Radical Addition to N,N-Diaryl Dihydrophenazine Photoredox Catalysts and Implications in Photoinduced Organocatalyzed Atom Transfer Radical Polymerization
| Autor: | Jordan C. Theriot, Brian S. Newell, Chern-Hooi Lim, Katherine O. Puffer, Daniel A. Corbin, Blaine G. McCarthy, Justin P. Cole, Garret M. Miyake, Katherine A. Chism, Sarah R. Lincoln, Bonnie L. Buss |
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| Rok vydání: | 2021 |
| Předmět: |
chemistry.chemical_classification
Polymers and Plastics Atom-transfer radical-polymerization Chemistry Radical Organic Chemistry Dispersity Radical polymerization 02 engineering and technology Polymer 010402 general chemistry 021001 nanoscience & nanotechnology 01 natural sciences 0104 chemical sciences Catalysis Inorganic Chemistry Polymerization Polymer chemistry Materials Chemistry Molar mass distribution 0210 nano-technology |
| Zdroj: | Macromolecules. 54:4507-4516 |
| ISSN: | 1520-5835 0024-9297 |
| DOI: | 10.1021/acs.macromol.1c00501 |
| Popis: | Photoinduced organocatalyzed atom transfer radical polymerization (O-ATRP) is a controlled radical polymerization methodology catalyzed by organic photoredox catalysts (PCs). In an efficient O-ATRP system, good control over molecular weight with an initiator efficiency (I* = Mn,theo/Mn,exp × 100%) near unity is achieved, and the synthesized polymers possess a low dispersity (Đ). N,N-Diaryl dihydrophenazine catalysts typically produce polymers with low dispersity (Đ < 1.3) but with less than unity molecular weight control (I* ~ 60-80%). This work explores the termination reactions that lead to decreased control over polymer molecular weight and identifies a reaction leading to radical addition to the phenazine core. This reaction can occur with radicals generated through reduction of the ATRP initiator or the polymer chain end. In addition to causing a decrease in I*, this reactivity modifies the properties of the PC, ultimately impacting polymerization control in O-ATRP. With this insight in mind, a new family of core-substituted N,N-diaryl dihydrophenazines is synthesized from commercially available ATRP initiators and employed in O-ATRP. These new core-substituted PCs improve both I* and Đ in the O-ATRP of MMA, while minimizing undesired side reactions during the polymerization. Further, the ability of one core-substituted PC to operate at low catalyst loadings is demonstrated, with minimal loss of polymerization control down to 100 ppm (weight average molecular weight [Mw] = 10.8 kDa, Đ = 1.17, I* = 104% vs Mw = 8.26, Đ = 1.10, I* = 107% at 1000 ppm) and signs of a controlled polymerization down to 10 ppm of the catalyst (Mw = 12.1 kDa, Đ = 1.36, I* = 107%). |
| Databáze: | OpenAIRE |
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