Vesicles micelles and

Functionalized polyelectrolytes are promising candidates for photoinduced ET reaction systems. In recent years, much attention has been focused on modifying the photophysical and photochemical processes by use of polyelectrolyte systems, because dramatic effects are often brought about by the interfacial electrostatic potential and/or the existence of microphase structures in such systems [10, 11], A characteristic feature of polymers as reaction media, in general, lies in the potential that they make a wider variety of molecular designs possible than the conventional organized molecular assemblies such as surfactant micelles and vesicles. From a practical point of view, polymer systems have a potential advantage in that polymers per se can form film and may be assembled into a variety of devices and systems with ease. 

C12-0029. Write a paragraph that describes the types of substances that form monolayers, micelles, and vesicles in water. Explain the differences among these structures. 

Fendler, J. H., Microemulsions, Micelles, and Vesicles for Membrane Mimetic Photochemistry, J. Phys. Chem., 1980, 84, 1485. 

Zana R. 2004. Micelles and vesicles. In Atwood JL and Steed JW, eds. Encyclopedia of Supramolecular Chemistry. Marcel Dekker, New York, pp. 861-861. 

However, microemulsions have a significant advantage as reaction media over micelles and vesicles in one key respect. They are excellent solubilizing media and will tolerate high concentrations of apolar solutes they are much superior to micelles and vesicles in this respect (Mackay, 1981). 

Micelles and vesicles can also be used in the preparation of very small submicroscopic particles which may be useful as heterogeneous catalysts or because of their properties as semiconductors (Lufimpadio et al., 1984 Tricot and Fendler, 1984). 

Ester aminolysis and hydrolysis coi Alkylammonium alkanoates. The amine can react nucleophilically or as a general base Rates of decarboxylation compared in various solvents and in aq. micelles, reversed micelles and vesicles M. I. El Seoud et al., 1982 Sunamoto et a/., 1983a... 

Bile acids have long been known to aid digestion of dietary fats, but are not essential. Some 50% of dietary fats are absorbed in rats where bile acids are diverted by biliary fistula.Similar results were found in man. This suggested that the micellar phase isolated by ultracentrifugation of duodenal contents was in fact composed of both bile-acid micelles and vesicles, a suggestion supported by a systematic study of the physical chemistry of fat digestion in human small bowel. 

Self-aggregating amphiphiles can broadly be divided into hydrotropes and surfactants. The main difference between hydrotropes and surfactants lies in the fact that hydrotropes are typically not sufficiently hydrophobic to cooperatively self-aggregate and form organized structures, whereas surfactants form distinct aggregates such as micelles and vesicles above their critical aggregation concentrations. 

Depending on the shape of the surfactant, different highly dynamic aggregates can be formed. The morphologies of different micelles (and vesicles - vide infra) are... 

To understand the effects of micelles and vesicles on (organic) reactions, it is important to know where reactants are located in the micellar and vesicular pseudophase and what this region looks like in terms of a reaction medium. As mentioned above, micelles (but similar arguments are valid for vesicles) can be thought of as offering... 

Various techniques are suitable for the study of binding locations of organic solubi-lizates in micelles and vesicles. Typically, these methods have included changes in NMR chemical shifts as a result of aromatic ring current effects, paramagnetic relaxation... 

In the remainder of this article, discussion of surfactant dissolution mechanisms and rates proceeds from the simplest case of pure nonionic surfactants to nonionic surfactant mixtures, mixtures of nonionics with anionics, and finally to development of myehnic figures during dissolution, with emphasis on studies in one anionic surfactant/water system. Not considered here are studies of rates of transformation between individual phases or aggregate structures in surfactant systems, e.g., between micelles and vesicles. Reviews of these phenomena, which include some of the information summarized below, have been given elsewhere [7,15,29]. 

The emergence of novel properties due to self-assembly is also present in much simpler systems. Consider, for example, the formation of micelles and vesicles from surfactants, as already seen (Figure 5.3). 

