Liquid based precursors

The synthesis of nanostructured carbon using aliphatic alcohols as selfassembling molecules has demonstrated that this strategy can be extended beyond metal oxide-based materials [38]. Recently, we have reported the synthesis of a novel carbon material with tunable porosity by using a liquid-crystalline precursor containing a surfactant and a carbon-yielding chemical, furfuryl alcohol. The carbonization of the cured self-assembled carbon precursor produces a new carbon material with both controlled porosity and electrical conductivity. The unique combination of both features is advantageous for many relevant applications. For example, when tested as a supercapacitor electrode, specific capacitances over 120 F/g were obtained without the need to use binders, additives, or activation to increase surface area [38]. The proposed synthesis method is versatile and economically attractive, and allows for the precise control of the structure. 

In this chapter, the structures and textures of carbons at different scales are explained. The carbon materials are classified into four families, diamond, graphite, fullerene, and carbyne on the basis of hybridized sp3, flat sp2, curved sp2, and sp orbitals used, respectively. Each family has its own characteristic diversity in structure and also in the possibility of accepting foreign species. The formation of these carbon materials from organic precursors (carbonization) is shortly described by dividing the process into three phases (gas, solid, and liquid), based on the intermediate phases formed during carbonization. The importance of nanotexture, mainly due to the preferred orientation of the anisotropic BSU in the graphite family, i.e., planar, axial, point, and random orientation schemes, is particularly emphasized. 

Ionic liquid Catalyst precursor Base Comments Ref... 

From the above, it is clear that almost all of the metals can be electrodeposited from ionic liquids. However, there are still some key issues that need further study. The deposited layers of metal from ionic liqnids are too thin to use for the commercial industrial production. The efficiency for Mg and Ti deposition was not very high, and most metals were deposited from the aluminum chloride-based ionic liquids as mention above. It is known that these ionic liquids can absorb significant amount of water from the air which can react with the ionic liquids based on PF or AICI3 to produce HF or HCl. Therefore, efforts may be directed to find more suitable ionic liquid and suitable precursors for a technically relevant process. Again, the mechanism of the electrodeposition of metals from ionic liquids still needs to be clarified. 

Several fibers based on liquid crystal precursors have been subsequently produced. Keller [23] postulates the existence of a liquid crystalline phase during the melt-crystalline transition in polyethylene (and other polymers). 

A closely related method to the in situ polymerisation processing of composites is based on epoxy resins thermosets. In this approach, CNTs can be dispersed in a liquid epoxy precursor and then the mixtures can be cured by the addition of hardener, such as triethylene tetramine (TETA), and the application of temperature or pressure. In most cases, the epoxy monomer exists in liquid state, facilitating nanotube dispersion. Curing is then carried out to... 

For example, stereolithography can be used. It is a liquid-based technique that utilizes LBL curing of a photosensitive hydrogel precursor solution by means of a laser. Alternatively, nozzle-based systems are applied. They process the material chemically as it passes through the nozzle (ink-jet printing, 3D printing cf. Section 3.10). Cells and biomolecules can be simultaneously printed with the scaffold material [79]. 

Pitch as a precursor material is cheaper than PAN as a precursor fiber, but the conversion of pitch into mesophase pitch and subsequent fiber formation is complex and costly. When a pitch is not transformed into a mesophase and is spun as an isotropic liquid, the resulting carbon fibers have extremely poor mechanical properties. These considerations explain why more than 90% of today s carbon fibers are fabricated from PAN based precursors. Processes for fabricating carbon fibers from PAN or pitch based precursor fibers differ in important aspects, but also share important commonalties (Figure 2). Finally, the carbon yield from PAN based precursor fibers is 50%, that from mesophase pitch is 70-80%, and that from rayon is 25%. 

Smiglak, M., Hines, C.C. and Rogers, R.D., New hydrogen carbonate precursors for efficient and byproduct-free syntheses of ionic liquids based on l,2,3-trimethylimidazolium and iV,iV-dimethylpyrrolidinium cores. Green Chem. 12 (3), 491-501 (2010). 

Synthesis of a cerium based precursor An acidic solution of cerium salt is transformed by a liquid process into a reactive cerium precursor as cited above. At this step, alkali metal and/or alkaline earth metal salts can be added depending on the color targeted. The resulting precipitate is not yet colored, and must next be transformed into a colored sulfide. 

Fig. 5. Chiral ionic liquids prepared from carbohydrate derived precursors with tosylate anions, top chiral tosylate ionic liquid based on methyl ot-D-glucopyranoside bottom chiral tosylate ionic liquid based on derivative of D-mannose.

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