Self-assembly procedure

The films formed in these covalent layer-by-layer assembly procedures are similar to the ionic assemblies prepared by other layer-by-layer self assembly procedures. Unlike the more defined Langmuir-Blodgett multilayer assemblies that have well defined layers, the layers of electrophilic polymer and nucleophihc polymer are intermixed to an extent. Similar effects are seen in ionic layer-by-layer assembhes. 

Monodisperse spherical colloids and most of the applications derived from these materials are still in an early stage of technical development. Many issues still need to be addressed before these materials can reach their potential in industrial applications. For example, the diversity of materials must be greatly expanded to include every major class of functional materials. At the moment, only silica and a few organic polymers (e.g., polystyrene and polymethylmethacrylate) can be prepared as truly monodispersed spherical colloids. These materials, unfortunately, do not exhibit any particularly interesting optical, nonlinear optical or electro-optical functionality. In this regard, it is necessary to develop new methods to either dope currently existing spherical colloids with functional components or to directly deal with the synthesis of other functional materials. Second, formation of complex crystal structures other than closely packed lattices has been met with limited success. As a major limitation to the self-assembly procedures described in this chapter, all of them seem to lack the ability to form 3D lattices with arbitrary structures. Recent demonstrations based on optical trapping method may provide a potential solution to this problem, albeit this approach seems to be too slow to be useful in practice.181-184 Third, the density of defects in the crystalline lattices of spherical colloids must be well-characterized and kept below... 

A great variety of (functional) supramolecular architectures has been generated by complex self-assembly procedures, of purely organic as well as of inorganic natures [3-5, 12-17, 26-30]. The latter have led to a range of metallosupra-molecular entities presenting original structural, physical, and chemical properties. 

In an extension of the previous studies involving 13, it has been demonstrated that a number of other [2]-catenanes can be synthesised using self-assembly procedures in which the donor macrocyclic polyethers incorporate both hydroquinone and 1,5-dioxynaphthalene units, while the acceptor tetracationic cyclophanes contain bipyridinium and/or its extended analogue, bis(pyridinium)ethylene. Although the trans carbon-carbon double bond in the bis(pyridinium)ethylene units are... 

In an extension of this study, the analogous complexes with R = H (42) and 9-anthryl (44) were prepared. The crystal structure of derivative 44 has been determined. Once again, the generation of an ordered, rack-type structure is revealed with steric interactions between the anthryl moieties and the ancillary terpyridyl ligands in evidence. A related self-assembly procedure employing the corresponding tris-tridentate derivative led to 46 being obtained in 58% yield. 

A similar three-step sequential self-assembly procedure was applied to prepare gold electrodes modified in a stable and controlled way by a monolayer of per(6-dexy-6-thio-2,3-di-OMe)-jS-CyD, with methylene blue (MB) in its cavity as the active component of the monolayer (Fig. 10.5.6) [46]. 

Uniform PANI thin shells and hollow capsules have been formed using polyelectrolyte-coated microspheres as a template [285]. Multilayers of poly (diallyldimethylammonium chloride) and PSS pre-coated onto melamine formaldehyde particle via the LBL self-assembly procedure was used as a template for the subsequent deposition of PANI. 

Our further collaboration with IBM involved an extension of printing methods to small objects rather than molecules. This is of practical interest for device manufacture, since it could potentially allow the integration of high-resolution self-assembly procedures, physically separated from the main fabrication line, followed by a printing step to place the objects onto the device (an approach called Self-Assembly, Transfer, and Integration (SATI)) (4.14). This has been extended to the nanometer scale (4.15), and by means of specially structured surfaces, can also be used to place objects of different sizes in distinct patterns onto a surface (4.16). 

The preparation of superconductor/organic conduc-tor/superconductor structures suitable for supercurrent measurements is important for the continued growth of this new area of research. Toward this objective, methods have been developed for the controlled growth of conductive polymer and vapor-phase deposition of (BEDT-TTF Ia systems. Molecular engineering of high-7c structures and devices made possible with the newly discovered high-7c self-assembly procedure will aid in the further development of these studies. 

Fig. 3.4 Self-assembly procedure of PW12-TH multilayer films on magnetic microspheres (Reprinted with permission from Ref. [69]. Copyright 2013, Elsevier)...

Fig. 6.10 TEM (a, b) and HRTEM (c) images of CdS/g-CaNa core/shell NWs CN2 (a) and CN4 (b, c) fabricated via a two-step self-assembly procedure. A given amount of g-C3N4 was grounded to fine powder and then added into 25 mL methanol. After ultrasonically treated for 30 min, bulk g-C3N4 was exfoliated into thin sheets and disintegrated into a homogeneous suspension. Then, CdS NWs were dispersed in the suspension and stirred at room temperature for 24 h. The residual methanol was removed by a stream of nitrogen. The obtained yellow solid was collected and dried in a vacuum oven at 60 °C. The nominal weight ratios of g-C3N4 to CdS were 2 and 4 wt%, and the samples were labeled as CN2 and CN4, respectively (Reprinted with permission from Ref [176]. Copyright 2013,American Chemical Society)...

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