Contribution of Size Exclusion Chromatography, Light Scattering, Viscometry, and Conductimetry to the Study of Solution and Gel Properties of a Cationic Polyelectrolyte

Abstract

Solution properties of a cationic polyelectrolyte poly (acrylamide-co-diallyldimethylammonium) were studied by size exclusion chromatography with double detection (differential refractive index and light scattering), viscometry, and electrical conductimetry, in water containing different ionic salts. These techniques allow not only the determination of molecular weights, molecular dimensions, and scaling law coefficients, but also study the influence of the counterion on the unperturbed dimensions of the chain. Moreover, swelling properties of crosslinked gel samples of this copolymer, both in pure water and water containing ionic salts, were also studied. The swelling degree is also sensitive to the nature of the anion of the salt and there is a direct correlation between the solution properties of the linear samples and the swelling behaviour of their crosslinked counterparts. Thus, measurements of the polymer in aqueous solution can be used to anticipate the swelling behaviour of the corresponding hydrogel.

Keywords:

• Conductimetry
• Hydrogels
• On line light scattering
• Poly(acrylamide-co-diallyldimethylammonium chloride)
• Polyelectrolytes
• Size exclusion chromatography
• Viscometry

ACKNOWLEDGMENTS

The financial support provided by the the Spanish DGICYT (project: CTQ2005-04710/BQU) and the CAM (project: S-055/MAT/0227), are gratefully acknowledged. One of us (G.M.) is grateful to the Spanish MEC for a PFPU grant.