Guiding the Design of Organic Photocatalyst for PET-RAFT Polymerization: Halogenated Xanthene Dyes

Abstract

By examining structurally similar halogenated xanthene dyes, this study establishes a guiding principle for resolving structure−property− performance relationships in the photocontrolled PET-RAFT polymerization system (PET-RAFT: photoinduced electron/energy transfer−reversible addition−fragmentation chain transfer). We investigated the effect of the halogen substituents on the photophysical and electrochemical properties of the xanthene dyes acting as photocatalysts and their resultant effect on the performance of PET-RAFT polymerization. Consideration of the structure− property−performance relationships allowed design of a new xanthene photocatalyst, where its photocatalytic activity (oxygen tolerance and polymerization rate) was successfully optimized for PET-RAFT polymerization. We expect that this study will serve as a theoretical framework in broadly guiding the design of high performance photocatalysts for organic photocatalysis.

Precise growth of polymer brushes on silica-based nanocomposites via visible-light-regulated controlled radical polymerization

“…[12][13][14] In the pursuit of solar-driven synthesis of natural polymers with well-preserved chain terminus fidelity as well as composition, spatiotemporal and sequence control, extensive research has been devoted to the development and exploitation of visible-light-mediated modern polymer synthesis for precise control over the polymerization procedures. [15][16][17][18][19][20][21][22][23][24] Arising from its highly advantageous characteristics including low cost, user-friendly operation, fast initiation efficiency and convenient spatiotemporal polymerization modulation, photoinduced electron/energy transfer reversible addition fragmentation chain transfer (PET-RAFT) polymerization enables a versatile toolkit for controlled polymerizations of diverse functional monomers from nanomaterials and is universal in its specificity to satisfy the energetic criteria for conducting such polymerization, which would be otherwise inaccessible by thermal counterparts. [25][26][27][28][29] To the best of our knowledge, the current work is the first example to illustrate a systematic method to propagate well-defined polymer brushes directly from the surface of various silica-assisted nanomaterials using a PET-RAFT approach.…”

Polythioethers with Controlled α,ω‐End Groups Prepared by Visible Light Induced Thiol–Ene Click Polymerization of Dithiol and Divinyl Ether with 4‐(N,N‐diphenylamino)benzaldehyde as Organocatalyst

“…[ 40–44 ] For the RAFT polymerization, a highly reductive photocatalyst exhibited a better catalytic effect. [ 51 ] In addition, the reaction between dithiol and divinyl has been carried out using triethylamine as a catalyst. [ 52 ] Therefore, control runs using triphenylamine (TPA) and dimethylaniline (DMA) as photocatalysts were also carried out to determine whether the catalytic activity of DPAB is attributed to an aldehyde group or a tertiary amine group.…”

A Versatile 3D and 4D Printing System through Photocontrolled RAFT Polymerization

“…EY is frequently used as a biological stain, and has also previously been used to initiate free‐radical polymerization in the presence of tertiary amines as co‐catalysts via a type II photoinitiation mechanism, as well as other organic synthetic transformations . The structurally similar EB has been used by our group for PET‐RAFT polymerization, where it was determined to be a more effective PC compared to EY and similar halogenated xanthene dyes, such as phloxine B and rose bengal, due to its favorable photophysical and electrochemical properties, including a higher triplet quantum yield ( Φ T ), decreased fluorescence quantum yield ( Φ F ), and a higher excited state reduction potential ( E 0 (PC .+ / 3 PC*)) . In addition to the organic dye as PC, we also included a tertiary amine as co‐catalyst in this system as these formulations have previously shown the ability to mediate rapid PET‐RAFT polymerization .…”