A neutral Ni(II) acetylide-mediated radical polymerization of methyl methacrylate using the atom transfer radical polymerization method

A neutral nickel σ-acetylide complex [Ni(CCPh)2(PBu3)2] (NBP) is used for possible atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA) in conjunction with an organic halide as an initiator [R–X: CCl4, CH3Cl, BrCCl3, C2H5Br, and C5H9Br] in toluene at 80 °C. Among these initiating systems, BrCCl3/NBP gave the best controlled radical polymerization of MMA and produced polymer with relatively narrow molecular weight distribution (Mw/Mn≈1.3). The ATRP of MMA is preliminarily identified by the following facts: (1) the present MMA polymerization initiated by BrCCl3/NBP is completely hindered by the addition of TEMPO; (2) the conversion shows a typical linear variation with time in semilogarithmic coordinates; (3) the measured number-average molecular weights of polymer show a linear increase with conversion and agree closely with the theoretical values; (4) the resulting polymer chain contains a dormant carbon–halogen terminal.