Hydrophobic and Hydrophilic Ag–In–Zn–S Alloyed Quantum Dots as Efficient Photocatalysts for Controlled RAFT Polymerization of Vinyl Monomers

We demonstrate for the first time that nonstoichiometric quaternary Ag–In–Zn–S semiconductor nanocrystals, which do not contain toxic elements, can be used as efficient photocatalysts in photoinduced electron transfer reversible addition‐fragmentation chain transfer (PET‐RAFT) polymerization. Careful tuning of their composition yielded two types of alloyed nanoparticles, namely emitting red and green light. The PET‐RAFT polymerizations were carried out at room temperature, under UV, blue and green illuminations. Chain transfer agents such as 4‐cyano‐4‐(phenylcarbonothioylthio)pentanoic acid (CPADB) or 4‐cyano‐4‐[(dodecylsulfanylthiocarbonyl)sulfanyl]pentanoic acid (CDTPA) were added to a dispersion of nanocrystals, completed by introduction of triethylamine (TEA). Nanocrystals/RAFT reagent/TEA systems, in the presence of green light, turned out to be very efficient, especially in the polymerizations of “model” monomers such as methyl methacrylate (MMA) and N , N ‐dimethyl acrylamide (DMA). In particular, hydrophobic nanocrystals in combination with the CDTPA/TEA, under green radiation initiated photocontrolled polymerization of MMA yielding PMMA whose molecular mass could be precisely controlled, simply by changing the RAFT reagent concentration. The same set of reagents was used for the MMA photopolymerization under the sunlight at ambient (laboratory) conditions resulting in PMMA of M n = 45.4 kDa and Ð = 1.21.