Copper-catalysed polymerisation enables the growth of polymer chains in a controlled manner with low polymer polydispersities. For industrial applications, the amount of copper must be reduced to ppm levels. This can be achieved with relatively simple copper polyamine coordination compounds, which are very effective atom transfer radical polymerisation (ATRP) catalysts. The copper(I) form of the catalyst activates the alkyl halide initiator (RX) by abstracting a halogen atom (X) and releasing a radical (R·). An example is shown below for the initiator ethyl bromoisobutyrate in its reaction with the tetraamine complex [Cu(Me6tren)]~+. A key to ATRP catalysis is the reversible formation of R· (governed by the equilibrium constant K_(ATRP)) to avoid undesirable radical termination and other side reactions.
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