Solvents micellization

Micelle formation in standard organic solvents such as toluene or THF is very useful, since fluorinated polymers are usually not soluble in standard solvents micelle formation therefore enables processing of fluorinated products with classical technologies, e.g., for coating applications. 

Lewis-acid catalysis of Diels-Alder reactions involving bidentate dienophiles in water is possible also if the beneficial effect of water on the catalyzed reaction is reduced relative to pure water. There are no additional effects on endo-exo selectivity. As expected, catalysis by Cu ions is much more efficient than specific-acid catalysis.Using a-amino acids as chiral ligands, Lewis-acid enan-tioselectivity is enhanced in water compared to organic solvents. Micelles, in the absence of Lewis acids, are poor catalysts, but combining Lewis-acid catalysis and micellar catalysis leads to a rate accelaration that is enzyme-like. 

Dan, N. and M. Tirrell. 1993. Self-assembly of block copolymers with strongly charged and a hydrophobic block in a selective, polar solvent. Micelles and adsorbed la ifasromolecule 6 4310—4315. 

Hydrophobic bonding caimot occur in apolar solvents. Micelles in such media have the hydrophilic groups inside, the hydrophobic ones sticking out. Their formation must be primarily erithalpically determined. 

The most serious limitations of pure micellar solutions are their weak elution strength and poor efficiencies. As early as 1983, the addition of a small percentage of 1-propanol was found to enhance the efficiencies and decrease the asymmetries of chromatographic peaks. Later, the term hybrid micellar mobile phases was given to the ternary eluents of water/organic solvent/ micelles. Although 1-propanol is still the most frequently used additive, other alcohols (methanol, ethanol, 1-butanol, and 1-pentanol) and organic solvents common... 

X-Ray crystallographic analysis of two crystalline forms of tetrameric melittin showed that the conformation of the peptide is essentially the same in each form. " Melittin was found to adopt a helical conformation in the crystalline state. The presence of Pro-14 also caused the helix to bend with an angle of about 120° between residues 1-10 and 16-26. The large helix bend allows for the optimal packing of hydrophobic side-chains vnthin the tetramer. Melittin provides a rare example of a membrane-bound peptide whose structure has been determined in low dielectric solvents, micelles and in the crystalline state and found to be quite similar. The similarities of these structures lends confidence to the idea that they represent good models for the membrane-bound conformation. ... 

Formamide exhibits a high dielectric constant, is strongly H-bonding, and is a highly organizing solvent. Micelles, and even vesicles, have been obtained in... 

To understand the effects produced, it is necessary to distinguish between two classes of organic materials that markedly affect the CMCs of aqueous solutions surfactants class I, materials that affect the CMC by being incorporated into the micelle and class II, materials that change the CMC by modifying solvent-micelle or solvent-surfactant interactions. 

Polymer Solvents, Micelle-forming Agents and Dendrimers... 

In Fignre 23.8, it is seen that hexane flux along time remains constant in the six polymeric membranes studied, indicating that these membranes are resistant or showed chemical stability to this organic solvent and, thus, are suitable for applications in permeation processes with nonaque-ous media such as oil-solvent micelle. 

The elution rates of solvent, micelles and the monomer, is given as R and R, respectively. The cross-sectional area of the gel column through which the micellar phase or the monomer moves is given as and respectively. From the areas depicted in Fig. 14b we can obtain the following ... 

Soft templating by Molecules (solvent) Micelles Bicontinuous microemulsion... 

Yang L, Alexandridis P (2000) Polyoxyalkylene block copolymers in formamide-water mixed solvents micelle formation and structure studied by SANS. Langmuir 16 4819-4829... 

Polymer-polypeptide hybrid block copolymers are able to self-assemble either in bulk (microphase separation) or in selective solvents (micellization), like conventional block copolymers, and in addition are organized within the microphases into a-helix or j5-sheet... 

Diblock copolymers are known to form mesophases[9,10] in selective solvents micelles, lamellae, worm-like micelles. .. These aggregation effects are relevant for the interfacial behavior of the copolymers the bulk solution acts as a reservoir for the adsorbed layer and imposes the chemical potential //ex- To study the adsorbed layer we write the siuface grand canonical free energy of the layer as... 

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