Eosin Y is used as a photocatalyst for the acceleration of the depolymerization of polymethacrylates.

Photochemistry has attracted great interest in the last decades in the field of polymer and material science for the synthesis of innovative materials. The merging of photochemistry and reversible-deactivation radical polymerizations (RDRP) provides good reaction control and can simplify elaborate reaction protocols. These advantages open the doors to multidisciplinary fields going from composite materials to bio-applications. Photoinduced Electron/Energy Transfer Reversible Addition-Fragmentation Chain-Transfer (PET-RAFT) polymerization, proposed for the first time in 2014, presents significant advantages compared to other photochemical techniques in terms of applicability, cost, and sustainability. This review has the aim of providing to the readers the basic knowledge of PET-RAFT polymerization and explores the new possibilities that this innovative technique offers in terms of industrial applications, new materials production, and green conditions.

A photocatalytic RAFT‐controlled radical depolymerization method is introduced for precisely conferring temporal control under visible light irradiation. By regulating the deactivation of the depropagating chains and suppressing thermal initiation, an excellent temporal control was enabled, exemplified by several consecutive “on” and “off” cycles. Minimal, if any, depolymerization could be observed during the dark periods while the polymer chain‐ends could be efficiently re‐activated and continue to depropagate upon re‐exposure to light. Notably, favoring deactivation resulted in the gradual unzipping of polymer chains and a stepwise decrease in molecular weight over time. This synthetic approach constitutes a simple methodology to modulate temporal control during the chemical recycling of RAFT‐synthesized polymers while offering invaluable mechanistic insights.

A photocatalytic RAFT‐controlled radical depolymerization method is introduced for precisely conferring temporal control under visible light irradiation. By regulating the deactivation of the depropagating chains and suppressing thermal initiation, an excellent temporal control was enabled, exemplified by several consecutive “on” and “off” cycles. Minimal, if any, depolymerization could be observed during the dark periods while the polymer chain‐ends could be efficiently re‐activated and continue to depropagate upon re‐exposure to light. Notably, favoring deactivation resulted in the gradual unzipping of polymer chains and a stepwise decrease in molecular weight over time. This synthetic approach constitutes a simple methodology to modulate temporal control during the chemical recycling of RAFT‐synthesized polymers while offering invaluable mechanistic insights.

Lead‐free bismuth‐based perovskite‐like materials have emerged as promising alternatives to lead halide perovskites due to their enhanced stability and lower toxicity. Colloidal approaches for the synthesis of such materials offer the advantage of morphology engineering and precise control over size and shape. However, conventional approaches require long‐chain organic ligands, which hinder charge transport and limit their applicability in optoelectronic devices. Herein, a ligand‐free Solvent‐Assisted Reprecipitation (SARP) approach is introduced, exploiting solvent‐mediated synthesis to control the nucleation and growth of Cs ₃ Bi ₂ I ₉ nanocrystals. The use of solvent descriptors, such as Kamlet–Taft parameters, enables preliminary screening of suitable solvents, suggesting five key candidates, including the green solvents triethyl phosphate and Cyrene, best suited to control crystal size, aspect ratio, and morphology. Electrostatic stabilization, induced by the solvent, promoted the formation of small Bi ⁰ islands at the surface, which is key to ensuring colloidal stability and processability. Computational and experimental analyses agree on highlighting the role of solvents in controlling nucleation and growth of the nanocrystals, paving the way for the rational design of ligand‐free nanomaterials for a platform of different applications.