Polymer, Metal, and Hybrid Nano- and Mesotubes by Coating Degradable Polymer Template Fibers (TUFT Process)

Abstract

pected, when the nanocrystal is isolated on a substrate a Coulomb blockade behavior is observed. With a monolayer both ohmic and Coulomb blockade contributions are observed, whereas with a fcc structure a well-defined ohmic behavior is seen. ExperimentalSilver nanosized particles were synthesized using reverse micelles, as described previously [19,20]: Colloidal silver particles were prepared by mixing two reverse-micellar solutions having the same water-content (i.e., the molarThe first was made with 30 % Ag(AOT) and 70 % Na(AOT), and the second with hydrazine N 2 H 4 as reducing agent with an overall concentration of 71 0 ±2 M and with 100 % Na(AOT). This gave an average particle diameter of 3.4 nm with 43 % size distribution. Dodecanethiol was added to the micellar solution (1 mL/cm 3 ). Selective reaction with the silver atoms at the interface of the particles occurred and the coated particles were then extracted from reverse micelles. The powder of coated nanocrystals thus obtained was then dispersed in hexane, giving an optically clear solution. The size distribution was still rather large (30 %), and to reduce it a size-selected precipitation process [20] was used. In this process two solvents, such as hexane and pyridine, are mixed. The first is a good solvent and the second a poor solvent for the alkyl chains. With this solvent mixture, the larger coated particles flocculated whereas the smaller ones remain in the solution, thus providing size selection. By repeating this process several times, a homogenous clear colloidal solution of dispersed 4.3 nm nanocrystals is obtained. The concentration of nanocrystals with final size distribution around 13 % was controlled.

Functional Porous Structures Based on the Pyrolysis of Cured Templates of Block Copolymer and Phenolic Resin

“…[2,[11][12][13][14][15][16][17][18][19][20] These materials can have large void volumes and high internal surface areas, but the supramolecular materials often tend to collapse upon emptying the pores. Several approaches have also been presented to prepare mesoporous and macroporous materials, such as "track-etching", [4][5][6] using honeycomb structures, [27][28][29] and emptying nanostructured templates (e.g., sol-gel processing of surfactants or block copolymers, [7][8][9][10] selective degradation of material with UV exposure, [24][25][26] pyrolysis, [21][22][23]34] and selective removal of lowmolecular-weight amphiphiles (combs) from hierarchically self-assembled polymeric comb-coil supramolecules [35,36] ). Block copolymers provide ideal structures for templates, as, by a facile route, they self-assemble into various structures as a result of the repulsion between the covalently bonded blocks; examples include the spherical, cylindrical, lamellar, and gyroid structures.…”

Visible Light Photocatalytic Degradation of Methylene Blue and Malachite Green Dyes with BaWO4-Go Nano Composite

“…Strong interactions at the interface between two different layers in a hybrid material can produce unexpected novel properties and can have synergetic effects [2], therefore they can be regarded as new materials due to the emergence of these new properties. Many hybrid materials have been studied such as metal-metal hybrids, metal-organic hybrids [3], inorganic semiconductors [4], inorganic-organic hybrids [5] and carbon materials [6]. The synthesis of hybrid materials has been demonstrated using several methods, including chemical vapor deposition (CVD) [7], template-assisted synthesis [8] and self-assembly methods [9].…”

Hydrothermal Synthesis and Characterization of PEG-Mn3O4 Nanocomposite

“…It has been reported that PEG with a uniform and ordered chain structure is easily absorbed at the surface of metal oxide colloid [21]. When the surface of the colloid adsorbs this type of polymer, the activities of colloid greatly decrease and the growth rate of the colloids in some certain facet will be confined [22,23]. Therefore, the addition of PEG in the metal oxide colloids will modify the growth kinetics of the growing colloids, which finally, leads to anisotropic growth of the crystals.…”

“…Therefore, the addition of PEG in the metal oxide colloids will modify the growth kinetics of the growing colloids, which finally, leads to anisotropic growth of the crystals. For this reason, linear PEG has been widely used in the synthesis of a series of nanoparticulates and 1D materials in solution [22].…”