Determination of sulfate and similar end groups in polymers [poly(methyl methacrylate) and polystyrene] by an improved dye interaction method

Abstract

It has been observed that in a benzene medium the carbinol base of a cationic dye reacts with a polymer with —SO₃Na and similar end groups that give rise to a reversible color formation of the dye cation. This reaction can be pushed to completion and consequent intensification of color by adding a benzene-insoluble acid such as citric acid. This principle has been applied to develop an improved dye interaction method of determining such end groups. The end groups values thus obtained by this method for different poly(methyl methacrylate) and polystyrene samples were found to be in fairly good agreement with those obtained by the dye partition (extrapolation) method.