Precursors doped

Figure 1.1 A silica sol precursor doped with a coloured organic molecule.

Highly anisotropic copper-containing polyimide films have been produced through the homogeneous incorporation of bis(trifluoroacetyl-acetonato)copper(II), Cu(TFA), with the polyimide precursor followed by thermal cyclodehydration. By judious choice of polyimide precursor, doping level, and curing atmosphere two specific types of surface structure have been obtained. Bi- and tri-layered. 

Tkalcec, E., Kurajica, S., and Schmauch, J. 2007. Crystalhzation of amorphous Al203-Si02 precursors doped with nickel. J. Non-Cryst. Solid. 353 2837-2844. 

A comparison of the properties of neat PPV films and conducting composite beads is interesting. The conductivity of a PPV film made from precursor I was 1.8 X lO S/cm (Table 1) after doping for 8 days at 100 torn The conductivity of the pellet prepared from the same precursor doped and measured under identical conditions was 2.4 x 10" /cm. The decreased conductivity for the beads was probably due to gaps between the beads. Also, as expected, the conductivities increased as the doping period increased from 6 to 8 days for IV. 

An innovative idea for inexpensive large area SERS substrate fabrication was proposed by Akil-Jradi et al. (2012). A solution was prepared by dissolving AgN03 in ethanol and mixing it with PMMA dissolved in acetone. The manufacture of substrates was based on the vapor-induced phase separation and chemical reduction of a metal precursor-doped... 

To answer questions regarding dislocation multiplication in Mg-doped LiF single crystals, Vorthman and Duvall [19] describe soft-recovery experiments on <100)-oriented crystals shock loaded above the critical shear stress necessary for rapid precursor decay. Postshock analysis of the samples indicate that the dislocation density in recovered samples is not significantly greater than the preshock value. The predicted dislocation density (using precursor-decay analysis) is not observed. It is found, however, that the critical shear stress, above which the precursor amplitude decays rapidly, corresponds to the shear stress required to disturb grown-in dislocations which make up subgrain boundaries. 

There have been very few examples of PTV derivatives substituted at the vinylene position. One example poly(2,5-thienylene-1,2-dimethoxy-ethenylene) 102 has been documented by Geise and co-workers and its synthesis is outlined in Scheme 1-32 [133]. Thiophene-2,5-dicarboxaldehyde 99 is polymerized using a benzoin condensation the polyacyloin precursor 100 was treated with base to obtain polydianion 101. Subsequent treatment with dimethyl sulfate affords 102, which is soluble in solvents such as chloroform, methanol, and DMF. The molar mass of the polymer obtained is rather low (M = 1010) and its band gap ( ,.=2.13 eV) is substantially blue-shifted relative to PTV itself. Despite the low effective conjugation, the material is reasonably conductive when doped with l2 (cr=0.4 S cm 1). 

Fig. 1(b) represents the selectivity to styrene as a ftmcfion of time fijr the above catal ts. It is observed that the selectivity to styrene is more than 95% over carbon nauofiber supported iron oxide catalyst compared with about 90% for the oxidized carbon nanofiber. It can be observed that there is an increase in selectivity to styrene and a decrease in selectivity to benzene with time on stream until 40 min. In particrdar, when the carbon nanofiber which has been treated in 4M HCl solution for three days is directly us as support to deposit the iron-precursor, the resulting catalyst shows a significantly lows selectivity to styrene, about 70%, in contrast to more than 95% on the similar catalyst using oxidized carbon nanofiber. The doping of the alkali or alkali metal on Fe/CNF did not improve the steady-state selectivity to styrene, but shortened the time to reach the steady-state selectivity. 

Mixtures of a nematic liquid crystal (LC or LC ) with small quantities of gold nanoparticles coated with alkylthiolates (<5 wt%) including an alkylthiolate functionalized with a chiral group have been studied (Figure 8.29) [72]. All mixtures show nematic mesophases with transition temperatures and phase stability very similar to those oftheliquid crystal precursors LC or LC. The introduction ofachiral center into the mixtures (mixtures of Au ) produce chiral nematic mesophases. A similar result is obtained in mixtures of Au and LC doped with the chiral dopant (s)-Naproxen. 

Figure 13 shows the irreversible conversion of a nonconjugated poly (p-phenylene pentadienylene) to a lithiun-doped conjugated derivative which has a semiconducting level of conductivity (0.1 to 1.0 S/cm) (29). Obviously, the neutral conjugated derivative of poly (p-phenylene pentadienylene) can then be reversibly generated from the n-type doped material by electrochemical undoping or by p-type compensation. A very similar synthetic method for the conversion of poly(acetylene-co-1,3-butadiene) to polyacetylene has been reported (30), Figure 14. This synthesis of polyacetylene from a nonconjugated precursor polymer containing isolated CH2 units in an otherwise conjugated chain is to be contrasted with the early approach of Marvel et al (6) in which an all-sp3 carbon chain was employed.

A rapidly increasing number of publications on polysilanes documents current interest in these polymers (JJ. Polysilanes are potentially applicable in microlithography as high resolution UV-resists (2J, imageable etch barriers ), or contrast enhancement layers (4). They have been successfully used as precursors to Si-C fibers (5J and ceramic reinforcing agents ((L). Polysilanes have also initiated polymerization of vinyl monomers (J ). Doping of polysilanes have increased their conductivity to the level of semiconductors (8). Very recently polysilanes were used as photoconductors (9) and non-linear optical materials (10b... 

Estruga, M., Domingo, C., Domenech, X., and Ayllon, J.A. (2010) Zirconium-doped and silicon-doped Ti02 photocatalysts synthesis from ionic-liquid-like precursors. Journal of Colloid and Interface Science, 344 (2), 327-333. 

Li, D., Haneda, H., Hishita, S., and Ohashi, N. (2005) Visible-light-driven nitrogen-doped Ti02 photocatalysts effect of nitrogen precursors on their photocatalysis for decomposition of gas-phase organic pollutants. Materials Science and Engineering B, 117 (1), 67—75. 

Dai, S Liu, Y. and Lu, Y. (2010) Preparation of Eu3+ doped (Y,Gd)203 flowers from (Y.GdjflCO ) vn - jO flowerlike precursors microwave hydrothermal synthesis, growth mechanism and luminescence property. Journal of Colloid and Interface Science, 349, 34-40. 

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