Nanostructured materials solution

Although solution-based approaches can be used as a direct replacement for vacuum-based processes, one of the key aspects of atmospheric solution-based processing is that, by virtue of it being non vacuum and using conformal solution-based precursors, it can lead to a next generation of hybrid and nanostructured materials and devices by enabling unique composites... 

The examples discussed above illustrate the importance of block copolymer chain segment incompatibilities for the phase separation of bulk materials, combined with the ability to perform chemistry within specific nanoscale domains to impose permanence upon those self-assembled nanostructured morphologies. Each is limited, however, to crosslinking of internal domains within the solid-state assemblies in order to create discrete nanoscale objects. To advance the level of control over regioselective crosslinking and offer methodologies that allow for the production of additional unique nanostructured materials, the pre-assembled structures can be produced in solution (Figure 6.4), as isolated islands with reactivity allowed either internally or on the external... 

Figure 6.4 The preparation of nanostructured materials in solution evolves from (a) the classic examples of suspension, dispersion, or emulsion polymerization, to the methods that include the covalent crosslinking of select domains within supramolecular polymer assemblies (b) core crosslinking of polymer micelles (c) shell crosslinking of polymer micelles (SCKs) (d) nanocages from core-eroded SCKs (e) shaved hollow nanospheres from outer shell/core-eroded vesicles.

Fig. la. Atomic structure ofa two-dimensional nano-structured material. For the sake of clarity, the atoms in the centers of the crystals are indicated in black. The ones in the boundary core regions are represented by open circles. Both types of atoms are assumed to be chemically identical b Atomic arrangement in a two-dimensional glass (hard sphere model), c Atomic structure of a two-dimensional nanostructured material consisting Of elastically distorted crystallites. The distortion results from the incorporation of large solute atoms. In the vicinity of the large solute atoms, the lattice planes are curved as indicated in the crystallite on the lower left side. This is not so if all atoms have the same size as indicated in Fig. la [13]... 

It is remarkable that this - more or less - first publication on this topic already contained the main questions and ideas that are still in the focus of many investigations supramolecular structure of the ionic liquid phase, ion-pairing and the interaction of ILs with solute (or solvent) molecules. The same group continued their investigations and subsequently focussed on a larger variety of imidazolium salts with different weakly-coordinating anions (BF 4, PF 6, and BPh 4) [7]. They were able to demonstrate that each cation was surrounded by at least three anions (and vice versa) and by this fashion hydrogen-bound supermolecules were present in the liquid state. Therefore, one could honestly speak of ILs as nanostructured materials . 

The used carbons consist of a skeleton of glassy carbon surrounding a periodic array of uniform spherical pores that are interconnected in three dimensions. Pore sizes are of a few hundred nanometers, whereas skeletal walls are tens of nanometers thick. As a result of the mutually interconnected pore-wall structure of such materials, filling pores with an electrolyte solution results in a nanostructured material with both ionic and electronic conductivities (Lai et al., 2009). 

The non-specific adsorption of proteins on carbon nanotubes is an interesting phenomenon but represents a relatively less controllable mode of protein-CNT interaction. Moreover, in non-covalent immobilization process, the immobilized protein is in equilibrium between the surface of the carbon nanotubes and the solution and can therefore be gradually detached from the nano-material surface, a phenomenon called protein leakage [127]. To prevent the leaching of enzymes, covalent bonds have been used to attach the enzyme molecules to the nanostructured materials, which lead to more robust and predictable conjugation. Experimental evidences prove that proteins can be immobilized either in their hollow cavity or on the surface of carbon nanotubes [130]. 

A key issue in nanostructured materials is the dipole coupling between nanocrystals which will cause the optical properties of a nanocrystal ensemble to become like those of the bulk material. There has been extensive investigation of the interactions between particles embedded within media for a range of boundary conditions. We have found that the effective dielectric function given by Eq. (10), based on the Maxwell-Garnett model [1] is very accurate for quite dense nanocrystal arrays. In practice, one measures the transmittance of a thin film of the dense nanoparticle based film. Conventional solutions are simply... 

As another method, sonolysis has been developed by Suslick to decompose carbonyl metal complexes into nanopowders, nanostructured materials, and nanoparticles in solution. Superparamagnetic iron nanoparticles stabilized by polyvinylpyrrolidone (PVP) or oleic acid were thus obtained upon sonochemical decomposition of... 

The study of naked transition metal clusters forms the basis and reference for understanding the properties of the corresponding ligated and supported species. Most of the experimental evidence so far available deals with ligand-stabilized or supported clusters which are the species commonly encountered in colloidal solutions, catalytic materials, and cluster based nanostructured materials. Thus, systematic theoretical work on free unperturbed transition metal clusters is especially needed to provide fundamental information, since these clusters are not so easily accessible experimentally. 

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