Effect of Polymer Polarity on the Estimation of Charged Groups in Polymers by Dye-Partition Technique
Physico-chemical aspects of the extraction of pinacyanol dye from basic solution by carboxyl-ended polymers of varying chain lengths into low dielectric constant organic solvents are discussed. Dye extraction is greater the higher the pH, the higher the aqueous phase dye concentration, the higher the chain length of the carboxylic acid and the greater the polarity of the organic solvent. The effect of chain length of the carboxylic acid on dye extraction is considerably reduced in dipolar organic solvents. The results have been interpreted in terms of the solvation of extracted dye carboxylate ion pairs with the solvent through dipole-dipole interaction. It has been pointed out that the success of the dye partition method of analysis of polymer end groups depends greatly on the organic solvent and not on the polarity of the polymer. Use of detergents as model carboxylate compounds leads to overestimation. The danger in using mixed-bed resins for cleaning polymer latices to process polymers for end group study by the dye partition method has been pointed out.
A method for the estimation of -COOH end groups in polymers is proposed.
KeywordsCarboxylic Acid Polymer Polarity Vary Chain Length Chain Length Dependence Carboxylic Acid Concentration
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