A DYE DIFFUSION TECHNIQUE TO EVALUATE GEL PROPERTIES

Abstract

ABSTRACT A diffusion method is described which can be used to evaluate the properties of macromolecular gelling agents. A dye solution is layered onto the top of a gel prepared to different concentrations and the solution is allowed to diffuse until a concentration gradient has formed. The concentration gradient as a function of distance and time is then evaluated using a scanning densitometer. From these results the apparent diffusion coefficient of the dye using Fick's second law is calculated. Care must be taken when evaluating gel systems using this method to account for dye:polymer interactions and to minimize polymer gel swelling. From the diffusion coefficient an evaluation of the structure of the gel can be made with respect to its degree of spacing.