EFFECT OF BINDING OF CATIONS TO POLYETHYLENE-GLYCOL ON ITS INTERACTIONS WITH SODIUM DODECYL-SULFATE

Interactions between polyethylene glycol and sodium dodecyl sulfate have been studied using fluorescence spectroscopy. Changes in polymer conformation on its association with the surfactant were monitored using polymers end-labeled with pyrene. The effect of various salts of sodium, cesium, lithium, and magnesium on the binding between polymer and surfactant was determined. The conformation of the polyethylene glycol is affected significantly by sodium dodecyl sulfate binding. Initial binding of the surfactant causes the polymer to coil whereas saturation of the polymer by the surfactant causes the coiled polymer to stretch out. The amount of surfactant bound to the polymer depends on the cations in the solution as well as the affinity of the cation toward polyethylene glycol. The stronger the binding of the cation to polyethylene glycol the less is the interaction between sodium dodecyl sulfate and the polymer.