ISSN:
1022-1352
Keywords:
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Physics
Notes:
Poly(styrene-co-acrylic acid) on sulfonation with concentrated sulfuric acid exhibits an unusual acid-base indicating property: an intense purple colour in alkali which changes sharply to yellow at the equivalence point. The acid-base indicating property of the polymer can not be explained by the simple structure of the sulfonated copolymer. On the basis of infrared and nuclear magnetic resonance studies it is suggested that the copolymer during sulfonation undergoes an internal Friedel Crafts acylation followed by cyclic dehydration leading to a conjugated structure. A possible mechanism is proposed for the colour change with change in pH. The copolymer was prepared also in form of spherical beads which can be used repeatedly as indicator in acid-base titrations.
Additional Material:
7 Ill.
Type of Medium:
Electronic Resource
