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Modification of carbohydrate polymers via grafting in air. 1. Ceric-Induced synthesis of starch-g-polyacrylonitrile in presence and absence of oxygen [electronic resource]

Pourjavadi, A. (Ali)

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  1. Type of Document: Article
  2. DOI: 10.1002/1521-379X(200204)54:3/4<140::AID-STAR140>3.0.CO;2-I
  3. Abstract:
  4. Monomer grafting, a unique technique for polysaccharide modification, is always performed under inert (e.g., N2) atmosphere. This work is the first report related to evaluating the possibility and efficiency of the grafting of acrylonitrile (AN) onto starch in presence of oxygen. Thus, corn starch (in both granular and gelatinized states) as well as soluble starch were grafted by AN using a ceric-carbohydrate redox initiating system. Graft copolymerizations were performed under nitrogen, air, and oxygen atmospheres at similar conditions. Grafting occurrence was verified using chemical and spectral proofs. The polymerization mechanism and kinetics were investigated by recording the temperature variation of the exothermic reactions and by measuring grafting parameters. A paradoxical action of oxygen was observed. In spite of dictating a retardation period, molecular oxygen obviously favors efficient grafting of AN onto gelatinized starch. In case of soluble and granular starch, however, oxygen inhibits grafting under the same reaction conditions. Presence of DMF-insoluble fractions within the released polyacrylonitrile (PAN) side-chains, obtained from the starch-polyacrylonitrile (SPAN) products of reactions performed under O2 and air, is attributed to some crosslinking reactions occurring during graft polymerization and/or acidic hydrolysis of the starch backbone of SPAN
  5. Keywords:
  6. Starch grafting ; Atmospheric oxygen ; Acrylonitrile ; Ceric ion
  7. Source: Starch - Starke ; Volume 54, Issue 3-4, pages 140–147, April 2002
  8. URL: http://onlinelibrary.wiley.com/doi/10.1002/1521-379X%28200204%2954:3/4%3C140::AID-STAR140%3E3.0.CO;2-I/abstract