Redox-Initiated Grafting of Acrylic Monomers onto Poly(vinyl Alcohol)

Abstract

Loss of capacity of magnetic micro ion-exchange resins has been suggested to be caused by cleavage of unstable linkages formed during the graft polymerization reaction. The nature of the grafting process was investigated by using a series of model compounds having the same structural features as the glutaraldehyde-crosslinked poly(vinyl alcohol) core matrix. These compounds were then subjected to hydrogen peroxide oxidation, followed by the addition of monomer in the presence of iron(II). The identity and extent of peroxidation of the intermediate compounds was determined. In each of the peroxidation reactions the tertiary acetal hydrogen was oxidized to a hydroperoxy derivative. Some of these derivatives were able to dimerize to form peroxy compounds. The reactions occurred rapidly at room temperature when an acetal compound was shaken with hydrogen peroxide. Good yields could be obtained by precipitation of the sodium salts of the hydroperoxides. The hydroperoxy derivatives were shown to initiate polymerization of methyl acrylate, acrylic acid, and acrylamide when in the presence of iron(II).