The microstructure of vinylidene cyanide-vinyl acetate copolymer was studied by 125-MHz 13C NMR spectroscopy. Compositional sequence distributions obtained from cyanide (VDCN-centered) and methyl (VAc-centered) triads were in good agreement with the predicted sequence distributions calculated by using the reactivity ratios (r1; r2) and the conditional probabilities for cross propagation (Pl2, P21). Configurational results in the alternating sequence were interpreted in terms of our defined e-enchainments (those of a group relative to the other separated by five skeletal carbons) assuming VAc-VDCN as a repeating unit. e-Isotacticity , could be obtained from cyanide carbon resonance as well as from methine carbon resonance, showing good agreement with each other. It was found that vinylidene cyanide-vinyl acetate copolymer is a highly alternating copolymer with a nonstereoregular structure.

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