Cyclic voltammetry polyacetylene

The cis/trans isomerization of cw-polyacetylene, previously only disclosed from spectroscopic data, has recently been detected by cyclic voltammetry The analysis of the redox data reveals that the trans-form is thermodynamically more favorable in the charged than in neutral state. 

Fig. 9.10 Cyclic voltammetry of a polyacetylene film electrode in the LiC104-propylene carbonate electrolyte. Scan rate 0.4 mV s. ...

The examples of polyacetylenes whose main chain is directly bonded to heteroaromatic rings (e.g., silole, carbazole, imidazole, tetrathiafulvalene, ferrocene) are increasing in number. Such polymers are usually obtained by one of catalysts (W, Mo, and Rh). The formed polymers are expected to display interesting (opto)electronic properties such as electrochromism, cyclic voltammetry, electroluminescence, and so on. 

Polyacetylene can be controllably oxidized or reduced by simple electrochemical procedures Cyclic voltammetry studies on free-standing films of cw-polyacetylene show that they can be reversibly oxidized at ca +3.6 V Li and reversibly reduced at ca +1.4 V vs Li. The reactions occurring at the cathode (equation 18a) and at the anode (equation 18b) are given below. 

Kaufman reported a lower value of 4 x cm s [21]. Because of the slow diffusion of dopants in polyacetylene, an electrode with a higher surface area is preferable for obtaining a high current density. Padula et al reported that highly porous polyacetylene (foam type) showed a higher current density than an ordinary film in cyclic voltammetry measurements [22]. 

The electrochemical behavior of poly(RCOT)s has also been examined [40]. As expected from the electrochemical properties of unsubstituted polyacetylene, films of poly(RCOT)s coated on an electrode and immersed in an acetonitrile electrolyte solution (in which the polymers are not soluble) are found to undergo reversible oxidative and reductive doping. Unlike unsubstituted polyacetylene, these films may be prepared readily by casting from solution, or, in the case of poly(scc-butylCOT), by electrodecomposition from a THF solution. In contrast to the voltammetry of polymer films, cyclic voltammograms of methylene chloride... 

---