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Acetic Anhydride - Accelerating Agent for Nitroxide-Controlled Free-Radical Copolymerization of Styrene and Acrylonitrile

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2001

Year

Abstract

The influence of acetic anhydride on the controlled radical copolymerization of styrene and acrylonitrile was studied. If benzoyl peroxide/2,2,6,6-tetramethylpiperidine-N-oxyl (BPO/TEMPO) are used the addition of acetic anhydride up to a molar ratio of additive/TEMPO = 2 : 1 results in a twelve times higher rate of polymerization. The molecular weights are increased and the molecular weight distributions are slightly broadened. A further increase of this molar ratio did not accelerate the polymerization rate further, but broadened the molecular weight distributions. Contrarily, the influence of acetic anhydride on the PS-TEMPO controlled radical copolymerization is less pronounced. By means of UV-VIS spectroscopy the reduction of the concentration of free TEMPO through reaction with acetic anhydride at 125°C in ethylbenzene was demonstrated.