Developments in the Components of Metal‐Free Photoinitiated Organocatalyzed‐Atom Transfer Radical Polymerization (O‐ATRP)

Abstract

The evolution of the atomic transfer radical polymerization (ATRP) has instigated an increased demand for designing versatile and tailored polymeric structures. However, the use of metal catalysts in traditional ATRP limits the use of polymers in many niche applications. The recent advancement in ATRP has engendered the substitution of metal‐catalysts by a more user‐friendly class of organic photoredox catalysts, which offer enhanced control over the polymerization reaction as these compounds can be easily activated and deactivated with just a source of light. These new photocatalysts have transformed the traditional ATRP to a metal‐free photoinitiated organocatalyzed – ATRP (O‐ATRP), which has potential applications in the medical and electronic sectors. This review covers the reductive and oxidative quenching mechanism of the metal‐free photoinduced O‐ATRP reaction and the function of each component to establish a successfully controlled polymerization reaction. The scope for each component has been encompassed in the study, which paves the way for future developments in the field.

Photoinduced Organocatalyzed Atom Transfer Radical Polymerization (O-ATRP): Precision Polymer Synthesis Using Organic Photoredox Catalysis

“…Finally, we conclude this review with an opinion overviewing future directions that could expand the capabilities and utility of this method. While other reviews have been written on this topic, − they have typically focused on specific aspects of this method (ex., catalyst design, applications, etc.) rather than providing a complete overview of its development and uses.…”

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.…”

From non-conventional ideas to multifunctional solvents inspired by green chemistry: fancy or sustainable macromolecular chemistry?

“…Concerning current developments of ATRP, regarding the decrease in the concentration of catalytic complex 64,76,77,161 or its overall elimination, 49,98,102,162 many researchers are focused on the search of efficient yet low-cost and ecological reducing factors, enabling constant regeneration of activator thorough the reaction and thus employing only ppm amounts of catalyst. 23,64,76,77,163 Depending on the type of reducing factor used, various techniques of ATRP might be distinguished starting with electrochemically mediated ATRP (eATRP), 70,103,137,[164][165][166] photochemically induced ATRP ( photo-ATRP), 5,43,64,72,76,111 mechanically controlled ATRP (mechano-ATRP) 167,168 or ultrasound-mediated ATRP (sono-ATRP) [169][170][171][172][173] employing external reductors, followed by methods applying compounds present in reaction mixtures, such as zero-valent metals in SARA ATRP 10,48,67,132,174 or chemical substance in Activators Regenerated by Electron Transfer (ARGET) ATRP.…”