Stereo-regulated methyl methacrylate (MMA) polymerization catalyzed by asymmetric Salen-type Schiff-base Cu(II) complexes

Abstract

A series of mononuclear asymmetric Salen-type Schiff-base complexes [Cu(Ln)] (n=1–5, 1–5) were obtained by the Cu(II)-templated approach in the presence of one of five salicylaldehyde derivatives, respectively. These complexes could effectively catalyze the metal-coordinative polymerization of MMA for the formation of the syndio-enriched PMMAs (poly(methyl methacrylates)) in the presence of AIBN, where the Cu(II)-to-chelate-plane distances are positively relative to the catalytic activity. Moreover, the introduction of the encumbering substituent ortho to the phenoxide ring of the ligands plays a much more important and influential role on the tacticity and chain-growth of the obtained PMMAs than the variation of reaction conditions under the controllable polymerization.