Advances in Organocatalyzed Atom Transfer Radical Polymerization

Figure 9

(a) pH-dependent equilibrium between the spirolactone form and the ring-opened form of fluorescein (FL) and optical properties of fluorescein in ring-opened structure. (b) Proposed mechanism of metal-free PET–ATRP photo-mediated with fluorescein as an organic photocatalyst. (c) Plot of monomer conversion versus time demonstrating the effect of blue light on the control over polymerization propagation through repeated “on-off” cycling of irradiation (blue regions) and light source removal (shaded regions); number-average molecular weight () and molecular weight distribution () versus conversion (d) and as a function of exposure time (e) for metal-free PET–ATRP of MMA in the “on/off” light irradiation experiment. Polymerization conditions: , VMMA = 1.0 mL, VDMSO = 2.0 mL; samples were irradiated by a blue LED at rt. (Adapted with permission from Ref. [50]).

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