Photoinduced electron/energy transfer reversible addition - fragmentation chain-transfer (PET-RAFT) polymerization enables precise light-controlled polymer growth. While conventional near-infrared strategies often rely on nonlinear optical processes such as two-photon absorption or photon upconversion, which typically require high-intensity laser excitation. In contrast, direct shortwave infrared (SWIR) light-driven PET-RAFT offers distinct advantages, including higher selectivity, deeper tissue penetration, and potential applications in 3D printing and transdermal polymerization. However, efficient photocatalysts that can directly utilize SWIR photons remain rare
CuInSe2/CuInS2 quantum dots for SWIR-driven PET-RAFT polymerization (Image by DU Jun)
In a study published in Journal of the American Chemical Society, a research team led by Prof. WU Kaifeng and Prof. DU Jun from the Dalian Institute of Chemical Physics (DICP) of the Chinese Academy of Sciences (CAS), in collaboration with Prof. Cyrille Boyer at the University of New South Wales, achieved living radical polymerization using low-toxicity copper indium selenide (CuInSe2) quantum dots (QDs), extending PET-RAFT excitation into the SWIR region at 1,050 nm.
Researchers synthesized highly luminescent CuInSe2/CuInS2 QDs with an absorption onset extended to 1,100 nm and hybridized them with 4-Cyano-4-(dodecylsulfanylthiocarbonyl)sulfanylpentanoic acid as a photocatalyst. Under 1,050 nm excitation, this hybrid system effectively triggered PET-RAFT polymerization, achieving efficient polymerization through 3 mm of biological tissue.
Furthermore, researchers revealed that long-lived shallow defect-state electrons in CuInSe2 QDs play a key role during organic photochemical reactions, providing theoretical guidance for the development of high-performance SWIR photocatalysts.
"With further optimization of QDs, this strategy could enable efficient polymerization at even longer wavelengths, paving the way for SWIR-driven synthesis of advanced functional polymer materials," said Prof. DU.