Controlled growth of layer-by-layer assembled polyelectrolyte multilayer films under high electric fields

Hypothesis: The application of an external electric Field (E-Field) to control layer-by-layer (LBL) growth of polyelectrolyte multilayers (PEM) typically involves hydrolysis of the water at the electrodes. We hypothesize that by isolating the electrodes from contact with the water, high E-Fields could be used to control the conformation of the polyelectrolytes in the solution phase and thus, enable non-chemical control of the LBL growth. Experimental: Attenuated total reflectance infrared spectroscopy was used to monitor the bound fraction and adsorbed amount as a function of time for the sequential addition of polyacrylic acid and polydiallyldimethylammonium chloride adsorbed on a TiO2 film under the applied E-Field. Findings: The direction of the E-Field relative to the TiO2 film controlled the PEM growth, resulting in non-linear growth or decay. In the case of non-linear LBL decay, there was a decrease in adsorbate mass in successive layers to a point of no growth. (C) 2019 Elsevier Inc. All rights reserved.