Formation of free films of aqueous solutions of poly(ethylene oxide): The influence of surfactant

We report on the formation of films supported by a wire frame using aqueous solutions of PEO with and without SDS. We find that it is possible to make films in the absence of the surfactant SDS, and that films can be made that are thicker than the diameter of the wires that support them. Upon addition of SDS, for capillary numbers (Ca) above 10^-3 we find that initial film thickness decreases as a function of Ca when using high molecular weight PEO (10⁶ g/mol) at concentrations above 0.5%wt. Comparisons with data in the literature are provided, as well as a discussion of the general rheology of PEO-SDS complexes to gain an understanding of the experimental observations. Finally, we observe abrupt changes in the rate of film thinning corresponding to the moment when film formation stops. We discuss this change in thinning rate and how it may relate to mechanisms of film formation.