So far, only the self-replication mechanisms of linear molecules have been described it is now time to consider closed spherical structures, such as micelles and vesicles. Here, the term self-reproduction will be used rather than self-replication, because, as it will be seen, the population increase is generally based on statistical processes. The subject of micelles and vesicles self-reproduction is dealt with in other chapters in this book a certain degree of repetition and/or mis-match is unavoidable. 

In general, the mechanism of self-reproduction of micelles and vesicles can be considered an autopoietic mechanism, since growth and eventually division comes from within the structure itself. This point will be considered again in Chapter 8, on autopoiesis, where the mechanism of the self-reproduction process will also be discussed. 

In the various reviews on self-reproduction in recent years, practically no mention is made of such micelles or vesicle systems. The reason lies most prohahly in the bias of classic hiochemical literature, according to which self-replication is tantamount to nucleic acid systems lacking this are therefore deemed not to he relevant. In this particular regard, it is argued that self-reproduction of micelles and vesicles proceeds without transmission of information. 

We have also learned that self-replication is not a prerogative only of nucleic acids, but it can be shared by different kinds of chemical families see the formose reaction, the self-replicating peptides, and the self-reproducing micelles and vesicles. The list should include the cellular automata and the corresponding devices of artificial life. Self-reproduction of vesicles and liposomes is important because it represents a model for cell reproduction. 

The term chemical autopoiesis indicates the experimental implementation of autopoiesis in the chemistry laboratory. The most well known of these processes is the self-reproduction of micelles and vesicles. This has been discussed in the previous chapter, where the original idea of Francisco Varela and myself was to work with bounded systems that would produce their own components due to an internal reaction, respecting the scheme illustrated in Figure 8.3. We came up with the idea of using reverse micelles (refer back to Figure 7.13) with two reagents. 

A and B, which could react inside the boundary (but not outside) to yield as a product the very surfactant that builds the boundary (Luisi and Varela, 1990). In Chapter 7 it was also indicated how this theoretical paper led to the experimental implementation of self-reproducing reverse micelles, aqueous micelles, and vesicles (Bachmann et al., 1990, 1991, 1992 Luisi, 1994 Walde et al., 1994b). 

The basic common denominator for all these applications is qualitatively well understood surfactants and their aggregates permit mixing, or at least close interaction, between phases or substances that are per se immiscible with each other -mostly oil and water. This is how grease is washed off from our hands when we use soap, the removal being mediated by micelles. In turn, micelles and vesicles permit the formation of an extraordinarily efficient interfacial system. Figure 9.3 gives a dramatic demonstration of this, showing that the total surface of a concentrated soap solution in your sink may well correspond to the surface of a stadium ... 

Reverse micelles are the first compartment structures for which the phenomenon of micelle self-reproduction has been described (Bachman et al., 1990 1991). This experimental work was a follow up of a theoretical study by Varela and Luisi (Luisi and Varela, 1990), and is it this that eventually brought to light the self-reproduction of aqueous micelles and vesicles. This has been covered already in Chapter 7, on the chemistry of self-reproduction. 

Of all mentioned prebiotic membranogenic molecules, the ones that have gained more attention in the literature are long-chain fatty acids. In addition to their prebiotic relevance, these compounds are relatively simple from the structural point of view, and most of them are easily available. We will see in the next chapter that these vesicles have acquired a particular importance in the held of the origin of life. In fact, the hrst inveshgations on self-reproducing aqueous micelles and vesicles were carried out with caprylate (Bachmann et al, 1992) and most of the recent studies on vesicles involve vesicles from oleic acid/oleate (for simplicity we will refer to them as oleate vesicles). In this section, I would like to illustrate some of the basic properties of these surfactant aggregates. 

In the case of mineral particles, by making them smaller and smaller, you gain a larger and larger total surface. Is this also true for the total surface of micelles and vesicles when they divide What about the total volume ... 

Self-reproduction of micelles and vesicles models for the mechanisms of life from the perspective of compartmented chemistry. Adv. Chem. Phys., 92,425-38. 

Are micelles and vesicles chemical equilibrium systems J. Chem. Educ., 78, 380. ... 

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