Conductive Electroactive Polymers temperature

Poly(2-acrylamido-2-methyl-l-propanesulfonic acid) (PAMPS) is a highly ionic conductive synthetic polymer that has been used in combination with PVA in order to produce an electroactive network membrane as an artificial muscle (Dai et al. 2009). The PVA/PAMPS blends were subjected to a heat treatment at high temperatures (above 60°C) to facilitate formation of physical crosslinks in the ionic network (see Figure 4.2). 

Finally, in lightly doped electroactive polymers and for a sufficiently high temperature, one can consider that conduction takes place along the conducting paths by sufficiently mobile polarons to obtain a frequency-independent law (in the low frequency range) that is thermally activated ... 

Another class of thermally stable materials with electroactivity are polyacene quinone radical (PAQR) polymers. The thermal stability of PAQR polymers was. studied up to 1200°C under helium. The electrical conductivity was found to go through a minimum at about 500"C, showing that the original synthetic structure of a PAQR polymer is unique and thermally sensitive and that the negative temperature dependence of e.c. makes it similar to degenerate semi-metals [237]. 

The thermal stability of electroactive polyacene quinone radical polymers was studied up to 1200° C under helium and the electrical conductivity was observed to pass through a minimum at about S00°C with a negative temperature dependence like in the case of degenerate semimetals hence, these polymers show unique thermal properties [351]. The electrically conducting films of polyazulene were found to be stable in different enviromnental... 

The overall electroactivity of carbon-based actuators, including CNTs, CDCs, or activated carbons, predicates on two main actuation mechanisms. The first principle is based on the electronic (metallic) conductivity of carbon material. Actuators of such type need high electrical potential (field) for actuation. Actuation occurs due to carbon-carbon interaction change due to high electrical field and increased temperature (electrothermal effect) (Liu et al. 2014 Zhang et al. 2014). Another principle is diffusion of ions and ion pairs induced by applied low potential as shown in Fig. 1. These transducers usually combine carbon materials with polymer matrix and some ionic conducting media. They seem to have much more possible applications in the near future (Asaka et al. 2013). 

Table 20.8 contains a compilation of literature entries on the voltammetry of conducting polymer films. The scope of these studies is similar to that of the transient experiments discussed in Section V.A in terms of the types of electrodes and media employed. Both cyclic and hydrodynamic voltammetry have been used as shown in Table 20.8. Other aspects under discussion include the mathematic modeling of cyclic voltammo-grams [277,278], the occurrence and origin of prewaves in the cyclic voltammograms [319], the use of very fast scan rates [220], structural relaxation effects and their manifestation in voltammetry [304,317,320], the inactivation of polymer electroactivity when driven to extreme potentials, and the so-called polythiophene paradox [225,226,306,321]. Unusual media and cryogenic temperatures have also been employed for the volta-mmetric observation of doping phenomena [322-325]. Dual-electrode voltammetry (Section II.1) has been performed on derivatized polypyrrole [290] in an attempt to deconvolute the electronic and ionic contributions to the overall conductivity of the sample as a function of electrode potential. Finally, voltammetry has been carried out in the solid state , i.e., in the absence of electrolyte solutions [215,323].

Exposure to extreme pH, temperature, or ionic strengths can result in denaturation of bioactive species and a subsequent loss in bioactivity. As with all sensors, CEP sensors will be subject to chemical fouling and biofouling. The design of polymer surfaces and the use of impressed potentials may be useful in addressing this problem. As mentioned, if exposed to extreme positive potentials (>0.80 V), conducting polymers will become overoxidized. This results in a loss of conductivity and electroactivity and a degradation of mechanical properties. 

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