Vinyl polymerization by metal complexes, 19. Formation of copper(II) chelates of vinylamine/vinyl alcohol copolymers

Chelate formation of vinylamine/vinyl alcohol copolymers with copper(II) was studied both by the spectrophotometric and by titrimetric methods. For comparison, polyvinylamine/poly(vinyl alcohol) mixtures were also taken up for measurements. In the case of the copolymer systems, copper(II) ions were found to be coordinated exclusively by nitrogen atoms of the copolymer ligand. The complexation constants of the chelates were determined by applying the modified Bjerrum method, in neglect of the acid dissociation of hydroxy groups in the copolymers. It was found that the copolymer/Cu(II) chelates tend to be unstable with decreasing contents of NH₂ groups in the copolymers. In the homopolymer mixture systems, copper(II) ions are not coordinated by the oxygen atoms of poly(vinyl alcohol), but only by the nitrogen atoms of polyvinylamine.