Optical materials are needed for various applications that emit light. Highly emissive dyes are expected to be widespread in materials creation but they display emission quenching in the solid state. Flood, Laursen, and colleagues discovered the first universal solution to this 150-year-old problem. They report a class of fluorescent materials and the design rules that allow cationic dyes to be plugged into an ionic lattice to reinstate their bright emission.
Activators regenerated by electron transfer atom transfer radical polymerization (ARGET ATRP) conditions utilizing a low concentration of catalyst are successfully applied for the preparation of well-defined poly(glycidyl methacrylate) without the addition of external reducing agents. The living character of polymerization is evidenced by successful chain extensions with methyl methacrylate and methyl acrylate, again, in the absence of additional reducing agents, yielding block copolymers. The epoxide groups in glycidyl methacrylate or the corresponding polymer can serve as an intrinsic reducing agent to continuously regenerate the Cu(I) -based ATRP activator from the Cu(II) halide complex present in the systems. The reactivity of various epoxides in the reduction of the Cu(II) Br2 complex of tris(2-pyridylmethyl)amine is compared.
To date, it has been generally assumed, based on early experimental work, that ATRP in aqueous dispersed systems is incompatible with anionic surfactants. In the present work, it is clarified that this incompatibility originates in the anionic surfactant (sodium dodecyl sulfate, SDS) displacing the halide ligand from the Cu II bromide-based deactivator, converting it to a Cu II complex, unable to deactivate radicals. This results in a very high polymerization rate as well as essentially no control over the molecular weight distribution. It is demonstrated how such loss of deactivator can be minimized by the addition of a source of halide ions, thus enabling one to conduct ATRP in aqueous dispersed systems using commonly available and inexpensive anionic surfactants such as SDS.
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