Characterization of Water Soluble Polymers by Ion Chromatography. I. Poly(Acrylamide-co-Sodium Acrylate)

Abstract

Abstract The sodium counterion contents of a series of poly(acrylamide-co-sodium acrylate) copolymers of varying composition have been investigated by Ion Chromatography (IC). Sodium ion contents obtained by IC are comparable with values based on either elemental analysis or titration techniques. Therefore, IC results can be used to determine the degree of polymer hydrolysis. Since sodium ion can be quantified at ppm levels, this analysis is possible with solutions containing =20 ppm polymer. At such concentrations, there is no evidence for column plugging or excessive system backpressure. Ionic contamination from glass storage vessels can be significant at these dilutions, however. The results of polymer dialysis and sonication studies are included. This study has explored the effects of key polymer and IC variables on the determination of Na+ ion content of aqueous HPAM solutions. Good agreement with the results based on elemental analysis or an ion-exchange/titration technique was established. A good correlation was also obtained between the sodium ion content of replicated samples of HPAMs versus the degree of hydrolysis of these polymers. Thus the feasibility of using IC for compositional analyses of these water soluble polymers has been demonstrated. Refinement of the method should lead to improved precision and several useful applications. Based on the inherent attributes of ion chromatography (e.g. small sample size requirements, high precision, quick analysis times, etc.) IC should have wide applicability in studies of ionic water soluble polymer systems. Potential applications include investigation of polymer composition, polymer concentration, polymer adsorption, and effects of processes such as dialysis.