Self-assemblies, formation

Many substances as found in nature (lipids) exhibit unique properties in aqueous media. Some lipids (such as lecithins or alike), when dispersed in water, form very well-defined assemblies, in which the alkyl part of the molecule is in close proximity to each other. This leads to self-assembly formation with many important consequences. 

The surface tension of a liquid becomes important when it comes into contact with a solid surface. The interfacial forces are responsible for self-assembly formation and stability on solid surfaces. The interfacial forces present between a liquid and solid can be estimated by studying the shape of a drop of liquid placed on any smooth solid surface (Figure 5.2). 

Yang J, Fan EK, Geib SJ, Hamilton AD. Hydrogen-bonding control of molecular self-assembly—formation of a 2 + 2 complex in solution and the solid-state. J Am Chem Soc 1993 115 5314-5315. 

This study demonstrated that the micro-mesoporous composite materials could be synthesized with two-step treatment by microwave using two different templates system with TPABr and MTAB. This formation was controlled by the self-assembly formation of supramolecular templates between MTA micelles and SiO /TPA gels. As varying microwave irradiation time of micro-mesoporous materials, gradually transition from the mesophase to micro-mesophase was occurred. These materials have higher dm spacing of mesoporous materials and lead to transition from mesophase to micro-microphase by an increment of synthetic time, while the calcined products is formed with bimodal and trimodal pore size distribution under microwave irradiation within 3 h. From TG-DTA and PL analysis, the self-assembly formation of supramolecular templates between MTA+ micelles and SiO /TPA+ gels were monitored. 

Fig. 12 Tendency to self-assembly formation of homodimeric chiral assemblies for disubstituted and tetrasubstituted peptido calix[4]arenes...

We report on self-assembled formation of spherically shaped voids in MBE grown SiGe alloy layers implanted in-situ at elevated temperature with low-energy Ge ions, followed by thermal annealing. The voids are of nanometer size and are exclusively assembled in thin SiGe quantum wells. The voids only appear in the layers after heat treatment at a temperature higher than 700 °C, and they are stable up to 950 °C. The results are discussed in terms of the separation of the vacancies and interstitials induced by the strain situation around the SiGe quantum wells. 

Fig. 2 Thermodynamic self-assembly Formation of a [2]-catenane. mediated by coordinative and other noncovalent interactions.

Scheme 14.1 Self-assembling formation of nanocomplexes at neutral pH by charge attraction between a negatively charged protein and a positively charged pol nner.

We have discussed in the previous sections about the physical properties and surfactant-assisted self-assembly formations of metal nanoparticles. These assembling methods are quite beautiful and intelligent, because they are induced by the spontaneous driving force for assembling by smart choice of the conditions. In the cases of practical use, however, the methods described below are rather tend to be required (1) the method to make a desirable size, length, shape, architecture and position, etc., (2) a simple and easy method, and (3) highly stable assemblies. From these viewpoints, as a final section for a preparation of nanoparticle assembly, we introduce here the template assisted self-assemblies of nanoparticles. This section is classified to three stories corresponding to the dimension (such as ID, 2D and 3D) of the template and assembly. 

Supramolecular Self-Assembly Formation of 2D Arrays of Colloidal Spheres... 

Abstract The self-assembled formation of PFDTS features on mono- and multilayered silica sphere arrays is studied. The multiscaled roughness induced by PFDTS nanostructures on multilayer arrays gives rise to superhydrophobic behaviour. In contrast to previous work, the role of PFDTS is two-fold it lowers the surface energy and simultaneously provides the essential roughness to achieve superhydrophobicity. The importance of water in the formation of the nanostructured surfaces is discussed. 

In the present work we show that under specific experimental conditions, the adsorption of PFDTS on silica sphere arrays leads to the self-assembled formation of nanostructures. Therewith the role of the fluoroalkylsilane polymer becomes two-fold (i) it simultaneously reduces the surface energy and (ii) leads to an increase of the surface roughness. As far as we are aware, such a double role for PFDTS has not been observed previously. 

Y. Kotsuchibashi, M. Ebara, K. Yamamoto, and T. Aoyagi, On-off switching of dynam-ically controllable self-assembly formation of double-responsive block copolymers with tunable LGSTs,/. Polym. Sci. Part A Polym. Chem., 48, 4393-4399, 2010. 

Matsumoto K, Mizuno U, Matsuoka H, Yamaoka H (2002) Synthesis of novel silicon-containing amphiphilic diblock copolymers and their self-assembly formation in solution and at air-water interface. Macromolecules 35 555-565... 

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