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Capacitance polymer films

Figure 16. General transmission-line model for a conducting polymer-coated electrode. CF is the faradaic pseudo-capacitance of the polymer film, while Rt and Rt are its electronic and ionic resistance, respectively. R, is the uncompensated solution resistance. Figure 16. General transmission-line model for a conducting polymer-coated electrode. CF is the faradaic pseudo-capacitance of the polymer film, while Rt and Rt are its electronic and ionic resistance, respectively. R, is the uncompensated solution resistance.
On the basis of experimental findings Heinze et al. propose the formation of a particularly stable, previously unknown tertiary structure between the charged chain segments and the solvated counterions in the polymer during galvanostatic or potentiostatic polymerization. During the discharging scan this structure is irreversibly altered. The absence of typical capacitive currents for the oxidized polymer film leads them to surmise that the postulated double layer effects are considerably smaller than previously assumed and that the broad current plateau is caused at least in part by faradaic redox processes. [Pg.24]

They produced high performance electrets from thin polymer films metallized so as to yield high capacitance. Both electrical and mechanical properties of these transducers have been remarkable examples of how applications of science of solids, including knowledge of electron traps, conduction processes in insulators and the viscoelastic phenomena of semicrystalline polymers, can be combined.(6) Incidentally, similar ideas have been applied to optimization of the properties of particle microphones, through assemblies of perfectly microspherical polymer carbon systems. These have shown what limits of performance... [Pg.167]

A very common and useful approach to studying the plasma polymerization process is the careful characterization of the polymer films produced. A specific property of the films is then measured as a function of one or more of the plasma parameters and mechanistic explanations are then derived from such a study. Some of the properties of plasma-polymerized thin films which have been measured include electrical conductivity, tunneling phenomena and photoconductivity, capacitance, optical constants, structure (IR absorption and ESCA), surface tension, free radical density (ESR), surface topography and reverse osmosis characteristics. So far relatively few of these measurements were made with the objective of determining mechanisms of plasma polymerization. The motivation in most instances was a specific application of the thin films. Considerable emphasis on correlations between mass spectroscopy in polymerizing plasmas and ESCA on polymer films with plasma polymerization mechanisms will be given later in this chapter based on recent work done in this laboratory. [Pg.13]

For further electrochemical characterization of the conducting polymer films, the charge passed during the electrochemical synthesis can also be used to estimate the film thickness and level of doping, and thus the capacitance of the... [Pg.192]

The corresponding time constant mil be T(2 = 9 x 10 s, and the corresponding characteristic frequency mil be f(2 = 7 x 10 Hz or 700 MHz. This frequency is well above the capabilities of electrochemical impedance instrumentation. Thus, the capacitive loop corresponding to the outer layer will not be observed experimentally. The resistance of the layer influences measurements at all frequencies thus, the presence of a growing layer thickness will be manifested as an apparent increase cf the Ohmic resistance. For the situation described in this example, the circuit shown in Figure 9.5 should be amended as shown in Figure 9.6P- The ability to measure the capacitive loop associated with the outer porous layer does not depend on layer thickness, but it is sensitive to the effectixje conductivity of the layer. The effective conductivity of paints and polymer films is much... [Pg.161]

The synthesis of the metal containing polymer films involves a capacitively coupled diode reactor configuration in which one electrode is grounded, (the anode). [Pg.195]

To excite the polymer film, an input voltage waveform causes current to flow through the cells in a cartridge. An AC signal was chosen to (i) facilitate the capacitance measurement (ii) avoid electrode polarization and (iii) lower susceptibility to noise. [Pg.473]

A capacitive sensor with a molecularly imprinted polymer film as a sensitive layer has been reported. The layer was prepared by electropolymerization of phenol on a gold electrode with the template molecule, phenylalanine. The sensor capacitance was decreased by the addition of phenylalanine, but there was almost no change with glycine, tryptophan and phenol. The response time was 15 min (time for a half of the stationary value, 60 min), and the dynamic range was given as 0.5 to... [Pg.98]

In the diagram the cychc voltammogram of the polymer film is also shown. At positive potentials the film is metal conducting with high capacitance values and low resistance values. Capacitance decreases and resistance increases as the polymer becomes reduced. With the reduction the anions are expelled. The film becomes neutral state. [Pg.336]


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See also in sourсe #XX -- [ Pg.33 ]




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