Amphiphiles self-assembly

Moghaddam, M., Seddonand, J.M. and Drummond, C.J. (2010) Ordered nanostructured amphiphile self-assembly materials from endogenous nonionic unsaturated monoethanolamide lipids in water. Langmuir, 26 (5), 3084—3094. 

Figure 11.1 The amphiphilic self-assembly of lipids into bilayers.

A range of amphiphilic dendrimers have been reported based on fullerene C60 or a calix[4]arene core with dendritic branches on one side and long aliphatic tails on the other, Figure 14.8. The amphiphiles self-assemble into micelles with the aliphatic chains buried in the micelle core and the more hydrophilic dendritic portion facing out.14... 

Mileva, E. Exerowa, D. Foam films as instrumentation in the study of amphiphile self-assembly. Adv. Colloid Interface Sci. 100-102, 547-562 (2003). 

Stupp, S.I., Hulvat, J.F., and Rajangam, K. Angiogenic Heparin-Binding Epitopes, Peptide Amphiphiles, Self-Assembled Compositions and Related Methods of Use, 2006-US7864 2006096614 (2006). 

Greavesa TL, Drummond CJ (2008) Ionic liquids as amphiphile self-assembly media. Chem Soc Rev 37 1709 1726... 

Water is not a necessary element for self-assembly, which requires only two immiscible components and a suitable amphiphile. Self-assembly in non-aqueous systems could be fluid-like as in the case of RTIL and non-aqueous polar solvents, or solid-like as in polymer blends and sugar glasses. Expanding the realm of self-assembly and complex fluids to non-aqueous systems, and in particular, to the solid state holds great promise in revolutionising several commercial encapsulation, polymerisation, membrane and optical technologies. 

The SF-SCF approach has been used to consider many aspects of amphiphile self-assembly [77, 82, 88, 93-96]. Here, we focus on results that are relevant for the self-assembly of non-ionic copolymers in spherical micelles. The self-assembly of non-ionic copolymers is characterized by relatively few parameters, and we will use this system to show the micellar properties as a function of the most relevant molecular parameters. 

The spherical micelle discussed so far is but one possibility of an amphiphile self-assembly. The spherical micelle does not form at all for many amphiphiles, while for others it occurs only in a limited range of concentrations and temperatures. In general, we can distinguish between three types of behaviour of a surfactant or a polar lipid as the concentration is varied ... 

As we will see below, bicontinuous structures are very significant in many contexts of amphiphile self-assembly. Another type of bicontinuous structure in simple surfactant-water solutions is the sponge phase , formed also in quite dilute surfactant solutions (Figure 19.26). This structure forms for all classes of surfactants but in particular for nonionics. We will also mention that the structure of the sponge phase is related to that of many microemulsions. 

Figure 19.27. Amphiphile self-assembly structures can be divided into discrete micellar-type and connected forms. There may be connectivity in one, two or three dimensions...

Most often, commercially available and purely organic amphiphilic, self-assembling molecules are applied in the synthesis of mesostructured materials such as ionic surfactants or block copolymers, i.e. Pluronic surfactants (PEO-f>-PPO-f>-PEO with PPO = poly(propylene oxide)) or poly(ethylene oxide) alkyl ether surfactants (Brij ). However, due to the restricted availability of amphiphilic block copolymers, not only are the accessible pore sizes and phases limited, but commercial products are sometimes inhomogeneous and have high molecular weight distributions [2]. 

Ben-Shaul, A. and Gelbart, W.M., Statistical thermodynamics of amphiphile self-assembly Structure and phase transition in micellar solution, in Micelles, Microemulsions, and Monolayers, W.M. Gelbart, A. Ben-Shaul, and D. Roux (eds.). Springer, New York, 1994, p. 1. 

Kaasgaard, T. Dmmmond, C. J. (2006). Ordered 2-D and 3-D nanostructured amphiphile self-assembly materials stable in excess solvent. Physical Chemistry Chemical Physics, 8(43), 4957-75. 

Henze, O. Feast, W. J. Gardebien, F. Jonkheijm, P. Lazzaroni, R. Leclere, P Meijer, E. Schenning, A. P. H. J. Chiral amphiphilic self-assembled a, a -linked quinque-, sexi-, and septithiophenes synthesis, stability and odd-even effects. J. Am. Chem. Soc. 2006, 128, 5923-5929. 

The Gordon parameter, G, gives a measure of the eohesiveness of a solvent and, hence, a measure of the abihty of the PIL to be amphiphile self-assembly media. The Gordon valne is described by eq 1, where y is the snrface tension and Fm is the molar volnme, and can be considered to indicate the driving force of the PILs toward self-assembly. 

In this review, the known range of protie ionie liqnids has been disenssed, inelnding their reported physicoehemical properties and the applieations where they have been used. In comparison to the vast amount of hterature for AILs, there have been relatively few papers on PILs, despite the fact that PILs can be nsed for many of the same applications as AILs, snch as in chromatography, in organic synthesis, as amphiphile self-assembly media, in electrochemistry, and as explosives, as well as additional applications where having an available proton is essential snch as many biological uses and as proton-condncting media for polymer membrane fuel cells. 

In both models facial amphiphilicity is the key factor. If the peptides are also long enough, they are able to span the entire membrane. Because of their facial amphiphilicity, self-assembly into pores is self-complementary and as a result pores can form with low aggregation numbers, typically around five monomers. As a result, the diameter of the pores formed by alpha-helical peptides are relatively small, however, sufficiently large to induce leakage of small molecules and ions, and becoming lethal for the cell. 

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