Volumetric Properties of Poly (Vinyl Alcohol, Vinyl Sulfate Ester Salt) Polyelectrolytes in Salt Free Aqueous Solutions

Abstract

Sharp break points in the apparent molar volume and compressibility functions of poly (vinyl alcohol co‐vinyl sulfate sodium salt) copolymers were found in the 0.01–0.03 molal‐segment concentration range in aqueous solution. Both apparent molar volume and compressibility increase linearly with concentration below the break point, while they show saturation type characteristic above the break point. The position of break point is independent of the vinyl‐sulfate/(vinyl‐sulfate and vinyl‐alcohol) group‐ratio of the polyelectrolyte. An association process between the individual polyelectrolyte molecules is suggested for the interpretation of break points. The partial molar volumes at infinite dilution depend linearly on the vinyl sulfate sodium salt group content. The partial molar volume contribution of (vinyl sulfate sodium salt)‐group and (vinyl alcohol)‐group were determined from concentration ranges corresponding to both the associated and non‐associated state of the polyelectrolyte salt.

Keywords:

• PVA
• Poly vinyl alcohol
• Vinyl sulfate ester
• Apparent molar volume
• Partial molar volume
• Molar compressibility
• Ultrasound velocity
• Association
• Hydrophotic hydration
• Copolymer
• Polyelectrolyte

Acknowledgments

OTKA support provided through T022935 and T025878 projects is gratefully acknowledged. The authors would like to thank Péter Máhr, Mrs. Jaksity, Rozália Engel, and Einar Høgseth for sample preparation and technical help. The authors acknowledge the work of Referee #1 who helped improve the interpretation of the data.