Abstract
Abstract The cobalt(II) [N,N‘-bis(3,5-di-tert-butylsalicyli-dene)-1,2-cyclohexanediamine] (CoII(Salen*)) could be mediated in the controlled/living radical polymerization of vinyl acetate and methyl acrylate successfully. The poly(vinyl acetate) (VAc) and poly(methyl acrylate) (MA) with living characters were obtained. In VAc system, the PVAc polymer chains were growth with conversion linearly and agree to the theoretical molecular weight. The conversion could arrive to 60% with narrow polydispersity index (PDI) were between 1.09 and 1.25. All CoII(Salen*) transform to CoIII(Salen*)-R during induction period. Because of one chain per catalyst, the equilibrium constant could be estimated (> 109 M-1). The macro-initiator, CoIII(Salen*)-PVAc was also synthesized and could be performed in the PVAc chain extension with additives (THF and pyridine). In MA system, the PMA with high conversion (> 60%) and low PDI (1.20~1.30) were obtained. The polymer chains were growth with conversion linearly and agree to the theoretical molecular weight. The equilibrium between cobalt(II) and organo-cobalt(III) species in methyl acrylate polymerization was followed by UV-vis spectroscopy and the equilibrium constant was determined to be 2.4 × 107 M-1. The kinetic studies showed the mechanism of polymerization of VAc could be degenerative transfer (DT) major and the MA system could be reversible termination (RT) major. The facile formation of block copolymers of PVAc like PVAc-b-PMA (poly(vinyl acetate)-block-poly(methyl acrylate)) and PVAc-b-PAN (poly(vinyl acetate)-block-poly(acrylonitrile)) illustrates the unusual capability of the cobalt Salen* catalyst system to generate new applications in materials science.