Endgroup studies in persulfate-initiated vinyl polymer by dye techniques. Part II. Initiation by redox persulfate systems

Abstract

Poly(methyl methacrylate) samples obtained by aqueous redox initiation with persulfate in conjuction with reducing sulfoxy compounds such as HSO₃^-, SO₃^-, S₂O₃^-, S₂O₄^-, and S₂O₅^- are found by dye techniques to contain both hydrolyzable sulfate endgroups (derived from persulfate) and nonhydrolyzable sulfonate endgroups or the like (derived from the activator) to an average total of about 2 endgroups per polymer molecule. Sulfide (S^-) is unique as an activator, as only sulfate endgroups ( no sulfonate or hydroxyl) have been found in the polymers. Persulfate used in conjunction with other activators (such as Ag⁺, Fe⁺⁺ hydrazine and hydroxylamine, aliphatic amines, alcohols, reducing acids and their salts, etc.) produce polymers with both sulfate and hydroxyl endgroups. Incorporation of sulfate endgroups is favored under basic conditions and tends to be suppressed under acid conditions.