Polymer thiophene-based

J. Pei, W.-L. Yu, J. Ni, Y.-H. Lai, W. Huang, and A.J. Heeger, Thiophene-based conjugated polymers for light-emitting diodes effect of aryl groups on photoluminescence efficiency and redox behavior, Macromolecules, 34 7241-7248, 2001. 

All the copolymers showed similar absorptions with Lmax at 470 nm, which was more intense for polymers with higher thiophene content. In contrast, their emission colors were progressively red shifted with increasing thiophene-based comonomer content. Copolymer 596a emitted bright red light (620 nm) with reasonably high photoluminescent quantum yields (34-69%). 

Polyrotaxanes have been prepared by threading multiple a-cyclodextrin units onto a bulky benzimidazole-based linear chain polymer with an aliphatic spacer where the cyclodextrin resides. The rotaxane forms as the cyclodextrin-bound precursor amine is polymerised. Compared to the polymer in the absence of the cyclodextrins, the glass transition temperature is raised by some 20 °C even though only ca. 16 % of the aliphatic spacers in the polymer are rotaxanated.28 A novel approach to polyrotaxanes involved the use of a metal ion such as Zn2+ to thread a phenanthroline-based macrocycle onto a thiophene-based complementary monomer. The resulting pseudorotaxane can then be electropolymerised and the Zn2+ ions removed to give a polyrotaxane, Scheme 14.5. The redox and conductivity properties of the polymer are very much dependent on whether a metal ion is bound or not.29... 

EDOS, 89), a novel building block for electron-rich -conjugated polymers, is based on condensation of diethyl selenodiglycolate (87) with diethyl oxalate to tet-rasubstituted thiophene (88) followed by modification of the hydroxy substituents and decarboxylation [128]. 

Figure 9 shows the discharge curves of a Type I polypyrrole-based, a Type II polypyrrole/poly(3-methylthiophene)-based and a Type III poly(dithieno[3,4-6 3, 4 -d]thiophene-based supercapacitor at 4 mA cm discharge current. Types I and II can be assembled using such conventional heterocyclic polymers as polypyrrole, polyaniline and polythiophene, which are efficiently p-dopable polymers and can easily be chemically or electrochemically synthesized from inexpensive... 

Dopants also influence the emission processes from PPVs. Improved red dopants have been based on pyran dyes" while Qo doping appears to be variable" "". Doping with electron transport materials such as oxadiazoles give polymers with balanced properties for hole transport". The avoidance of low molecular weight material in the synthesis of cyano based PPVs is important" as are head to head and tail to tail chain sequences in thiophene based polymers. Head to tail tetramer sequences were the most fluorescent. Metal ion doped PPV s are claimed to be good chemosensors and broad emission is observed from titania doped PPV . Electron rich dopants enhance the emission in the red region while electro and photoinduced infrared bands from PPV are similar . ... 

A second major class of emissive polymer is based on polythiophene [8], Again, substitution in this case at the -3- position of the thiophene ring is used to solubilize the polymer and to time the emission wavelength [9]. Other heterocyclic conjugated polymers are represented by polypyridine [10] and polypyridi-nevinylene [11]. Since each of these contains electron-deficient aromatic groups, they lend to be better electron transporters than their phenylene analogs. They emit primarily in the blue. 

FIGURE 3.1.14 Thiophene copolymers and non-thiophene-based polymers. 

A thiophene based polymer poly(2,5-thienylenevinylene) (PTV, 43b) has been synthesized using the precursor method.[242] The dimethylformamide solution of the PTV precursor polymer was spun-cast and then heated to 200°C for 5 min under a nitrogen stream containing a small amount of HCl gas. During the heat treatment, HCl effectively acts as a catalyst for the conversion of the precursor polymer to the PTV.[243] Mobilities as high as 0.22 cm V s were reported. The same polymer has been used for fabrication of integrated circuits, [244] with reported mobilities of... 

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