| Abstract: | The use of Cobalt(II) complexed with various polyaminocarboxylic acids and hydrogen peroxide has been shown to be an effective initiator for the emulsion polymerization of styrene. The polyaminocarboxylic acids used were ethylenediaminetetraacetic acid (EDTA), ammonia diacetic acid (ADA), N,N′-bis(2-aminoethyl)ethylenediaminehexaacetic acid (TTHA), ammonia triacetic acid (ATA), and N′-hydroxyethylethylenediamine-N,N,N′-triacetic acid (HEEDTA). In the case of the HEEDTA system, the effect of varying the concentrations of the initiator components was examined and found to be broadly similar to that observed in other metal ion chelate-hydrogen peroxide initiators. All the systems were effective over a wide pH range (generally 3–9), and zero-order rates in the range of 30–90%/hr were observed, although there was considerable variation in detail in the manner in which the zero-order rate depended on pH. The behavior of these systems is commented upon in the light of earlier results on similar systems and of previously published redox potentials of the related cobalt(II)–cobalt(III) chelate systems. |
