Micelles size, shape

The self-diffusion coefficient method was developed originally by Lindman and co-workers [42], This method is by far the most powerful and successful application of NMR in the study of surfactant systems. The self-diffusion method permits a full characterization of the system under investigation, since it can yield the values of the free monomeric surfactant concentration, the degree of counterion binding, and the amount of water bound (hydration). Moreover, these data can help one deduce the information on micelle size, shape, and composition from the monomer surfactant concentration in a surfactant mixture ... 

As has been stated often, the ability of a given surfactant to solubilize an additive is intimately related to the characteristics of the micelle (size, shape. 

With the development of new instrumental techniques, much new information on the size and shape of aqueous micelles has become available. The inceptive description of the micelle as a spherical agglomerate of 20-100 monomers, 12-30 in radius (JJ, with a liquid hydrocarbon interior, has been considerably refined in recent years by spectroscopic (e.g. nmr, fluorescence decay, quasielastic light-scattering), hydrodynamic (e.g. viscometry, centrifugation) and classical light-scattering and osmometry studies. From these investigations have developed plausible descriptions of the thermodynamic and kinetic states of micellar micro-environments, as well as an appreciation of the plurality of micelle size and shape. 

Templates made of surfactants are very effective in order to control the size, shape, and polydispersity of nanosized metal particles. Surfactant micelles may enclose metal ions to form amphiphilic microreactors (Figure 11a). Water-in-oil reverse micelles (Figure 11b) or larger vesicles may function in similar ways. On the addition of reducing agents such as hydrazine nanosized metal particles are formed. The size and the shape of the products are pre-imprinted by the constrained environment in which they are grown. 

In contrast to dendrimers built up from aliphatic chains, polyphenylene dendrimer micelles possess shape and size persistent cavities due to their rigid scaffold which strongly depends on the type of dendrimer. In this case a selective incorporation of guest molecules, e.g., fluorescent dyes, should be possible, dependent on the size of the guest molecule and the cavity of the host. The non-covalent uptake of dyes with an appropriate size thus allows the investigation of their interactions within the dendritic micelle. In our case we made the second-generation polyphenylene dendrimer 48, which bears 16 carboxy-functions at the periphery, by starting from a tetrahedral core and an appropriately... 

The largest portion of the monomer (>95%) is dispersed as monomer droplets whose size depends on the stirring rate. The monomer droplets are stabilized by surfactant molecules absorbed on their surfaces. Monomer droplets have diameters in the range 1-100 pm (103-105 nm). Thus, in a typical emulsion polymerization system, the monomer droplets are much larger than the monomer-containing micelles. Consequently, while the concentration of micelles is 1019-1021 the concentration of monomer droplets is at most 1012-1014 L 1. A further difference between micelles and monomer droplets is that the total surface area of the micelles is larger than that of the droplets by more than two orders of magnitude. The size, shape, and concentration of each of the various types of particles in the... 

Hayashi S, Ikeda S. Micelle size and shape of sodium dodecyl-suUate in concentrated NaCl solutions. J Phys Chem 1980 84 744-751. 

From these data it is concluded that the size, shape, and polydispersity of nanoparticles depend critically on the colloidal structure in which the synthesis is performed. This is well demonstrated when, by changing the water content, similar colloidal structures (reverse micelles or interconnected cylinders) are obtained ... 

Although a number of infrared bands can be used to establish that a micellar shape change has occurred, it is difficult to determine the actual shape unambiguously from the spectroscopic data alone. We therefore make use of micelle aggregation numbers and solution rheological properties, which depend on micelle size and shape, for correlation with the structural information (packing) provided by the FTIR spectra. 

Self-Assembly through Micelle Formation Self-assembly at the nanoscale is deemed important to be able to produce commercially viable products and processes, since it offers a mode of bulk production with control over features such as size, shape, and morphology at the nanoscale. The basic principle of self-assembly is based on the simultaneous coexistence of two parallel forces ... 

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