Internal structures, micelles

Fig. 7 Some peculiar morphologies observed for crew-cut micelles. Baroclinic tubes (a). Tube-walled vesicles (b). Large compound micelles insert shows their internal structure (c) and interconnected tubules or plumber nightmare (d) (images downloaded from http //ottomaass.chem.mcgill.ca/groups/eisenberg/). Adapted from [35]...

Xing, L. and W L. Mattice. 1998. Large internal structures of micelles of triblock copolymers with small insoluble molecules in their corelsangmuir14 4074-4080. 

The unterstanding of amphiphile association clearly must include detailed knowledge of the internal structure and dynamics, e.g., what is the conformation of the alkyl chains and what are their flexibility and packing conditions is the interior of micelles exclusively of hydrocarbon nature or is there any water penetration We will here consider the state of the hydrocarbon chains and defer a discussion of water penetration to the section on hydration. 

The internal structure of polyelectrolyte block copolymer micelles such as their core radius Rc and micellar radius Rm can be determined by a variety of methods involving static and dynamic light scattering (SLS, DLS), small-angle X-ray (SAXS) and neutron scattering (SANS) as well as imaging techniques such as transmission electron microscopy (TEM) or atomic force mi-... 

It is usually assumed that the micellar corona is a continuous phase extending from the micellar core to the micellar radius Rm. The internal structure of the micelle can be described by a density profile as shown in Fig. 8. The micellar core is a homogeneous melt or glass of insoluble polymer blocks. For hydrophobic blocks in aqueous solutions, the polymer volume fraction in the micellar core is 0C 1. The micellar shell is swollen with water or aqueous salt solution and has a polymer segment density that is expected to decrease in the radial direction as 0(r) r-a as typical for star polymers or... 

Precrosslinked" or "intramolecularly crosslinked" particles are micronetworks [1]. They represent structures intermediate between branched and macroscopically crosslinked systems. Their overall dimensions are still comparable with those of high molecular weight linear polymers, the internal structure of micronetworks (p-gels), however, resembles a typical network [2]. Synthesis is performed either in dilute solution or in a restricted reaction volume, e.g., in the micelles of an emulsion. Particle size and particle size distribution can be controlled by reaction conditions. Functional groups can be... 

The microemulsion method utilizes a water/oil/surfactant system to construct a micro reactor, in which NCs could be s)mthesized. The microemulsions have a wide range of applications from oil recovery fo fhe s)mfhesis of nanoparticles. Microemulsion is a system of water, oil, and surfactant, and it is an optically isotropic and thermod3mamically stable solution. At molecular scale, the microemulsion is heterogeneous with an internal structure either of nanospherical monosized droplefs (micelles or reverse micelles) or a bicontinuous phase, depending on the given temperature as well as the ratio of its constituents (Eriksson et al., 2004). The small droplets could be utilized as microreactors in order to s)mthesize the fine NCs in a controllable way. 

When neutron scattering of a sample is combined with contrast variation, information can be obtained not only about the shape and size of the micelle but also about its detailed (internal) molecular architecture. Because of the unique level of information about micellar systems that can be obtained from SANS experiments, the technique is now an extremely well-established tool for investigating the shape, size, and, to a lesser extent, the internal structure of micellar aggregates with several hundreds of papers being published since the 1970s when micelles were the first colloidal systems to be studied using SANS. 

M. C. Woods, J. M. Haile, and j. P. O Connel, ]. Phys. Chem., 90, 1875 (1986). Internal Structure of a Model Micelle via Con iputer Simulation. 2. Spherically Confined Aggregates with Mobile Head Groups. 

However, joining of K-casein to any of other caseins via its hydrophobic region leads to the termination of micelle growth because /c-casein just owns 1 hydrophobic segment and does not interact with CCP nanoclusters due to the lack of phosphoseiyl residues [2, 40]. This model is basically different in comparison with previous models in term of internal structure of micelles however, the cement role of CCP and location of K-casein on the surface of micelle are identical. 

Thanks to the contrast variation and detailed model fitting, the internal structure could be obtained showing that the micelles are rather poorly segregated with a large quantity of solvent (approx. 30-50%) penetrating the core and a smaller compact corona. This important feature will be discussed in more detail in Sect. 4.3. 

To discuss further the shape and internal structure of the micelles, the hydrodynamic radii calculated from the self-diffusion coefficients according to Equation 10.2 were combined and compared with the SAXS results. The self-diffusion coefficient of a hard sphere at infinite dilution. Do, is described by [46],... 

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