled carboxylated porphyrin, rhombic dodecahedral Ag 3 PO 4 , CsPbBr 3 nanocrystals, and bacteriochlorophyll a have been reported to initiate photopolymerization under NIR light irradiation. 7 However, there is poor recyclability and low photocatalytic efficiency. In addition, the binary synergistic hybridization can effectively augment the photocatalytic performance of the resultant photocatalysts.…”

“…In particular, the capability of NIR light to penetrate barriers is expected to get a wide development in biomedical applications and other fields . Some photocatalysts such as lanthanide-doped upconversion nanoparticles, self-assembled carboxylated porphyrin, rhombic dodecahedral Ag 3 PO 4 , CsPbBr 3 nanocrystals, and bacteriochlorophyll a have been reported to initiate photopolymerization under NIR light irradiation . However, there is poor recyclability and low photocatalytic efficiency.…”