Electrical Poly 3- thiophene

In this paper we describe the preparation of thin polymer films by surface catalysis and anodic deposition. The results indicate that both synthesis routes produce orientationally ordered films that have similar infrared spectra. It is also shown that thin ordered films of poly(thiophene) have different electrochemical behavior than the fibrous films that are electrically conducting. 

The synthesis and characterization of polyacetylene (PA) provided new incentive for understanding 7r-electronic spectra, electron-phonon interactions and electronic correlations[l, 2, 14]. The electrical conductivity of chemically doped PA rivals that of metals. Families in Fig. 2 such as polydiacetylenes (PDAs), poly thiophenes (PTs), cr-conjugated polysilane (PSs) and polyparaphenylene vinylene (PPVs), among... 

Several conjugated polymers such as polyaniline, polypyrrole and poly thiophene have been prepared by chemical methods using doping. The electrical conductivity of these polymers has been controlled by (i) the type of dopant, (ii) the concentration of doping, (iii) the conditions of doping (the current density, temperature of reaction, etc.)... 

As mentioned in the introduction, the electrical conductivity upon doping is one of the most important physical properties of conjugated polymers. The conductivity ranges from lOOOOOS/cm for iodine-doped polyacetylene [41], 1000 S/cm for doped and stretched polypyrrole [42], to 500 S/cm for doped PPP [43], 150 S/cm for hydrochloric acid doped and stretched polyaniline [44], and 100 S/cm for sulfuric acid doped PPV [45] to 50 S/cm for iodine-doped poly thiophene [46]. The above listed conductivities refer to the unsubstituted polymers other substitution patterns can lead to different film morphologies and thus to a different electrical conductivity for the same class of conjugated polymer in the doped state. 

Depending on their structure, the polymers containing heterocycles have various applications. For example, poly(furfuryl alcohol) is used in composite materials with fillers such as sand and concrete, in copolymers with formaldehyde, etc. Some of the polymers from this group have special properties such as good electrical conductivity (after appropriate doping). Among these polymers are poly(thiophene-2,5-diyl) and particularly polypyrrole, CAS 109-97-7, (usually in carbon black doped with an organic acid anion). The structure of this polymer is shown below ... 

Table 2 contains idealized structures of some CPs with typical dopants and values for the conductivities of thin films. The exact structures of PPy and poly thiophene (PT) are unknown. Polyacetylene is the most crystalline and PANi can exist in several oxidation states with electrical conductivities varying from 10 S/cm to the values reported in Table 2. In its undoped state, PPS is an engineering thermoplastic with a conductivity of less than 10 S/cm. Upon doping with ASF5, conductivities as high as 200S/cm have been obtained after casting a film from a solution of AsFsP ...

It is often observed that the pharmacological effect of a thienyl or thenyl substituent is the same or similar to that of a phenyl or benzyl substituent. This phenomenon is known as bioisosterism [26]. Poly(thiophenes) can be used as electric conducting polymers [27]. 

Heterocycle-based electroconductive polymers , Berlin, A., Plastic Eng. (N.Y.) (Electrical and Optical Polymer Systems), 1998, 45, 47 Heterocycle-based electric conductors , Pagani, G. A., Heterocycles, 1994, 37, 2069 Conjugated poly(thiophenes) synthesis, functionalisation and applications , Roncali, J., Chem. Rev., 1992, 92, 711. 

The double-gyroid templates were found to be stable in a number of polar protic solvents, but these do not support the electrosynthesis of poly(thiophene), since the intermediate radical is extremely reactive towards nucleophilic species. Further, nonpolar solvents such as hexane and various fluorinated solvents were compatible with the styrenic templates, but unfortunately common ionic salts, which are usually added to increase the electrical conductivity of the electrolyte are not soluble in these. 

A number of conjugated heterocyclic polymers, viz., poly(pyrrole) [9], poly(p-phenylene) [10], poly(thiophene) [11], and poly(aniline) [12] are also electrically conducting and continue to be developed and studied for electrochromic devices [13-14 see also the companion chapter in this volume] and ion switching devices [15-16], among others. Polymer films with high electrical conductivity have been generated by electrochemical polymerization of benzenoid, nonbenzenoid and heterocyclic aromatics, in particular from the derivatives of pyrrole, thiophene, carbazole, azulene, pyrene, triphenylene and aniline. The electrochemical approach for making these films is very versatile and it provides a facile way to vary the properties of the films. The realization of the applications for each electroactive polymer depends on the control and particularly the enhancement of the... 

Y. Furnkawa, M. Akimoto and I. Harada. Vibrational key bands and electrical conductivity of poly thiophene. Synth. Met. 18(1-3), 151-156 (1987). 

Superconducting ceramics of Y,Ba2Cu30jj g have been used as substrates for the electrochemical deposition of either poly pyrrole or poly thiophene [87]. Ceramics are typically obtained by firing pressed powders of the oxide compounds. Thus, electrical and mechanical contacts made between the ceramics and wires produced mechanically or by vacuum deposition of metal are often found to be inadequate. Superconductors modified by conducting polymers may help improve the contact area. 

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