| Abstract
| - Transition-metal-mediated living radical polymerizations (atom transfer radical polymerization, ATRP) have many potential applications, but the high concentration of residual catalyst colorstheir products. Supporting catalyst on insoluble solids has been used to reduce the content of residualcatalyst and to reuse the catalyst, but the ability of the supported catalyst to mediate a polymerizationis substantially reduced due to heterogeneity. Here we report a soluble but recoverable catalyst supportfor ATRP. Poly(ethylene)-block-poly(ethylene glycol) (PE-PEG) was soluble in toluene above 70 °C butinsoluble at room temperature. CuBr supported on PE-PEG via tetraethyldiethylenetriamine thusmediated living polymerizations of methyl methacrylate, 2-(dimethylamino)ethyl methacrylate, and styreneas homogeneous catalyst at 80 or 100 °C, producing polymers with well-controlled molecular weight andvery low polydispersity. The catalyst recycled at ambient temperature retained high activity and stillmediated living polymerizations as well as the fresh catalyst. Subsequent block copolymerization confirmedits living nature.
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