Metal‐Free Organocatalyzed Atom Transfer Radical Polymerization: Synthesis, Applications, and Future Perspectives

Abstract

Reversible deactivation radical polymerization (RDRP) is a class of powerful techniques capable of synthesizing polymers with a well‐defined structure, properties, and functionalities. Among the available RDRPs, ATRP is the most investigated. However, the necessity of a metal catalyst represents a drawback and limits its use for some applications. O‐ATRP emerged as an alternative to traditional ATRP that uses organic compounds that catalyze polymerization under light irradiation instead of metal. The friendly nature and the robustness of O‐ATRP allow its use in the synthesis of tailorable advanced materials with unique properties. In this review, the fundamental aspects of the reductive and oxidative quenching mechanism of O‐ATRP are provided, as well as insights into each component and its role in the reaction. Besides, the breakthrough recent studies that applied O‐ATRP for the synthesis of functional materials are presented, which illustrate the significant potential and impact of this technique across diverse fields.

Acridinium salts as photoredox organocatalysts for photomediated cationic RAFT and DT polymerizations of vinyl ethers

“…In addition to organic reactions, photoredox catalysts can also mediate polymerizations under light-irradiated mild conditions to enable precision synthesis of tailor-made macromolecules with precise structural design, 7–10 as summarized in the review by Yagci, who has greatly contributed to the developments of polymer chemistry based on photomediated polymerizations and polymer syntheses. 9,11,12 In particular, recent advances in various metal or organic photoredox catalysts have contributed to great developments in controlled/living or reversible deactivation radical polymerization (RDRP), such as atom transfer radical polymerization (ATRP) 13–19 and reversible addition–fragmentation chain transfer (RAFT) 20–25 polymerization, because they enable reversible formation of radical species from dormant species with covalent carbon–halogen and carbon–sulfur bonds even at room temperature, where thermal-induced side reactions are suppressed and fine control is thus enhanced. In most cases, these photoredox catalysts are excited by visible or ultraviolet (UV) light to obtain a potential high enough to reduce the stable dormant species to radical anions and to generate the propagating radical species via mesolytic cleavage of the covalent bonds.…”

Synthesis of Bottlebrush Copolymers Using a Polypseudorotaxane Intermediate

“…Accordingly, the complexation could include other known host–guest pseudorotaxanes, for example, cyclodextrin-admantyl (and other hydrophobic guests), ,,,,, pillararene-aliphatic chains, aromatics, − and so on; note that these would produce systems without ionic charges. Finally, the brushes could be constructed using other approaches, for example, atom transfer radical polymerization, ,,,,,− reversible addition-fragmentation chain transfer polymerization (RAFT), ,,,− ring-opening polymerization (ROP), including ring-opening metathesis polymerization ,,,− and so on. Therefore, we believe that this approach represents a new, useful, and flexible paradigm for the synthesis of bottlebrush polymers.…”

Use of anN-heterocyclic carbene (NHC)-based interacting Lewis pair for the synthesis of a cyclic poly(alkyl acrylate)viachain-growth polymerization and subsequent ring-closing without extreme dilution

“…The development of anionic [1][2][3] as well as radical polymerization [4][5][6][7][8] has enabled the fabrication of a wide range of various polymeric materials. However, in contrast to the remarkable progress of radical polymerization, the progress of anionic polymerization is suffering from the lack of a variety of initiator systems.…”