Chemical and mechanical properties of redox polymer-modified electrodes

Swelling of electrochemically active polyelectrolyte multilayers

“…However, electrochemistry is used to determine parameters, which are needed to develop a thermodynamic picture of this process. Nernst plots, derived from controlled potential coulometry, showed coupling between mechanical and electrochemical thermodynamics and were used to estimate the mechanical energy consumed during the swelling [27][28][29]. Cyclic voltammetry with standard redox probes like hexacyanoferrate was applied and the Donnan potential of the multilayer films was calculated using the measured shift in apparent redox potential (see Fig.…”

“…In fact, the field of electroactive PEMs is largely dominated by the effort to realize new amperometric biosensors [26]. Even though the electrochemical swelling of redox modified electrodes was already discussed in the 1980s [27][28][29], no attention was paid to this phenomenon for electroactive PEMs until Calvo's group described it in 2002 for several different polymer systems [30-32 • ]. By now, redox-driven swelling has been characterized for a variety of PEM systems with different physicochemical properties, among them linear growing multilayers (poly(allylamine) derivatized with Os(bpy) 2 PyCl + (PAH-OS) and poly(vinyl sulfonate) (PVS) or poly(styrene sulfonate) (PSS) [32 • ,33-37 •• ,38,39]), exponentially growing ones (ferrocyanide containing multilayers of poly(allylamine) hydrochloride (PAH) and poly (glutamic acid) (PGA) [40,41 •• ]) as well as multilayers containing enzymes (PAH-FC and GOx [31]) or Prussian Blue (PB) nanoparticles (with linear poly(ethylene imine) (LPEI) [42 • ]).…”

Voltammetric potentials of polyaniline varying with electric percolation

“…4. All points fell on a line that was empirically subject to (12) The value of n is reported to range from 0.2 to 0.4, which has been explained by a redox reaction in which one unit of the four aniline moieties participates in the conversion of emeraldine to leucoemeraldine [39 β ≡ Γ OS /Γ O = k/r (13) ]. In this case, the power, -3.3n, ranges from -0.7 to -1.2, and is close to -1.…”

“…This asymmetry is a central theme in the characterization of conducting polymers [7][8][9][10][11][12][13].…”

“…Asymmetry may be caused by the structure change between local and extended polymer motions [11], the mechanical work coupled with the redox reaction [13], the propagation of the conducting zone [ 24 , 25 ], the logarithmic relaxation [ 26 12 ], and/or the structural rearrangement of polyaniline during the redox reaction [ ].…”