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

Abstract

The development of photoinduced organocatalyzed atom transfer radical polymerization (O-ATRP) has received considerable attention since its introduction in 2014. Expanding on many of the advantages of traditional ATRP, O-ATRP allows well-defined polymers to be produced under mild reaction conditions using organic photoredox catalysts. As a result, O-ATRP has opened access to a range of sensitive applications where the use of a metal catalyst could be of concern, such as electronics, certain biological applications, and the polymerization of coordinating monomers. However, key limitations of this method remain and necessitate further investigation to continue the development of this field. As such, this review details the achievements made to-date as well as future research directions that will continue to expand the capabilities and application landscape of O-ATRP. CONTENTS 4.5. Styrene and 4-Vinylpyridine 4.6. Vinyl Cyclopropanes 4.7. Other Monomers 5. Applications of O-ATRP 5.1. Synthesis of Block Copolymers 5.2. Synthesis of Graft Polymers 5.3. Synthesis of Hyperbranched Polymers 5.4. Synthesis of Star Polymers 5.5. Surface-initiated O-ATRP 5.6. Synthesis of Polymers in Continuous Flow 5.7. Metal Sensitive Applications of O-ATRP 6. Conclusions and Future Directions Author Information Corresponding Author Author Notes Biographies Acknowledgments References

Effects of the Chalcogenide Identity in N‐Aryl Phenochalcogenazine Photoredox Catalysts

“…In O‐ATRP, control of polymer structure is achieved through a reversible activation/deactivation mechanism (Figure 2a), which maintains a low concentration of propagating polymer radicals (P n ⋅ ) to minimize biomolecular radical side reactions caused by these intermediates. In order for a PC to successfully mediate this process, several catalyst properties are necessary, including a sufficiently reducing excited state to reduce a polymer alkyl bromide bond [ E °(C−Br/C−Br ⋅− ) ∼−0.8 to −0.6 V vs. saturated calomel electrode (SCE)], an excited state lifetime ( τ ) long enough to engage in bimolecular reactions (typically nanoseconds or longer), and chemical reversibility so the PC can be regenerated after electron transfer (ET) [9] …”

“…In order for a PC to successfully mediate this process, several catalyst properties are necessary, including a sufficiently reducing excited state to reduce a polymer alkyl bromide bond [E°(CÀ Br/CÀ Br *À ) ~À 0.8 to À 0.6 V vs. saturated calomel electrode (SCE)], an excited state lifetime (τ) long enough to engage in bimolecular reactions (typically nanoseconds or longer), and chemical reversibility so the PC can be regenerated after electron transfer (ET). [9] Following early O-ATRP reports, the superior catalytic properties of 10-phenyl phenothiazine [6] over perylene [10] motivated the development of new phenochalcogenazine PCs, including numerous phenothiazines [11,12] and phenoxazines. [7,13,14] In particular, significant research efforts were devoted to tuning the yield of PC triplet excited states ( 3 PC*), [7,12,15,16] which may benefit catalysis due to their longer lifetimes than singlet excited states ( 1 PC*) by making them more likely to engage in catalysis.…”

A New Protocol for Ash Wood Modification: Synthesis of Hydrophobic and Antibacterial Brushes from the Wood Surface

“…In addition, it is possible to incorporate polymers with different characteristics by polymerizing different types of monomers simultaneously, giving the wood more than one property. Moreover, ATRP methods enable the creation of polymer chains with a strictly designed structure and architecture [33,34]. Therefore, polymers and biopolymers produced by the ATRP technique are characterized by a narrow molecular weight distribution (M w /M n ), control over their molecular weight (MW) [30,35], and topology (geometry) [36,37] to obtain structures ranging from linear chains, stars, cyclic structures, combs, and regular polymer networks [32,[37][38][39].…”

Organocatalytic orthogonal ATRP and ring-opening polymerization using a single dual-function photocatalyst

“…[9][10][11][12][13][14][15][16][17] Accordingly, the development of effective orthogonal polymerization systems has attracted considerable research interest in the past few years, which are highly desirable in both academia and industry. [18][19][20][21][22] The reversible-deactivation radical polymerization (RDRP) method represents a powerful tool for the precise construction of macromolecules with a predictable molecular mass, low dispersity, high end-group fidelity, and advanced complex structures [23][24][25][26][27][28][29][30] and could serve as a useful and versatile component in orthogonal polymerization. [15][16][17][18][19][26][27][28][29][30][31][32][33][34] For example, as early as 1998, Jérôme, Hedrick and co-workers 31 demonstrated the one-pot preparation of block and graft copolymers by combining nitroxide-mediated living free-radical polymerization (NMP) and ring-opening polymerization (ROP) with the help of Sn and Al metal complexes, but high polydispersity indices were observed even with this dual-living polymerization strategy.…”

“…[18][19][20][21][22] The reversible-deactivation radical polymerization (RDRP) method represents a powerful tool for the precise construction of macromolecules with a predictable molecular mass, low dispersity, high end-group fidelity, and advanced complex structures [23][24][25][26][27][28][29][30] and could serve as a useful and versatile component in orthogonal polymerization. [15][16][17][18][19][26][27][28][29][30][31][32][33][34] For example, as early as 1998, Jérôme, Hedrick and co-workers 31 demonstrated the one-pot preparation of block and graft copolymers by combining nitroxide-mediated living free-radical polymerization (NMP) and ring-opening polymerization (ROP) with the help of Sn and Al metal complexes, but high polydispersity indices were observed even with this dual-living polymerization strategy. In 2005, the Howdle group disclosed a successful combination of conventional metal-based atom transfer radical polymerization (ATRP) and enzymatic ROP using supercritical carbon dioxide as a solvent.…”