Soluble and recoverable support for copper bromide-mediated living radicalpolymerizatian

Transition-metal-mediated living radical polymerizations (atom transfer rad ical polymerization, ATRP) have many potential applications, but the high c oncentration of residual catalyst colors their products. Supporting catalys t on insoluble solids has been used to reduce the content of residual catal yst and to reuse the catalyst, but the ability of the supported catalyst to mediate a polymerization is substantially reduced due to heterogeneity. He re we report a soluble but recoverable catalyst support for ATRP. Polg(ethy lene)-block-poly(ethylene glycol) (PE-PEG) was soluble in toluene above 70 degreesC but insoluble at room temperature. CuBr supported on PE-PEG via te traethyldiethylenetriamine thus mediated Living polymerizations of methyl m ethacrylate, 2-(dimethylamino)ethyl methacrylate, and styrene as homogeneou s catalyst at 80 or 100 degreesC, producing polymers with well-controlled m olecular weight and very low polydispersity. The catalyst recycled at ambie nt temperature retained high activity and still mediated living polymerizat ions as well as the fresh catalyst. Subsequent block copolymerization confi rmed its living nature.