13C NMR study of hydrolyzed poly(acrylonitrile)

A method for the determination of chain microstructure of hydrolyzed poly(acrylonitrile) (PAN) and of copolymers of acrylonitrile with acrylamide by means of 13 C NMR spectroscopy is described. Besides the overall composition of poly(acrylonitrile-co-acrylamide), this method permits the population of all acrylamide-centered compositional triads to be determined; it is then possible to follow the values of the rate constants of nitrile group hydrolysis in dependence on its neighbours. Under certain circumstances the knowledge of the mentioned triads permits also the copolymerization parameters for copolymerization of acrylonitrile with acrylamide to be determined. It was confirmed that acid-catalyzed hydrolysis of PAN in concentrated nitric acid yields acrylonitrile-acrylamide block copolymers.