Surface charge effects on the redox switching of LbL self-assembled redox polyelectrolyte multilayers

Charge Transport in Redox Polyelectrolyte Multilayer Films: The Dramatic Effects of Outmost Layer and Solution Ionic Strength

“…[45][46][47] The magnitude of these processes in similar systems to the osmium pyridine-bipyridine derivatized poly(allylamine) (PAH-Os)/poly(vinyl sulfonate) (PVS) films studied here is less than about 30%. [30,[44][45][46][47] Since the error that would be introduced in D app by neglecting a swelling of this magnitude [48] is much smaller than the variations observed due to the nature of the outmost layer and changes in ionic strength, we will assume a constant film thickness as determined in water: [14] 1.5 nm for Au/3-mercapto-1-propanesulfonate (MPS)/PAH-Os, 10.2 nm for Au/MPS/(PAH-Os/ PVS) 4 PAH-Os, and 11.5 nm for Au/MPS/(PAH-Os/PVS) 5 .…”

“…Following the first examples of LbL-modified electrodes in 1997, the toolbox of redox-active building blocks has grown to include redox proteins, [2][3][4][5] inorganic complexes, [6,7] nanocrystals, [8] and several types of redox polyelectrolytes. [2,[9][10][11][12][13][14] Electrochemically active polyelectrolyte multilayers [15] have received widespread interest due to their potential applications in sensing, [2,4,9,10] electrochromic devices, [7][8][9]11] and as platforms for fundamental studies of redox proteins. [5] The timescale required to electrochemically switch the oxidation state of surface-confined redox species is a parameter that directly impacts on device performance.…”

“…In a previous report, we showed by electrochemical impedance spectroscopy (EIS) that polyanion-terminated films exhibit a hindrance for redox switching as compared to polycation-terminated ones. [14] However, it could not be determined whether the polyanion topmost layer affects the electron transfer, charge transport or another process. An important difference between chemically cross-linked hydrogels and PEMs is that the latter are ion-pair cross-linked films and therefore soluble salt plays an important role controlling the degree of crosslinking.…”

“…[14] In spite of these previous efforts, a systematic analysis of the electrochemical kinetics in LbL films has remained elusive because of the nonideal electrochemical response of polyanion capped films, which precluded the analysis with theoretical models. [14] Herein, we use variable-scan-rate cyclic voltammetry to characterize charge transfer and transport for different film architectures and solution ionic strengths. This approach has been pioneered by Laviron [31,32] and subsequently employed to study several diffusion-controlled electrochemical systems.…”

Bio‐interfaces—Interaction of PLL/HA Thick Films with Nanoparticles and Microcapsules

“…[18] Polyelectrolyte multilayer films are extremely versatile; they can possess porosity [19] and thermochromism, [20] and can be controlled electro-chemically. [21] Besides, their thickness can be controlled by the ionic strength. [22] LbL films can be further enhanced by cross-linking aiming for construction of free-standing films.…”