Chemical polymerization poly thiophene

With the aid of NMR spectroscopy ( H- H NOESY) for PDDT and its copolymer with 3-methylthiophene in deuterated chloroform, the configurational structures were determined [90,91]. The 3-dodecylthiophene monomer is proved to be attacked predominantly at the p position of the thiophene ring (head) with a probability of 82% during the electrochemical polymerization [90]. PHT prepared by using a zero-valent nickel complex contains a larger proportion of HH units than HT units [92]. Chemically polymerized poly-(3-cyclohexylthiophene) contains HT and HH-TT coupled components in the ratio of 7 3 [93]. 

Summaries on the synthesis, properties, and uses of polythiophenes are included in two general reviews on poly thiophenes [259,260]. A synopsis of important aspects of polythiophenes are also included in several reviews on various aspects of conducting polymers [221-226], Cation radicals are the propagating species in both electrochemical and chemical oxidative polymerizations of thiophene and its derivatives. The polymer obtained by this method is linked primarily by a,a-linkages. However, other types of linkages (a,f3 and /3,/3) are present in varying amounts (Fig. 59). Substituted thiophene derivatives can couple in a head-to-tail or head-to-head manner. 

Several mechanisms have been proposed for both electrochemical and chemical oxidative synthesis of poly thiophenes. The proposed mechanisms are similar to those proposed for polypyrrole formation. The first step of the polymerization is the oxidation of the thiophene monomer to a cation radical. The subsequent steps are controversial. There are several possibilities. The cation radical can couple with another cation radical or with a neutral species. Alternatively, the cation radical can deprotonate to form a neutral radical. This radical can then couple with another radical or with a neutral species. Several of these possibilities are discussed below. 

Polymer materials possess varying physical and structural properties dependent upon the route of synthesis and polymerization, as was discussed in Section 4.1. Properties also depend upon their actual physical form or state. The as prepared samples obtained by chemical polymerization are in the state of powder. Polymer films are prepared by dissolving the powder in an appropriate organic solvent and then letting the solution dry by slow evaporation. Common solvents with poly(alkylthiophene)s are chloroform, tetrachlormethane, toluene, tetrahydrofuran, decaline, anisole, thiophene and some others, whereas acetone. 

Conducting poly thiophene (PTh)-SWCNTs composites were synthesized by the in situ chemical oxidative polymerization method.Using an excitation wavelength of 514 nm, the authors studied the pristine and the derived materials. The Raman spectrum for the SWCNT PTh composites is clearly an addition of the corresponding spectra of PTh and SWCNTs, demonstrating that SWCNTs served as templates in the formation of a co-axial nanostructure for the composites. ... 

SnOj hollow spheres/poly-thiophene nanohybrid (PTh-SnOj) In-situ chemical polymerization Pellet NO [24]... 

Nicolas et al. also synthesized semi-fluorinated polythiophenes (Scheme 4) [52, 53]. The monomers were chemically polymerized by oxidation with FeCls, or electrochemically polymerized in acetonitrile containing BU4NPF6 as the supporting electrolyte. The electrochemically synthesized films showed rough surfaces. The poly(fluorinated thiophene) films electropolymerized from the monomer with n = 8 and m = 2 showed a WCA of 153°, while the corresponding spin-coated films exhibited a much smaller WCA, due to their smooth surfaces. Their results indicated that the length of the fluorinated chain had weak influence on the surface property of the resulting film. 

Chemical synthesis Poly condensation reaction of di-functional thiophene in presence of Ni catalysts Oxidative coupling reaction of bi-thiophene in presence of ferric chloride using AICI3, CUCI3 and organic solvents Plasma polymerization from 3-methyl thiophene or thiophene (1-6)... 

Vanderzande et al. reported the facile synthesis to 5,6-disubstituted-l,3-dithienylbenzo[c]thiophenes 3.10 via Pd°-catalyzed coupling reaction of 5,6-dichloroterthiophenes 3.9 with an alkyl Grignard reagent (Scheme 1.30) [309, 321]. Chemical polymerization of the 5,6-modified monomers with FcCIb yielded polymers with bandgaps of 1.4-1.8 eV, which are similar to that of poly(dithienylbenzo[c]thiophene) P3.3 [309]. Application of these polymers as donors and fullerene PCBM as acceptor in bulk heterojunction solar cells (BHJSC) was also investigated and reported. An overall power conversion efficiency of 0.3 % and an internal power conversion efficiency of 24% were obtained for PMMA-poly-P3.9c-PCBM (1 2 6) blended devices [321]. 

Homopolymers of the DTT series can be obtained by chemical or electrochemical oxidation of the monomer units or by photochemical polymerization [46,47]. Electron delocalization is greater in DTTs than for thiophene, hence the polymers are expected to have lower bandgaps than poly(thiophene) (ca 2.0 eV),... 

Early progress in polythiophene chemistry was achieved by the synthesis of mono- and dialkoxy-substituted thiophene derivatives developed by Leclerc s group [6], industrial scientists at Hoechst [7-9] and Japanese researchers [10, 11], However, most polymers of mono- and dialkoxythiophenes exhibited low conductivity in the oxidized, doped state. A breakthrough in this area was the synthesis of polymers of the bicyclic 3,4-ethylenedioxythiophene (EDOT) and its derivatives - electrochemically polymerized by Heinze and co-workers and chemically polymerized by Heywang and Jonas of the Bayer Corporate Research Laboratories [12, 13]. In contrast to the non-bicyclic polymers of mono- and dialkoxythiophenes, poly-3,4-ethylenedioxythiophene (PEDOT) has a very stable and highly conductive cationic doped state. The low HOMO-LUMO bandgap of conductive PEDOT [14] allowed the formation of a tremendously stable, highly conductive ICP. Technical use and commercialization quickly followed today, ICPs based on PEDOT are commercially available in multi-ton quantities. 

Electrically conductive PTs are prepared by polymerization in an electrolyte in the presence of polymeric compounds with sulfonic acid groups [692]. The electrochemical polymerization of thiophene and Nafion gives a self-supporting film showing a uniform distribution of sulfur across the film and a reversible voltammogram [693]. Alkoxy substituted thiophene derivatives are electro-chemically polymerized in a solvent in the presence of a proton source in the form of a Bronsted acid [694]. The electrochemical preparation of poly-(3-alkyloxythiophene) without a Brdnsted acid has also been studied [695]. 

The synthetic methods used to polymerize the 3-alkyl thiophene do not differ substantially from these employed for thiophene. The good choice of the solvent is important to ensure a complete dissolution of the monomer and the electrolyte in the electrosynthesis case. Chemically polymerization is based on the Grignard coupling method used by Yamamoto et al. [71] and later revised by Kobayashi et al. [72]. Some polymerizations carried out with chemical oxidants are also known with poly(3-alkyl-thiophene) [73]. 

In contrast to thieno[3,4-fe]thiophene (2), electropolymerization of which was not reported until 2001 [42], electrochemical and chemical polymerizations of thieno [3,2-( ]thiophene (1) were conducted in the 1980s [18], thus electrochemical polymerization of thieno[3,2-b]thiophene (1), results in poly(thieneno[3,2-b]thiophene) (PTT, 85) with the units linked through the 2- and 5-positions. 

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