✍ Scribed by C. Mijangos; G. Martínez; J. Millán
No coin nor oath required. For personal study only.
A~traet--The nucleophilic substitution reactions of a commerciaL poly(vinylchloride) with sodium isooctylthioglycolate and sodium isooctylthiosalicylate have been studied in solutions in cyclohexanone. The kinetic results show that only a fraction of polymer is capable of reacting even if ,severe experimental conditions such as high temperature and concentration of nucleophile are used. The reactive parts, as quantitatively estimated according to earlier results, is shown to be higher for sodium isooctylthiosalicylate than for sodium isooctylthioglycolate probably because of the higher nucleophility of the former species despite its higher steric hindrance. ~)C-NMR measurements for all the modified samples demonstrate the content of unreacted isotactic and heterotactic triads to be lower as the degree of substitution increases, this effect being more important for triads of the former type during the first stages of the reaction. It is inferred that the stereoselectivity of substitution on PVC is independent of the nucleophile, while both the total reactive parts and the rate of substitution depend on the type of nucleophile. Degrees of substitution of I 1.3% enhance the thermal stability of the polymer and cause pronounced changes in the u.v.-visible spectrum of the polymer after degradation. Both features are explained on the basis of earlier results with sodium thiophenate. The results indicate a useful pathway for controlled grafting of suitable functions on PVC.
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