Solvent dependence of stereoselective substitution reaction on poly(vinyl chloride). A useful tool to investigate the tacticity effect on Tg

✍ Scribed by N. Guarrotxena; G. Martinez; J.M. Gomez-Elvira; J. Millan

• Publisher: Elsevier Science
• Year: 1993
• Tongue: English
• Weight: 334 KB
• Volume: 29
• Category: Article
• ISSN: 0014-3057
• DOI: 10.1016/0014-3057(93)90129-4

✦ Synopsis

The substitution reaction of PVC with sodium benzenethiolate has been performed in two series of solvents. The one series includes solvents bearing C~-----O or --O--function; the other includes some more basic solvents such as N-methylpyrrolidone and hexamethylenphosphotriamide. ~3C-NMR analysis of the modified polymers shows that reactions in the former type of solvent involve first a fast period in which the mm terminal triad of isotactic sequences of at least one heptad react exclusively. Then, a slower stage involves the mr triads in the atactic parts, besides the mm terminal triads of isotactic sequences shorter than one heptad. The glass transition temperature, as measured by DSC, is shown to decrease linearly with degree of substitution at a definite rate for each series of solvents. The results, as analyzed in the light of earlier work, provide some novel ideas on the role of distinct reactive structures in polymer-solvent and polymer~olymer interactions of PVC.