Kinetics and mechanism of the K₂CrO₄NaAsO₂ redox-initiated aqueous polymerization of acrylonitrile

The kinetics and mechanism of acrylonitrile polymerization initiated by a redox pair [potassium chromate (K₂CrO₄) and sodium arsenite (NaAsO₂)] were studied. The overall rate of polymerization was proportional to √[K₂CrO₄] × [NaAsO₂], and the energy of activation was approximately 10.5 kJ/mol. Polyacrylonitrile was recovered as a coagulum in the medium. The formation of polyacrylonitrile was confirmed with Fourier transform infrared and ¹H-NMR analyses. Scanning electron microscopy analysis of the polymer revealed the formation of aggregates of polymer particles (3–67 nm). Thermogravimetric studies indicated 50% weight loss at 400°C, and dynamic thermal analysis scan studies revealed an exothermic peak at 507°C due to massive oxidative thermal degradation of the polyacrylonitrile backbone. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 276–280, 2005