Transfer of electroactive agents of different molecular size through the polyelectrolyte membranes

The layer by layer (LbL) sequential adsorption of oppositely charged polyelectrolyte multilayers (PEM) is the simple method for forming ultrathin membranes with controlled properties. In our paper we examined transfer of electroactive agents through the polyelectrolyte membranes formed from the pair of synthetic polyelectrolytes polyallylamine hydrochloride (PAH) and poly(4-styrenesulfonate) (PSS). Films were formed at the gold electrode surface and p-Benzoquinone (pBQ), 1,2-Naphthoquinone-4-sulfonic acid sodium salt (NQS), and Manganese(III)5,10,15,20-tetra(4-pyridyl)-21H,23H-porphin chloride tetrakis(methochloride) (MnP) were chosen as the electroactive compounds, which differed in the molecular size. We found that the oxidation/reduction current decreased with the number of deposited polyelectrolyte layers and that decrease strongly depended on the molecular size of the electroactive probe. We tried to find the relation between the film permeability and its thickness measured by single wavelength ellipsometry. Selection of electroactive compounds with different molecular size allowed to determine differences in PAH/PSS films permeability in multilayer polyelectrolyte membranes.