Physicochemical and Electrochemical Characterization of Electropolymerized Polydopamine Films: Influence of the Deposition Process

Abstract

Polydopamine (PDA) is a synthetic eumelanin polymer which is, to date, mostly obtained by dip coating processes. In this contribution, we evaluate the physical and electrochemical properties of electrochemically deposited PDA films obtained by cyclic voltammetry or pulsed deposition. The obtained PDA thin films are investigated with respect to their electrochemical properties, i.e., electron transfer (ET) kinetics and charge transfer resistance using scanning electrochemical microscopy and electrochemical impedance spectroscopy, and their nanomechanical properties, i.e., Young’s modulus and adhesion forces at varying experimental conditions, such as applied potential or pH value of the medium using atomic force microscopy. In particular, the ET behavior at different pH values has not to date been investigated in detail for electrodeposited PDA thin films, which is of particular interest for a multitude of applications. Adhesion forces strongly depend on applied potential and surrounding pH value. Moreover, force spectroscopic measurements reveal a significantly higher percentage of polymeric character compared to films obtained by dip coating. Additionally, distinct differences between the two depositions methods are observed, which indicate that the pulse deposition process leads to denser, more cross-linked films.

Band Gap Engineering toward Semimetallic Character of Quinone-Rich Polydopamine

“…8 nm (inset in Figure 8b). Similar behavior was observed in the work of Kund et al 59 Diffuse reflectance spectra and KM functions show that as the PDA thickens, absorption in the visible range is more pronounced and the band-to-band absorption edge plummets (Figure 8b,c).…”

“…The thickness of PDA depends on many factors such as the solvent, ionic environment, and synthetic approach, 11,12,58,59 which have a profound role in the properties of the semiconductor|PDA heterojunctions. 23,25 In our work, the thickness of the PDA electropolymerized in TiO 2 is almost linearly dependent on the number of CV cycles during electropolymerization with the limiting value of ca.…”

Highly sensitive capacitance-based nitrite sensing using polydopamine/AuNPs-modified screen-printed carbon electrode

“…Electrochemical behaviour of the pDA/AuNPs/SPCE 3.1.1. pDA deposition. The electrochemical deposition of polydopamine (pDA) on conductive substrates can be achieved through cyclic voltammetry 38,39 or pulsed deposition, 40,41 both of which are fast-coating processes that offer excellent control over lm thickness. While pDA lm growth via auto-oxidation or dipcoating typically takes several hours, electrochemically deposited pDA lms can be obtained with reproducible thickness and morphology within a few minutes.…”

Effects of olanzapine and lithium carbonate antipsychotic agents on dopamine oxidation

“…The literature 55,61 has shown that when the pH value is greater than 7, dopamine can rely on the dissolved oxygen in the solution to generate polydopamine, which becomes easier under electrooxidation conditions. 62,63 Therefore, it can be inferred that the addition of Li 2 CO 3 leads to the continuous increase of pH (from 7.47 to 9.73), which promotes the formation of polydopamine and leads to electrode passivation. This passivation effect exceeds the deprotonation effect, so that the dopamine oxidation peak current decreases in alkaline media.…”