Photoinduced Electron Transfer Reactions for Macromolecular Syntheses

Abstract

Photochemical reactions, particularly those involving photoinduced electron transfer processes, establish a substantial contribution to the modern synthetic chemistry, and the polymer community has been increasingly interested in exploiting and developing novel photochemical strategies. These reactions are efficiently utilized in almost every aspect of macromolecular architecture synthesis, involving initiation, control of the reaction kinetics and molecular structures, functionalization, and decoration, etc. Merging with polymerization techniques, photochemistry has opened up new intriguing and powerful avenues for macromolecular synthesis. Construction of various polymers with incredibly complex structures and specific control over the chain topology, as well as providing the opportunity to manipulate the reaction course through spatiotemporal control, are one of the unique abilities of such photochemical reactions. This review paper provides a comprehensive account of the fundamentals and applications of photoinduced electron transfer reactions in polymer synthesis. Besides traditional photopolymerization methods, namely free radical and cationic polymerizations, step-growth polymerizations involving electron transfer processes are included. In addition, controlled radical polymerization and "Click Chemistry" methods have significantly evolved over the last few decades allowing access to narrow molecular weight distributions, efficient regulation of the molecular weight and the monomer sequence and incredibly complex architectures, and polymer modifications and surface patterning are covered. Potential applications including synthesis of block and graft copolymers, polymer-metal nanocomposites, various hybrid materials and bioconjugates, and sequence defined polymers through photoinduced electron transfer reactions are also investigated in detail.

Evaluating brominated thioxanthones as organo‐photocatalysts

“…[1,2] Thioxanthone and its derivatives are frequently used in organo-photocatalytic reactions [3,4] and as initiator in photopolymerization formulations. [5] Although 1 absorbs strongly in the near-UV spectral region (λ max = 381 nm), its absorption shows only a minor tailing in the visible region above 400 nm, which makes it only poorly suited as a sensitizer/catalyst for visible light illumination.…”

Shining a light on an adaptable photoinitiator: advances in photopolymerizations initiated by thioxanthones

“…In this section, we briefly evaluate the fields in which the REVIEW Polymer Chemistry 16 with narrow size distributions were obtained. 167 CuAAC is known to be promoted by photochemical processes in which the required copper(I) catalyst for CuAAC is achieved by photoreduction of copper(II) species. [164][165][166] Our group recently reported a new TX-based copper catalyst for the photochemically conduction of CuAAC click reaction.…”

Photoinitiated Metal Free Living Radical and Cationic Polymerizations

“…However, they usually do not yield well-defined polymers with precise average molar masses, low molecular weight distributions and pre-designed architectures due to the inevitable transfer and termination reactions manifesting the overall process. Combining photoinduced electron transfer reactions developed for the conventional systems with controlled polymerization techniques has recently revolutionized the synthesis of well-defined macromolecular architectures [6]. Many attempts have been devoted to apply photochemical systems to existing controlled/living polymerization methodologies by photochemically effecting initiation, mediation and control of these processes [7][8][9][10][11][12][13][14][15][16][17][18][19].…”