Self-catalyzing growth

Self-catalyzed growth of nanorods is also possible. For example, MgO nanorods with spherical metal particles at the tips have been produced (Fig. 7.5) by the reaction of commercial magnesium ribbons with oxygen under a flow of argon/oxygen mixture at 900°C (40). Magnesium metal is not only the reactant but also a catalyst and the reaction involved is 2Mg (vapor) + O2 (g) 2MgO (s). 

In the case of aniline electropolymerization, the radical cation of ani-Une monomer is formed on the electrode surface by oxidation of the monomer [ 100,105-114]. This process is considered to be the rate-determining step. Radical coupUng and elimination of two protons make mainly para-formed dimers. Chain propagation proceeds with oxidation of the dimer and aniUne monomer on the electrode surface. In this step, the radical cation of the ohgomer couples with a radical cation of aniline monomer. In the final step, PANI is doped by the acid (HA) present in solution. The growth of PANI has been considered to be self-catalyzed. This means that the polymers are formed at the higher rate as the more monomers are deposited onto the polymer smface. It involves the adsorption of the aniUnium ion onto the oxi zed form of PANI, followed by electron transfer to form the radical cation and subsequent reoxidation of the polymer to its most oxidized state. 

Short (or discontinuous) fibers are best prepared in a batch process, e.g., in a small cylindrical reaction chamber. The value of the technology, however, lies in its capability to facilitate the growth of continuous (potentially endless) fibers with a recently discovered automatic self-regulating growth mechanism [2], Finally, the diameter of the laser focus determines the diameter of fibers grown by laser assisted chemical vapor deposition, just as the diameter of the metal particles determines the diameter of the whiskers grown by metal catalyzed chemical vapor deposition. 

The growth of polyaniline has been found to be self-catalyzing the more polymer deposited, the higher the rate of polymer formation. A mechanism for this has been proposed, involving adsorption of the anilinium ion... 

Galit Zilberman joined the research group at Drexel in November 2003. Her previous research at Tel Aviv University with QCM measurements at the solution/electrode interface [59] led us to e q)lore the use of the QCM/HCC as a detector of protein-ligand interactions in aqueous solution [60], and as a detector of the growth of E Coli bacteria on thin film of nutrient medium deposited on the QCM [61]. Zilberman also studied the growth kinetics of alkyl- and carboxylic acid self-assembled monolayers (SAMs) on gold and the EDC-catalyzed amide bond formation on a carboxylic acid-tenninated SAM. 

The scientific literature has shown that self-assembled nanorod structures have been grown fi om a large number of materials and for a wide variety of engineering applications. For illustrative purposes, in this entry we focus on the fabrication and growth characteristics of ruthenium oxide nanorods the target application lies in the catalyzed decomposition of hydrogen peroxide... 

A-A/B-B monomers, polycondensations, 157 A-B monomers, polycondensations, 157 AB monomers, self-polymerization via benzimidazole-activated ether synthesis, 266--274 Acetophenones Ru-catalyzed addition, 67-69 Ru-catalyzed step-growth copolymerization with a,(0-dienes for high-molecular-weight polymer synthesis, 99-112 4-(Acryloxy)benzoic acid, ordered polymer synthesis, 442-450 Acyclic diene metathesis polymerization cycle, 116,118/... 

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