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Polydopamine (PDA) coatings appear as a universal functionalization methodology allowing to coat the surface of almost all kinds of known materials with a conformal, stable, robust and reactive material. Relatively few investigations were dedicated to the incorporation of other molecules in PDA coatings during their deposition from dopamine solutions under oxidative conditions. Herein we rely on the assumption that the basic building blocks of PDA could be porphyrin like tetramers (as well as higher order oligomers) of 5,6-dihydroxyindole and we investigate the influence of a cationic Cu(II) phtalocyanine, namely Alcian Blue (AB), on the deposition kinetics and on the properties of PDA films. We demonstrate that AB is indeed incorporated in the PDA films to yield a composite PDA–AB coating displaying the optical features of both PDA and AB. The amount of incorporated dye depends on its concentration in solution. The obtained PDA–AB films have a smaller thickness than their related PDA counterparts, a different morphology and a higher permeability to the anionic hexacyanoferrate redox probe. In addition, the incorporation of AB in the films is not homogeneous through their thickness as inferred by means of X-ray photoelectron spectroscopy. The reason for this interesting finding is discussed on the basis of the interactions between AB and PDA as well as on the basis of the structure of PDA films. [ABSTRACT FROM AUTHOR]

Highlights: [•] Step-by-step assembly of dopamine-eumelanin and metal cations (Cu2+, Fe3+, La3+) is possible. [•] The coatings made from trivalent cations growth faster than those made from Cu2+. [•] Fe3+ does not undergo a change in its redox state upon incorporation in the coatings. [ABSTRACT FROM AUTHOR]

Highlights: [•] The zeta potential of (PAH-polyoxometalate) n films is measured as a function of the ionic strength. [•] The zeta potential is stable as a function of time when the ionic strength is higher than 50mM. [•] At smaller ionic strengths, the zeta potential decreases without desorption. [ABSTRACT FROM AUTHOR]