CONTROLLED LIVING RADICAL POLYMERIZATION - ATOM-TRANSFER RADICAL POLYMERIZATION USING MULTIDENTATE AMINE LIGANDS/

Three multidentate amines, tetramethylethylenediamine (TMEDA), N,N,N', N',N''-pentamethyldiethylenetriamine (PMDETA) and 1,1,4,7,10,10-hexame thyltriethylenetetramine (HMTETA) have been successfully used as new l igands in the copper mediated atom transfer radical polymerization (AT RP) of styrene, methyl acrylate and methyl methacrylate. All the polym erizations were well controlled with a linear increase of molecular we ights (M-n) with conversion and relatively low polydispersities throug hout the reactions. Compared to the 2,2'-bipyridine (bipy) based ligan ds, most multidentate amines are less expensive and the polymerization mixtures are less colored. In particular, the use of the tridentate P MDETA and the tetradentate HMTETA as the ligands resulted in faster po lymerization rates for styrene and methyl acrylate than those using bi py as the ligand. This may be in part attributed to the fact that the coordination complexes between copper and the simple amines have lower redox potentials than the copper-bipy complex, resulting in higher ra tes of activation of the dormant halides. Additional rate effects may originate from the solubilities of the copper(I) and copper(II) comple xes. The new ligands are very attractive alternatives to bipy and its derivatives as ligands.