Polythiophenes copolymers

Pyrolysis-MS, together with TGA analysis, was chosen recently as the technique with which to investigate the thermal behaviour of two polythiophene copolymers, since insolubility in common solvents of conducting polymers limits... 

Samuelson, L.A., D.L. Kaplan, J.O. Lim, M. Kamath, K.A. Marx, and S.K. Tripathy. 1994. Molecular recognition between a biotinylated polythiophene copolymer and phycoerythrin utilizing the biotin-streptavidin interaction. Thin Solid Films 242 50-55. 

Catellani, M., S. Luzzati, N.-O. Lupsac, R. Mendichi, R. Consonni, A. Famulari, S.V. Meille, F. Giacalone, J.L. Segura, and N. Martin. 2004. Donor-acceptor polythiophene copolymers with tunable acceptor content for photoelectric conversion devices. / Mater Chem 14 67-74. 

As an example, Hotta et al. [61] prepared composites based on poly(3-hexylthiophene-co-3-benzylthio-phene), P3HT3BzT, and polystyrene. These composites are allowed to be conducting by a routine doping process. Their conductivities were measured by varying the P3HT3BzT contents in the composites. A striking threshold in the conductivity was found around 16% volume fraction of this polythiophene copolymer. This can be interpreted in terms of the onset of the percolation of the conducting paths that are formed in the three-dimensional network of the composites [62]. 

This chapter is divided into two main parts polythiophene copolymers and polypyrrole copolymers. Each part reviews the random copolymerization of the heterocyclic monomer and important derivatives, principally those with substituents at the 3-position of thiophene and at the 1- and 3-positions of pyrrole. Alternating, block and graft copolymers are covered in both segments. Because applications of conducting polymers are reviewed in Volume 4, only applications unique to specify copolymers are covered here. In addition, a few theoretical studies dealing with conducting copolymers are reviewed. 

One of the important goals of research on conducting polymers is to synthesize small-gap conjugated polymers, and since copolymerization can influence the bandgap [172], the few theoretical studies dealing with polypyrrole and polythiophene copolymers that have been published are briefly mentioned here. 

PBT = polybithiophene PDMTT = polydimethyltetrathiophene PHT = polyhexylthiophene, PS-PT = polystyrene-polythiophene copolymer. 

Fig. 11 Examples of polythiophenes and polythiophene copolymers with modified ionization potential or higher charge carrier mobility than P3HT...

The presence of small amounts of thiophene monomer (25-75 mM) in acetonitrile solutions of aniline (250 mM) has been reported to accelerate the electrochemical formation and conductivity of PAn homopolymer. This was attributed to catalysis by thiophene cation radicals. When higher concentrations of thiophene (>100 mM) were used in the monomer feed, increasing amounts of a polyaniline/polythiophene copolymer were shown to be present in the product. ... 

Polythiophenes functionalized with monosaccharides have been evaluated for their ability to detect the influenza virus and E. coli (Baek et al. 2000). Copolymers of thiophene acetic acid 10 and carbohydrate-modified thiophenes 11 have been prepared via iron(III) chloride mediated polymerization. Addition of influenza virus to a sialic acid containing copolymer resulted in a blue shift of the polymer absorption maximum, resulting in an orange to red chromatic transition. Mannose-containing polythiophenes underwent color changes upon the addition of the lectin ConA or E. coli cells that contain cell surface mannose-binding receptors. A similar biotinylated pol5hhiophene afforded a streptavidin responsive material (Paid and Leclerc 1996). 

Further materials that have been evaluated as supports for solid-phase synthesis include phenol-formaldehyde polymers [239,240], platinum electrodes coated with polythiophenes [241], proteins (bovine serum albumin) [242], polylysine [243], soluble poly (vinyl alcohol) [244], various copolymers of vinyl alcohol [4,245,246], and soluble dendrimers [14,247]. 

McCullough and coworkers had synthesized block copolymers of poly(3-hexylthiophene) and polystyrene or PMA by ATRP of the vinyl monomer from a polythiophene macroinitiator, which was prepared in several steps... 

After the development of catalyst-transfer condensation polymerization of polythiophene, the block copolymer of polythiophene and PMA could be prepared more easily. As mentioned above, the vinyl-terminated polythiophene was first prepared. The vinyl group was converted to the 2-hydroxyethyl group by hydroboration, followed by esterification with 2-bromopropionyl bromide to give a macroinitiator for ATRP (Scheme 101)... 

Recently, Dai, Su, and coworkers synthesized the block copolymer of polythiophene and polypyridine from the vinyl-terminated polythiophene (Scheme 102) [336]. Meijer and coworkers used an allyl-terminated polythiophene to synthesize a block copolymer of poly(3-hexylthiophene) and polyethylene the ring-opening metathesis polymerization of cyclooctene in the presence of the allyl-terminated polythiophene was followed by hydrogenation (Scheme 103) [337]. 

The second method is the synthesis of copolymers or derivatives of a parent conjugated polymer with more desirable properties. This method is the more traditional one for making improvements to a polymer. It modifies the structure of the polymer to increase its processibility without compromising its conductivity or its optical properties. All attempts to do this on polyacetylene have failed as they always significantly reduced its conductivity. However, such attempts on polythiophenes and polypyrroles proved more fruitful. 

The rationale for preparing this hybrid copolymer was to combine the desirable properties of polyaniline with those of polythiophene. For example, polythiophene has demonstrated thermo- and electrochromism, solvatochromism, luminescence, and photoconductivity while polyaniline has demonstrated reversible protonic dupability, excellent redox re-cyclability, and chemical stability. 

Synthesis of aryl coupled thiophenes and polymerization of these by conventional procedures leads to new copolymers which have different properties compared to the parent polythiophenes. This oligomeric approach towards building novel copolymers has been used to modify the main-chain and also to incorporate fractional amounts of functionalities in the side chains of the polymer back-bone. 

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