Shear induced changes in the streaming potential of polyelectrolyte multilayer films

Streaming potential measurement is one of the most frequently used characterization methods of polyelectrolyte multilayer films. In most cases, the adsorption of a polyelectrolyte occurs up to an overcompensation of the surface charge. Herein, we generalize previous findings that the obtained streaming potential (transformed into a relative ζ potential) is dependent on the history of the measurement and in particular that shear stresses due to the flow of the solution induce a reduction in the absolute values of the ζ potential. These findings show that huge care should be taken when defining an experimental protocol aimed to measure the zeta potential of polyelectrolyte multilayer films using the streaming potential method. Ideally, to avoid the influence of shear induced desorption of polyelectrolytes on the zeta potential values, polyelectrolyte multilayer films made from different number of layers should be characterized independently under overall identical conditions.