Amphiphilic additives

Most characteristics of amphiphilic systems are associated with the alteration of the interfacial stnicture by the amphiphile. Addition of amphiphiles might reduce the free-energy costs by a dramatic factor (up to 10 dyn cm in the oil/water/amphiphile mixture). Adding amphiphiles to a solution or a mixture often leads to the fomiation of a microenuilsion or spatially ordered phases. In many aspects these systems can be conceived as an assembly of internal interfaces. The interfaces might separate oil and water in a ternary mixture or they might be amphiphilic bilayers in... 

K. Izutsu, S. Yoshioka, and T. Terao, Stabilizing of P-galactosidase by amphiphilic additives during freeze-drying, Int. J. Pharm. 90. 187-194 (1993). 

PAMAMs constructed starting with lipophilic C12 cores have been exploited as hosts for studies using the dye Nile red. Notably, aqueous fluorescence emission was significantly enhanced by the formation of a dendrimer-surfactant assembly upon amphiphile addition. Modification of PAMAM surfaces by treatment with epoxyalkanes,such as 1,2-epoxyhexane and 1,2-epoxyoctane. produced nanoscopic container molecules... 

M.R. Brunsledt, NT. Zials, M. Schubert, PA. Hiltner, J.M. Anderson, Protein adsoption onto poly(ether urethane ureas) containing methacrol 2138F a surface-active amphiphilic additive, J. Biomed. Mater. Res. 27 (1993) 255-267. 

The use of amphiphilic additives as surfactants appears to be an extremely effective way to obtain bubbles with either extreme or zero I potential magnitude from the —60 mV of the bubbles in pure water. Anionic surfactants and, to a lesser extent, nonionic surfactants allow to reach potential lower than —100 mV. Cationic surfactants allow to reach I, potential higher than -1-100 mV after the reversal of the sign obtained at intermediate concentrations or pH. 

Alonso et al. (2002) used a combination of H self-diffusion measurements and C chemical shift analysis to study the solubilization of amphiphilic additives C H, +iX (n=4, 6 X=OH, NHj) in cetyltrimethylammonium bromide (CTAB) micelles that provided complementary data on structures of micelles and conformations of alkyl chains. All the additives studied behave as cosurfactants affecting micellar structures and the degree of their solubilization was determined solely by their alkyl chain length. For different additives, the effects depend on cosurfactant penetration into micelles. 

Brunstedt, M. R., Ziats, N. P., Schubert, M., Hiltner, P. A., Anderson, J. M., Lodoen, G. A., Payet C. R. 1993. Protein adsorption onto poly(ether urethane ureas) containing methacrol 2138F A surface-active amphiphilic additive. ... 

Sangwan and Schneider have studied the effect of cyclodextrins on a number of aqueous Diels-Alder reactions between acrylate, fumarate and maleate derivatives of varying hydrophobicities and (mainly) cyclopenta-diene [26]. No simple correlation between substrate hydrophobicity and cyclodextrin-catalyzed rate enhancement was found. However, those systems that did respond to p-cyclodextrin catalysis exhibited enzyme-like saturation kinetics. This led these workers to conclude that the hydrophobic effect can, in fact, be counterproductive to the Diels-Alder reaction if it leads to unproductive orientation of the reactants. The same can be said about the effect of amphiphiles (detergents capable of micellization) on aqueous Diels-Alder reactions since sodium dodecylsulfate (SDS) decelerated the reaction between cyclopentadiene and methyl acrylate. Those cases in the literature claiming micellar catalysis of the aqueous Diels-Alder reaction may simply be benefiting from the solubilizing effect of the amphiphilic additives rather than any bona fide preorganization of the reactants within a micelle [27,28]. 

Kumar, R., Yakabu, M. K., and Anandjiwala, R. D. (2010) Effect of mont-morillonite clay on flax fabric reinforced poly lactic acid composites with amphiphilic additives. Compos Part A, 41,1620-1627. 

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