Poly thiophene

Kaneto et al.523) have made measurements on the diffusion of lead perchlorate in polythiophene by following the colour change. They found a diffusion coefficient which varied from 10-1° to I0-12 cm2 s 1, depending upon the applied potential. The complexities introduced by morphological heterogeneity, counter-ion motion and solvent effects mean that further studies will be required to determine the relative importance of factors affecting diffusion in these materials. 

The colour change from black to pale yellow, which accompanies undoping, has been proposed as the basis for optical switching devices524), requiring very thin (less than 1 micron) films. 

---

Polypyrrole, poly thiophene, polyfuran, polycarbazole, polystyrene with tetrathi-afulvalene substituents, polyethylene with carbazole substituents, and poly-oxyphenazine as electrochemically active polymers for rechargeable batteries 97CRV207. 

Synthetic principles for bandgap control in tt-conjugated systems of poly-(thiophene) and related systems with fused thiophene rings 97CRV173. 

BEH-PPV Poly(2,5-bis(2 -elhylhcxyloxy)-psubstituted poly thiophene... 

We Finally note that the MTR model is a priori more appropriate to disordered materials. It is not expected to give good results with single crystal OFET, especially when the mobility becomes temperature-independent (see Section 14.6.1.2). However, it has recently been invoked in the case of poly thiophene [112], the mobility of which is also thermally activated. 

As all measurements were performed in air, il is mosl probably due lo oxygen doping, a feature that lias been already noticed in oligolhiophene 1101 and poly-thiophene 11281 OFETs. 

Linear Polymer with Chiral Units 9.4.2.1 Synthesis of Poly (thiophene) 11724a... 

A number of approaches are available to improve the morphology and homogeneity of electrochemically deposited conducting polymer films. Priming of the electrode surface with a monolayer of adsorbed or covalently bonded monomer leads to more compact deposits of polyaniline,87,88 poly thiophene,80 and polypyrrole.89,90 Electrode rotation has been shown to inhibit the deposition of powdery overlayers during poly(3-methylthiophene) deposition.81... 

The huge literature on the electronic conductivity of dry conducting polymer samples will not be considered here because it has limited relevance to their electrochemistry. On the other hand, in situ methods, in which the polymer is immersed in an electrolyte solution under potential control, provide valuable insights into electron transport during electrochemical processes. It should be noted that in situ and dry conductivities of conducting polymers are not directly comparable, since concentration polarization can reduce the conductivity of electrolyte-wetted films considerably.139 Thus in situ conductivities reported for polypyrrole,140,141 poly thiophene,37 and poly aniline37 are orders of magnitude lower than dry conductivities.15... 

The use of organic polymers as conductors and semiconductors in the electronics industry has led to a huge research effort in poly(thiophenes), with a focus on the modification of their electronic properties so that they can behave as both hole and electron conductors. Casado and co-workers [60] have performed combined experimental and theoretical research using Raman spectroscopy on a variety of fluorinated molecules based on oligomers of thiophene, an example of one is shown in Figure 7. 

Figure 2.62 The l/t transient obtained during the growth of a poly thiophene film on a 6.30 cm2 Pt electrode at 1.80V vs. SCE in acetonitrile/0,1 M tetraethylammonium tetrafluoroborate electrolyte. At f = 7 s, the potential was switched to OV to terminate the growth process. After...

Thin polymer films have been prepared by surface catalysis in ultrahigh vacuum and electrochemical deposition from solution. These two routes of synthesis result in poly(thiophene), poly(aniline) and poly(3,5-lutidine) films that have similar infrared spectra. These polymer films are highly orientationally ordered the rings are perpendicular to the surface in poly(thiophene) and poly(3,5-lutidine) films, and the phenyl rings are parallel to the surface in poly(aniline). 

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. 

Figure 2. Reflection infrared spectra of thiophene films (a) thiophene adsorbed on Ni(111) at 170 K (b) thiophene adsorbed on Ni(111) at 170 K heated to 320 K (c) electrochemically grown poly(thiophene) on Pt...

Poly(thiophene) films have also been formed on a Pt foil potentiostatically from 1 M thiophene in 1M LiC104/CH3CN at 1.74 V vs. Ag/AgCl(lM). The films were then removed from the thiophene solution and placed in 1M LiC104/CH3CN and cycled between 0 V to 2.0 V vs. Ag/AgCl to test for the presence of polymer films. At deposition potentials below 1.74 V no film deposition was detected, at higher... 

Conductive polymers have attracted increasing attention because they have wide applications. Recently, very stable poly(thiophenes) with polyfluorinated side chains have been electrochemically synthesized and characterized [81]. Furthermore, notably novel conductive materials have been prepared by cathodic electropolymerization of perfluoro cvclobutene and cyclopentene [82]. 

J. Roncali, Conjugated poly(thiophenes) synthesis, functionalization, and applications, Chem. Rev., 92 711-738, 1992. 

T. Yamamoto, A. Morita, Y. Miyazaki, T. Marayama, H. Wakayama, Z.H. Zhou, Y. Nakamura, T. Kanbara, S. Sasaki, and K. Kubota, Preparation of ir-conjugated poly(thiophene-2,5-diyl), poly(p-phenylene), and related polymers using zerovalent nickel complexes. Linear structure and properties of the TT-conjugated polymers, Macromolecules, 25 1214—1223, 1992. 

T. Yamamoto and H. Hayashi, ir-Conjugated soluble and fluorescent poly(thiophene-2,5-diyl)s with phenolic, hindered phenolic and /j-C6H4OCH3 substituents. Preparation, optical properties, and redox reaction, J. Polym. Set, Part A Polym. Chem., 35 463-474, 1997. 

M.R. Andersson, M. Berggren, O. Inganas, G. Gustafsson, J.C. Gustaffson-Carlberg, D. Seise, T. Hjertberg, and O. Wennerstrom, Electroluminescence from substituted poly(thiophenes) from blue to near-infrared, Macromolecules, 28 7525-7529, 1995. 

Y. Li, G. Vamvounis, and S. Holdcroft, Tuning optical properties and enhancing solid-state emission of poly(thiophene)s by molecular control a postfunctionalization approach, Macromolecules, 35 6900-6906, 2002. 

M. Granstrom, Novel polymer light-emitting diode designs using poly(thiophenes), Polym. Adv. Technol., 8 424 130, 1997. 

X Wang, MR Andersson, ME Thompson, and O Inganas, Electrophosphorescence from substituted poly(thiophene) doped with iridium or platinum complex, Thin Solid Films, 468 226-233, 2004. 

Another approach to CPL is the synthesis of conjugated polymers with intrinsic chiro-optical properties. A variety of polymers with CPPL have been synthesized so far. Most of them are based upon well-known conjugated polymers such as poly(thiophene)s [4,111], polyphenylene vinylene)s [123], poly(thienylene vinylene)s [124], ladder polymers [125], PPPs [126], polyphenylene ethynylene)s, [127] and poly(fluorenes) [128]. All of them have been modified with chiral side-chains, which induce the chiro-optical properties. 

The synthesis of well-defined LCB polymers have progressed considerably beyond the original star polymers prepared by anionic polymerization between 1970 and 1980. Characterization of these new polymers has often been limited to NMR and SEC analysis. The physical properties of these polymers in dilute solution and in the bulk merit attention, especially in the case of completely new architectures such as the dendritic polymers. Many other branched polymers have been prepared, e.g. rigid polymers like nylon [123], polyimide [124] poly(aspartite) [125] and branched poly(thiophene) [126], There seems to be ample room for further development via the use of dendrimers and hyperbran-... 

---