Polymer Bulletin, Vol.47, No.3-4, 359-366, 2001
Partition of potassium nitrate between polyacrylamide gel and aqueous methanol solutions
Samples of nonionic polyacrylamide (PAAm) gel were equilibrated in water-methanol-KNO3 mixtures and distribution of salt and methanol between gel and surrounding liquid was examined. In water and mixtures of low methanol concentration the both components were almost equally partitioned. On the other hand, in methanol-rich media the accumulation of KNO3 and water uptake in the gel were observed. Changes in the salt and solvent distribution occurred around the same mixture composition which correspond to the Theta-solvent composition for linear PAAm. The results point to the importance of preferential gel hydration in salt partitioning. However, possible role of other factors (e.g., the specific ion binding to the polymer) in the salt distribution is also shown.