Green-light ATRP that tolerates open air
Eosin Y plus a copper ATRP catalyst polymerizes OEOMA under green light in open vials, giving low dispersity even at 1000 rpm stirring.
Source
Open-air green-light-driven ATRP enabled by dual photoredox/copper catalysis
Inspect source passages
Green-light ATRP that tolerates open air
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EY without Cu reached 89% conversion but Đ of 4.30
O-ATRP catalyzed with the EY/TPMA (without CuBr 2 ) enabled rapid polymerization, reaching 89% monomer conversion within 30 min (entry 2, ), but size exclusion chromatography (SEC) analysis showed that the polymer had a high dispersity ( Đ ) of 4.30.
EY plus CuBr2 gave 88% conversion and Đ = 1.19
when EYH 2 was used in combination with CuBr 2 and excess TPMA ligand, high monomer conversion (88%) and well-controlled polymerization ( Đ = 1.19) were achieved (entry 3, ).
What they did
They ran photo-ATRP of OEOMA500 in PBS/DMSO open vials with eosin Y (EYH2), CuBr2, and TPMA under green light. Controls omitted EY or copper. Kinetics, SEC, Stern–Volmer quenching, and ΔGet estimates compared oxidative vs reductive quenching of 3EY*.
What they found
Without EY, no conversion. EY without copper gave 89% conversion but Đ = 4.30. EY + Cu gave ~88% conversion and Đ = 1.19. Stirring up to 1000 rpm still kept Đ < 1.18. Even 7.5 μM EY (25 ppm) gave 80% conversion and Đ = 1.16. Oxidative quenching of 3EY* by Cu(II) is downhill (ΔGet = −0.92 eV).
The limits
What it doesn't show
Oxygen tolerance is demonstrated for this aqueous OEOMA system; hydrophobic monomers in DMSO are only briefly extended. Protein/DNA hybrids are claimed but cytocompatibility is comparative, not a full toxicology study.
Key terms
- ATRP
- Atom transfer radical polymerization: Cu-catalyzed reversible activation of C–X chain ends.
- Photoredox catalyst
- Here eosin Y, which absorbs green light and exchanges electrons with the copper ATRP cycle.
- Dispersity (Đ)
- Mw/Mn; values near 1.1–1.2 mean a narrow polymer size distribution.
- Oxidative quenching
- Excited 3EY* donates an electron to Cu(II), generating Cu(I) activator.
- Oxygen tolerance
- Polymerization still controlled in open vials despite O2 quenching radicals and Cu(I).
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Copper is required in this dual system to:
Common questions
Why add copper if eosin Y already starts radicals?
Copper enforces the ATRP equilibrium so chains stay dormant most of the time and Đ stays low.
Why green light instead of UV?
UV can damage biomolecules; eosin Y absorbs near 520 nm.
Can you stir in air?
Yes—up to 1000 rpm still gave Đ < 1.18.
Which quenching path is favored?
Oxidative quenching of 3EY* by Cu(II) (ΔGet ≈ −0.92 eV), not reductive quenching by TPMA.
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